with oth pin sis Tr. Ewf. tionships in Jeffrey A. Hawk: Currently Chief of the Materials Conser- m ch Center). He graduated [25) H.H. K Xu, 5,Jah Yang, Effed od MS(1983)and Ph-D.(1986)in cranes Ill, Crystallization of high-caleia boudary glass, J, sity of Alabama, Tuscaloosa, Al 工上解如 Materia Branc ansley research center. hap, on va. B m邮 tribo- environC.P. Do&n. IA. Hawk/ Wear 203-204 (1997) 267-277 211 [IS] D. Wang and Z. Mao. Sludies of abrasive wear of monolithic silicon nitride and a silicon carbide whisker-reinforced silicon &ride composile. 1. Am. Ccrom. Sot., 78 ( 1995) 2705-2708. [ 191 G.R. Anstis, P. Chantikul. B.R. Lawn, and D.B. Marshall. A critical evaluation of indentation techniques for measuring ftactue Rn@ness: 1. direct crack measunment~. 1. Am. Ccram. Sot , 64 (1981) 533- 538. (201 R. Blickmsderfer and G. Laird II. A pin-on-drum abrasive wear test and comparison with other pin tests. 1. Test. Evol.. 16 (1988) 516 526. [21] DIN 50 321. Verschlciss-Mrssgrocssen. Beuth. Berlin. 1979. (221 A.M. H8ger and M. Davies. in K. Friedrich (4.). Advances m Composire Tribology. Elwvier. Amsterdam. 1993. pp. I IS-I 16. 1231 H. Sin, N. Saks and N.P. Sub, Abrasive wu mecnanisms and the grit sizeeffecfeer. Wear, 55 (1979) 163-190. (2411. Larsen-Basse and 8. Premualne. in KC. L&ma (ed.). Wear of Mofcria/s. ASME. New York. 1983. pp. 161-166. [25] C. Cm. Wu. R.W. Rice. D. Johnson and B.A. Platt. Grain size dependence of wear in ceramics. Cerumic En.5 Sci Proc.. 6 ( 1985) 995-1011. [26] H.H.K. Xu. S. Jabanmir and Y. Yang. Effect ot grain size on scrach interactions and material removal m alumina, J. Am Ceram. Sot.. 78 (1995) 881-891. [27] C.He.Y.S.Wang.J.S.Wallacear~dS.M. ~su.Effec~ofmicrosuwture on the wear transition of zirconia-Rwgbened aluti~na, Wear. 162-164 (1993) 314-321. [28] 0.0. Ajayi and K.C. Ludema, in KC. Ludema and R.G. Bayer (eds. ). WeorofMarerioIs. Vol. I. ASMB. New York. 1991. pp. 307-318. 1291 R.M. Anderson. T.A. Adler and J.A. Hawk. Scale of micnxt~ctw effects on the impact resistance of AI+?;. !+‘cu-_;. X2-iM (1w3) XX?-iO%U. [30] C.A. Powell ~&an and A.H. Hew. Micmsuucrure of %% alumina ceramics: 111. Crystallization of high-ealeia boundary glass, 1. Am. Ceram. Sot., 73 (1990) 3684-3691. [3l] I.M. Peterson and T-Y. Tien. Effect of the grain boundary lhennal expansion coefficient on the fracwe tx@mesr of silicon nitride. 1. Am. Ceram. Sot.. 78 (1995) 23452352. Biographies Cynthia Powell Do&t: Currently a materials engineer in the Materials Conservation Divisiou of the US Department of Energy’s Albany l&search Center in Albany, Oregon, USA (formerly the US Bureau of Mines Albany ResearchCenter). She received her Ph.D. in Materials Science from Case West￾ern Reserve University in 1989. preceded by an M.S. and B.S. in ceramic engineering from Clemson University, in 1985 and 1983, respectively. Her research has addressed microstructure/propertyandmicrostructure/processingrela￾tionships in a wide range of ceramic, intermetallic. metallic and composite materials, and is currently focussed on under￾standing the influence of microstructure on the tribological performance of ceramics and ceramic-based composites. Jeffrey A. Hawk: Currently Chief of the Materials Conscr￾vation Division of the US Department of Energy’s Albany Research Center in Albany, Oregon, USA (formerly the US Bureau of Mines Albany Research Center). He graduated in Civil Engineering in 1979 at the University of Virginia, and subsequently received an M.S. (1983) and Ph.D. (1986) in Materials Science at the University of Viiginia, Charloats￾ville, VA. Subsequent to arriving at the Albany Research Center, he worked as a Senior Scientist (19864989) at the Light Metals Center, University of Virginia. on microstruc￾turai stability and mechanical behaviorofdiiinnsti2gth￾end dnmixm iiiuys for elevated tempemture applications. Hc was an Assistant Professor (19904991) in dx Depart￾ment of Metallurgy and Materials Engineering at the Univer￾sity of Alabama, Tuscaluosa, AL, evahmtingtheperformance characteristics of light a!loys and composites. In 199i he was awarded a NASA Summer Faculty Fellowship, Metallic Materials Branch, Langley Research Center. Hampton, VA, for assessing candidate alloys and composites for use in the high-speed civilian transpntt. His current research focuses on understanding the relationship between nticrostntcture and impact-fracture-wear behavior of metals, alloys, ceramics and composites as the.y pertain to aggressive tribo-environ￾ments, and the processing of materials for wear applications