( 武汉理工大学 材料复合新技术国家重点实验室, 武汉 430070)
摘 要: 采用热压n(TiC)∶n(Ti)∶n(Si)∶n(Al)=2∶1∶1∶0.2的混合粉末制备了高纯度、 固溶有铝的Ti3SiC2。研究了该材料在1100℃和1200℃空气中的循环氧化行为。 结果表明, 含铝Ti3SiC2的循环氧化可以分为氧化层的形成、致密和稳定。 40次循环后, 试样表面形成6~10μm的致密氧化膜, 其主要由固溶的铝所形成的α-Al2O3组成, 并含少量的SiO2和TiO2。 这种致密氧化膜有利于提高Ti3SiC2的氧化性能。热应力计算表明, 氧化层内部存在很大的压应力。
关键字: Ti3SiC2;循环氧化; 热应力; 动力学
( State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China)
Abstract: The cyclic oxidation behavior of Ti3SiC2 sintered by hot pressing with the start powder mixture of n(TiC)∶n(Ti)∶n(Si)∶n(Al)=2∶1∶1∶0.2 was investigated. The results indicate that the oxidation of Ti3SiC2 with the solute Al follows a three-step rate law at 1100℃ and 1200℃ for 40 cycles, i.e. formation, densification and stabilization of the oxide layers. The oxide scales, with the thickness of 6-10μm, consisting of α-Al2O3, and little SiO2 and TiO2, make the samples have excellent oxidation resistance. The approximate calculation results indicate that a large compressive stress occurs in the oxide scale.
Key words: Ti3SiC2; cyclic oxidation; thermal stress; kinetics