Fabrication and Characterization of Composite Materials Made from Intermetallic Compounds and Zirconia Ceramics

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Intermetallic compounds, MoSi_2, WSi_2, TiC,TiB_2, and TiN,are considerable of interest from views points such as high melting points, excellent high-temperature oxidation resistance, hardness, and good heat conductor. The main difficulty with these materials is an inherent lack of thoughness, which limits their applications. They need to be reinforced in order to improve their mechanical properties. In the present study, ZrO_2 has been proved to be a very attractive reinforcement material for these intermetallic compounds. Dense sintered composites of ZrO_2 (2mol% Y_2O_3) and these intermetallic compounds have been fabricated by hot isostatic pressing (HIPing) for 2 h under 196 MPa at 1400ﾟ to 1500ﾟC.Their mechanical and electrical properties have been evaluated in connection with their compositions and microstructures. On the other hand, little attention has been paid to the fabrication and measurement of properties of laminated materials of composites between ceramics and intermetallic compounds. On the basis of the present results, dense laminated materials with the compositions of ZrO_2 (2Y)/MX=(60/40)/(80/20)/(60/40)mol% (MX=MoSi_2, WSi_2), (50/50)/(80/20)/(50/50) (MX=TiC), and (40/60)/(70/30)/(40/60) (MX=TiN) have been prepared by HIPing. Overall electric resistivities in directions perpendicular and parallel to the interfaces are insulative (<approximately equal>10^<11> OMEGA・cm) and conductive (<approximately equal>10^<-4> OMEGA・cm), respectively. Residual stresses of as much as 150-200 MPa are induced near the interfaces. The fracture toughnesses are greatly affected by the residual stresses.