热压烧结碳化硅陶瓷的氧化性能
Oxidation Resistance Analysis of Silicon Carbide Sintered by Hot-pressing
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摘要: 采用硅作为烧结助剂热压烧结SiC陶瓷,用扫描电镜、X射线衍射仪和热重分析仪研究了不同状态SiC陶瓷的氧化性能.结果表明:未预处理SiC在等温氧化过程中,600~1 100 ℃区间内,等温氧化动力学曲线服从抛物线规律;而在1 100~1 300 ℃区间,则偏离了抛物线规律,氧化速率随温度的升高先增大后减小.经过高温预氧化处理之后,SiC试样在等温氧化过程中,氧化动力学曲线为直线,较未预处理试样氧化增重显著减少;连续升温氧化过程中,和未预处理试样相比,剧烈氧化开始温度升高,同时其氧化速率及最终的氧化增重均大幅度降低.说明了高温预氧化处理能够有效提高SiC陶瓷的抗氧化性能.Abstract: SiC ceramic was prepared by hot-pressing method with Si as an additive.XRD,SEM,isothermal oxidation-weight gain and non-isothermal oxidation (TG) were used to study the oxidation properties of SiC.The results show that the kinetics of isothermal oxidation without pre-oxidation SiC obey a parabolic rule at 600-1 100 ℃,and the oxidation speed of SiC increased at first and then decrease with temperature increasing at 1 100-1 300 ℃.After pre-oxidation process,the kinetics of isothermal oxidation of SiC obey a linear rule in the whole experimental temperature range.The sample has a higher severe oxidation temperature than the origin sample in the non-isothermal condition.The weight gain of SiC after pre-oxidation is less than that of the origin sample remarkably.The pre-oxidation process is a useful method to improve the oxidation resistance of SiC ceramic.