凝胶注模Sialon-SiC材料流变性研究及其性能

摘要

The Sialon-SiC suspension with 70vol.% -78vol.% solid loading was found to exhibit shear thinning power-law characteristic in a range of shear rate from 10 to 160 s-1, which is satisfactory for the gelcasting process.Rheological model of the suspension has been simulated using the MatLab software, the suspension characteristics agree with the Sisko rheological model.Green bodies were produced by gelcasting using the suspension with 78vol.% solid loading, and Sialon-SiC materials are fabricated by nitridation sintering.XRD and SEM analysis indicates that SiC, Si4Al2O2N6 and a small amount of Si2ON2 exist in the materials.The shape of the sialon phase is hexagonal short rods and the materials have a uniform microstructure.Bulk density and flexural strength of the materials are 2.69 g/cm3 and 56 MPa, respectively.%70vol.％～78vol.％的Sialon-SiC悬浮体在10～160 s-1范围内显示剪切变稀的幂率特征,突出的“切稀”行为满足凝胶注模成型的要求.建立的悬浮体流变模型与试验值吻合,其流变特征符合Sisko模型.氮化烧结材料的XRD检测和SEM观察显示,材料主要由SiC相和Si4Al2O2N6相组成,显微组织中六方柱状Sialon晶体发育完整,形成了Sialon晶体紧密环绕SiC颗粒的均匀结构.材料的体积密度和抗折强度分别为2.69 g/cm3和56 MPa.