原位合成MoSi_2-SiC复合材料700℃的氧化行为  

Oxidation Behavior of in-situ Synthesized MoSi_2-SiC Composites at 700℃

作　　者：张来启[1] 段立辉[1] 林均品[1] 

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083

出　　处：《材料研究学报》2015年第8期561-568,共8页Chinese Journal of Materials Research

基　　金：国家自然科学基金50871012;国家重点基础研究发展计划2011CB605502资助项目~~

摘　　要：研究了不同SiC体积分数原位合成MoSi2-SiC复合材料在700℃空气中1000h的长期氧化行为。结果表明:复合材料氧化1000h后,均未发生pest现象。复合材料的氧化抗力明显好于单一MoSi2,原位合成复合材料的氧化抗力好于传统的热压商用MoSi2粉末和SiC粉末混合物制备的复合材料(外加复合材料)。复合材料氧化膜相组成仅为非晶SiO2,材料的氧化过程主要是O2与MoSi2的作用,SiC未发生氧化。材料在700℃下仍发生硅、钼的同时氧化,因MoO3的挥发较快没有晶须形成,因而在材料表面快速形成一薄层连续、致密的非晶SiO2保护膜,使材料表现出优异的长期抗氧化性。The long-term air oxidation behavior of in situ synthesized composites MoSi2-SiC with different volume fractions of SiC at 700 ℃ for 1000 h was investigated. The disintegration （pest） of the composites has not been observed after oxidation for 1000 h. The oxidation resistance of composites is signif- icantly higher than that of monolithic MoSi2. The in situ synthesized composite MoSi2-30%SiC possesses higher oxidation resistance than the traditional composite with the same chemical composition fabricated by hot-pressing the mixture of commercial powders of MoSi2 and SiC. The oxide scale formed on the prepared composite is only composed of amorphous silica, therefore, the oxidation reaction of the materials may mainly occur between MoSi2 and O2. Silicon and molybdenum may simultaneously be oxidized at 700℃ for the composite, however, due to the faster volatilization of MOO3, thereby a thin continuous and dense amorphous SiO2 protective scale is rapidly formed on the composite surface, so the composite exhibits excellent long-term oxidation resistance.

关 键 词：材料失效与保护 MOSI2-SIC复合材料 原位合成 低温氧化行为 pest现象 

分 类 号：TB333[一般工业技术—材料科学与工程] TG178[金属学及工艺—金属表面处理]