多孔Si3N4-SiO2复相陶瓷及其性能

采用近净尺寸成型制备工艺-氧化烧结结合溶胶浸渍再烧结法,制备了多孔Si3N4-SiO2复相陶瓷.讨论了制各工艺对材料的成分、微结构和性能的影响规律.研究表明:随着硅溶胶浸渍量的增加,材料的抗弯强度、硬度、断裂韧性、密度和介电常数均增大.分别采用压痕法和单边切口梁法对材料的断裂韧性进行了测定和比较.结果表明:采用压痕法测定断裂韧性时,多孔Si3N4-SiO2复相陶瓷的增韧机理有裂纹偏转、裂纹分叉、裂纹桥接以及孔的钝化.采用单边切口梁法测定断裂韧性时,多孔Si3N4-SiO2复相陶瓷的增韧机理只有裂纹偏转.

POROUS Si3N4-SiO2 COMPOSITE CERAMIC AND ITS PROPERTIES

A Si3N4-SiO2 composite ceramic was fabricated by using a near net-shape preparation method that was combined process of oxidation-bonding, sol-gel infiltration and sintering. The relationship of the process, composition, microstructure, and properties of the as-received composite ceramic was discussed in detail. The results indicate that with the increase of SiO2 derives from the sol-gel infiltration and sintering process, the flexural strength, hardness, fracture toughness, density, and dielectric constant all increase. The fracture toughness of the as-received composite ceramic was tested by using the Vickers indentation fracture toughness (VIF) and single-edge notched beam (SENB) methods. Crack deflection, crack branching, crack bridging, and the blunting of pores were detected in the Si3N4-SiO2 composite ceramic when the toughness was measured by the VIF method. However, crack deflection was detected in the Si3N4-SiO2 composite ceramic measured by the SENB method.