凝胶注模技术制备高强度多孔氮化硅陶瓷

Preparation of High Strength Porous Silicon Nitride Ceramics by Gel-casting

采用凝胶注模技术和无压烧结工艺制备高孔隙率、高强度多孔氮化硅陶瓷。研究了浆料固相含量对多孔氮化硅陶瓷坯体相对质量损失和收缩率的影响,测定了材料在烧结前后的物相组成,分析了浆料固相含量对多孔氮化硅陶瓷显微结构、孔隙率、弯曲强度及断裂韧性的影响。结果表明:随浆料固相含量增大,坯体相对质量损失率和收缩率减小,烧结后的多孔氮化硅陶瓷孔隙率由65.24%减小到61.19%;而弯曲强度和断裂韧性分别由93.91MPa和1.48MPa·m1/2提高到100.83MPa和1.58MPa·m1/2。长棒状β-Si3N4晶粒无规律的交错搭接和相互咬合是多孔氮化硅陶瓷在保持高孔隙率的同时具有高强度的主要原因。

Porous silicon nitride ceramics with high porosity and flexural strength were prepared viagel-casting and pressureless sintering.The effect of solid content in slurry on the relative mass loss and shrinkage of the green body of porous silicon nitride ceramics was investigated.The phase composition,microstructure,porosity,flexural strength and fracture toughness of the prepared ceramics were analyzed.The results show that the relative mass loss and shrinking of green body decrease with the increase of solid content.The porosity of the sintered body decreases from 65.24%to 61.19% when the solid content increases.The flexural strength and fracture toughness of the ceramics increase from 93.91 MPa to 100.83 MPa and from 1.48MPa·m1/2to 1.58MPa·m1/2,respectively,when the solid content increases.The rod-shapedβ-Si3N4 grains in the sintered porous silicon nitride ceramics overlaps,leading to the greater porosity and the higher flexural strength.