无压烧结Si_3N_4-3YZrO_2复相陶瓷材料的力学性能和增韧机理研究

MECHANICAL PROPERTIES AND TOUGHENING MECHANISM OF Si 3N 43YZrO 2 COMPOSITE

在以４％Ａｌ２Ｏ３（以质量计，下同）作为烧结助剂的Ｓｉ３Ｎ４基体中分别添加５％，１０％，２０％，３０％的３ＹＺｒＯ２，经１８００℃无压烧结。其室温断裂韧性达到５．２～７．６ＭＰａ·ｍ１／２，是基体材料的２．４～３．５倍。室温抗弯强度达４２０～６１０ＭＰａ，是基体材料的１．６～２．３倍。高温（１０００℃）抗弯强度较基体材料略有增加，达到３３４～３８２ＭＰａ。通过ＳＥＭ观察和ＸＲＤ分析，探讨了３ＹＺｒＯ２对Ｓｉ３Ｎ４基体的增韧机理。

Al 2O 3 ceramics with 4%(in mass)of Si 3N 4 as sintering agent and added with 5%,10%,20% and 30%(in mass)of 3YZrO 2 respectively(ZrO 2 containing 3% Y 2O 3, in mole)are fabricated by pressureless sintering at 1800℃.Fracture toughness of Si 3N 4ZrO 2 composites at room temperature reaches 5.2 ～ 7.6 MPa·m 1/2 ,which is 2.4 ～ 3.5 times as that of Si 3N 44%(in mass)Al 2O 3 matrix.Bending strength at room temperature reaches 420～610MPa which is 1.6 ～ 2.3 times as that of Si 3N 44%(in mass)Al 2O 3 matrix.Fracture toughness at high temperature (1000℃)reaches 4.2 ～ 8.3 MPa·m 1/2 ,which is 1.1 ～ 2.4 times as that of the Si 3N 44%(in mass)Al 2O 3 matrix.Strength at high temperature reaches 334～382MPa which is near to that of the matrix.In the paper,the microstructure and phase composition of the composites are studied by SEM and XRD.The toughening mechanism of ZrO 2 in the Si 3N 4ZrO 2 composities is discussed.