CP DoMn J.A. Hawk/Wew 203-204(/)257-277 aerial than are the SiaN4+SiC, composites. are smaller, a similar effect is not observed in that material provided by Cercom Inc. We greatly appreciate the provision mic and ceramic composite References U MA Moere and FS KGg Abrasive wea of brite sods, Wear, 60 2】A [3].A, Libet. P.C. Ehaolurtc valuc (eds, ) Adanced Cerumin r per unit are resulted in the power law relationship. w=1072c07 The relationship derived for the Asilicon nitride materials is ed on 60and 180-grit SiC. In tied fro m o. 6i for ahras t. Cerat Soe.. tween those obtained by moore and King mle nerin eempeoiles. [12]G H Campbell M. Ruh study of the influence of randomly oriented Sic m 13] M. Bengisu, O.T. Inal IP. sainik, I,Dusra dition of Sic whiskers to a Si, N4 matrix sets up ten 1cHMm(门比一水m noting casler 117]H, Uiu M face, producing a relatively stronger bond that can better soF419122M4223C.P. Do&n. J.A. Hawk/ Weor203-204 11997) 267-277 size approaches that of the reinforcement phase in the silicon nitride-based materials that the composite becomes more wear resistant than the matrix material. In this study, this phenomenon is observed only for the S&N.,-A materials in wear tests against 400-grit SIC. where the composite is 25% more wear resistant than the monolithic material. Under these conditions, the Sic abrasive particles arc no longer large enough to fracture and/or scoop the Sic whiskers from the surface of the composite, and the wear rate is correspondingly reduced. Because the SE whiskers in the S&N.,-B composite are smaller, a similar effect is not observed in that material for the range of abrasive sizes used. 4.3. Effect of load on ceramic and ceramic composite wear The S&N.,-A and the Si,N,-A + Sic, materials wereexam￾ined to determine the dependency of wear on load. The wear was measured against 150-g& SIC for applied loads per unit area (u) of between 0.93 and 3.27 MN m-* (see Table 4). The graph of the wear constant (w) vs. applied load per unit area is shown in Fig. 3. For the two A-silicon nihide mate￾rials, there is very little difference between the absolute value of rhe w for the monolith and the composite. It is also observed that the value- of w for S&N,-A at each load increment is slightly less than that of the composite. In performing a regression analysis of the combined datacontained in Fig. 3, the calculated wear constant (w) as a function of applied load per unit are resulted in the power law miationship: w= 10.72~~” (3) The relationship derived for the A-silicon nitride materials is similar to that found by Moore and King [ I ] in their analysis of 97.5% A&O3 alumina abraded on 60- and HO-grit SIC. In the Moore and King investigation, the exponent for the applied load per unit area varied from 0.61 for abrasion on the I SO-grit SE to 1.04 for abrasion on the 60-g& Sic. The value obtained in this study for silicon nitride abr; -‘ad on IX-grit Sic falls between those obtained by Moore and King for 97.5% A1203. 5. Conclusions A detailed study of the influence of randomly oriented Sic whisker reinforcement on the abrasive wear behavior of sil￾icon nitride- and alumina-based ceramicr suggests that it is the residual stress state of the whisker-matiix inretiace that determmes the wear r&stance of the composite material. The addition of SIC whiskers to a S&N4 matrix sets up tensile stresses at the whisker-matrix interfaces, enhancing the bulk toughness of the composite, but degrading the abrasive wear properties by promoting easier whisker debonding and removal by the abrasive particles. The addition of Sic whisk￾err to an alumina matrix, on the other hand, results in the creation of compressive stresses at the whisker-matrix inter￾face, producing a relatively stronger bond that can better withstand the rigors of an abrasive wear environment. As a result, the Al,03 + SE, composite is consistently a more wear resistant material than are the S&N, + Sic, composites. Acknowledgements The 99.5% A1203 was provided by the Coors Ceramic Company. All other ceramic and ceramic composites were p:ovidcd by Cercom Inc. We greatly appreciate the provision of these materials by the aforementioned companies. References [II MA. Moore and F.S. King. Abrasive weat of brittle solids, Wear. 60 (1980) 123-140. I21 A.G. Evansand D.B. Marshall. in D.A. Rigoey fed.). Fun&men&& of Friction and Wear of Maferials, ASM, Metals Park. OH, 1980. pp. 439-452. [31 T.A. Libsch. P.C. Becker and SK. Rbee. Dry friction and wear of toughened zircottiar end toughened alumhw against steel. Wear. 111 ( 1986) 263-268. 141 J.A. Hawk and C.P. Do&o. in H.M. Hawthorne and T. Tmczyoskt (cd%). Advanced Ceramics for Strucmral and Trib&gical Apphfions. CIM. Monaal. Qwhec. 1995. pp. 139-150. [S] T. Yamamoto. M. Olsson and S. Hogmark. Three-body nh&v::eacai of ceramic !!tzte?ids. Tear. ii4 (1994) 21-31. 161 C.P.Do@mndJ.A. Hawk.Effe~ofgrainbound~glasseomposition end devittilication on tile e%esive wear of AIzO,, Wear, 181-183 (1995) 129-137. 171 C.P. Do&o and J.A. Hawk. in H.M. Hwthome ettd T. Ttoczynski (e&h Advanced Ceramics for Shucnwal and Tribological Apph?ions. CIM. Montreal. Qoebec. 1995. pp. 181-192. [S] S-J. Cho. B.J. Hockey, B.R. Lawn end S.J. Bermsion. Chain size attd R-curve effects in the abrasive wear of elomhw 1. Am Ceram. Sot., 72 (1989) 1249-1252. [91 M. RUhle. B.J. Dalgkish and A.G. &tts. On tbc touglwting of ceramics by whiskers, kripfa Metoll.. 21 ( 1987) 681486. [ 101 PP. Becher. C-H. Hseuh. P. Angeiini and T.N. Tiegs. Toughening behavior in whisker-reinforced caamic matrix composites. _I. Am Cerom. Sot.. 71(1988) 1050-1061. [II] P.G. Chamlambides and A.G. Evans, Debonding pmpetties of residually sttessed btitt&nattix composites. 1. Am. Ccranr. Sot.. 72 ( 1989) 746-753. [I21 G.H. Campbell, M. RUhle. 8.1. Delgleish and A.G. Evens. Whisker toughening: a comparison b&vex% ahnmna oxide and silicon nitride toughened with silicon carbide. 1. Am Cerom. Sot.. 73 (1990) 521- 530. [ I31 M. Bengisu. O.T. lnel and 0. Tosyeli. Oo w!ttker tougixoing to e+voic zxwiais. Acta Met&. Mater, 39 (1991) 2sO9-2517. !I41 P. &tjgaiik. J. Dosw and M.J. Hoffman. Relationship between micfostmcture. tooghentng mechattisrr~. attd ftactuve toughness of ninforccd silicon nitride ceramics. 1. Am. Gram. Sot.. 78 (1595) 2619-26240. II51 C.S.Yost.J.M.L&ttakereedC.E.Devote.Wearofattalumine-silicon carbide whiskercomposits. Wear. 122 (1988) 151-164. [ 161 SC. Farmer. C. Dcllacortc and P.O. Book, Sliding wear of self-mated Al,O,-SIC whisker-reinforced composites at 23-1200 “C, 1. Mater. Sci.. 28 (1993) 1147-l 154. 1171 H. Liu. ME. Fine end H.S. Chettg. Ttibological behavior of Sic whisker/&O, composites against catburized 8620 steel in lubricated sliding, 1. Am. Ceram. Sot.. 74 (1991) 2224-2233