Sialon结合SiC复相材料的高温氧化行为

利用X射线衍射仪、扫描电子显微镜、压汞仪和热重分析仪等方法,在1100～1500℃范围内研究了Sialon结合SiC复相材料的高温抗氧化行为.结果表明:(1)随氧化温度升高,由于氧化致密层的形成,试样氧化增重速率降低,在1500℃氧化试样由于气泡破裂严重,氧化面积增大使氧化增重率有所提高；(2)随氧化温度升高出现氧化钝化现象,使得Sialon结合SiC复相材料表现出很好的高温抗氧化性能；(3)高温氧化使得Sialon结合SiC复相材料常温抗压强度比氧化前提高；随氧化温度升高,氧化膜表面形成较多气泡和开口空洞,使耐压强度呈下降趋势.

High Temperature Oxidation Behavior of Sialon-bonded SiC Multiphase Material

High temperature oxidation behavior of Sialon-bonded SiC multiphase material was investigated in 1100-1500 ℃ by means of X-ray diffractometer,scanning electronic microscopy,mercury injection apparatus and thermogravimetry.The results showed that:(1)The oxidation weight increment rate of sample decreased with increasing oxidation temperature due to the formation of dense oxidation layer.The oxidation weight increment rate of sample oxidized at 1500 ℃ elevated owing to the increase of oxidation area resulting from the burst of surface bubble;(2)Oxidation passivation occured with the increase of oxidation temperature,so Si3N4-bonded SiC multiphase materials had excellent oxidation resistance;(3)High temperature oxidation resulted in the decrease of apparent porosity and increase of compressive strength at room temperature of Sialon-bonded SiC multiphase material.The compressive strength of samples oxidized at high temperature decreased with the increase of oxidation temperature as a result of formation and burst of surface bubble.