反应合成AlN／TiB_2复相陶瓷及残余应力分析  

REACTIVE SYNTHESIS OF AIN/TiB_2COMPOSITE AND ITS RESIDUAL STRESSES

作　　者：张国军[1] 金宗哲[1] 

机构地区：[1]中国建筑材料科学研究院高技术陶瓷研究所

出　　处：《硅酸盐学报》1996年第2期152-159,共8页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金

摘　　要：采用ＸＲＤ法研究了ＴｉＨ_２，Ａｌ及ＢＮ反应过程中物相的生成机理，发现在不同温度下存在ＴｉＡｌ_３，ＴｉＮ，α－Ａｌ_２Ｏ_３等过渡相，但最终只有ＡｌＮ和ＴｉＢ_２两相存在，并结合热力学分析，认为合成ＡｌＮ／ＴｉＢ_２的反应温度应在１７００℃以上。通过反应热压法制备出了ＡｌＮ／ＴｉＢ_２复相陶瓷，材料的三点弯曲强度为５３９ＭＰａ，Ｋ_（Ⅰｃ）为５．０５ＭＰａ·ｍ^（１／２）。通过ＸＲＤ法测试了复相陶瓷中残余应力的大小，并结合显微结构分析，认为复相陶瓷的主要增韧机理为残余应力场增韧和裂纹偏转增韧。The phase formation mechanism in the chemical reaction 2Al+Ti+2BN=TiB_2+2AlN was investigated using X-ray diffraction. It is observed that several transient phases (such as TiAl_3, TiN and α- Al_2O_3) exist at different temperatures. It is suggested that the forming of α-Al_2O_3 at temperatures below 1600℃ is due to B_2O_3 present in BN powder and oxygen absorbed by Al powder. But such α-Al_2O_3 will be reduced by the C atmosphere in the graphite-heating furnace and disappears at the temperature higher than 1700℃. Thus based on thermodynamic analysis, the synthesis temperature of AlN/TiB_2 must be above 1700℃. Further, the AlN/TiB_2 composite is prepared by reactive hot pressing at 1850℃ under 25MPa for 30min in Ar atmosphere, The three-point bending strength and SENB fracture toughness are 539MPa and 5.05MPa·m￣(1/2) respectively. The residual stresses in the composite caused by the considerable difference of thermal expansions between AlN matrix and TiB_2 particles was analysed and measured by XRD method. Then based on the crack propagation path analysis by SEM, the toughening mechanisms of the composite are suggested to be thermal residual stress toughening and crack deflection toughening.

关 键 词：氮化铝 二硼化钛 复相陶瓷 残余应力 增韧机理 

分 类 号：TQ174.758[化学工程—陶瓷工业]