为了防止SiC颗粒与过渡金属在高温下混合应用时发生反应,使用流化床PECVD在名义粒度 180μm SiC颗粒表面镀覆完整的 Al2O3 隔绝膜.通过SEM、XRD等对膜层的形态、组成和物相进行了表征,利用混合烧结法模拟SiC颗粒与过渡金属在高温下混合应用的状态.当膜层厚度在 4μm以上,膜层主要成分为无定形氧化铝和少量含碳杂质.在 700℃/1 060℃的温度和空气氛围中保温 12h,膜层发生相变,生成γ-Al2O3/α-Al2O3.经高温真空腐蚀实验验证,证实膜层能有效防止 SiC 与 Ni 等过渡金属反应,提高了SiC颗粒高温应用的性能.
Insulation Properties of Alumina Film Coated on SiC Particles
In order to stop reaction between silicon carbide particle and transition metals in high temperature,this research introduces a new core-shell material consisting of 180μm SiC particle and uniform alumina insulation layer,which is made by fluidized bed plasma enhanced chemical vapor deposition(FB-PECVD)method.The morphology,composition and phase structure of the coating were characterized by scanning electron microscope and X-ray diffractometer.The mixed sintering method was conducted to simulate the state of SiC particles mixed with transition metals at high temperatures.The alumina layer is 4 μm thick and made of amorphous alumina with little carbonaceous impurities.After 12 hours calcination at 700℃/1 060℃in air,the amorphous alumina layer transform to γ-Al2O3/α-Al2O3 layer.After high-temperature vacuum calcination,this insulation layer effectively prevents SiC particle from reaction with Ni-alloy metal material,resulting in better performance of SiC in high temperature.
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