无压烧结Ca_3(PO_4)_2/Si_3N_4复合陶瓷的组织结构与性能

以Ca_3(PO_4)_2和Si_3N_4为原料,采用无压烧结的方法制备Ca_3(PO_4)_2/Si_3N_4系列复合陶瓷.复合材料中Ca_3(PO_4)_2能与Si_3N_4稳定共存,烧结后未发现有新相生成.随着烧结温度的提高,复合材料的致密度和β-Si_3N_4的相对含量也随之升高,柱状β-Si_3N_4晶粒的生长更加充分,晶粒相互搭接、交织.复合陶瓷的力学性能随着烧结温度的提高而升高,1700 ℃无压烧结复合材料的抗弯强度达到547 MPa,断裂韧性达到7.3 MPa·m~(1/2),从断口照片中可以观察到β-Si_3N_4晶粒的拔出和桥联作用.通过加热试样并在水中骤冷后测弯曲强度的方法,表明Ca_3(PO_4)_2/Si_3N_4复合材料具有良好的抗热震性能.

Microstructures and Mechanical Properties of Pressureless Sintered Ca_3(PO_4)_2/Si_3N_4 Composite Ceramics

The Ca_3(PO_4)_2/Si_3N_4 composite ceramics prepared by pressureless sintered at different temperature were studied in the paper. In the ceramics, Ca_3(PO_4)_2 and Si_3N_4 could steadily caexist and there is no new phase after sintering. The relative density and contents of β-Si_3N_4 increased with the increase of sintering temperature, and The growth of rodlike β-Si_3N_4 was much full, the grains were bridged and connected. The mechanical properties enhanced as the sintering temperature elevating. The flexural strength and fracture toughness of Ca_3(PO_4)_2/Si_3N_4 composites sintered at 1700 ℃ reached 547 MPa and 7.3 MPa·m~(1/2) respectively. The improve of fracture toughness is contributed by the pull-out and bridging effort of rodlike β-Si_3N_4, which could be found from the images of fracture. Through flexural strength test of the samples which were heated in furnace and suddenly cooled in water, one can see the Ca_3(PO_4)_2/Si_3N_4 composite has good thermal shock resistance properties.