CA1162443A - Highly concentrated supersonic liquified material flame spray method and apparatus - Google Patents
Highly concentrated supersonic liquified material flame spray method and apparatusInfo
- Publication number
- CA1162443A CA1162443A CA000386388A CA386388A CA1162443A CA 1162443 A CA1162443 A CA 1162443A CA 000386388 A CA000386388 A CA 000386388A CA 386388 A CA386388 A CA 386388A CA 1162443 A CA1162443 A CA 1162443A
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- CA
- Canada
- Prior art keywords
- nozzle
- bore
- combustion chamber
- nozzle bore
- flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/16—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed
- B05B7/20—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed by flame or combustion
- B05B7/201—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed by flame or combustion downstream of the nozzle
- B05B7/203—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed by flame or combustion downstream of the nozzle the material to be sprayed having originally the shape of a wire, rod or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/16—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed
- B05B7/20—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed by flame or combustion
- B05B7/201—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed by flame or combustion downstream of the nozzle
- B05B7/205—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed by flame or combustion downstream of the nozzle the material to be sprayed being originally a particulate material
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
- C23C4/129—Flame spraying
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Nozzles (AREA)
Abstract
HIGHLY CONCENTRATED SUPERSONIC LIQUIFIED
MATERIAL FLAME SPRAY METHOD AND APPARATUS
ABSTRACT OF THE DISCLOSURE
Within ultra high velocity flame spray apparatus, the oxy-fuel products of combustion under pressure exit from an internal burner and pass through a spray nozzle of extended length. Metal or ceramic material in thin diameter rod form or as particles are fed to the nozzle inlet at a point at or just ahead of the throat of the nozzle bore. The exceptionally long nozzle flow path and the mode of introduction of the material into the flame spray insures a concentrated and highly focussed more of spray material for material spray coating downstream of the nozzle at supersonic speed.
MATERIAL FLAME SPRAY METHOD AND APPARATUS
ABSTRACT OF THE DISCLOSURE
Within ultra high velocity flame spray apparatus, the oxy-fuel products of combustion under pressure exit from an internal burner and pass through a spray nozzle of extended length. Metal or ceramic material in thin diameter rod form or as particles are fed to the nozzle inlet at a point at or just ahead of the throat of the nozzle bore. The exceptionally long nozzle flow path and the mode of introduction of the material into the flame spray insures a concentrated and highly focussed more of spray material for material spray coating downstream of the nozzle at supersonic speed.
Description
1 1 S24~3 This invention relates to supersonic molten metal or ceramic spraying systems and, more particularly, to a method and apparatus for increasing the temperature and velocity of the molten spray stream to effect flame spray application of particles in liquid form at extremely high supersonic velocities.
Attempts have been made to provide flame spray apparatus which include an internal burner operating to produce an ultra-high velocity flame jet. One such ultra-high velocity fla~e jet apparatus is set forth in my earlier U.S. patent 2,990,653 entitled "Method and Apparatus for Impacting a Stream of High Velocity Against the Surface to be Treated" issued July 4, i961. Such apparatus comprises an air cooled double or triple wall cylindrical internal burner whose interior cavity forms a cylindrical combustion chamber.
Downstream of the point of initial combustion, the chamber is closed off by a reduced diameter flame jet nozzle.
In a further attempt to provide such ultra-high velocity flame spraying apparatus for metal, refrac-tory material or the like, introduced to the high velocity flame spray stream in powder form or in solid small diameter rod form, an arrangement was devised involving the utilization of a hot gaseous primary jet stream of relatively low momentum which fuses and projects a stream of molten particles into a second gaseous jet stream of lower temperature, but possess-ing a very high momentum. The method and apparatus of a recent development by the applicant herein employs the first stream in the form of an oxy-fuel flame or an electric arc-producing plasma, while the second stream comprises a flame-jet produced by an air/fuel flame reacting at high pressure in an internal burner device. In combining the two streams, preferably the '~
.
1 1 62~3 molten particles are carried by the first stream at relatively low velocity but relatively high tempera~
ture, while the supersonic jet stream which impinges the entrained molten particles against the surface to be coated at ultra high velocity is discharged from an internal burner combustion chamber wherein combustion is effected at relatively high pressure.
The second stream is directed through an annular nozzle surrounding the primary stream. Further, the primary and secondary streams are projected through a nozzle structure to the point of impact against the s~bstrate to be coated by the liquid particles travelling at supersonic speed, under the acceleration provided by the secondary jet of heated gas.
The present invention relates to a flame spray method comprising the steps of combusting, under pressure, an oxy-fuel mixture within an internal burner combustion chamber, discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity hot gas stream, and feeding material to the stream for high temperature liquefaction and spraying at high velocity onto a surface positioned in the path of the stream at the discharge end of the nozzle, the improve-ment wherein the step of feeding the material comprises introducing the material in solid form out-side of the combustion chamber and axially into the flow expansion nozzle at the throat or just upstream o~ the nozzle and within a nozzle bore having an extended length.
~he invention also relates to a highly concen-trated supersonic li~uified material flame spray apparatus comprises a spray gun body, a high pressure combustion chamber within the body, means for continuously flowing an oxy-fuel mixture under high pressure through the combustion chamber for ignition _~_ , , ~
1 ~ 62~3 within the chamber, the body including combustion chamber products of combustion discharge passage means at one end thereof, the body further comprising an elongated nozzle downstream of the combustion chamber discharge passage means, the nozzle including a converging inlet bore portion and an extended outlet bore portion, the combustion chamber discharge passage means comprising means for conveying the flow of the discharging hot gas products of combustion into the entrance of the nozzle inlet bore portion and means for introducing material in solid form into the hot gases for subsequent meltiny and acceleration with the point of introduction of the solid material being at the entrance to or just upstream of the bore of the nozzle.
In particular, the invention relies on the specific manner of introduction of the material in powder or rod form into the flame produced at the internal burner and the provision of an exception-ally -2a-lJ62-~3 long flow path for the flow of metallic or ceramic particles which are supersonically applied at the end of a nozzle of extended length, against a substrate to be coa~te~. Further, the ma~erial is introducPd to the gas flow at a point ahead of the maximum nozzle restriction or throat, thus confining the particle f-low to a small diameter cylindrical core throuyh the center of the nozzle ~ore. The presen~ invention involves a method and apparatus in which the flow of liquid metal or ceramic droplets mav pass ~hrough a small diameter no2zle with a pa~h length more than -ten tlmes in excess of the nozzle restriction diameter~
Maximum particle velocity may be achiev~d from an o~y-fuel metallizing internal burner. The burner comprises a nozzle communicating with an upstream i~ternal combustion chamber which burns a fuel wi~h an oxidizer, at elevated pressure. The hot combustion product gases are discharged through the nozzle. A
rod or particle flow of metal or other solid material such as ceramic material is introducted into the hot gases for subsequent melting and acceleration. The improvement resides in the introduction point for the solid material to ~e at or just upstream of the throa~
of an extended length nozzle. ~
Th~ solid material in the form of a small diameter rod may be introduced to the gas flow stream from a hole within the nozzle casing aligned with the nozzle throat. Means are provided for providing an inlet flow of hot gas from the-internal burner combus-tion chamber to the nozzle throat which has a radial inlet component of its velocity which tends to restrict the the diameter of the column of particles when particulate matter is used or to maximize heat transfer to the rod periphery where the solid material is in small diameter rod or wire form. Preferably, the length of the nozzle bore is a~ least five times 1 ~ 62~3 that of the minimum diameter of the nozzle bore.
Additionally, the pressure within the combustion chamber should be maintained at 75 PSIG or greater.
Embodiments of the invention will now be described by way of example with reference to the drawings in which:
Figure 1 is a longitudinal, sectional view of one embodiment of the highly concentrated supersonic liquid material flame spray apparatus of the present invention.
Figure 2 is an enlarged view of the venturi nozzle throat o~ the apparatus of Figure lo Figure 3 is a transverse cross-sectional view of a portion of the apparatus of Figure 1, taken about line III-III.
Figure 4 is a longitudinal sectional view of a similar supersonic liqu~d material flame spray apparatus to that shown in Figures 1-3 inclusive, but utilizing a rod feed and forming a second embodiment of the present invention.
Figure 5 is a longitudinal sectional view of a nozzle forming a part of a supersonic liquid material flame spray apparatus constituting a further embodi-ment of the invention.
Figure 6 is a plot of hot gas and metal particle temperatures versus distance for the carrier gas and iron and aluminum particles passing through the bore of the nozzle of Figure 5 under exemplary use.
Figure 7 is a plot of hot gas and particle velocities against distance during passage through the nozzle of the embodiment of Figure 5.
Referring to Figures 1-3 inclusive, there is illustrated in longitudinal, sectional form, and somewhat schematically, the main elements of the improved flame spraying apparatus oE the present invention, as one embodiment thereof. The apparatus indicated generally at 1 takes the form of a metal 5 1~ 3 flame spray l-gunll, being comprised of a main body 10 bearing a threaded cylindrical metal nozzle insert indicated generally at 11. In that respect, the main body 10 which is L-shaped in longitudinal section, bears a cylindrical bore 4 from one end 30 inwardly, terminating at the end of the bore in a transverse wall 5. A portion of the bore 4 is threaded as at 4a.
Fur~her, the insert 11 which is T-shaped in cross-section, including a radially enlarged flange lla, is threaded as at llb ~o match the thread 4a of body 10, and is in mesh therewith, when assembled. End face llc of the insert 11 faces the su~strate being flame spray coated, while the opposite end facP lld abuts the bore end face 5 as best seen in Figure ~.
Body 10 is further provided with cylindrical ca~ity within a portion at right angles to that bearing the noæ21e insert 11, the cavity forming an elongated, cylindrical high-pressur~ combustion chamber 12 pro-- ; viding a restricted volume for the high-pressure combustion of oxygen and fuel, pressure fed to the combustion chamber, a6 indicated by arrows 31, 32, respectively~ An oxygen supply tube or line 14 projects into a cylindrical hole 7 within end lOa o~
I body 10. There is also provided an inclined oxygen passage 23, opening to the interior of the combustion chamber 12 at one end and, at the other end, opening to hole 7 bearing the oxygen tube 14, Adjacent the oxygen tube 14 is a second somewhat smaller diameter fuel supply tube 13, the end of which is sealably received within a cylindrical hole 6. Fuel is delivered through a small diameter fuel passage 24 which leads from the fuel inlet tube 13 to the combus-tion chamber 12. Passage 24 is inclined appositely to passage 23 and opens to the interior of the combustion chamber adajcent the end of oxygen supply passage 23.
The fuel may be in either liquid or gas form and, i liquid, is aspirated into the ox,gen which i~ ed ~2~3 to the combustion ch~er 12 at substantial pressure, thereby forming a fuel air mixture with ~he fuel in particle form. Buxning is effected within the combus-tion chamber 12 by ignition means such as a spark plug S ~not shown) with burning being i~itiated at ~he point of delivery o fuel and air, that i5, in Fig ure 1, at the upper end of the combustion cham~er 12.
Annular passages as at 15, 16, 17 and 18 provide cooling of the "gun" body 10: ~a~er or other cooling ~edia being circulated through ~he various annular passages. Additionally, annular passages as at 27, ~8 are provided within the noæzle insert for cooling of that member. A circulation loop ~no~ shown) may commonly feed water to all passage~ indicated abo~e to effectively reduce the external tempera~ure of the flame spray apparat~s Within the main ~ody 10 are pro~ided multiple i~clined holes as at 19 (four in number in the ~ illustrated embodiment) as may ~e best in Figure 3, which holes converge towards a point downstream of end wall 5, within ~ore 4 recei~in~ the nozzle i~sert 11.
` The hole~ 19 open to wall 5 at ports l9a. The upper two inclined holes 19 open directly to the l~wer end i ~ of com~ustion chamber 12, while the lower up~ardly and inwardly directed inclined holes 19 ope~ at their ups~ream ends to co~bustion chamber 12 hy means of a pair of vertical bores 20. Bores 20 which are laterally spaced and to opposite sides of a metal or cexamic powder feed hole 21 of relatively small diameter which opens to end wall 5 of bore 4, to the i center of ports l9a which ~hus ~urround the opening of ~ the powder feed hole 21. The powder f:eed hole 21 is ¦ formed by a small diameter bore which bore is count~r-bored at 28 and furthe.r counterbored at 29. Counter-bore 29 receives the projecting end of a pow~er feed ~ tube 22 which is sealably mounted ~o the main body 10 .~ .
11 ~ 62~3 .~
La alignment with powder feed hole 21 and counter;- -boæe 28. Means are provided (not-shown] for supplying a pow~ered metal or ceramic material M to the powder f~ed hole 21.
s The ~ozzle insert ll is provided wi~h converging and diverging ~ore portia~s 25a, 25~, respectively, from end lld towards ~he end llc and forming a ven~uri type nozzle passage including a bore throat or con-striction 25c which is the smallest diameter por-tion o of the flow passa~e as defined ~y the intersection of ~on~erging and divergi~g bore portions 2~a, 25b. The converging gas j ets indicated ~y ~he arrow~ J, ~ig-ure 2, from the holes 19, cQmbine ~nto a si~Fle- flow-stream con~ergi~g radially inwaxdly as the~ maximum re~triction or throat 25c of nozzle 11 is approached.
The powder M which ~xits~ from port or end 21a of the powder ~eed hole 21 is swept radiall~ inwardly or, at the least, is not pe ~ i~ted to eæpand as it en-ters the high ~elocity gas passing i~to the venturi nozzle of nozzle insert 11, ~that is~, the cinYergin~ bore por-tioR 25a of the nozzle insert 11. Thus, the powder is ~ot permitted to touch the walls of the hore 25 ; - ~ei~her at its mos~ narrowed diameter portiQn, that i is, cons~riction 25c, nor aver the balance of th~
bore 25.
For one case tested, the diameter of the con-s~ricted portion 25c ~as 5/16 of an inch an~ the length of bore 25 was four inches. By~ thr~ading o~
the noz~le insert 11 and forming this as a separate element from body lQ, ~he nozæle insert. may be replaced i~ it is damaged or upon wear during use as well as to ef~ect change in ~th~ configuration and characteristics of ~he metal ~lame spra~ "gun" nozzle portion. By visual observation, it was noted that t~ere exists an essen~ially cyli~drical core 26 of high ~elocity powder flow centrally through nozzle , 1 1 ~2~3 bore 25 and remote ~rom the suraces of ~ore 25. Su~h ~ylindrical core is approximately 1/8 inch in diameter. After many extended runs using powders ranging from aluminum to tungsten-car}~ide-cobalt mixtures, no evidence of powder migration with build-up on the bore walls was ascertained.
Concentration or "focussing" effect by the novel .~thod and apparatus involving specific powder intro-duction techniques appears to be directly related to the ~as flow rate, which for a given nozzle insert may be ~xpressed by the pressure maintained in combustion chamber 1~. Detailed photomicrographic studies of the spray coating deposits o~ ~he ~ubstrate (not shown) dow~stream of nozzle discharge port 2~e indica~es both ian increased de~sity a~d ~oati~g hard~ess as the combustion chamber pres ure increases~ At pressure~
above 200 PSIG for combustion chamber~12, the coatings appear to be superior to those deposited by plasma spray guns operating wi~h gas temperatures nearly an-order-of-magnitude greater than for the oxy-fuel i~ternal burner o~ the present invention. It thus . appears that ~ e greater velocities available with the:
; oxy-fuel system are more than su~ficient to overcome the lesser heat intensity of the unit. To alIow su~ficient "dwelll' time of the particles as at 26 to achieve melting in these in lower temperature gases, r~latively long nozzle bare path lengths are required.
Necessarily, the apparatus opera~i~g under the~
method o~ the present inYention requires that the material for deposit, either in powder or in solid orm, be introduced into a con~erging flow o~ the products of com~ustion, prior t~ those products of combustion passing through the narrowest restriction portion of the nozzle. Gas veloci~ies must be extremely high to achieve supersonic particle impact ve}ocities against the surface ~eing coated. Super gonic veloci~y for the purposes of this discussion.
Attempts have been made to provide flame spray apparatus which include an internal burner operating to produce an ultra-high velocity flame jet. One such ultra-high velocity fla~e jet apparatus is set forth in my earlier U.S. patent 2,990,653 entitled "Method and Apparatus for Impacting a Stream of High Velocity Against the Surface to be Treated" issued July 4, i961. Such apparatus comprises an air cooled double or triple wall cylindrical internal burner whose interior cavity forms a cylindrical combustion chamber.
Downstream of the point of initial combustion, the chamber is closed off by a reduced diameter flame jet nozzle.
In a further attempt to provide such ultra-high velocity flame spraying apparatus for metal, refrac-tory material or the like, introduced to the high velocity flame spray stream in powder form or in solid small diameter rod form, an arrangement was devised involving the utilization of a hot gaseous primary jet stream of relatively low momentum which fuses and projects a stream of molten particles into a second gaseous jet stream of lower temperature, but possess-ing a very high momentum. The method and apparatus of a recent development by the applicant herein employs the first stream in the form of an oxy-fuel flame or an electric arc-producing plasma, while the second stream comprises a flame-jet produced by an air/fuel flame reacting at high pressure in an internal burner device. In combining the two streams, preferably the '~
.
1 1 62~3 molten particles are carried by the first stream at relatively low velocity but relatively high tempera~
ture, while the supersonic jet stream which impinges the entrained molten particles against the surface to be coated at ultra high velocity is discharged from an internal burner combustion chamber wherein combustion is effected at relatively high pressure.
The second stream is directed through an annular nozzle surrounding the primary stream. Further, the primary and secondary streams are projected through a nozzle structure to the point of impact against the s~bstrate to be coated by the liquid particles travelling at supersonic speed, under the acceleration provided by the secondary jet of heated gas.
The present invention relates to a flame spray method comprising the steps of combusting, under pressure, an oxy-fuel mixture within an internal burner combustion chamber, discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity hot gas stream, and feeding material to the stream for high temperature liquefaction and spraying at high velocity onto a surface positioned in the path of the stream at the discharge end of the nozzle, the improve-ment wherein the step of feeding the material comprises introducing the material in solid form out-side of the combustion chamber and axially into the flow expansion nozzle at the throat or just upstream o~ the nozzle and within a nozzle bore having an extended length.
~he invention also relates to a highly concen-trated supersonic li~uified material flame spray apparatus comprises a spray gun body, a high pressure combustion chamber within the body, means for continuously flowing an oxy-fuel mixture under high pressure through the combustion chamber for ignition _~_ , , ~
1 ~ 62~3 within the chamber, the body including combustion chamber products of combustion discharge passage means at one end thereof, the body further comprising an elongated nozzle downstream of the combustion chamber discharge passage means, the nozzle including a converging inlet bore portion and an extended outlet bore portion, the combustion chamber discharge passage means comprising means for conveying the flow of the discharging hot gas products of combustion into the entrance of the nozzle inlet bore portion and means for introducing material in solid form into the hot gases for subsequent meltiny and acceleration with the point of introduction of the solid material being at the entrance to or just upstream of the bore of the nozzle.
In particular, the invention relies on the specific manner of introduction of the material in powder or rod form into the flame produced at the internal burner and the provision of an exception-ally -2a-lJ62-~3 long flow path for the flow of metallic or ceramic particles which are supersonically applied at the end of a nozzle of extended length, against a substrate to be coa~te~. Further, the ma~erial is introducPd to the gas flow at a point ahead of the maximum nozzle restriction or throat, thus confining the particle f-low to a small diameter cylindrical core throuyh the center of the nozzle ~ore. The presen~ invention involves a method and apparatus in which the flow of liquid metal or ceramic droplets mav pass ~hrough a small diameter no2zle with a pa~h length more than -ten tlmes in excess of the nozzle restriction diameter~
Maximum particle velocity may be achiev~d from an o~y-fuel metallizing internal burner. The burner comprises a nozzle communicating with an upstream i~ternal combustion chamber which burns a fuel wi~h an oxidizer, at elevated pressure. The hot combustion product gases are discharged through the nozzle. A
rod or particle flow of metal or other solid material such as ceramic material is introducted into the hot gases for subsequent melting and acceleration. The improvement resides in the introduction point for the solid material to ~e at or just upstream of the throa~
of an extended length nozzle. ~
Th~ solid material in the form of a small diameter rod may be introduced to the gas flow stream from a hole within the nozzle casing aligned with the nozzle throat. Means are provided for providing an inlet flow of hot gas from the-internal burner combus-tion chamber to the nozzle throat which has a radial inlet component of its velocity which tends to restrict the the diameter of the column of particles when particulate matter is used or to maximize heat transfer to the rod periphery where the solid material is in small diameter rod or wire form. Preferably, the length of the nozzle bore is a~ least five times 1 ~ 62~3 that of the minimum diameter of the nozzle bore.
Additionally, the pressure within the combustion chamber should be maintained at 75 PSIG or greater.
Embodiments of the invention will now be described by way of example with reference to the drawings in which:
Figure 1 is a longitudinal, sectional view of one embodiment of the highly concentrated supersonic liquid material flame spray apparatus of the present invention.
Figure 2 is an enlarged view of the venturi nozzle throat o~ the apparatus of Figure lo Figure 3 is a transverse cross-sectional view of a portion of the apparatus of Figure 1, taken about line III-III.
Figure 4 is a longitudinal sectional view of a similar supersonic liqu~d material flame spray apparatus to that shown in Figures 1-3 inclusive, but utilizing a rod feed and forming a second embodiment of the present invention.
Figure 5 is a longitudinal sectional view of a nozzle forming a part of a supersonic liquid material flame spray apparatus constituting a further embodi-ment of the invention.
Figure 6 is a plot of hot gas and metal particle temperatures versus distance for the carrier gas and iron and aluminum particles passing through the bore of the nozzle of Figure 5 under exemplary use.
Figure 7 is a plot of hot gas and particle velocities against distance during passage through the nozzle of the embodiment of Figure 5.
Referring to Figures 1-3 inclusive, there is illustrated in longitudinal, sectional form, and somewhat schematically, the main elements of the improved flame spraying apparatus oE the present invention, as one embodiment thereof. The apparatus indicated generally at 1 takes the form of a metal 5 1~ 3 flame spray l-gunll, being comprised of a main body 10 bearing a threaded cylindrical metal nozzle insert indicated generally at 11. In that respect, the main body 10 which is L-shaped in longitudinal section, bears a cylindrical bore 4 from one end 30 inwardly, terminating at the end of the bore in a transverse wall 5. A portion of the bore 4 is threaded as at 4a.
Fur~her, the insert 11 which is T-shaped in cross-section, including a radially enlarged flange lla, is threaded as at llb ~o match the thread 4a of body 10, and is in mesh therewith, when assembled. End face llc of the insert 11 faces the su~strate being flame spray coated, while the opposite end facP lld abuts the bore end face 5 as best seen in Figure ~.
Body 10 is further provided with cylindrical ca~ity within a portion at right angles to that bearing the noæ21e insert 11, the cavity forming an elongated, cylindrical high-pressur~ combustion chamber 12 pro-- ; viding a restricted volume for the high-pressure combustion of oxygen and fuel, pressure fed to the combustion chamber, a6 indicated by arrows 31, 32, respectively~ An oxygen supply tube or line 14 projects into a cylindrical hole 7 within end lOa o~
I body 10. There is also provided an inclined oxygen passage 23, opening to the interior of the combustion chamber 12 at one end and, at the other end, opening to hole 7 bearing the oxygen tube 14, Adjacent the oxygen tube 14 is a second somewhat smaller diameter fuel supply tube 13, the end of which is sealably received within a cylindrical hole 6. Fuel is delivered through a small diameter fuel passage 24 which leads from the fuel inlet tube 13 to the combus-tion chamber 12. Passage 24 is inclined appositely to passage 23 and opens to the interior of the combustion chamber adajcent the end of oxygen supply passage 23.
The fuel may be in either liquid or gas form and, i liquid, is aspirated into the ox,gen which i~ ed ~2~3 to the combustion ch~er 12 at substantial pressure, thereby forming a fuel air mixture with ~he fuel in particle form. Buxning is effected within the combus-tion chamber 12 by ignition means such as a spark plug S ~not shown) with burning being i~itiated at ~he point of delivery o fuel and air, that i5, in Fig ure 1, at the upper end of the combustion cham~er 12.
Annular passages as at 15, 16, 17 and 18 provide cooling of the "gun" body 10: ~a~er or other cooling ~edia being circulated through ~he various annular passages. Additionally, annular passages as at 27, ~8 are provided within the noæzle insert for cooling of that member. A circulation loop ~no~ shown) may commonly feed water to all passage~ indicated abo~e to effectively reduce the external tempera~ure of the flame spray apparat~s Within the main ~ody 10 are pro~ided multiple i~clined holes as at 19 (four in number in the ~ illustrated embodiment) as may ~e best in Figure 3, which holes converge towards a point downstream of end wall 5, within ~ore 4 recei~in~ the nozzle i~sert 11.
` The hole~ 19 open to wall 5 at ports l9a. The upper two inclined holes 19 open directly to the l~wer end i ~ of com~ustion chamber 12, while the lower up~ardly and inwardly directed inclined holes 19 ope~ at their ups~ream ends to co~bustion chamber 12 hy means of a pair of vertical bores 20. Bores 20 which are laterally spaced and to opposite sides of a metal or cexamic powder feed hole 21 of relatively small diameter which opens to end wall 5 of bore 4, to the i center of ports l9a which ~hus ~urround the opening of ~ the powder feed hole 21. The powder f:eed hole 21 is ¦ formed by a small diameter bore which bore is count~r-bored at 28 and furthe.r counterbored at 29. Counter-bore 29 receives the projecting end of a pow~er feed ~ tube 22 which is sealably mounted ~o the main body 10 .~ .
11 ~ 62~3 .~
La alignment with powder feed hole 21 and counter;- -boæe 28. Means are provided (not-shown] for supplying a pow~ered metal or ceramic material M to the powder f~ed hole 21.
s The ~ozzle insert ll is provided wi~h converging and diverging ~ore portia~s 25a, 25~, respectively, from end lld towards ~he end llc and forming a ven~uri type nozzle passage including a bore throat or con-striction 25c which is the smallest diameter por-tion o of the flow passa~e as defined ~y the intersection of ~on~erging and divergi~g bore portions 2~a, 25b. The converging gas j ets indicated ~y ~he arrow~ J, ~ig-ure 2, from the holes 19, cQmbine ~nto a si~Fle- flow-stream con~ergi~g radially inwaxdly as the~ maximum re~triction or throat 25c of nozzle 11 is approached.
The powder M which ~xits~ from port or end 21a of the powder ~eed hole 21 is swept radiall~ inwardly or, at the least, is not pe ~ i~ted to eæpand as it en-ters the high ~elocity gas passing i~to the venturi nozzle of nozzle insert 11, ~that is~, the cinYergin~ bore por-tioR 25a of the nozzle insert 11. Thus, the powder is ~ot permitted to touch the walls of the hore 25 ; - ~ei~her at its mos~ narrowed diameter portiQn, that i is, cons~riction 25c, nor aver the balance of th~
bore 25.
For one case tested, the diameter of the con-s~ricted portion 25c ~as 5/16 of an inch an~ the length of bore 25 was four inches. By~ thr~ading o~
the noz~le insert 11 and forming this as a separate element from body lQ, ~he nozæle insert. may be replaced i~ it is damaged or upon wear during use as well as to ef~ect change in ~th~ configuration and characteristics of ~he metal ~lame spra~ "gun" nozzle portion. By visual observation, it was noted that t~ere exists an essen~ially cyli~drical core 26 of high ~elocity powder flow centrally through nozzle , 1 1 ~2~3 bore 25 and remote ~rom the suraces of ~ore 25. Su~h ~ylindrical core is approximately 1/8 inch in diameter. After many extended runs using powders ranging from aluminum to tungsten-car}~ide-cobalt mixtures, no evidence of powder migration with build-up on the bore walls was ascertained.
Concentration or "focussing" effect by the novel .~thod and apparatus involving specific powder intro-duction techniques appears to be directly related to the ~as flow rate, which for a given nozzle insert may be ~xpressed by the pressure maintained in combustion chamber 1~. Detailed photomicrographic studies of the spray coating deposits o~ ~he ~ubstrate (not shown) dow~stream of nozzle discharge port 2~e indica~es both ian increased de~sity a~d ~oati~g hard~ess as the combustion chamber pres ure increases~ At pressure~
above 200 PSIG for combustion chamber~12, the coatings appear to be superior to those deposited by plasma spray guns operating wi~h gas temperatures nearly an-order-of-magnitude greater than for the oxy-fuel i~ternal burner o~ the present invention. It thus . appears that ~ e greater velocities available with the:
; oxy-fuel system are more than su~ficient to overcome the lesser heat intensity of the unit. To alIow su~ficient "dwelll' time of the particles as at 26 to achieve melting in these in lower temperature gases, r~latively long nozzle bare path lengths are required.
Necessarily, the apparatus opera~i~g under the~
method o~ the present inYention requires that the material for deposit, either in powder or in solid orm, be introduced into a con~erging flow o~ the products of com~ustion, prior t~ those products of combustion passing through the narrowest restriction portion of the nozzle. Gas veloci~ies must be extremely high to achieve supersonic particle impact ve}ocities against the surface ~eing coated. Super gonic veloci~y for the purposes of this discussion.
2 ~ ~ ~
is at ambient atmosphere, about 1200 feet per second.
At combustion chamber pressures greater than 200 PSIG, the par~icles may well travel at speeds above 2000 feet per second and at 500 PSIG for chamber 12, the velocity rises to over 3000 feet per second. Such a velocity is greater than that recorded by detonatio~
gun spraying which-heretofore to the ~nowledge of the applicant has achieved th~ highest spray imp~c~
velocities.
! 10 Turning next to ~igure 4, the second illustrated embodiment of the i~en~ion in~lve~ ~he substitution for the material delivered to the high velocity hish temperature produc~s o combustio~ of a solid m~ass o~
material to be ~lame sprayed rather than the powd~r o the embodi.ment of -Figures 1-3. ~owe~er, the major principles employed in the fir~t embodiment of the in~ention operate e~ually wPll for the atomization of material in ro~ or wire farm. In ~ e simplified-~ illustration of the embodiment, ~schematically "gun" 40 has a body 41-which is provided with~a ~ore 52 wi~hin one leg thereof, which bore bears a cylindrical nozzle insert 42 having a venturi nozzle type ~ore as at 47 ~ luding a diverging portion~47a and a converging i portion 47b, downstream and ups~ream-of-the smallest diameter portio~ of the bore at cons~ruction 48,:
. respectively. Body 41 also includes a combustion chamber 43 which extends generally the full height of the vertical body portion. Within the lower portion of the cyli~drical combustio~ chamber body 41 :is provided a conical projection as at 46 which is at ~ righ~ a~gles to th~ axis of combustion chamber. The ! center o projection 46 is formed with a small diam~ter bore 53, the conical projection 46 beinq axially aligned with nozzle insert 42. The top of ! 35 conical projection 46: terminates slightly upstream I ~ fro~ the inner end 42a of the nozzle lnsert 42. The ..
1 3 62~3 small diameter b~re 43 slidably bears an elongated deposit material rod or wire 44 which is positively fed, by way of opposed motor dri~en rollers 45 sand-wlching the wire or rod, towards ~he venturi nozzle 47 wi~h ~ha end 44a of ~he rod projecting well into the ~ozzle ~ore. The no~zle diverging bore portion 47a is exte~ded to assure fine atomization of the molten film as.it passes from the sharp-pointed terminal end 44a -of the wire or rod 44 upon melting~ The operatio~ of 1 10the second embodiment of ~he in~ention is identical to that of the first embodiment. oxygen under pressure is ~ed to the combustion chamber 43 through o~ygen feed supply passage 53, while a liquid or gaseou~ fuel enters the combustion chamber through fuel supply passage 54, the flow of o~ygen and fuel ~eing indi-cated by the arrows as shown.
- As the result of ignition of oxygen and ~uel : under pressure within com~ustion cham~er 43, the hi~h velocity products of combustion contact wire 44 upstream of the noz21e bore co~s~riction 48. This m~Lmizes heat transfer to the wire assuring rapid melting of i~s sur~ace layers~. The high momentum gases of the nozzle throa~ or: restriction 48 and of the extended nozzle bore 47 assures the fine atomiza-tio~ of the molten film as it-passes from the sharp-pointed terminal end of the~wire 44a. Instead of a metal wire a~ shown at 44, a ceramic rod may be used in exactly the same way an~:fed in similar fashion by powered driving -of the opposed~ set of rollers 45.
Again, due to the nature ~f introduction of ~he metal wi~e 44 or a ~ceramic rod; which projects axially b~yond the small diametex bore- 53 of ~he conical - projection 46 into the elongated nozzle bore, upstream of throat 48 and with the converging gas jet due to the presence of the conical projection 46 and its alignment with the inlet end of ~he nozzle bore 47, .
t 1 3 ~2~3 .
1 1 , the molten particles susp~nded in the high velocity gas stream of supersonic velocity are maintained well away from the wall of the di~erging bore por~ion 47a with the metal or ceramic molten particles exiting from the discharge end of the nozzle insert in an essentially cylindrical core 50. This may be on the order of lJ8 inch in dîameter corresponding to the molten powder particles exiti~ from the elongated ~ozzle bore 25 of the em~odiment of Figures 1-3 j 10 i~clusive Preferably, the leng~h ~ the nozzle bore beyo~d the point of i~troduction sf the flow of powder or rod or solid wire form should have a length 4~ at least five times that of ~he miDlmum diameter of the nozzle borP, that is, at the throa~ or smallest r~strictions for the nozzle bore.
Additionally, ~he pressure within the combustion chamber should be maintained at 150 PSIG or greater i~
both embodiments Referring next ~o Figure 5, a further embodiment . 20 of the invention is illustrated in which only ~he ~ozzle and immediately adjacent components of ~he . ultra-high velocity flame spray apparatus.indicated ge~erally at 60 are shown. In this em~odiment, I optimum results are obtained when rotational compo-1 25 nents of ~he hot gas 10w emanating from the co~bus-tion ch~nber (not shown) are eliminated at the point where the hot gas flow contacts the metal particles to be passed at high velocity through ~he nozzle bore of the flame spray apparatus 60. With respe~t to the embodiment of Figure 5, like elements to:that of the !~ embodiment of Figures 1, 2 and 3 are provided with like numeral designations. The mul~iple holes 1~
conYerge towards the axis ~f the extended noz21e I passage provided by bore indicated generally at 25 for the spray apparatus formed by a threaded cylindrical metal nozzle insert indicated generally at 11. The 'I
i!
1 ~2~1~3 1~ , hsles 19 for optimum performance must lie in plane common to ~he nozzle bore axis for bore 25. As a result, there will no directional component radial to the bore axis, and ~he ~otal flow through the bore 25 is free of tangential, whirli~g: components. Under ~hese co~ditions, maximum nozzle Lengths are possible without particle build up on the nozzle wall A
nozzle length: o~ nine i~ches operates satisfactorily usi~g a straight bore (no ve~turi expansion) as i~ the pre~iously described embodiment of Figures 1-3 inclu-sive. For a bore 25 whose m~jor portion 25b down-stream ~f the throat provided by converging inle-t portion 2~a, is of S/l~ I~ch diam~etex. Thus, a length to diam~ter ratio of nearly 30 ~o 1 is exp~rienced in:
lS the embodi~ent of Figure 5.
Although the pri~ciples of operation i~ which the particles are spaced away-from ~he nozzle bo~e wall ~hroughout the length of the nozzl;e portion 25b as well as 25a, is fully understood, increase of nozzle l~n ~ to certain critical vàl~es` is o-f -extreme importance to maximize the e:f~ectiveness:of th~ super sonic flame spra~ resul~i~g ~rom ~the use of the apparatus and ~nder the ~ n~ethod: of ~he present inven-tion. Such parameters ~ and: thei~ critIcality may be s~en by ~urther reference to Figures 6 and 7 In FigNre 5~, the: ~yp:lcal nozzle provided~ by~
~ozzle insert 11 of extended~ ~ore:~ length involves converging.s~ctiorl 25a which is: coIlical ~nd intersects the constant diameter extended length portion ~25b of the ~re 25 and forming the thr~at: of the nozzle bore.
The converging section wall ~5a~commences at the circumference~outlining ~the~outer: wall ~ af the part bearing flame orifices orl holes l9.: As illustrated, powder in a-flow of carrier gas passes into the con~ .
'~ 35 verging portion 25a of the nozzle bore through a i. central passage 21 coaxial~ with~ the bore and opening ¦ thereto:upstream of ~he throa~. ~
' ~ '; , ' ' ., ~ ~ 62~
.
With this in mind, Figure 6 traces ~he tempera-ture history of the gases, as at 7ine 62, and in thi5 case iron particles, and- aluminum as at Iines 64, 66 respectively passi~g through the nozzle. For a `5 propane o~ygen flame, the products of com~ustion approximate 5400F at the. entrance to the ~ozzle bore 25. The temperature gradient of ~hese gases alo~g the nozzle bore is i~iti~lly low due to the re-combination of the dissociated spe~iae~ Wi~h full re-combination, the gradient incr~ases. ~Hea-t from the flame gases pass to the walls of: ~he.nozzle body and to the lower temperature particles:. -Illustràtively, an iron particle enters the nozzle bore at about 70F.~ A~ first, its ~emperature increases rapi~ly wi~hi~ the region:o i~tense dis-sociation. The particle has`:i~s tempera~ure remai~
constant at 2802F, when it reaches its melting poi~t AFE, The co~stant temperatur~ occurs up untiI
the particle.is molten at poi~t BFE. Beyond BFE, the molten metal again in~reases in temperature- as is~
illustrated by ~he solid line~. :The dotted plot:
li~e 66 includes points AAl and BAl ~and Lllustrate the:~
significant temperature~di:f~erence~ experienced by a lower:melting ~emperature pa~ticle such as a~uminum.
.2S rt also experiences an initially~constant tempera~ure once the particle~ reaches its melting poin~which continues until thé particle is completely molte~. A5 a particle travels~:down the bore: Q~ ~he no2zle, i~s t~perature steadily increases-. The~ olid; and dotted `
3Q line curves~ for iron~and aluminum re:spèctively are of s~milar form Referring next to Figure 7,: this igure is a plot of velocity times distance -rathar than temperature times distance as is the pl~ of Figure 6. Figure 7 shows, at line 68, a steady decrease in gas vel~city with Ioss of: tempera~ure for a particle passing .
1 ~ ~2~3 , through the nozzle ~ore. The point to point velocity value is that of the sonic velocity i~ the gas at ~he particular temperature. Beyond ~he nozzle, assuming an underexpanded condition, a free expansion o~ the gases into the free atmosphere leads to a ~e~y rapid increase in velocity.
Where the purpose is to accelerate particles, the optimum condition is at the noz~le throat; in the case o~ Figure 5 the conditi~n carries throughou~ the e~tended leng~h constant diameter bore portion ~Sb.
Therefore, a long straight nozzle will accelera~e a particle, as seen by plot line 70, more rapidly than a di~ergent noæzle designed to maximize gas velocity.
On the ~ther hand, the diverge~t nozzle increases the radial path leng*h the particle must travel to reach the wall As may be appreciated, a straight or constant diameter bore nozzle would "plug" firs~.
~ . The particle envelope core 26 of Figure 5 I hypothesis one theory of particle passage through an extended nozzle. There will, of c~urse, be local pertur~ations in particle velocity which~will impart a radial velocity to the par~icles.~ I~ the a~ial velocity is sufficiently greater than its radial component, the particle could issue from ~the nozzle passage prior to a radial motion equivalent to the nozzle bore radius. Therefore, there would be no bore wall impact during movement o~ ~he~ particle as it~
e~its rom passage or hole 21 into ~he converging bore portion ~5a of the nozzle ll.
This hypothesis may be true for a majority of the particles, but it is possible that some may~reach:the nozzle wall within bore portio~: 25b.~ They do not stick (thus building up a plu~) as the angle of impact `~ is so very small:due to the high axial velocity. In addition, as may be~appreciated at least to the extent of point B~E and BAl, Figure 6, which plots correspond 1 ~ ~2~3 . 15 - lengthwise to bore 25 of no~zle ll, the particle : particularly where it i5 introdu~ed in solid particle from at the end of hole or passage 21 to the high temperature gas exiting from the combustion chamber, is in a plastic state, that is, it is heat softened but is not at:ligui~ication although at ~ear liquifi-cation. Thus, the heat sotened-or plas*ic particles simply bounce off the metaI surface upon co~tact therewith.
Whether the separated core flow or particle bouncing theory controls, the same practical result occurs. Beyond a certain di~tance along the-~ozzle, a build up of impactlng particles~ will result. This is ` particularly true where the impa~tin~ particles result from melting of a ~solid rod rat~er than the introduc-tion of solid particles through:passa~e 21 into the high~ velocity converging gas ~stream~ emanating from holes l9. In eithe:r case, ~he nozzle length must be restricted to less than the ~alue~ wherei~ build up-occurs.
An unforeseen :ad~antage of the~use ~f e~tended , nozzle~ is the lowered temperature~o~ the~ jet gases~
; ~mpinging o~ the work ~eing:sprayed. The longer the I nozzle, the less this del~terious heating. This~ is i 25 particuIarly true where these gases are cooled to below the dissociatlon point. ~ Disso~iated spec~e r~combining on a cool surface present a tremendous .
' heat source an~ thus require means~ for dissipating i such heat at the spray application point.
j 30 The discussion above and~the~plots illustrated in Figures 6 and~7 ~oncern~one parti~le of ~iven~material and~ si~e. For gi~en: reac~ants~ and fl~w rates, an . optimum nozzl~e length may ~be determined by tests.
Change of material or particla size distribution will ; 35 lead to diffe~e~t::~ozzle lengths. For example, by re~ere~ce to the dotted line lower plo~ in Figure 6, `: ~
.
1 ~ ~2~3 for aluminum, the molten poi~t B~ is reached far ups~ream of the noz~le bore exit~ Plugging will thus occur sooner for alumin ~ than for iron and its ~lloys.
Where a long nozzle length for aluminum is desired, a reduction in the hot gas temperature curve will delay melting. This may ~e accomplished by diluking the oxygen flow~ with i~ert gas; i.e., addi~g air to the flow stream.
Longer nozzles a~e also possible usi~g an i~creased bore diame~er. To keep the same values of speciic momenta, increased reac~ance flows are neces-sary to compensate Eor the increase in bore diame~er.
Additionally, delay in melti~g can result by increas-i~g the average particle dia~eter whexe the matexial introduced through hole 2l is in ~olid particle ~or~.
In summary, the invention maximizes the heating and acceleration of sprayed particles hy uslng-high nozzle bore length to diameter ratios. These ratios 'are only possi~le using a c~l~mmated hot gas flow, parti ularly where the whirling component is purposely mi~imized or eliminated. In some case, as in sprayi~g of high temperature ceramics, the oxy îuel flame may not be hot enough to provide ade~uate~melting of the 2S particles. In this casej the combustion reac~ion must be replaced by electrically heati~g the flow gas.
~hen a wire or rod is~ used in place of the powdered material, that is;, in solid particulate form, in the form and manner illustr~ted .in Figure g, the rod begins to i~crease in temperature until ~ a liquid film ~orms on its surface. The hot hi~h~velocity gases sweep this film~ from the~tip of.~he rod passing a~ially longitu~inally a1Ong the:nozzle~ borè. Thus, each particle produces a break ~up o ~his~film and~is molten. It would appear that the mode of possible particle impingemen~ and bulld up on the bore wall is .
- ~ .
~ 1 52~3 the impaction of fully liquid material rather than plastic particles as occurs in th~ powdered particle situation. Thus, the ma~imum nozzle lengths for wire and rod is shorter than that where powdered material is introduced to the hot gas supersonic flow stxeamO
.
'-
is at ambient atmosphere, about 1200 feet per second.
At combustion chamber pressures greater than 200 PSIG, the par~icles may well travel at speeds above 2000 feet per second and at 500 PSIG for chamber 12, the velocity rises to over 3000 feet per second. Such a velocity is greater than that recorded by detonatio~
gun spraying which-heretofore to the ~nowledge of the applicant has achieved th~ highest spray imp~c~
velocities.
! 10 Turning next to ~igure 4, the second illustrated embodiment of the i~en~ion in~lve~ ~he substitution for the material delivered to the high velocity hish temperature produc~s o combustio~ of a solid m~ass o~
material to be ~lame sprayed rather than the powd~r o the embodi.ment of -Figures 1-3. ~owe~er, the major principles employed in the fir~t embodiment of the in~ention operate e~ually wPll for the atomization of material in ro~ or wire farm. In ~ e simplified-~ illustration of the embodiment, ~schematically "gun" 40 has a body 41-which is provided with~a ~ore 52 wi~hin one leg thereof, which bore bears a cylindrical nozzle insert 42 having a venturi nozzle type ~ore as at 47 ~ luding a diverging portion~47a and a converging i portion 47b, downstream and ups~ream-of-the smallest diameter portio~ of the bore at cons~ruction 48,:
. respectively. Body 41 also includes a combustion chamber 43 which extends generally the full height of the vertical body portion. Within the lower portion of the cyli~drical combustio~ chamber body 41 :is provided a conical projection as at 46 which is at ~ righ~ a~gles to th~ axis of combustion chamber. The ! center o projection 46 is formed with a small diam~ter bore 53, the conical projection 46 beinq axially aligned with nozzle insert 42. The top of ! 35 conical projection 46: terminates slightly upstream I ~ fro~ the inner end 42a of the nozzle lnsert 42. The ..
1 3 62~3 small diameter b~re 43 slidably bears an elongated deposit material rod or wire 44 which is positively fed, by way of opposed motor dri~en rollers 45 sand-wlching the wire or rod, towards ~he venturi nozzle 47 wi~h ~ha end 44a of ~he rod projecting well into the ~ozzle ~ore. The no~zle diverging bore portion 47a is exte~ded to assure fine atomization of the molten film as.it passes from the sharp-pointed terminal end 44a -of the wire or rod 44 upon melting~ The operatio~ of 1 10the second embodiment of ~he in~ention is identical to that of the first embodiment. oxygen under pressure is ~ed to the combustion chamber 43 through o~ygen feed supply passage 53, while a liquid or gaseou~ fuel enters the combustion chamber through fuel supply passage 54, the flow of o~ygen and fuel ~eing indi-cated by the arrows as shown.
- As the result of ignition of oxygen and ~uel : under pressure within com~ustion cham~er 43, the hi~h velocity products of combustion contact wire 44 upstream of the noz21e bore co~s~riction 48. This m~Lmizes heat transfer to the wire assuring rapid melting of i~s sur~ace layers~. The high momentum gases of the nozzle throa~ or: restriction 48 and of the extended nozzle bore 47 assures the fine atomiza-tio~ of the molten film as it-passes from the sharp-pointed terminal end of the~wire 44a. Instead of a metal wire a~ shown at 44, a ceramic rod may be used in exactly the same way an~:fed in similar fashion by powered driving -of the opposed~ set of rollers 45.
Again, due to the nature ~f introduction of ~he metal wi~e 44 or a ~ceramic rod; which projects axially b~yond the small diametex bore- 53 of ~he conical - projection 46 into the elongated nozzle bore, upstream of throat 48 and with the converging gas jet due to the presence of the conical projection 46 and its alignment with the inlet end of ~he nozzle bore 47, .
t 1 3 ~2~3 .
1 1 , the molten particles susp~nded in the high velocity gas stream of supersonic velocity are maintained well away from the wall of the di~erging bore por~ion 47a with the metal or ceramic molten particles exiting from the discharge end of the nozzle insert in an essentially cylindrical core 50. This may be on the order of lJ8 inch in dîameter corresponding to the molten powder particles exiti~ from the elongated ~ozzle bore 25 of the em~odiment of Figures 1-3 j 10 i~clusive Preferably, the leng~h ~ the nozzle bore beyo~d the point of i~troduction sf the flow of powder or rod or solid wire form should have a length 4~ at least five times that of ~he miDlmum diameter of the nozzle borP, that is, at the throa~ or smallest r~strictions for the nozzle bore.
Additionally, ~he pressure within the combustion chamber should be maintained at 150 PSIG or greater i~
both embodiments Referring next ~o Figure 5, a further embodiment . 20 of the invention is illustrated in which only ~he ~ozzle and immediately adjacent components of ~he . ultra-high velocity flame spray apparatus.indicated ge~erally at 60 are shown. In this em~odiment, I optimum results are obtained when rotational compo-1 25 nents of ~he hot gas 10w emanating from the co~bus-tion ch~nber (not shown) are eliminated at the point where the hot gas flow contacts the metal particles to be passed at high velocity through ~he nozzle bore of the flame spray apparatus 60. With respe~t to the embodiment of Figure 5, like elements to:that of the !~ embodiment of Figures 1, 2 and 3 are provided with like numeral designations. The mul~iple holes 1~
conYerge towards the axis ~f the extended noz21e I passage provided by bore indicated generally at 25 for the spray apparatus formed by a threaded cylindrical metal nozzle insert indicated generally at 11. The 'I
i!
1 ~2~1~3 1~ , hsles 19 for optimum performance must lie in plane common to ~he nozzle bore axis for bore 25. As a result, there will no directional component radial to the bore axis, and ~he ~otal flow through the bore 25 is free of tangential, whirli~g: components. Under ~hese co~ditions, maximum nozzle Lengths are possible without particle build up on the nozzle wall A
nozzle length: o~ nine i~ches operates satisfactorily usi~g a straight bore (no ve~turi expansion) as i~ the pre~iously described embodiment of Figures 1-3 inclu-sive. For a bore 25 whose m~jor portion 25b down-stream ~f the throat provided by converging inle-t portion 2~a, is of S/l~ I~ch diam~etex. Thus, a length to diam~ter ratio of nearly 30 ~o 1 is exp~rienced in:
lS the embodi~ent of Figure 5.
Although the pri~ciples of operation i~ which the particles are spaced away-from ~he nozzle bo~e wall ~hroughout the length of the nozzl;e portion 25b as well as 25a, is fully understood, increase of nozzle l~n ~ to certain critical vàl~es` is o-f -extreme importance to maximize the e:f~ectiveness:of th~ super sonic flame spra~ resul~i~g ~rom ~the use of the apparatus and ~nder the ~ n~ethod: of ~he present inven-tion. Such parameters ~ and: thei~ critIcality may be s~en by ~urther reference to Figures 6 and 7 In FigNre 5~, the: ~yp:lcal nozzle provided~ by~
~ozzle insert 11 of extended~ ~ore:~ length involves converging.s~ctiorl 25a which is: coIlical ~nd intersects the constant diameter extended length portion ~25b of the ~re 25 and forming the thr~at: of the nozzle bore.
The converging section wall ~5a~commences at the circumference~outlining ~the~outer: wall ~ af the part bearing flame orifices orl holes l9.: As illustrated, powder in a-flow of carrier gas passes into the con~ .
'~ 35 verging portion 25a of the nozzle bore through a i. central passage 21 coaxial~ with~ the bore and opening ¦ thereto:upstream of ~he throa~. ~
' ~ '; , ' ' ., ~ ~ 62~
.
With this in mind, Figure 6 traces ~he tempera-ture history of the gases, as at 7ine 62, and in thi5 case iron particles, and- aluminum as at Iines 64, 66 respectively passi~g through the nozzle. For a `5 propane o~ygen flame, the products of com~ustion approximate 5400F at the. entrance to the ~ozzle bore 25. The temperature gradient of ~hese gases alo~g the nozzle bore is i~iti~lly low due to the re-combination of the dissociated spe~iae~ Wi~h full re-combination, the gradient incr~ases. ~Hea-t from the flame gases pass to the walls of: ~he.nozzle body and to the lower temperature particles:. -Illustràtively, an iron particle enters the nozzle bore at about 70F.~ A~ first, its ~emperature increases rapi~ly wi~hi~ the region:o i~tense dis-sociation. The particle has`:i~s tempera~ure remai~
constant at 2802F, when it reaches its melting poi~t AFE, The co~stant temperatur~ occurs up untiI
the particle.is molten at poi~t BFE. Beyond BFE, the molten metal again in~reases in temperature- as is~
illustrated by ~he solid line~. :The dotted plot:
li~e 66 includes points AAl and BAl ~and Lllustrate the:~
significant temperature~di:f~erence~ experienced by a lower:melting ~emperature pa~ticle such as a~uminum.
.2S rt also experiences an initially~constant tempera~ure once the particle~ reaches its melting poin~which continues until thé particle is completely molte~. A5 a particle travels~:down the bore: Q~ ~he no2zle, i~s t~perature steadily increases-. The~ olid; and dotted `
3Q line curves~ for iron~and aluminum re:spèctively are of s~milar form Referring next to Figure 7,: this igure is a plot of velocity times distance -rathar than temperature times distance as is the pl~ of Figure 6. Figure 7 shows, at line 68, a steady decrease in gas vel~city with Ioss of: tempera~ure for a particle passing .
1 ~ ~2~3 , through the nozzle ~ore. The point to point velocity value is that of the sonic velocity i~ the gas at ~he particular temperature. Beyond ~he nozzle, assuming an underexpanded condition, a free expansion o~ the gases into the free atmosphere leads to a ~e~y rapid increase in velocity.
Where the purpose is to accelerate particles, the optimum condition is at the noz~le throat; in the case o~ Figure 5 the conditi~n carries throughou~ the e~tended leng~h constant diameter bore portion ~Sb.
Therefore, a long straight nozzle will accelera~e a particle, as seen by plot line 70, more rapidly than a di~ergent noæzle designed to maximize gas velocity.
On the ~ther hand, the diverge~t nozzle increases the radial path leng*h the particle must travel to reach the wall As may be appreciated, a straight or constant diameter bore nozzle would "plug" firs~.
~ . The particle envelope core 26 of Figure 5 I hypothesis one theory of particle passage through an extended nozzle. There will, of c~urse, be local pertur~ations in particle velocity which~will impart a radial velocity to the par~icles.~ I~ the a~ial velocity is sufficiently greater than its radial component, the particle could issue from ~the nozzle passage prior to a radial motion equivalent to the nozzle bore radius. Therefore, there would be no bore wall impact during movement o~ ~he~ particle as it~
e~its rom passage or hole 21 into ~he converging bore portion ~5a of the nozzle ll.
This hypothesis may be true for a majority of the particles, but it is possible that some may~reach:the nozzle wall within bore portio~: 25b.~ They do not stick (thus building up a plu~) as the angle of impact `~ is so very small:due to the high axial velocity. In addition, as may be~appreciated at least to the extent of point B~E and BAl, Figure 6, which plots correspond 1 ~ ~2~3 . 15 - lengthwise to bore 25 of no~zle ll, the particle : particularly where it i5 introdu~ed in solid particle from at the end of hole or passage 21 to the high temperature gas exiting from the combustion chamber, is in a plastic state, that is, it is heat softened but is not at:ligui~ication although at ~ear liquifi-cation. Thus, the heat sotened-or plas*ic particles simply bounce off the metaI surface upon co~tact therewith.
Whether the separated core flow or particle bouncing theory controls, the same practical result occurs. Beyond a certain di~tance along the-~ozzle, a build up of impactlng particles~ will result. This is ` particularly true where the impa~tin~ particles result from melting of a ~solid rod rat~er than the introduc-tion of solid particles through:passa~e 21 into the high~ velocity converging gas ~stream~ emanating from holes l9. In eithe:r case, ~he nozzle length must be restricted to less than the ~alue~ wherei~ build up-occurs.
An unforeseen :ad~antage of the~use ~f e~tended , nozzle~ is the lowered temperature~o~ the~ jet gases~
; ~mpinging o~ the work ~eing:sprayed. The longer the I nozzle, the less this del~terious heating. This~ is i 25 particuIarly true where these gases are cooled to below the dissociatlon point. ~ Disso~iated spec~e r~combining on a cool surface present a tremendous .
' heat source an~ thus require means~ for dissipating i such heat at the spray application point.
j 30 The discussion above and~the~plots illustrated in Figures 6 and~7 ~oncern~one parti~le of ~iven~material and~ si~e. For gi~en: reac~ants~ and fl~w rates, an . optimum nozzl~e length may ~be determined by tests.
Change of material or particla size distribution will ; 35 lead to diffe~e~t::~ozzle lengths. For example, by re~ere~ce to the dotted line lower plo~ in Figure 6, `: ~
.
1 ~ ~2~3 for aluminum, the molten poi~t B~ is reached far ups~ream of the noz~le bore exit~ Plugging will thus occur sooner for alumin ~ than for iron and its ~lloys.
Where a long nozzle length for aluminum is desired, a reduction in the hot gas temperature curve will delay melting. This may ~e accomplished by diluking the oxygen flow~ with i~ert gas; i.e., addi~g air to the flow stream.
Longer nozzles a~e also possible usi~g an i~creased bore diame~er. To keep the same values of speciic momenta, increased reac~ance flows are neces-sary to compensate Eor the increase in bore diame~er.
Additionally, delay in melti~g can result by increas-i~g the average particle dia~eter whexe the matexial introduced through hole 2l is in ~olid particle ~or~.
In summary, the invention maximizes the heating and acceleration of sprayed particles hy uslng-high nozzle bore length to diameter ratios. These ratios 'are only possi~le using a c~l~mmated hot gas flow, parti ularly where the whirling component is purposely mi~imized or eliminated. In some case, as in sprayi~g of high temperature ceramics, the oxy îuel flame may not be hot enough to provide ade~uate~melting of the 2S particles. In this casej the combustion reac~ion must be replaced by electrically heati~g the flow gas.
~hen a wire or rod is~ used in place of the powdered material, that is;, in solid particulate form, in the form and manner illustr~ted .in Figure g, the rod begins to i~crease in temperature until ~ a liquid film ~orms on its surface. The hot hi~h~velocity gases sweep this film~ from the~tip of.~he rod passing a~ially longitu~inally a1Ong the:nozzle~ borè. Thus, each particle produces a break ~up o ~his~film and~is molten. It would appear that the mode of possible particle impingemen~ and bulld up on the bore wall is .
- ~ .
~ 1 52~3 the impaction of fully liquid material rather than plastic particles as occurs in th~ powdered particle situation. Thus, the ma~imum nozzle lengths for wire and rod is shorter than that where powdered material is introduced to the hot gas supersonic flow stxeamO
.
'-
Claims (38)
1. In a flame spray method comprising the steps of:
combusting, under pressure, an oxy-fuel mixture within an internal burner combustion chamber, discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity hot gas stream, and feeding material to said stream for high temperature liquefaction and spraying at high velocity onto a surface positioned in the path of the stream at the discharge end of the nozzle, the improvement wherein said step of feeding said material comprises introducing said material in solid form outside of said combustion chamber and axially into the flow expansion nozzle at the throat or just upstream of said nozzle and within a nozzle bore having an extended length.
combusting, under pressure, an oxy-fuel mixture within an internal burner combustion chamber, discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity hot gas stream, and feeding material to said stream for high temperature liquefaction and spraying at high velocity onto a surface positioned in the path of the stream at the discharge end of the nozzle, the improvement wherein said step of feeding said material comprises introducing said material in solid form outside of said combustion chamber and axially into the flow expansion nozzle at the throat or just upstream of said nozzle and within a nozzle bore having an extended length.
2. The flame spray method as claimed in claim 1, wherein the step of discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity gas stream includes the step of minimizing the whirling velocity component of the gaseous flow through the flow expan-sion nozzle bore.
3. The flame spray method as claimed in claim 1, wherein the step of discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity gas stream and through a nozzle bore of extended length, comp-rises causing said gases to pass through said extend-ed length nozzle bore over a nozzle bore length of such an extent that the temperature of the hot gas flow is reduced to below the dissociation temperature of the gas flow.
4. The flame spray method as claimed in claim 1, wherein said step of discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzles as a high velocity gas stream and through a nozzle bore having an extended length, comprises passing said hot combustion product gases through a nozzle whose length is such that the particles discharged are still in their plastic state.
5. The flame spray method as claimed in claim 1 further comprising the step of adding an inert gas to the reactants to reduce the combustion temperature.
6. The flame spray method as claimed in claim 1, further comprising the step of adding com-pressed air to supply inert gas contained in the compressed air to the reactants to reduce the combus-tion temperature and to thereby prevent plugging of the nozzle bore by molten material particles on the bore of the nozzle upstream of the exit end of the nozzle bore.
7. The flame spray method as claimed in claim 1, wherein said step of feeding said solid material into the flow of hot gases comprises the introduction of said solid material from a hole aligned with the axis of the nozzle bore upstream of the nozzle and at a point where the inlet flow of the hot gases to the nozzle bore throat has a radial velocity component which tends to restrict the diameter of a column of particles when said solid material is in particulate form and which maximizes heat transfer between the hot gases and the case of the rod when the solid material is in rod form and projects into the axis of the nozzle bore, through said hole.
8. The flame spray method as claimed in claim 1, wherein the hot gas stream is projected through a nozzle bore whose length is at least five times that of the diameter of said nozzle bore throat.
9. The flame spray method as claimed in claim 7, wherein the hot gas stream is projected through a nozzle bore whose length is at least five times that of the diameter of said nozzle bore throat.
10. The flame spray method as claimed in claim 1, wherein the pressure within the combustion chamber is maintained at least 75 PSIG.
11. A highly concentrated supersonic liquified material flame spray apparatus comprises:
a spray gun body, a high pressure combustion chamber within said body, means for continuously flowing an oxy-fuel mixture under high pressure through said combustion chamber for ignition within said chamber, said body including combustion chamber products of combustion discharge passage means at one end thereof, said body further comprising an elgonated nozzle downstream of said combustion chamber discharge passage means, said nozzle including a converging inlet bore portion and an extended outlet bore portion, said combustion chamber discharge passage means comprising means for conveying the flow of the discharging hot gas products of combustion into the entrance of the nozzle inlet for portion and means for introducing material in solid form into the hot gases for subsequent melting and acceleration with the point of introduction of the solid material being at the entrance to or just upstream of the bore of said nozzle.
a spray gun body, a high pressure combustion chamber within said body, means for continuously flowing an oxy-fuel mixture under high pressure through said combustion chamber for ignition within said chamber, said body including combustion chamber products of combustion discharge passage means at one end thereof, said body further comprising an elgonated nozzle downstream of said combustion chamber discharge passage means, said nozzle including a converging inlet bore portion and an extended outlet bore portion, said combustion chamber discharge passage means comprising means for conveying the flow of the discharging hot gas products of combustion into the entrance of the nozzle inlet for portion and means for introducing material in solid form into the hot gases for subsequent melting and acceleration with the point of introduction of the solid material being at the entrance to or just upstream of the bore of said nozzle.
12. The apparatus as claimed in claim 11, wherein the axis of the nozzle bore and the axis of the combustion chamber are at approximately right angles to each other, said combustion chamber discharge passage means comprises a plurality of circumferentially spaced converging, inclined small diameter passages open at one end to the inlet portion of said nozzle bore just upstream of the nozzle bore throat and at the other end to said combustion chamber, and wherein said means for introducing solid material into the hot gases comprises a small diameter material feed passage within said body centered within said circumferentially spaced, inclined passages which converge towards the axis of the bore, said material feed passage being coaxial with said nozzle bore.
13. The apparatus as claimed in claim 11, wherein said combustion chamber comprises an elongated cylindrical combustion chamber, and said body com-prises a conical projection within said combustion chamber at approximately right angles to the axis of said combustion chamber and projecting towards and being coaxial with said nozzle bore, and wherein the tip of said conical projection terminates adjacent the end of said nozzle at said converging inlet portion and forms, with said nozzle, said combustion chamber discharge passage means, and wherein said solid mate-rial comprises an elongated wire of rod and said conical projection includes an axially extending small diameter bore, and said apparatus further comprises means for positively feeding said solid material wire or rod through the axial bore of said conical projec-tion with the wire or rod opening to the throat of said nozzle at the tip end of said conical projection.
14. The apparatus as claimed in claim 12 or claim 13, wherein the length of said nozzle bore between its discharge end and the point of introduc-tion of the solid material at the entrance to or just upstream of the throat of said nozzle is at least five times that of throat diameter of said nozzle bore.
15. The apparatus as claimed in claim 12, wherein said plurality of circumferentially spaced converging, inclined small diameter passage for feeding the combustion chamber gases into the nozzle bore comprise means for minimizing the whirling velocity component of the gaseous flow through the nozzle bore.
16. The apparatus as claimed in claim 15, wherein said plurality of circumferentially spaced converging, inclined small diameter passages are coplanar with the axis of said nozzle bore.
17. The apparatus as claimed in claim 16, wherein the nozzle bore length is the maximum length in which particle build up is not effected on the inner bore surface.
18. The apparatus as claimed in claim 16, wherein the nozzle bore is the minimum length in which the temperature of the hot gas flow is reduced to below the dissociation temperature of the gas flow.
19. The apparatus as claimed in claim 16, wherein the nozzle length is such that the particle velocity is maximized at the exit plane of the nozzle.
20. The apparatus as claimed in claim 16, wherein the nozzle length is such that the particle temperature is maximized at the exit plane of the nozzle.
21. The apparatus as claimed in claim 16, wherein the particles are sized so as to be of a sufficient diameter to preclude build up on the inner surface of the bore during passage therethrough.
22. In a flame spray method comprising the steps of:
continuously combusting, under pressure, a continuous flow of an oxy-fuel mixture confined within an essentially closed internal burner combustion chamber, discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity hot gas stream, and feeding material to said stream for high temperature heat softening or liquefaction and spraying at high velocity onto a surface positioned in the path of the stream at the discharge end of the nozzle, the improvement wherein the step of feeding said mater-ial comprises introducing said material in solid form out-side of said combustion chamber and axially into a converging flow of hot combustion product gases after exit from the combustion chamber while entering a converging portion of the flow expansion nozzle having a nozzle bore of a length that is at least five times that of the nozzle bore throat, to restrict the diameter of the column of particles passing through the nozzle bore, to prevent builid-up of particle material on the nozzle bore wall while insuring heat soften-ing or melting and flow at supersonic flow velocity prior to impact against said surface.
continuously combusting, under pressure, a continuous flow of an oxy-fuel mixture confined within an essentially closed internal burner combustion chamber, discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity hot gas stream, and feeding material to said stream for high temperature heat softening or liquefaction and spraying at high velocity onto a surface positioned in the path of the stream at the discharge end of the nozzle, the improvement wherein the step of feeding said mater-ial comprises introducing said material in solid form out-side of said combustion chamber and axially into a converging flow of hot combustion product gases after exit from the combustion chamber while entering a converging portion of the flow expansion nozzle having a nozzle bore of a length that is at least five times that of the nozzle bore throat, to restrict the diameter of the column of particles passing through the nozzle bore, to prevent builid-up of particle material on the nozzle bore wall while insuring heat soften-ing or melting and flow at supersonic flow velocity prior to impact against said surface.
23. The flame spray method as claimed in claim 22, wherein the step of discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity gas stream includes the step of minimizing the whirling velocity component of the gaseous flow through the flow expansion nozzle bore.
24. The flame spray method as claimed in claim 22, wherein the step of discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity gas stream comprises causing said gases to pass through said nozzle bore over a nozzle bore length of such an extent that the temperature of the hot gas flow is reduced to below the dissociation temperature of the gas flow.
25. The flame spray method as claimed in claim 22, wherein said step of discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity gas stream comprises passing said hot combustion product gases through a nozzle whose length is such that the particles discharged are still in their plastic state.
26. The flame spray method as claimed in claim 22, further comprising the step of adding an inert gas to the reactants to reduce the combustion temperature.
27. The flame spray method as claimed in claim 22, further comprising the step of adding compressed air to supply inert gas contained in the compressed air to the reactants to reduce the combustion temperature and to there-by prevent plugging of the nozzle bore by heat softened or molten material particles on the bore of the nozzle up-stream of the exit end of the nozzle bore.
28. The flame spray method as claimed in claim 22, wherein said step of feeding said solid material into the flow of hot gases comprises the introduction of said solid material from a hole aligned with the axis of the nozzle bore upstream of the nozzle and at a point where the inlet flow of the hot gases to the nozzle bore throat has a radial velocity component which tends to restrict the diameter of a column of particles when said solid material is in particulate form and which maximizes heat transfer between the hot gases and the case of the rod when the solid mater-ial is in rod form and projects into the axis of the nozzle bore, through said hole.
29. The flame spray method as claimed in claim 22, wherein the pressure within the combustion chamber is main-tained at least 75 PSIG.
30. A highly concentrated supersonic material flame spray apparatus comprising:
a spray gun body, a high pressure essentially closed combustion chamber within said body, means for continuously flowing an oxy-fuel mixture under high pressure through said combustion chamber for ignition within said chamber, said body including combustion chamber products of combustion discharge passage means at one end thereof, said body further comprising an elongated nozzle down-stream of said combustion chamber discharge passage means, said nozzle including a converging inlet bore portion lead-ing to a throat and having an extended length outlet bore portion, and wherein said bore has a length that is at least five times the diameter of said nozzle bore throat, said combustion chamber discharge passage means com-prising means for conveying a converging flow of the dis-charge hot products of combustion, after exit from the combustion chamber into the entrance of the nozzle inlet bore portion and means for introducing material in solid form outside of the combustion chamber axially into the hot combustion gases for subsequent heat softening or melt-ing and acceleration with the point of introduction of the solid material being at the entrance to or within the con-verging inlet portion of the bore of said nozzle to restrict the diameter of the column of particles passing through the nozzle bore, prevent build-up of particle material on the nozzle bore wall while insuring sufficient particle dwell time within the gas stream to effect particle heat softening or melting prior to particle impact on a sub-strate downstream of the discharge end of the nozzle bore.
a spray gun body, a high pressure essentially closed combustion chamber within said body, means for continuously flowing an oxy-fuel mixture under high pressure through said combustion chamber for ignition within said chamber, said body including combustion chamber products of combustion discharge passage means at one end thereof, said body further comprising an elongated nozzle down-stream of said combustion chamber discharge passage means, said nozzle including a converging inlet bore portion lead-ing to a throat and having an extended length outlet bore portion, and wherein said bore has a length that is at least five times the diameter of said nozzle bore throat, said combustion chamber discharge passage means com-prising means for conveying a converging flow of the dis-charge hot products of combustion, after exit from the combustion chamber into the entrance of the nozzle inlet bore portion and means for introducing material in solid form outside of the combustion chamber axially into the hot combustion gases for subsequent heat softening or melt-ing and acceleration with the point of introduction of the solid material being at the entrance to or within the con-verging inlet portion of the bore of said nozzle to restrict the diameter of the column of particles passing through the nozzle bore, prevent build-up of particle material on the nozzle bore wall while insuring sufficient particle dwell time within the gas stream to effect particle heat softening or melting prior to particle impact on a sub-strate downstream of the discharge end of the nozzle bore.
31. The apparatus as claimed in claim 30, wherein the axis of the nozzle bore and the axis of the combustion chamber are at approximately right angles to each other, said combustion chamber comprises an end wall, said com-bustion chamber discharge passage means comprises a plurality of circumferentially spaced converging, inclined small diameter passages within said combustion chamber end wall, being open at one end to the inlet portion of said nozzle bore upstream of the nozzle bore throat and at the other end to said combustion chamber, and wherein said means for introducing solid material into the hot gases comprises a small diameter material feed passage within said body centered within said circumferentially spaced, inclined passages which converge towards the axis of the bore, said material feed passage being coaxial with said nozzle bore.
32. The apparatus as claimed in claim 30, wherein said combustion chamber comprises an elongated cylindrical combustion chamber, and said body comprises a conical pro-jection within said combustion chamber at approximately right angles to the axis of said combustion chamber and projecting towards and being coaxial with said nozzle bore, and wherein the tip of said conical projection terminates adjacent the end of said nozzle at said converging inlet portion and forms, with said nozzle, said combustion chamber discharge passage means, and wherein said solid material comprises an elongated wire or rod and said conical pro-jection includes an axially extending small diameter bore, and said apparatus further comprises means for positively feeding said solid material wire or rod through the axial bore of said conical projection with the wire or rod opening to the throat of said nozzle at the tip end of said conical projection.
33. The apparatus as claimed in claim 31, wherein said plurality of circumferentially spaced converging, in-clined small diameter passages for feeding the combustion chamber gases into the nozzle bore are oriented to eliminate tangential flow to said nozzle bore for minimizing the whirling velocity component of the gaseous flow through the nozzle bore.
34. The apparatus as claimed in claim 33, wherein said plurality of circumferentially spaced converging, in-clined small diameter passages are coplanar with the axis of said nozzle bore.
35. The apparatus as claimed in claim 34, wherein the nozzle bore length is the maximum length in which par-ticle build-up is not effected on the inner bore surface.
36. The apparatus as claimed in claim 34, wherein the nozzle bore is the minimum length in which the temper-ature of the hot gas flow is reduced to below the dissocia-tion temperature of the gas flow.
37. The apparatus as claimed in claim 34, wherein the nozzle length is such that the particle velocity is maximized at the exit plane of the nozzle.
38. The apparatus as claimed in claim 34, wherein the nozzle length is such that the particle temperature is maximized at the exit plane of the nozzle.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US19672380A | 1980-10-09 | 1980-10-09 | |
| US196,723 | 1980-10-09 | ||
| US287,652 | 1981-07-28 | ||
| US06/287,652 US4416421A (en) | 1980-10-09 | 1981-07-28 | Highly concentrated supersonic liquified material flame spray method and apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162443A true CA1162443A (en) | 1984-02-21 |
Family
ID=26892167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000386388A Expired CA1162443A (en) | 1980-10-09 | 1981-09-22 | Highly concentrated supersonic liquified material flame spray method and apparatus |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4416421A (en) |
| EP (1) | EP0049915B1 (en) |
| CA (1) | CA1162443A (en) |
| DE (1) | DE3171039D1 (en) |
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| US2436335A (en) * | 1943-12-17 | 1948-02-17 | Leo M Simonsen | Spray device for projecting molten particles |
| US2544259A (en) * | 1944-11-25 | 1951-03-06 | Duccini Gaetano | Metallizing spray gun |
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| FR1437713A (en) * | 1965-03-31 | 1966-05-06 | Union Carbide Corp | Furnace coating process |
| US4004735A (en) * | 1974-06-12 | 1977-12-25 | Zverev Anatoly | Apparatus for detonating application of coatings |
| US4078097A (en) * | 1976-07-09 | 1978-03-07 | International Prototypes, Inc. | Metallic coating process |
| US4358053A (en) * | 1980-11-26 | 1982-11-09 | Metco, Inc. | Flame spraying device with rocket acceleration |
-
1981
- 1981-07-28 US US06/287,652 patent/US4416421A/en not_active Expired - Lifetime
- 1981-09-22 CA CA000386388A patent/CA1162443A/en not_active Expired
- 1981-09-24 DE DE8181201061T patent/DE3171039D1/en not_active Expired
- 1981-09-24 EP EP81201061A patent/EP0049915B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0049915A1 (en) | 1982-04-21 |
| US4416421A (en) | 1983-11-22 |
| DE3171039D1 (en) | 1985-07-25 |
| EP0049915B1 (en) | 1985-06-19 |
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