|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1997 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1996 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1995 : ¥1,500,000 (Direct Cost : ¥1,500,000)
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 intermetal
lic 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.
機械的特性の破壊靭性値K_<IC>はそれぞれ10.1(試料A)と13.0MPa.m^<1/2>(同B)であり,三点曲げ強度は1040及び1180MPaの値が得られた.さらに試料AとBを積層した緻密な複合材料(A/B/A)を作製した.層に垂直方向に測った電気抵抗率p_⊥は【product】x10^9 Ω・m,層と平行に測定した抵抗率p_<//>は1x10^<-6> Ω・mであり,GEMに基づいて計算して得られた値p_<⊥(GEM)>【product】.73x10^9とp_<//(GEM)>【product】.95x10^<-6> Ω・mと一致した.次に各層内のK_<IC>の分布を調べるとA/B/Aの層の境界付近にA側では圧縮応力が,B側では引っぱり応力が誘起されており,K_<IC>の値とインデンテーションによって生じた圧コンの各四隅に発生したクラックの長さから評価した応力の大きさは約150MPaであった. Less