CA1229959A

CA1229959A - Composite bearing structure of alternating hard and soft metal, and process for making the same

Info

Publication number: CA1229959A
Application number: CA000449114A
Authority: CA
Inventors: Gunes M. Ecer
Original assignee: Smith International Inc
Current assignee: Smith International Inc
Priority date: 1983-03-09
Filing date: 1984-03-08
Publication date: 1987-12-08
Also published as: US4474861A

Abstract

COMPOSITE BEARING STRUCTURE OF ALTERNATING HARD AND
SOFT METAL, AND PROCESS FOR MAKING THE SAME

ABSTRACT OF THE DISCLOSURE
A bearing structure having a substrate and a bearing surface of alternating, spaced, hard metal and soft metal areas is disclosed. The hard metal is metallurgically bonded to the base metal substrate by rapidly melting in a predetermined pattern a powdered hardfacing composition disposed on a bearing precursor surface of the base metal substrate. The melting is accomplished by scanning with a laser beam, or like high intensity, concentrated energy source. The melt is allowed to solidify rapidly. Gaps formed between isolated areas of the solidified hard metal are filled with a melt of a soft metal.
After solidification of the molten soft metal, the resulting composite structure is machined to a desired depth to provide the composite bearing surface.

Description

81-~7 111;~29~5~ l

2 SOFT METAL, AND PROCESS FOR MAKING THE SAME

1. ruled of the lnv~
6 The present invention is directed to a composite 7 bearing structure More particularly, the present invention is 8 directed to a bearing structure having a bearing surface of alternating hard metal and soft metal area which are 10 metallurg~caily bonded to a base metal substrate. The present 11 inventions Allah directed to a process for making the composite 12 bearing structure.
13 2. Brief Description of the Prior Art 14 Bearings adapted for accommodating rotating or 15 lineal motion are well known in the prior art and are practically 16 ubiquitous in machines, engines and like mechanical device.
17 Generally speaking, friction bearings incorporate 18 two or more bearing surfaces which are in sliding motion relative 19 to one another. These bearing surfaces optimally should have 20 high load capacity, low friction, minimal wear and long useful 21 life. As is well appreciated by those skilled in the art, the 22 above-noted requirements are especially difficult to fiatisfy in 23 bearings used in certain harsh environments such a in internal 24 combustion engines and drilling machinery utilized "Donnelly", 25 when prospecting for oil, gay or minerals.
26 on its effort to meet the above-noted and other 28 requirements, and especially for "downholen and other "severe . If 2~99~9 I
1 environ~enta applications, the prior art has provided bearing Z surfaces jade of materials of very high hardness. Typically, these materials of high hardness are alloys of metal carbides, 4 and are known in the art as ~hardfacingr alloys ox various proprietor names (such as SATELLITE).
6 alternatively, the prior art has provided bearing 7 structures wherein one of the two adjacent, slidingly engaging 8 bearing surfaces is made of a soft metal, such as copper, silver, 9 or tin alloys. us still another alternative, the prior art has lo provided composite bearing surfaces which incorporate alternating 11 soft and relatively hard metal areas exposed for sliding 12 engagement with an adjacent bearing surface. Examples of bearing 13 structures of the above noted and related composite construction, 14 may be found in United States Patent Nosy Lowe 3,235,316;
2,37l~248; 2,268,869 and 356~331.
16 More specifically, United States Patent No 17 3,235,316 discloses a composite bearing wherein appropriate 18 recesses are machined into a suitable substrate. Inlays of an lo anti friction or Uanti-galling~ soft metal composition are I placed into the recesses. The resulting composite bearing 21 surface is said to have improved wear characteristics.
22 United States Patent No. 2,97l,248 discloses a 23 composite bearing wherein a first metal alloy of relatively high 24 load bearing rapacity (such as aluminum alloy) is applies to a I suitable backing strip or support. Recesses formed in the f first 26 metal alloy are mecharlically inlaid with a second metal alloy 27 (such as Babbitt metal) having anti-seizure qualities.
28 lJnited States Patent No. 2,268,869 describes Lo So 1 bearing structures wherein grooves or recesses machined into a 2 base metal are filled with a mixture of an abrasive metal oxide

3 and a suitable binder, such as sodium silicate. The resulting

4 bearings are said Jo have improved load bearing capacity.

A principal disadvantage of the prior art composite 6 bearing structures is that the grooves or recesses which accept 7 the sickened material to form the composite, are mechanically 8 placed or machined into the base or substrate petal.
9 understandably, machining the recesses into the substrate is costly, rendering the prior art composite bearings relatively 11 uneconomical .
12 Another disadvantage of prior art composite bearing 13 structures is that one of the materials of the composite bearing 14 surface is necessarily the very material of the base or substrate. This disadvantage inherently flows from the hitherto 16 known methods for fabricating the composite bearings. Thus, the 17 hitherto known composite bearings fail to take advantage of 18 specialized hard facing alloy compositions which are available in 19 the art Jo provide extra hard, thin surfaces on less expensive metal based substrates.
21 The present invention is designed to overcome the 22 problems experienced in the prior art regarding high costs of 23 composite bearings, and to provide for the f first time, a 24 composite bearing which utilizes specialized hard facing alloys in 26 conjunction with soft metals to provide an improved bearing 26 surface.
27 5DM~ARV OF MU IUVLN`I~
28 It is an object of the present invention to provide 3 I Z99 So 1 composite bearing structure of improved load bearing and wear 2 characteristics.
3 It is another object of the present invention to 4 provide a bearing structure wherein a hard facing metal is utilized together with a soft metal on a base metal substrate to 6 form a composite bearing surface.
7 It is still another object of the present invention to 8 provide a composite bearing structure wherein the hard facing 9 metal us metallurgically bonded to the underlying base metal 10 substrate .
11 It is yet another object of the present invention to 12 provide a relatively economical process for fabricating a 13 composite bearing surface composed of alternating hard metal and 14 soft metal areas on an underlying base metal substrate.
These and other objects and advantages are attained by 16 a bearing structure wherein a hard facing metal or like hard metal 17 composition is metallurgically bonded in a predetermined pattern 18 to a bearing precursor or support surface of a base metal 19 substrate. The predetermined pattern is configured to provide isolated areas of the hard facing metal which protrude from the 21 underlying base metal surface. Gaps between the isolated areas 22 contain a soft metal of a hardness of at least five Arc units less 23 than the hard facing metal.
24 An appropriately machined bearing surface of the I alternating hard metal and soft metal areas provides improved 26 load bearing and wear characteristics. These characteristics are 27 due to the good heat conducting ability of the soft petal, 28 entrapment of hard metal particles in the soft metal during use I

I ~L2299S9 1 of the bearing structure, and the high load capacity and 2 structural integrity of the isolated hard metal areas. These areas have high structural integrity because of the novel manner 4 provided by the present invention for establishing them on the base metal substrate.
6 In the process of the present invention, a powdered hard facing composition is deposited on the bearing support 8 sup face of the bass metal substrate. The h~rdfacing composition 9 is scanned in the predetermined pattern by a high intensity energy source, such as a laser beam, to cause rapid localized 11 melting of the hard facing composition and metallurgical bonding 12 to the underlying base metal. Subsequent rapid cooling of the 13 melt in the isolated areas of the predetermined pattern permits id an unconstricted solidification of the hard facing metal with the resulting high structural integrity. After bonding of the 16 hard facing metal composition to the base metal substrate, gaps 17 between isolated areas of the hard facing metal are filled with a I melt of the soft metal The joint hard facing metal-soft metal lo layer is then machined to a desired depth to expose the alternating hard metal-soft metal areas and to form the bearing 21 surface.
22 The features of the present invention can be best 23 understood together with further objects and advantages, by 24 reference to the following description, taken in connection with the accompanying drawings wherein like numerals indicate like 26 parts.

.
28 Figure l is a schematic perspective view of a base I

1 metal substrate having a powdered hard facing metal composition 2 deposited thereon in a predetermined pattern, the Figure alto 3 shows fichematically a step of the process of the present 4 invention wherein a laser beam it applied to melt the hard facing

5 metal composition in the predetermined pattern;

6 Figure 2 is a schematic perspective view of a base

7 metal substrate having deposited thereon a layer of powdered

8 hardîacing rectal company mired with a suitable binder; the

9 Figure alto shows schematically the step of the process of the

10 present invention wherein a layer beam is applied to melt the 1¦ hard facing metal composition in the predetermined pattern;
2¦ Figure 3 it a schematic perspective view of an 3¦ intermediate product obtained in the process of the present 14 invent ion wherein a hardfacin~ metal composition has been 15 metallurgically bonded to a bare metal substrate by a laser beam 16 of substantially rectangular energy profile:
17 Figure 4 is a schematic top view of an in ermediate 18 product wherein the hard facing metal composition ha been 19 metallurgically bonded to the base metal substrate in a 20 predetermined pattern of a first preferred configuration;
21 Figure 5 it a thematic top view of an intermediate 22 product wherein the hard facing metal composition ha been 23 metallurgically bonded to the base metal substrate in a 24 predetermined pattern of a second preferred configuration;
26 Figure 6 it a schematic top view of an intermediate 26 product wherein the hard facing metal composition has been 27 metallurgically bonded to the bate metal substrate in a 28 predetermined pattern of a third preferred configuration, I

1 Figure 7 is a schematic cross sectional view of an 2 intermediate product obtained in the process of the present 3 invention wherein a hard facing petal company has been 4 metallurgically bonded in a predetermined pattern to a base metal sister, and gaps between areas of the hard facing metal have 6 been filled with a soft metal;
7 Figure 8 is a schematic cross-sectional view of another 8 intermediate product obtained in the process of the present 9 invention, wherein a hard facing metal composition has been metallurgically bonded in a predetermined pattern to a base metal

11 substrate and gaps between areas of the hard facing metal have

12 been filled with a soft metal, and

13 Figure 9 is a schematic illustration of an electron

14 microscope view ox a composite bearing surface of the present invention; the view having been taken after a wear text, 16 illustrating a soft metal area between two hard metal areas and 17 shag debris of herd metal particles embedded in the soft metal 18 area.

The following specification taken in conjunction with 21 the drawings sets forth the preferred embodiments of the present 22 invention The embodiments of the invention disclosed herein are 23 the best modes contemplated by the inventor for carrying out his 24 invention in a commercial environment although it should be understood that various modifications can be accomplished within 26 the parameters of the present invention.
27 In accordance with the present invention hard petal I composition 20 is metallurgically bonded to a suitably formed Jo lass 1 support or bearing precursor surface 22 of a bate metal substrate 2 24. Pro simplicity of illustration the haze metal ~ub6trate 24 3 is schematically shown on the drawing figures a a rectangular 4 plate having a flat wearing support or precursor surface 22. In 5 actual precut of the present inventis~rl, however, the base 6 metal substrate 24 and it bearing Support surface 24 correspond to the configuration of the machine part (not shown) or bearing 8 assembly (not shown) on which the composite bearing surface 26 of 9 the present invention it to be formed. Thus, as it will be 10 apparent to those skilled in the art, the bearing support surface 11 22 may be a curvilinear surface (not shown).
12 The base metal substrate 24 comprises materials which 13 are ordinarily used in the art for manufacturing machine parts, 14 (not Shown) and bearing assumably (not shown). Thus the

15 substrate 24 may be made of various steel alloys, other ferrous

16 metal alloy, nickel, nickel based alloys, cobalt, cobalt based

17 alloy, copper and copper bayed alloy. The principal

18 requirement in this regard it determined by the nature ox the I machine part (not shown) in which the novel composite bearing 20 surface 26 of the present invention it incorporated.
21 Referring now principally to Figure l, a step in the 22 novel process of fabricating the bearing surface 26 of the 23 present invention is schematically shown. Thus, a powdered hard 24 metal composition 20 is deposited on the bearing support surface 26 22, and a concentrated beam of energy is applied in a 26 predetermined pattern to rapidly melt the deposited hard metal 27 composition 20 Jo provide isolated areas of hard metal 28 metallurgically bonded to the underlying support surface 22. The ~2~3g~

hard metal composition 20 utilized for the purposes of the present invention is usually of greater hardness than the underlying substrate 24.
A variety of commercially available hard metal compositions, commonly known in the art as hard facing compositions, are suitable for application in the present invention. Generally speaking, such hard facing compositions are either metal carbide based compositions, or inter metallic hard facing alloys. These materials are well known to those skilled in the art under various proprietor names such as SATELLITE (trade mark) alloys, AWNS (trade mark) alloys, DELCROME
(trade mark) alloys and TRULY (trade mark) alloys. SATELLITE
alloys are examples of a carbide based hard facing alloys, whereas TRIBALLY alloys are examples of inter metallic hard facing alloys.
A specific example of a carbide based hard facing alloy eminently suitable for use in the present invention is SATELLITE
alloy No. 1, the nominal chemical composition on which (in percentages of weight) is: Chromium 30~; Carbon 2.5%; Silicon 1%, Manganese up to a maximum of 1%; Molybdenum up to a maximum of 1%;
Iron up to a maximum of 3%; Nickel up to a maximum of 3%; Tungsten 12.5%, with the balance being Cobalt.
A specific example of an inter metallic hard facing alloy suitable for use in the present invention is TRIBALLY No. T-400, the nominal chemical composition of which tin percentages of weight) is: Chromium 8.5%; Carbon up to a maximum of 0.08%;
Silicon 2.6~; Molybdenum 28.5%, Nickel and Iron jointly up to a maximum of 3%, with the balance being Cobalt.
Figure 1 illustrate one specific manner of applying 1 the powdered hard facing composition I to the bearing support surface 22~ the powdered hard facing composition 20 is deposited in substantially parallel, elongated, spaced strips 28 on the 4 bearing precursor surface 22 Burr the concentrated beam of energy is applied to melt the strips 28.
6 Another, preferred manner of depositing 'eke hard facing 7 composition 20 on the bearing precursor surface 22 it to utilize 8 a powder feeding apparatus (not shown) ofterl used in conjunction 9 with laser welding apparatus (not shown). Such apparatus are well known to those skilled in the metallurgical arts, and are 11 commercially available. They are similar in construction and 12 operation to the apparatus described in United States Patent No.
18 4,243,867, the specification of which is hereby expressly 14 incorporated by reference.
16 When a powder weeding apparatus (not shown) is utilized 16 in the process of to present invention, the powdered hard facing 17 composition 20 is deposited from the apparatus (not shown), into 18 the path of a laser beam. The deposited powder is substantially

19 immediately impacted with the laser beam and melted thereby.
I Using the powder feeding apparatus together with the laser beam 21 in the process of the present invention can be characterized as 22 substantially simultaneously depositing and melting the powdered 23 hard facing composition 20 on the surface 22.
24 Referring now to Figure 2, yet another preferred mode is shown for depositing the hard facing composition 20 on the 26 bearing precursor surface 22. The powdered hardfaGing composition 27 22 is intermixed with a suitable binder Into shown) to form a 28 paste (not shown). The paste (not shown) is placed as a layer 30 lZZ9959 1 on the bearing precursor surface 22. The binder (not shown) may 2 be volatile solvent such as ethyl, isopropyl or n- bottle 3 alcohol. Alternatively, the binder snot shown) may be cellulose 4 ascot and tither cellulose based or like nonvolatile binding material.
6 The binder (not shown), however, is preferably resnoved 7 from the hard facing metal composition 20 before the composition 8 20 is melted by application of the high energy beam. As it will 9 be readily appreciated by those skilled in the art, a volatile solvent binder (not shown is readily removed from the Harding 11 eomposi~ion 20 by evaporation. the evaporation may ye 12 facilitated by heating in a furnace snot shown) or the like. A
13 non-volatile binder snot shown), such as cellulose acetate, may 14 be turnoff by baking in the furnace (not shown) or the like.
I Other methods for depositing the powdered hard facing 16 metal composition 20 on the bearing precursor surface 22 involve 17 painting or spraying a paste (not shown of the composition 20 18 (mixed with a binder) on the surface 22, or dipping the substrate 19 24 into the paste (not shown). Still other methods for applying the hard facing composition 20 to the bearing precursor surface 22 21 may become apparent to those skilled in the art in light of eke 22 present disclosure 23 In order Jo remove residual moisture, it is 24 advantageous Jo subject the composition 20, after it had been 23 deposited in the bearing precursor surface 22, to temperatures up 26 to approximately 300 degrees F. This is helpful even when a 27 volatile binding agent is not used. When a volatile binder is 29 used, this step helps to remove last residues of the volatile lZ29959 1 binder .
2 In accordance with an important feature of the present 3 invention, the hard facing metal composition 20 it rapidly melted 4 on the bearing precursor surface 22 and is permitted to rapidly 5 solidify in an unconstricted manner, in order to obtain a strong 6 metallurgical bond between the hard facing metal 20 and the 7 underlying bate metal of the substrate I The foregoing is 8 accomplished by scanning the powdered hard facing composition 20 9 with the above-~oted high intensity energy source or beam in a 13 predetermined pattern only, so a to melt the hard facing metal 20 11 only in areas isolated from one another. On Figures 2 through 8, I the solidified hard facing metal areas bear the reference numeral 13 I .
14 Isolated areas 32 of the hard facing metal fused or 15 metallurgically bonded to the bearing precursor surface 22 may be 16 in the configuration of elongated strips 28~ shown on Figures l, 17 2, 3, and 4, a chevron like pattern of strips 28 (Figure 5), or 18 in islands 34. The islands 34 art best obtained by using a 19 pulsating laser beam. The islands 34 may be round, a Winnie on

20 Figure 6, or substantially rectangular (not shown).

21 typical width of the strips 28 of the solidified areas

22 32 ox top hard facing metal 20 is between l/8" to l/4", whereas

23 separation between adjacent strips 28 is typically between l/32"

24 to l/8". Right of the solidified hard facing metal areas 32 or

25 strips 32 protruding from the underlying substrate 24 depends on

26 the desired qualities of the final bearing structure to ye

27 obtained in accordance with the present invention. Typically,

28

29 1 ¦ the height is between 1/16~ to 1/8~. In order to obtain a solid 2 ¦ hard facing eel area 32 of any desired height, the deposited 3 ¦ paste of hard facing composition 20 (before melting) must be 4 ¦ approximately twice the desired height.
S ¦ Figure 2 schematically shows a solidify ted hard acing 6 ¦ metal strip 28 formed from the layer 30 of hard facing composition 7 ¦ paste by passage of an appropriate high intensity energy beam ¦ The phantom lines of Figure 2 indicate rouser lines where the 9¦ energy beam is Jo be passed to obtain more, parallel disposed, 10 ¦ solid hard facing petal strips 28.
if¦ Presently available state-of-the-art laser devices can 12¦ be utilized for providing the scanning energy beam necessary for 13¦ practicing the process of the present invention.. Such laser 14 ¦ devices are available e.g. from the Industrial Laser Division ox I ¦ Spectra Physic Corporation, Mountain View, California. These 16 ¦ laser devices are well known by those skilled in the 17 ¦ metallurgical arts, and are presently used for laser welding 18 ¦ cladding, cutting and like applications 19 ¦ In connection with the foregoing, it is noted that 20 ¦ whereas use of a laser beam is preferred in the melting step of 21 ¦ the process of the present invention, other energy sources can 22¦ also be used. The principal requirement in this regard is for a 231 concentrated, intense heat or energy source which rapidly melts 241 the hard facing metal composition 20 on the surface 22 of the I substrate 24, and thereafter permits it to solidify rapidly in a 26 substantially unconstricted manner. Certain electron beam 27 emitting devices satisfy this requirement. As still another 28 possibility, gas tungsten arc welding devices may also be lZZ9959 1 utilized.
2 As is known in the established art of laser welding, 3 the application of the laser beam to effect fusion of two metal 4 objects must be performed under a protective blanket of an inert gas, such as argon. Therefore, in the present invention also, an 6 argon blanket is u Ed during the laser beam scanning step 7 Union or metallurgical bonding of the hard facing metal 8 composition 20 to the base metal substrate 24 in isolated areas 9 only, by a high intensity energy beam, such as the laser beam, 10 provides the the resulting solid hard facing metal areas 32 with 11 excellent structural integrity. Furthermore, the metallurgical 12 bond between the hard facing metal areas 32 and the underlying 13 substrate 24 is very good. Because the solid hardf~cin~ metal 14 areas 32 are narrow, cooling stresses are minimized, and there is only a low level of dilution of the hard facing metal areas with 16 the base metal of the substrate 24. Still further, the laser lo beam 3Ç passe only once upon each area of hard facing 18 composition, and therefore avoids tempering the solidified areas 19 32 with repeated or prolonged heat contact.
The foregoing advantages are in contrast with the 21 characteristics of the laser fused continuous hard facing metal 22 surface described in United States Patent No. 4,243,867 and 23 Reissue Patent No. 29,815. In these and other prior art I continuous hard facing material deposits, the cooling stresses are I large These stresses often cause cracking of the deposited hard 26 surface, particularly when the arrowhead carbide, bride, or nitride 27 content of the hard facing composition is high. Because cooling 29 stresses are minimized in accordance with the present invention, l ~Zz93~9 1 the hard facing materials used in the present invention may have 2 relatively high arrowhead material (such as carbide) contents.
3 Referring now to Figure 3, an intermediate product 38 4 is shown which is obtained in accordance with the present invention. In this intermediate 38, several strips 28 of the 6 hard facing meekly composition are metallurgically bonded to the 7 underlying surface 22 of the substrate 24. As shown, the strips 8 28 of the solidified hard facing metal arias 32 have a somewhat 9 trapezoidal cross-section. This is a typical t:ross-section 10 formed when the lo or beam 36 utilized for creating the strips 28 11 has a substantially square energy proof tie 12 The intermediate product 38 shown on Figure 3, has no 13 . excess powdered or pasty hard facing composition .20 on the 14 substrate surface 22. This is, because any excess hard facing I composition 20 has been removed in an intermediate step of the 16 process by simple brushing, blowing or like operation. Excess 1q hard metal splashing located in gaps 40 between the strips 28 18 are also removed from She base metal substrate 24 by grinding, 19 and the hard metal strips 28 are demurred in additional intermediate steps.
21 Referring now to Figures 7 and 8, still further 22 intermediate products go are shown which are obtained in the 23 course of practicing the process of the present invention After 24 the intermediate steps noted above, the gaps 40 between the I protruding solid, hard metal areas I are filled with a melt of a 26 soft metal 44. In order to obtain the composite bearing surface 27 26 of the present invention, the soft metal 44 should have an Arc 29 hardness of at least five (5) Arc units less than the hardness of I I

1 the solid hardfacir~g metal areas 32. Suitable soft metals 2 include commonly known brazing and bearing metals and alloys, 3 such a silver silver bayed alloys, copper, copper based alloys, 4 tin, tin bayed alloys, nickel, nickel based alloys, lead and lead base alloys 6 The manner of filling the gaps 40 with the soft metal 7 I is not an tidal, The 60ft metal 44 may be applied to the 8 hard facing metal areas 32 bearing 6urfacs 22 of the substrate 24 9 in the form of a powder, troupe or rod Into shown) of soft metal 0 44, or the like. The soft metal 44 it then melted in a furnace 11 snot shown), under a welding torch (not shown), or by layer or 12 electron beams.
13 Peter the melt of the soft metal 44 had solidified 14 thereby willing the gap 40, the intermediate product 42 it machined in a conventional manner to provide the composite 16 bearing surface I of the prevent invention.
17 With particular reference again to Figure 7 and 8, 18 several possible depths of machining art noted. It it apparent, 19 that different depth of machining remove differing amounts of metal from the composite structure. Figures 7 and 8, each WOW
21 schematically, as examples, two (2) different planes 46 and 48 to 22 which the composite beating may be machined down.
23 An inspection of these Figures reveals that the ratio 24 of exposed hard metal areas 32 Jo soft metal areas 50 in the 25 final bearing surface 26 depends on several factors. These I pharaoh include the dimensions and spacing of the hard metal 27 composition 20 on the bearing precursor surface 22, and the depth 28 of machining which it performed in the final step of the process.

Furthermore, the ratio of hard to soft metal areas I and 50 also i, 1 depends on the energy profile of the laser beam 36 which is used 2 in the scanning or melting step. As noted above, when the beam 3 36 is of a substantially square energy profile, the solidified 4 hard metal strips 28 have the trapezoidal cross-section indicated on figure I When the laser beam 36 has an energy profile 6 configured substantially as a Gaussian curve, the resulting hard 7 metal strips 28 have a configuration which is schematically 8 indicated on Figure 8.
9 Figure 9 shows an el~ctronmi~roscope view of a portion of the composite bearing surface 26 of a sample which way 11 prepared in accordance with the present invention, and was wear 12 tested. Dark areas on the Figure indicate hard metal surfaces 13 32, and the white area indicates a soft metal surface 50. Dark 14 spots in the white area of the figure indicate hard metal particles 52 which were abraded from the beaning surface 26 18 during wear, and were trapped in the soft metal surface area 50.
lo This represents another advantage of the novel bearing structure 18 of the present invention. As is known, abraded hard metal 19 particles 52 can cause serious damage when they remain between slidingly engaging bearing surfaces. By trapping the abraded 21 hard metal particles in the soft metal areas, the bearing surface 22 of the present invention eliminates or minimizes the above noted 23 source of damage.
24 In summary, the composite bearing surface of the I present invention has improved wear characteristics, because the 26 hard areas 32 have increased structural integrity and hardness, 27 the soft metal areas 50 act as effective heat sinks, abraded hard 28 metal particles are trapped in the soft metal, and certain soft lZZ9959 1 metal compositions have good lubricating properties. Whereas, 2 the improved bearing urge or trotter of the present 3 invention has many applications, it it especially advantageously 4 used in valve seats, rock bit tearings, engine and cranXfihaft 5 bearing, and in internal surfaces owe cylinders and pistons, 6 The following specific example de~cribe6 in detail the 7 preparation of a sample bearing surface or structure of the 8 present invention. It should be remembered, however, that rather 9 than the ensuing detailed example, solely the claims measure the 0 scope of the present invention.
11 Specific Employ 12 An ASSAY 4815 steel block of 4.00" x loon s 0.04"
lo dimensions had a depression or channel of 0.625" width and 0.04"
lo depth machined in one of its elongated face. nominal chemical 15 composition of the ASSAY 48l5 steel yin percentages Of weight it 18 as hollows: Carbon 0~13-0.18%; Manganese 0~40-0.60%; Silicon 17 0.15-0.3096; Nickel 3.25-3.75~; Molybdenum 0.20-0.3096; Phosphorous 18 up to a maximum of 0.035%; Selfware up to a maximum of 0.040%, lo with the balance being Iron.
2Q The machined channel in the steel block was filled with 21 a powder of STILT Jo. } hard facing composition, having an 22 average particle size of approximately 50jX m. The steel block 23 inlaid with the powdered hard facing composition, was placed on a 24 movable table. In one sample two (2), in another sample three (33 trips of the powdered hard facing composition were melted 26 under a laser beam of 5 OW energy output. During the melting 27 prows the table moved the sample at a rate of l5"/min., end the 28 laser beam diameter on the powder surface was 7.00 mm (0.28").

3~11 ~z9~

1 ¦ The eying was performed under a protective shroud of argon gas.
2 ¦ The elite strips quickly solidified into solid hard hardfa~ing 3 ¦ metal strips strongly bonded to the underlying steel 4 ¦ Excess, unsolidified hard facing powder was removed, and ¦ hard metal splashing between the strips wets removed by a 61 grinder. An aluminum bronze alloy was melted with an 71 oxygen-aoetylene torch Jo overlay the strips end fill the gaps 81 between the strips The aluminum bronze alloy had the following 9 ¦ nominal chemical composition (in percentages of weight):
10¦ Aluminum 14.5~; Iron I with the balance being Copper.
11 The composite deposits of SATELLITE and aluminum bronze 12 were machined Jo produce a flat surface of an 8 to 10 RUMS finish.
13 The surface showed the alternating layers of SATELLITE No. 1 and 14 aluminum-bronze. Sample blocks were cut from the finished steel 20 ¦ b1D~ks for we testing.

I

I
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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A composite metal member suitable for providing a bearing of improved wear characteristics, the member comprising:
a substrate of a base metal composition, having a bearing precursor surface;
a plurality of spaced areas of a hard metal composition metallurgically bonded to the bearing precursor surface and protruding therefrom, each area of hard metal composition being substantially entirely isolated from all other areas of hard metal composition thereby forming gaps between said protruding areas, and a soft metal composition disposed on the bearing precursor surface to substantially fill the gaps between the protruding areas of the hard metal composition, the combined spaced areas of the hard metal composition and the soft metal composition adapted for being machined into a bearing surface.

2. The composite metal member of Claim 1 wherein the areas of hard metal composition are substantially regularly spaced .

3. The composite metal member of Claim 2 wherein the areas of hard metal composition comprise substantially continuous strips.

4. The composite metal member of Claim 2 wherein the areas of hard metal composition comprise islands.

5. The composite metal member of Claim 1 wherein the base metal composition is selected from a group consisting of ferrous metals, ferrous metal based alloys, nickel, nickel based alloys, cobalt, cobalt based alloys, copper and copper based alloys.

6. The composite metal member of Claim 1 wherein the hard metal composition is a hardfacing alloy selected from a group consisting of metal carbide based hardfacing alloys and intermetallic alloys.

7 . The composite metal member of Claim 1 wherein the soft metal composition has an Rc hardness at least approximately 5 units less than the Rc hardness of the hard metal composition.

8. The composite metal member of Claim 1 wherein the soft metal composition is selected from a group consisting of copper, copper based alloys, silver, silver based alloys, tin, tin based alloys, lead, and lead based alloys.

9. A composite metal bearing comprising:
a substrate member of a base metal composition including a support surface underlying a bearing surface;
a plurality of spaced areas of a hardfacing metal different in composition than the base metal composition, said spaced areas of the hardfacing metal being metallurgically bonded to the support surface of the substrate, protruding therefrom, and being isolated from one another so as to form gaps between adjacent areas;
a soft metal composition having a hardness of at least five Rc units less than the hardness of the hardfacing metal, the soft metal being disposed on the support surface in the gaps among the spaced areas of hardfacing metal and substantially entirely filling said gaps, the areas of hardfacing metal and the soft metal jointly comprising the bearing surface.

10. The composite metal bearing of Claim 9 wherein the gaps between areas of the hardfacing metal are approximately of 1/32" to 1/8" magnitude.

11. The composite metal bearing of Claim 9 wherein the areas of hardfacing metal comprise substantially elongated strip being approximately 1/8"-1/4" wide.

12. The composite metal bearing of Claim 9 wherein the base metal composition is elected from a group consisting of ferrous metals, ferrous metal based alloys, nickel, nickel based alloys, cobalt, cobalt based alloys, copper and copper based alloys, the hardfacing metal is selected from a group consisting of carbide based hardfacing alloys and intermetallic hardfacing alloys, and the soft metal is selected from a group consisting of copper, copper based alloys, silver, silver based alloys, tin, tin based alloys, nickel, nickel based alloys, lead and lead based alloys.

13. A composite metal bearing having a bearing surface of alternating areas of a hardfacing metal composition and a soft metal composition, prepared by the process comprising the steps of:
depositing a powdered hardfacing metal composition on a suitable bearing precursor surface of a metal substrate of a base metal composition;
scanning with a high intensity energy source the powdered hardfacing composition in a predetermined pattern to cause rapid localized melting of the hardfacing composition in the predetermined pattern and to form in the predetermined pattern a metallurgical bond between the hardfacing composition and the substrate, the predetermined pattern being configured to provide spaced areas impacted by the energy source;
permitting rapid cooling of the molten hardfacing composition whereby isolated spaced areas of solid hardfacing composition are formed which protrude from the precursor surface in the predetermined pattern;
substantially filling all gaps between the protruding areas of the hardfacing composition with a melt of a soft metal composition;
permitting the melt of the soft metal to solidify, and removing a layer of the hardfacing composition and of the soft metal composition to provide the bearing surface of the alternating areas of hardfacing metal and soft metal.

14. The composite metal bearing of claim 13 prepared by the process wherein the powdered hardfacing composition is deposited on the precursor surface in a substantially uniform layer, and wherein after the step of rapid cooling of the molten hardfacing composition the process further comprises the step of removing remaining powdered hardfacing composition from the bearing precursor surface.

15. The composite metal bearing of Claim 14 wherein the powdered hardfacing composition is intermixed with a suitable binder for the step of depositing on the precursor surface.

16. The composite metal bearing of Claim 15 wherein the binder is a volatile solvent.

17. The composite metal bearing of Claim 15 wherein the binder is cellulose acetate.

18. The composite metal bearing of Claim 13 prepared by the process wherein the step of depositing the powdered hardfacing composition and the step of scanning with a high intensity energy source are conducted substantially simultaneously.

19. The composite metal bearing of Claim 13 wherein the bearing surface is substantially parallel with the underlying bearing precursor surface of the metal substrate.

20. The composite metal bearing of Claim 13 wherein the high intensity energy source used in the step of scanning is a laser beam.

21. The composite metal bearing of Claim 13 wherein the base metal composition is selected from a group consisting of ferrous metals ferrous metal based alloys, nickel, nickel based alloys, cobalt, cobalt based alloys, copper and copper based alloys, the hardfacing metal is selected from a group consisting of carbide based hardfacing alloys and intermetallic hardfacing alloys, and the soft metal is selected from a group consisting of nickel, nickel based alloys, copper, copper based alloys, silver, silver based alloys, tin, tin based alloys, lead and lead based alloys.

22. A process for preparing a composite metal bearing, comprising the steps of:
depositing a hardfacing metal composition on a suitable bearing precursor surface of a substrate member of a base metal composition;
scanning with a high intensity energy source the hardfacing composition in predetermined pattern to cause rapid localized melting of the hardfacing composition in the predetermined pattern and to form in the predetermined pattern a metallurgical bond between the hardfacing composition and the substrate, the predetermined pattern being configured to provide spaced areas impacted by the energy source:
permitting rapid cooling of the molten hardfacing composition whereby isolated, spaced areas of solid hardfacing composition are formed which protrude from the precursor surface in the predetermined pattern;
substantially filling all gaps between the protruding areas of the hardfacing composition with a melt of a soft metal composition;
permitting the melt of the soft metal to solidify, and removing a layer of the hardfacing composition and of the soft metal composition to provide a bearing surface of alternating areas of hardfacing metal and soft metal.

23. The process of Claim 22 wherein the high intensity energy source used in the step of scanning,is a laser beam.

24. The process of Claim 22 wherein the step of depositing the hardfacing metal composition and the step of scanning are conducted substantially simultaneously.

25. The process of Claim 22 where in the step of depositing, the hardfacing metal composition is mixed with a suitable binder, and the step of scanning is conducted after the step of depositing.

26. The process of Claim 22 where in the step of depositing, the hardfacing metal composition is deposited on the bearing precursor surface as a substantially uniform layer covering said precursor surface; the step of scanning is conducted after the step of depositing, and wherein after the step of rapid cooling the process further comprises a step of removing loose hardfacing composition remaining on the bearing precursor surface.

27. The process of Claim 22 wherein the step of scanning is conducted in a predetermined pattern configured for providing substantially parallel disposed, substantially regularly spaced strips on the precursor surface in which the hardfacing metal composition is to be impacted by the high intensity energy source and to be melted thereby.

28. The process of Claim 22 wherein the step of scanning is conducted in a predetermined pattern configured for providing isolated, substantially regularly spaced islands on the precursor surface in which the hardfacing composition is to be impacted by the high intensity energy source and is to be melted thereby.

29. The process of Claim 22 wherein the step of removing is conducted to provide a bearing surface disposed substantially parallel with the underlying precursor surface.

30. The process of Claim 22 wherein the base metal composition is selected from a group consisting of ferrous metal , ferrous metal based alloys, nickel, nickel based alloys, cobalt, cobalt based alloys, copper, and copper based alloys, the hardfacing metal composition is selected from a group consisting of carbide based hardfacing alloys, and intermetallic hardfacing alloys, and the soft metal is selected from a group consisting of nickel, nickel based alloys, copper, copper based alloys, silver, silver based alloys, tin, tin based alloys, lead, and lead based alloys .