TiC-MoSi_2复合材料的原位合成及其低温氧化特性

In-suit synthesis and low temperature oxidation properties of TiC-MoSi_2 composites

为了改善MoSi2力学性能和低温抗氧化性能,选用TiC颗粒来增强补韧MoSi2,通过XRD和SEM表征合成MoSi2基复合材料的微观结构并研究了预氧化对MoSi2基复合材料低温抗氧化性能的影响。结果表明,采用Mo、Si、Ti、C粉末可以自蔓延原位合成20 vol%TiC-MoSi2复合材料。复合材料在500℃氧化240 h增重1.261 mg.cm-2,氧化动力学呈线性关系,生成疏松多孔的氧化层导致"粉化"现象发生。经1200℃预氧化处理,20 vol%TiC-MoSi2复合材料在500℃氧化240 h增重4.83×10-4 mg.cm-2。预氧化处理后的材料表面形成致密的TiO2和SiO2复合膜抑制了TiC-MoSi2材料出现低温"粉化"现象。

In order to improve mechanical properties and low temperature oxidation resistance of MoSi2,TiC particle was employed to in situ prepare TiC-Mosi2 composites.The microstructure of TiC-MoSi2 composites was investigated by means of XRD,SEM and oxidation tests.The influence of pre-oxidation at high temperature on the oxidation behavior of 20 vol% TiC-MoSi2 composites at lower temperature was examined.The results indicate that the 20 vol% TiC-MoSi2 composites are synthesized with Mo,Si,Ti and C powders by self-propagation high temperature synthesis（SHS）.The mass gains of 20 vol% TiC-MoSi2 composites are increased by 1.261 mg.cm-2 after oxidizing at 500 ℃ for 240 h,and the oxidation kinetics nearly obeyed linear law.The loose oxidation scale is formed on the materials surface and caused the＂pesting＂.The mass gains of sample by pre-oxidation at 1200 ℃ are increased by 4.83 × 10-4 mg.cm-2 after oxidization at 500 ℃ for 240 h.The compound TiO2 and SiO2 oxidation scale effectively prevents the＂pesting＂phenomenon from occurring.