燃烧合成-热压制备Al_2O_3-TiC-ZrO_2纳米复合陶瓷的力学性能与显微结构

MECHANICAL PROPERTIES AND MICROSTRUCTURE OF Al_2O_3-TiC-ZrO_2 NANOCOMPOSITES PREPARED BY COMBUSTION SYNTHESIS-HOT PRESSING

以ＴｉＯ２，Ａｌ；Ｃ，纳米 ＺｒＯ２粒子为原料，利用燃烧合成－热压工艺制备了Ａｌ２Ｏ３－ＴｉＣ－ＺｒＯ２纳米复合陶瓷．添加ＺｒＯ２可使 Ａｌ２Ｏ３－ＴｉＣ断裂方式由沿晶断裂转变为穿晶断裂．ＺｒＯ２纳米粒子弥散于基体中，其周围产生的应力集中可引发位错，起到亚晶界的作甲，并可使位错钉扎、堆积，阻碍位错运动，从而使复合陶瓷的力学性能得到明显改善：抗弯强度为７０６ＭＰａ，提高幅度达１９．８％；断裂韧性为 ６．３ ＭＰａ·ｍ１／２，提高幅度１８．９％；洛氏硬度为 ９４．４．

Al2O3-TiC-ZrO2 nanocomposites were fabricated by combustion synthesis-hot pressing with the cheap reactants of TiO2, Al, C and ZrO2. The effects of ZrO2 nano-additives on the mechanical properties and microstructure of Al2O3-TiC ceramic-matrix composites were discussed. With the addition of ZrO2 nanoparticles, the dominant fracture mode of the composites changed from inter-granular fracture into transgranular fracture. ZrO2 nanoparticles dispersed mainly in Al2 O3 matrix. The residual stresses generated by the thermal expansion coefficient mismatch between ZrO2 particles and Al2O3 matrix induced dislocation and microcracks around the nanoparticles. And the effects of nanoparticles on the deflected propagation, nailing and blocking of the dislocation are remarkable and can be used to explain the improvement of the strength and toughness of Al2O3-TiC-ZrO2 composite. Al2O3-TiC-10ZrO2 composite exhibits good mechanical properties with the flexural strength of 706 MPa, the fracture toughness of 6.3 MPa.m1/2 and the HRA hardness values of 94.4, respectively.