CA1202836A - Method of producing novel silicon carbide articles - Google Patents

Method of producing novel silicon carbide articles

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Publication number
CA1202836A
CA1202836A CA000429296A CA429296A CA1202836A CA 1202836 A CA1202836 A CA 1202836A CA 000429296 A CA000429296 A CA 000429296A CA 429296 A CA429296 A CA 429296A CA 1202836 A CA1202836 A CA 1202836A
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Prior art keywords
sic
carbon
graphite
articles
whiskers
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French (fr)
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John V. Milewski
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US Department of Energy
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US Department of Energy
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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/56Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
    • C04B35/565Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
    • C04B35/573Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide obtained by reaction sintering or recrystallisation
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/71Ceramic products containing macroscopic reinforcing agents
    • C04B35/78Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
    • C04B35/80Fibres, filaments, whiskers, platelets, or the like
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00Energy generation of nuclear origin
    • Y02E30/10Nuclear fusion reactors

Abstract

METHOD OF PRODUCING NOVEL SILICON CARBIDE ARTICLES

ABSTRACT OF THE DISCLOSURE
A method of producing articles comprising reaction-bonded silicon carbide (SiC) and graphite (and/or carbon) 18 given. The process converts the graphite (and/or car-bon) in situ to SiC, thus providing the capability of eco-nomically obtaining articles made up wholly or partially of SiC having any size and shape in which graphite (and/or carbon) can be found or made. When the produced articles are made of an inner graphite (and/or carbon) substrate to which SiC is reaction bonded, these articles distinguish SiC-coated graphite articles found in the Prior art by the feature of a strong bond having a gradual (as opposed to a sharply defined) interface which extends over a distance of mils. A method for forming SiC whisker-reinforced ceramic matrices is also given. The whisker-reinforced articles comprise SiC whiskers which substantially retain their structural integrity.

Description

lZC12B3t;

METHOD OF PRODUCING NOVEL SILICON CAP~IDE ARTICLES
The present invention relates generally to reaction bonded sil~con carbide articles and to methods of prepara-tion thereof and more ~articularly to silicon carbide^
graphite articles of manufacture and to methods of produc-ing ~uch articles, In ceramic matrix technDlogies, there has been a need for high performance structural ceramic composites made of silicon c~rbide ~and optionally including some graphite).
These have ~een needed, for example, for liner6 of fusion reactors and for turbine blades and ~tators. Other 8ppli-cations have been for tubular heat exchangers, recupera-tors, and regenerators. ~owever, because silicon carb~de 18 a refractory material, it is made into complex shapes with great difficulty.
lS Whi~kers ~i.e., fibers which have been grown under controlled conditions that lead to the formation of hi~h-purity s~ngle crystals ln fiber form) of silicon carbide are known to have gre~t strengths. It would be desirable to u~e ~uch whi6kers to reinforce ceramic composites.
~owever, incorporating ~uch whiskers into ceramic compo~-~te~ has been difficult because blending the whiskers with the cer~mic powder followed by cold pressing, hot preQs-ing, or extruding will severely damage the whiskers and reduce ~helr reinforcement ability.
On the other hand, graphite and carbon can be easily formed lnto a wide variety of shapes and ~izes (e.g., by 12~ ~B;~

machining, by extruding precursors of graphlte, and by other means~ Therefore, ~t would be hiqhly desirable to be able to use the graphite and carbon shapes as forms and to convert those forms to 6ilicon carbide5 with the sili- .
5 oon carbide ~onvers~on extend~ng to any chosen depth withln the original carbon or graph~te structure. It would alco be very desirable to obtain whi~ker-reinfor~ed ~eramic matrix composite~ in which the ~ntegrity of the whiskers has been preserved.
~0 It ~s known that ~ on monoxide ~i.e~, SiO) and car-bon t~) react to form 6ll~con carbide tsic). Jt has been generally known that a thin ~urface layer of SiC ha~
formed zs ~ by-prod w t in various reactions. During the growth of SiC whi~kers on ~ carbon ~ubstrate in which S~O
and C~4 gases are present, not only are SiC whi~ker~
grown at e~ch catalyst site but most'of the surrounding areas o~ carbon are surface converted to SiC by the pre~-ence of low concentr~tion~ of SiO gas ln the atmosphere about the oarbon substrate.
~C ~0 date, attempts ~o obt~in economlc~lly goGd ~era~ic structures made of Si~ have includea forming a mixture of powder of ~Drbon or graphite with powdered s~l~con ~nd then he~t~n~ that mixture, ~o as to melt the s~licon in ~he presence of the carbon so they will react to form ~ con ~ar~ide~ ~his proeedure, however, has the draw-back of ~orming a silicon carbide material with a high degree of porosity since the mixture of pressed powders ha~ pvresJ and the c~nver~ion process i5 not h densifi~a-tion proces~ by the addit~on o~ new ~atter (l.e~S only old mat~r~al i~ reacted to change for~). Furthermore, the article~ of manufacture produced by thi~ pro~e~s may not be formed ~ompletely o~ s~licon carbide because o~ inade-qu~te ~xng ~nd disper~ion of the ln~t~al silicon and c~rbon p~w~er6 or because they may not bave been held long enouQh to complete the d~ffu~$on~ o; ~ t~e SiC i6 formed~ the article.~ shrink becau~e the bulk volume of S~C
less ~han that of carbon or sllicon alone.
Ano~her procedure is disclosefl ~n De ~a~c~ et al,, ~Preparation for Storage of Fission Products~ S~ Patent 3,994,822~ ~n thls proce~s, ob~ect~ m3de of carbon or graphite are s~tuated w~thin ~ bath o liqu~d silicon ~nd form ~ on carbide article~ of manufacture. Thi~ pro-cess would inv~lve ~ifficu~ties in workin~ with a large vGlume of hot l~quid metal ~n an inert atmosphere, and it ~s believed that the liquld would not have great penetra-tion abillty into fine pore~ due to it~ liqu~d viscosity ~nd r~te of reaction. Purthermore, the l$quid would rea~t mostly with the ~urfa~e.
Other attempts to obta~n go~d ceramic ~tructure~ eco-nomically h~Ye ~nclu~e~ coating mater~ls with ~ilicon carbide by deco~posing a ~ilane, CH3SiC13, ta~ dis-clo~ed for example in L. Aggour et al. ~VD of Pyro-Carbon Si~, TiC, ~iN, Si, and Ta on Different Type~ of ~arbon Fiber~," Carbon, 1974, vol. 12, pp. 358-362) and by chemi~ -cal vapor deposition reactions tsuch ~8 are disclo~ed in ~auer, U.S. Pat~nt 3,9gl,248, ~n Bourdeau, U.S. Patent 3,369,920, and in Wainer, ~.~. Patent 3,269,802). In ~u~h ? re~t~ons, however, the external volume of the ob~ect belng coateA ~ncrease~ a~ the coat~ng reaction proceed~.
Furthermore~ ~s the th~ckness of the coatin~ increases, problems c~f ~onding the ~oating to the fiubstr~te lncrea~e. Thi~ ~8 ~n ~ontradi~t~ction to ~ ~onver~on proces~ whereln the ~ub~trate ~tself i~ converted, rather than merely coated.
Therefore~ desp~te what has been known ~n the prior ~rt, a need ha~ exi~ted unt~l now for ~ method of easily an~ e~ono~ically making silicon carbide 6tru~tures o ~he Yame ~ize~ ~nd ~hape~ a~ the ~izes and ~hape~ ln ~hiGh graphit~ and c~rbon ean be obtained~

SUMMARY OF TH~ INVENTIO~
ObjQct~ of th~ inv~ntion ars a method of economicallymaking object~ compri~ing ~ilicon carbide, having ~ood mechanical strengths, and having little or no problem Oe S bond breakage between the converted SiC portion6 and the original carbon (and/or graphite~ matrix.
Other objects of this in~ention ar~ an economical method o~ making objec~ ~onsi~tinq oP silicon carbide.
Further object6 o~ this invention are a method of 10 easily incorporating SiC whiskers, SiC ~iber~, or SiC
filament~ into ~eramic matrix composites and the articles thus produced.
A further object of this invention is an inexpensive article of manufacture mad~ at lea~t partially of silico~
carbide whiskers and having any chosen ~hape and size in which carbon or graphite can be formed.
A still ~u~ther obje~ of thi~ invention is an article of manufacture in which sili~on carbide is located near the exterior ~urface of an in~r graphite structure, wherein the arSicle will have substantially improved shear strength between the carbon core and th~ heavily converted SiC surface a~ compared with coated graphite and carbo~
substrate~ (this imerovement being a direc~ predicted result of ~he graded density inter~ace).
Additional objec~s, advant~ges and novel features o~
the invention will be set for~h in part in the description which follow~, and in part will become apparent to those skilled in the art upon examination o~ the follo~ing or may be leasned by practice oP th~ invention. The objects and advantages of the invention may be realiz~d and attained by means of the i.nstrumental.ities and comhinations particularly pointed out in the appended claims.

Accordiny to the pre~ent invention there is provided a method of producing articles of manufacture which are reinforced with silicon carbide (SiC) whiskers, without destroying the integrity of the whiskers, comprising the steps of:
(a) dispersing and mixing SiC whiskers in a mi~ture of solvent and resin with carbon or graphite particles of a size chosen for good mixing and efficient packing, so as to form resin bonded and coated fibers and particles;
(b) allowing the solvent to evaporate from said mixture;
(c) forming said resin bonded fibers and particles into a final shape in which said resin will finally be cured;
(d) heating said final shape to about 800C to carbonize said resin and so as to form a carbon-bonded SiC whisker reinforced composite structure which is a non-abrasive matrix in which the whiskers maintain their structural integrity;
(e) generating SiO gas at a concentration of at least 5 volume percent by heating solid silicon dioxide (SiO2~ to a reaction temperature of between approximately 1400 and 1600C in an atmosphere of hydrogen; and (f) contacting said SiC whisker reinforced composite structure with said SiO gas at said reaction temperature of between approximately 1400C and 1500C for a period of time sufficient to convert at least some of the carbon in said structure to SiC, whereby there is formed a structure containing SiC as well as SiC whis~ers, and wherein said whiskers are not damaged by the fabrication process.

Also in accordance with the present invention there is provided a method of forming a shaped product having a surface layer of silicon carbide (SiC) reaction bonded to `1'` '1 an inner structure conxistincl essentially of carhonr CO]II-prisin~ the steps o~
(a) generating SiO gas at a concentra-tion of between about 5 and 50 volume percent by heating solid silicon dioxide (SiO2) to a reaction temperature of between approxi-mately 1500 and 1550C in an atmosphere of hydrogen, said solid silicon dioxide being in the form of a powder surround-ing said structure (b) contacting said structure with said SiO gas at said reaction temperature of between approximately 1500C and 1550C for a period o~ time sufficient to form a layer of SiC on the surface of said structure by chemical conversion of carbon in said structure to SiC, whereby a layer of reaction-bonded SiC is formed on the surface of said struc-ture without significantly changing the dimensions of saidstructure.

In a preferred embodiment said SiO2 is at least part of the composition of silica containing bricks which are sliced or powdered and fitted to surround said structure.

Further preferably said reaction time is about 12 hours, wherein the thickness of the layer of said conversion to SiC extends within said structure to about 1.5 millimeters, and wherein the density of said structure after conversion is about 2.~ g/cm3 (and has about 20% porosity).

Although SiO has reacted with carbon or graphite in the prior art to form SiC as a by product, that reaction has not until now been used to full advantage because the SiO has been present only in low concentration (i.e.~ 0 to 1 volume percent, v/o~. By the process of the invention, however, it is required that SiO gas be generated in substantial concen-tration (i.e., greater than 5 v/o and generally less than 50 v/o) and made available in close proximity to the graphite structure to be converted.

r ~

g~

The present invention als~ compri~es, in accordance with its ob~ects and purpo~es, articles of manufacture compris~ng silicon ~arbide and graphite (and/or carbon)~
wherein the silicon carbide and the graphite ~anaJor car ~on~ ~re reaction bondea together ~nd mer~e grad~ally into - e~sh other in a ~raduated ~nterface (3S opposed to a ~h~rply defined ~nterface) ~ver a di~tance ~f at least 50 to ~everal hundred micEons Sas opposed to 1 to 20 m~cron~, which i~ typ;cal of an interface from a coat~ng prooe~s).
DESCRIPTION OF PREFERRED F.MBODIMENT5 OF THE INVENTION
In the practi~e of the method of the invention, ~t 1~
required that the volume percent of SiO gas that contacts the surf~ce of the substrate (whlch ~s made either of ~raphite or ~arbon) be qu~te high (i.e., within the ranqe from a~out 5 to a~out 50 volume per~ent SiO gas~ and that that ~Gncentr~tîon be maintained during the time of reac~
tion Ide~cribed below). 10wer concentrations will requ~re conver~ion t~mes too long to be economical. It ~s gener-. 20 ally difficult to obtain greateE than 50 v/o S~O becausethe 510 generation proce~s ~ u~ually performed ln hy~ro-~en or other carrier ga~ ~hich i8 nGr~ally u~ed in at leAst a 50 ~o dilution.
Con~r~2y to other methods where only tbe ~urface $~
2S coated f ~ here delivered intO the porous graphite ~tru~ture~ bot~ ~nverting and filling by addin~ mass (o elemental ~ onl ~lth~n the ~omposi~e, thereby densify-ing the ~tructure while external d~mens~ons are hel~
con~tant.
~hieving thi~ high ~oncentration of ~iO gas will be done by one of the foll~wing methods, each of which gener-a~es SiO gas ~n close prox$~ity to the sub~trate7 thu6 prGduc~g 8~C t~ ~n extent ~uc~ that 1t ~s ~u~h ~ore than a ~ere by-pr~du~ of l~nother re~ction.

The reaction for formlng ga eous 5iO i~ a~ follows:
Si2 ~ H2 SiO ~ H20 (1) Thi~ reac~ion take~ place at temperatures aboYe about 1350C.
In order to use the reaction given in Equation above, SiO is generated in the practice of the invention by either o~ the following procedures.
In thQ f irst procedure, a porou~ brick that i~ high in ~ilica content is sliced into thin sections of about 5 to 20 millimeters thick. The sliced bric~ is then u~ed to enclose the gr~phite ~ub~trate which i~ to be converted in whole or in part to SiC. When the brick is exposed to a dry hydrogen atmospher~ at a temperature of at least about 1400~C, the SiO2 reduction of Equatio~ 1 takes place, slowly relea~ing SiO gas. A typic~l brick will convere about 3 to about 10 percent of its SiOz material to SiO
per hour depending on its geometr~, temperature, and hydrogen gas flow.
Alternatively, in the second procedure, instead of bricks. SiO2 powder can be used to en~ase the graphite ~ubs~rate ~o be converted by the reaction with hot hydrogen gas.

~h The SiO gas that i~ gener~ted in Equ~tion 1 li~ted above ii u~ea ~ penetrate th~ graphite or oarbon substrat~ anfl ~o convert the ~ubstrate ~o a sub~itrat~ of SiC. Thi~ a ~uite dif~erent prooe~i~ (a~ desicribed 5 below~ ~rom c:oating a graphite ~iubstrate with SiC, such as i8 de~icribed in Bauer. Wainer. and Bourdeau, ci'ced above~
In ~oating a partial vacuum i~ generally used, re~iulti~g in low co~centration~ of rea~tant~i; an~ often i~erfections due to holdin~ device~i re~ult.
Dur;ng the SiC eonvQrSiOn proces~ here used, the SiO
gas penetra~ion and subsequellt con~t~rsion is temp~rature and time de2end~n~. For example. an expo~iure of 16 hour~
at 1400C converts th~ surface o~ a carbon or graphite substrate to a depeh of aboue 1/2 mm7 whe~ea6 at 1500C
15 the ~onver~lion depth would be 2 to 3 mlo. Longer times and higher temp~ratures will convert th~ carbon or graphitt~
sub~itrate to furth~r depth. The temp~rature required for t~ onveriio~ is a~ lea~i~ about 1350 C, which temperatuce i~ required to allow the rea~tion to proceed 20 eo any extellt at all . E~owever, pref erably the temperature will be a minimum within the range fro~ about 1425 to about 1450 C in order to obtain a measurable reactio~
rate. And, more ~referably5 th~ minimu~ reactio~
te~perature will be withi~ the rlnge from about 1500 to about 1550~ in order to get a goo~ reac~ion rate without undestrable 6ide e~fects. I~ a reaceion temperature of ., i~`
~`~

about 1575~ to 1600C or Ihigher ~ ~ used, side reac-t~on~ may occur, incl~ldirlg (A) ~2t3 ~ C--~O + ~2 and ~B) 2~2 ~ C~4. Such ~lde reactions can cau~
the or~glnal carbon ~and/or graphite~ structure being eon-5 verted to shrink ~n ~izel, Flowever, these ~ide react~on~can be reduced and the temper~ture of the SiC-~orming react~on ~an be higher th~l- 1600~C if appropr iate chem~-cal procedures are use~ Such procedures include ~dding CO or C~4 to drive Reactons A and B to the left.
Sufficient t~me for the conver~ion reaction ~
required to allow the conversion to continue to the chosen depth in ~he graphite (and/or ~arbon) ~tructure. A~ des-~ribed above, the time chosen will be a function of the temperature of conver~ion and the desired depth of conver-15 ~lon (which will be ~ function of the geometry ~nd ~ize of the part that 1~ being converted). Larger part6 with ~any complex internal passageways wlll requ~re mo~e time for dl~fu~ion to occur lnto all ~ntri~:ate ar~a~.
The pres~ure in the reaction ves~el ~6 U8UAlly about 2û one atmo~phere in order for l:he converslon to proceed elt ~ati~fa~tory rate. ~t is al~o believed th~t ~he reaction can be run at partial atmospheres or multiple atmo~phere~
~8 long a~ the ~olume per~ent of SiO ~a~ is maintained in the 5 to 5CI v/o range. ~hi~ ~s different f~om greatly redu~ed 9~ concentrations due to reduced pres6ures which are generally u~ed in ~hemi~al-vapor deposition re~ctions ~n order to obtain coating of inter~or portlon~ of ~ub~trate~.
~he ~u~s~rate to be ~onverted ~an be made ei~her of carbvn ~r ~r~phite or ~ny precursor materihl that wil~
~a~i~y conver~ lnto carbon or grsphite, for ex~mple pit~h or phenollc-based re~n~.
~ h~ ~ubs~rate can ~ave a w~de poro~ity ran~e, a~ lOW
a~ a f~w p~r~ent ~nd ~p to 90 or more percent~ ~ddltion ally, the poros~ty ~ould be continuous.

~~

The ~hape of the carbon and,for graphite substrate to be converted to 5i~ ~hould preferably be made w~th a~ uni~
form a cross--~ectional thickness as possible and in ~
geometry that w~ll perm~t acces~ of most of the surfaces 5 to the ~;~O conversion gases. Rowever, any ~hape in which carbon or ~r~ph~te can be found or made is thought to be sui'cable for ~onversion. ~rhe ~lze of the part ~s oJlly l$mited to the ~ize of the atmosphere furnace that 1 avail~ble for use.
In the method of the invention, it is al~o important to pack internal surface~ ~uch as the insides of tubes with the SiO generating mzterial ~f SiC c~onversl~sn ~fi desired in that ~rea.
The f~llowing procedure which is believed to be n*w 15 and unobviou~ can be used to form SiC whi~ker re~nforced 4 cer~m~c matrix s~omposite having high whisker integritie~
which c:ould not be made in the prior art due to diffi-culties ln incorporat i ng SiC f iber~ ~nto an abras~e ~iC
matrix without destruetion of the fibers. In the prior 20 art pro~e~33e~ ixin~ and hot-pressing with ~:era~ic pow ders 1~ exl:remely damaging l:O the ~h~sker integrity. The SiC whi8ker~ are here f~r~t disper~ed or mixe~ with carbon or graphilte particles of a s~ze t:hosen for good mix~ng and efficient p~king (e~g., particles having diameters equal
2~ to or le6~ than fiber i3iameter~0 This mixin~ i8 gentle ~nd rstsn-de~3tructive to l~he whiskers and i~ ~one in ~
~ol~ent-th~inned phenoli~ res~n. ~he resin bonded and ~oated fibers ~nd part~les ~re then spread out to allow the ~olvent ~o evapor~te. Then the pheno~ re~in-~o~ted 30 f $ber~powder ~nix&ures ~re pre%~ed or moldea ~nto the ~hape ln whis:h the resin ~ill ~inally be cured. Next, the resin-bonded ~:omposite i~ slowly he~ted to abc~ut 800& tO ~r-bon~ze the r~in. Thi.s carbon-bon~ed whi~ker reinforce~
compo~te i~ then treated as descr~bed albove for the S~C
35 I:onver81On. At the cvnversion ~emper~tures u~ed, the $iC

whisker~ ar~ stabl~ and can be identified in the stru~tures ateL conversiQn.
EXAMPLES
The ~ollowing exampl~s which illustrate ehe invention ~ere carried out. In each o~ t~e following exampls~, tube~ consis~ing of ~arbo~ or graphite wieh 40% by volu~e of SiC powder were used and had an overall density of about 2.3 g/cc. Although the~ sub~trates w~re not ~ade ~ol~ly of carbon or graphite, such ~ubstrate~ can alternativaly bQ used in the processe~ described belo~
because planar ~tructure~ of carbon and graphite have be~n converted succe~sfully.
The compo~ite tube~ were made by an extru~ion proce~, using th~ following ~omposition and procedures. SiC
powder (obtained from Starck Company, B-10, having aveLag~
particle si2e 0~ 2.38 micron~) was dry mixed with graphite powder (200 ~e~h, or particle size le~s than 74 micron rea~tor grade, Hi CT~. obtained fro~ Spear Carbon Co.) iA
a jar roller. Next, a phenolic resin with 4~ catalyse maleic anhydride (o~tained ~rom Varcum Div. of R~ichold Chemical CC3. )~ wag addedd and the mixture was thinned to abou~ 50% with acetone (technical grade, which can be obtain~d from any chemical supply house). The mixture was hand mixed with a ~patula in the jar to a smooth con~i~tency. Thi~ mi~ed ~aterial was the~ spread out thinly o~ a t~ay and heated to about 50C eo evaporate the acetone ~ol~ent. Th~ mixture was then extrud~d to t~e shape of a tube. The tub0 was fir6t heated ~or 16 hours ae 200C ~o cure the r~sin. Then, th~ resin wa~
carboniz~d by a 810w heating to 800 C at a raee of 100C per hour. A~eer carbonization. th~ carbon was convert~d into graphi~e by gradually heating up to 2000 C in 4 hour~ and ~olding a~ 2009C for 2 hour~.
This final graphite conversion step i~ not necsssary for t~o ~iC converSio~ ~roces~, however ~, t:~

The SiC pow~er-~illed graph~t2 ~and~or ~arbon) compog-lte t~be~ that were formed ~n the above-des~ribed way were then subjected to the following SiC converB~on process .
The composite tubes were packed in a frame of K30 bri~.k (which can be obtained from Babcockæ and W~lcox Company), ~o that the tubes were ~ompletely enclosed within parallel layer~ of bri~ks. The brick~ were set on ~ solid carbon træy to facilitate handling. This assembly was 19 cen~l-meters long, 6 centi~eters wide, and 6 centimeters high.
This assembly was then in~erted into a 7.62 centimeter diameter hydro~en atmosphere tube furnace ~nd W8S then h~tea. In each of the examples described below, the heating procedure Yaried ~omewhat.
EXAMPL~ 1 In th~ 8 Example, a tube fuenace (as descr~bed above) . was flu~hed with dry hydrogen (e.g. -50C dew point or lower~ ~t a rate of 1500 cubi~ centimeters per minute, while the composite tube ~nd ~ssem~ly were heate~ ~o 1500C in about 4 hours, were held at that tempersture or 12 ~ours, ~nd were then cooled ~o 6nOC ~efore the composite tube ~nd ~ssembly were removed from the tu~e furn~cee These re~tion condition~ gave ~omplete penetra-tion converfiion through the 1.5 millimeter thick ~omposite tube wall. ~hi~ was evidenced by vl~ually observing a cro~s- ection ~f the composite tube at a magnification o~
50X. At that magn~ficat~on, the composite tube ~n its orlginal con~ition had s~all, white areas ~which were the original SiC powders~ interspersed w~thin lar~e, d~rk gr~in~ (~hi~h were graph~te po~der). Also present was ~
grey b~ckground ~loc~ted unif~rm~y through~ut the co~po~-lte tube3 which W58 the ~arbon ~nd ~ine gr~phite th~t were ~or~ed fro~ ~e original phenolic re~in after the tube W~8 formed ~n~ ~f~er the resin ~as converted to carbon ~nd gr~phite.

~2(1~8~ti ~3 After the react~on-bondiny SiC ConverS~OQ~ a magn~fied photograph of a cross-~ection of the converted composite tube ~howed that the en~ire cross~section had a white ~olor and ha~ the grain ~tructure of SiC ~with ~bout 20 voi~ spa~e) and thus wa~ completely converted to ~i~o EXAMP~E 2 In this Example, a tube prepared as described above in an assembly a~ de~cr~bed above was processed at a tempera-ture of ~bout 1400&, ~n~tead of 1500~C. ~he other variables were the 6ame a~ those described in Example 1 ~bove.
~ sln~ these lower temperature rea~tion conditions, the composite tube exhibited p~rtial penetration ~nd thu~ par-t~al conversion o ~he c~rbon ~and/or graphit~) ln the composite tube. As ~een in a photomicrograph at 50X sf a cross-section of the compos$te tube, the exterior of ~he tube after the procedure wa~ completely white ~nd the interlor o~ the tube was a~ $t had originally ~ppe2r~d before the reaction w~th hydrogen. These two ~nes gradu~
: 20 Dlly ~erged ~nto e~eh other ~nd produced a gradu~ted lnterface at about 30~ depth penetratlon level as measured from the exterior ~urf~ce.
EXAMPL~ 3 ~n thi~ Example, the converted tube from Rxample 1 wa~
reimpregnated ~ith the res~n de~cribed in Example 1 and reconverted to carbon by the following prooedure, for the p~rpose of increasing the den~ity of the tube~ The SiC-con~erted tube w~ vacuum impregnated with a ~olut~on con-ti~ of ~ 50-50 ~olume m~xture of acetone and pheno~c re3~n (4% cat~ly~t as des~ribed ~b~ve). Af~er ~mpre~n~-ing, the tube was dried ~lowly ~overn~ght ~ about 50C) to extra~t ~ olv~nt ~nd to leave the re~in ln place wlthln ~he v~ cf the SiC ~nverted tube. Th~ tube wa~
then ~te~ escr~bed in ~xa~ple 1 to firGt rure the res~n ~nd to then carbonize ~t. Thereafter, the re~mpreg~
nated ~nd carbon converted reS~n ~n the ~tructure wa~
reconverted to SiC by the procedure described in Example 1 by packing it in R30 brick ~nd heating it in a hydrogen furnace at 1500C for 12 hour~.
Thi~ pro~ess resulted ~n a substantial redustion ~n porosity down to S~ (with a ~pe~ifi~ gravity of 3.0), a~
opposed tG the 20~ porosity whi~h had been obta~ned ~n Example 1 tWith a ~pecif~o ~ravity of 2.6)., ~he conver-0 8ion to S~C was s~omplete as determ~ned by m~croscopi-~
examinatlon .
The fore~oing description of preferred embodiments of the ~nvention has been presented for purposes of illustra-tion and des~ript~on. It ~s not intended ~o be exhaustive or ~o limit the invention to the precise forms disclosed~
and obv~ously many modification~ and variaêions are possi-ble ~n light of the above teachlng. The embodimen'cs were ohosen and described ~n order to best explain the print:i-ples of the inventlon and ~ts practical Rpplication to - 20 thereby enable others skilled in the art to be~t utillze the inventiorl ~n var;ous embodiment~ and wi~h var~ou~
modificat~ons a~ ~re ~uited 'co the particular u~e con~em-p~ated. It i~ intended that the scope of the invent~on be defined by t:he ~laims appended hereto.

Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A method of producing articles of manufacture which are reinforced with silicon carbide (SiC) whiskers, comprising the steps of:
(a) dispersing and mixing SiC whiskers in a mixture of solvent and resin with carbon or graphite particles of a size chosen for good mixing and efficient packing, so as to form resin bonded and coated fibers and particles;
(b) allowing the solvent to evaporate from said mixture:
(c) forming said resin bonded fibers and particles into a final shape in which said resin will finally be cured:
(d) heating said final shape to about 800°C to carbonize said resin and so as to form a carbon-bonded SiC
whisker reinforced composite structure which is a non-abrasive matrix in which the whiskers maintain their structural integrity:
(e) generating SiO gas at a concentration of at least 5 volume percent by heating solid silicon dioxide (SiO2) to a reaction temperature of between approximately 1400 and 1600°C in an atmosphere of hydrogen; and (f) contacting said SiC whisker reinforced composite structure with said SiC gas at said reaction temperature of between approximately 1400°C and 1600°C for a period of time sufficient to convert at least some of the carbon in said structure to SiC, whereby there is formed a structure containing SiC as well as SiC whiskers, and wherein said whiskers are not damaged by the fabrication process.
2. A method of forming a shaped product having a surface layer Or silicon carbide (SiC) reaction bonded to an inner structure consisting essentially of carbon, comprising the steps of:
(a) generating SiO gas at a concentration of between about 5 and 50 volume percent by heating solid silicon dioxide (SiO2) to a reaction temperature of between approximately 1500 and 1550 °C in an atmosphere of hydrogen, said solid silicon dioxide being in the form of a powder surrounding said structure:
(b) contacting said structure with said SiO gas at said reaction temperature of between approximately 1500 C and 1550 °C for a period of time sufficient to form a layer of SiC on the surface of said structure by chemical conversion of carbon in said structure to SiC, whereby a layer of reaction-bonded SiC is formed on the surface of said structure without significantly changing the dimensions of said structure.
3. A method according to Claim 2 wherein said SiO2 is at least part of the composition of silica containing bricks which are sliced or powdered and fitted to surround said structure.
4. A method according to Claim 3, wherein said reaction time is about 12 hours, wherein the thickness of the layer of said conversion to SiC extends within said structure to about 1.5 millimeters, and wherein the density of said structure after conversion is about 2.6 g/cm3 (and has about 20% porosity).
CA000429296A 1982-06-18 1983-05-31 Method of producing novel silicon carbide articles Expired CA1202836A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111848196A (en) * 2020-07-24 2020-10-30 北京航空航天大学 Preparation method of in-situ silicon carbide nanowire toughened silicon carbide ceramic

Families Citing this family (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4481179A (en) * 1983-10-12 1984-11-06 The United States Of America As Represented By The United States Department Of Energy Method for forming fibrous silicon carbide insulating material
JPS60201876A (en) * 1984-03-23 1985-10-12 Ibiden Co Ltd Polishing of metal die using graphite tool
US4789537A (en) * 1985-12-30 1988-12-06 The United States Of America As Represented By The United States Department Of Energy Prealloyed catalyst for growing silicon carbide whiskers
US4702901A (en) * 1986-03-12 1987-10-27 The United States Of America As Represented By The United States Department Of Energy Process for growing silicon carbide whiskers by undercooling
EP0309272A3 (en) * 1987-09-25 1990-03-07 Southtech, Inc. Apparatus and method for sample holders and wafer cages fabricated from silicon carbide for processing semiconductor materials
GB8804174D0 (en) * 1988-02-23 1988-03-23 T & N Technology Ltd Coatings
US4864186A (en) * 1988-03-29 1989-09-05 Milewski John V Single crystal whisker electric light filament
US5017527A (en) * 1988-07-20 1991-05-21 Korea Advanced Institute Of Science & Technology Mechanical seals of SiC-coated graphite by rate-controlled generation of SiO and process therefor
US5116679A (en) * 1988-07-29 1992-05-26 Alcan International Limited Process for producing fibres composed of or coated with carbides or nitrides
DE3832692A1 (en) * 1988-09-27 1990-03-29 Leybold Ag SEALING ELEMENT WITH A SHUT-OFF BODY MADE OF A METAL OR NON-METAL MATERIAL AND METHOD FOR APPLYING HARD MATERIAL LAYERS TO THE SHUT-OFF BODY
US4997678A (en) * 1989-10-23 1991-03-05 Cvd Incorporated Chemical vapor deposition process to replicate the finish and figure of preshaped structures
US5248462A (en) * 1990-01-04 1993-09-28 Brotz Gregory R Process for making silicon carbide foam
DE4202804A1 (en) * 1992-01-31 1993-08-05 Man Technologie Gmbh Fibre composite ceramic article with durable surface - made by applying ceramic foil or consolidation material onto article surface
US5525372A (en) * 1992-09-08 1996-06-11 The United States Of America As Represented By The Secretary Of The Army Method of manufacturing hybrid fiber-reinforced composite nozzle material
US5332601A (en) * 1992-12-10 1994-07-26 The United States As Represented By The United States Department Of Energy Method of fabricating silicon carbide coatings on graphite surfaces
AU695440B2 (en) * 1995-08-16 1998-08-13 Northrop Grumman Corporation Reducing wear between structural fiber reinforced ceramic matrix composite automotive engine parts in sliding contacting relationship
US5668188A (en) * 1996-01-16 1997-09-16 Sandia Corporation Process for preparing silicon carbide foam
JPH1012692A (en) * 1996-06-25 1998-01-16 Nisshinbo Ind Inc Dummy wafer
US6251353B1 (en) * 1996-08-26 2001-06-26 Bridgestone Corporation Production method of silicon carbide particles
DE19710105A1 (en) * 1997-03-12 1998-09-17 Sgl Technik Gmbh Silicon carbide body reinforced with short graphite fibers
US5962135A (en) * 1997-04-09 1999-10-05 Alliedsignal Inc. Carbon/carbon friction material
DE19727586C2 (en) * 1997-06-28 2002-10-24 Daimler Chrysler Ag Brake unit consisting of brake disc and brake pad
US6309703B1 (en) 1998-06-08 2001-10-30 The United States Of America As Represented By The Secretary Of The Air Force Carbon and ceramic matrix composites fabricated by a rapid low-cost process incorporating in-situ polymerization of wetting monomers
US6073658A (en) * 1998-09-18 2000-06-13 General Electric Company Elbow for conveying particulate matter
US20050186878A1 (en) * 2004-02-23 2005-08-25 General Electric Company Thermo-mechanical property enhancement plies for CVI/SiC ceramic matrix composite laminates
FR2889087B1 (en) * 2005-07-28 2008-09-12 Saint Gobain Ct Recherches COOKING SUPPORT FOR CERAMICS AND METHOD OF OBTAINING
DE102006055469A1 (en) * 2006-11-23 2008-05-29 Universität Paderborn A method of making an article at least partially with silicon carbide fill from a blank of carbonaceous material
DE102007044783A1 (en) * 2007-09-19 2009-04-09 Audi Ag Method and apparatus for siliconising carbonaceous materials
DE102008058444B4 (en) 2007-11-21 2020-03-26 Antacor Ltd. Method and use of a device for the production of fuels, humus or suspensions thereof
JP2009210266A (en) * 2008-02-29 2009-09-17 Ibiden Co Ltd Tubular body
DE102010004017A1 (en) 2010-01-04 2011-07-07 Universität Paderborn, 33098 Process for the production of rolling bearing components at least partially made of Siliciumkarbidgefüge and erfore produced rolling bearing components
KR102090513B1 (en) 2015-08-20 2020-03-18 엔테그리스, 아이엔씨. Silicon carbide/graphite composite and articles and assemblies comprising same
CN112062573B (en) * 2020-09-11 2022-09-06 郑州大学 Sheet SiC-SiO2 composite material and preparation method thereof
CN113563082A (en) * 2021-08-06 2021-10-29 中国建筑材料科学研究总院有限公司 Thin-wall silicon carbide ceramic heat exchange tube and preparation method and application thereof
CN113979765B (en) * 2021-09-27 2022-10-04 武汉拓普准晶新材料有限公司 Silicon carbide porous ceramic and preparation method thereof

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3205043A (en) * 1962-04-04 1965-09-07 Carborundum Co Cold molded dense silicon carbide articles and method of making the same
US3269802A (en) * 1962-12-10 1966-08-30 Horizons Inc Preparation of carbide structures
US3369920A (en) * 1964-11-24 1968-02-20 Union Carbide Corp Process for producing coatings on carbon and graphite filaments
US3653851A (en) * 1966-04-04 1972-04-04 Monsanto Co High-strength metal-silicon carbide article
GB1180918A (en) * 1966-06-10 1970-02-11 Atomic Energy Authority Uk Improvements in or relating to the Manufacture of Dense Bodies of Silicon Carbide.
US3622272A (en) * 1968-04-01 1971-11-23 Gen Technologies Corp Method of growing silicon carbide whiskers
US3991248A (en) * 1972-03-28 1976-11-09 Ducommun Incorporated Fiber reinforced composite product
GB1417134A (en) * 1972-11-20 1975-12-10 Nippon Oil Seal Ind Co Ltd Production of shaped silicon carbide articles
GB1468233A (en) * 1974-02-08 1977-03-23 Atomic Energy Authority Uk Preparation for storage of fission products
JPS54122312A (en) * 1978-03-15 1979-09-21 Hiroshige Suzuki Silicon carbide powder for sintering use and preparation thereof
WO1982001545A1 (en) * 1980-10-27 1982-05-13 North Bernard Silicon carbide bodies

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111848196A (en) * 2020-07-24 2020-10-30 北京航空航天大学 Preparation method of in-situ silicon carbide nanowire toughened silicon carbide ceramic

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US4513030A (en) 1985-04-23
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DE3322060A1 (en) 1983-12-22

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