氧化对WC_p/钢基表层复合材料热裂纹萌生扩展的影响

利用负压实型铸渗工艺,通过涂覆预制块法,成功地制备了以高铬钢为基材,WC为增强颗粒的表层复合材料,通过氧化增重法、热震实验法及扫描电镜等分析测试方法重点研究了氧化对WC/钢基表层复合材料热裂纹萌生及扩展的影响。研究结果表明:WC颗粒在高于600℃时,会氧化成为结构疏松的WO3,并且随着温度的升高,氧化反应的速度加快,而WC的氧化,对热疲劳裂纹的萌生和扩展产生重要的影响。在500℃以上的空气环境中,复合材料基体会在裂纹源的尖端处形成氧化物。结合环境中的氧对裂纹扩展影响的分析可知,生成的氧化物为裂纹的扩展提供了途径,并且使复合材料极易在热应力的作用下导致开裂。

Effects of Oxidation on Initiation and Propagation of Thermal Crack for WCp/Steel Matrix Surface Composite

With casting-infiltration method,WC particles reinforced steel matrix surface-layer composites were successfully gained.The effects of oxidation on initiation and propagation of thermal fatigue crack for WC/steel matrix surface composite were tested by oxidation weight increase method,thermal shock experiment method,SEM and EDS.The results show that WC particles would become WO3 when the temperature was more than 600 ℃.As the temperature increases,the oxidation reaction speeds.The oxidation of WC has great effects on initiation and propagation of thermal fatigue crack for WC/steel matrix surface composite.Composites matrix would form oxide at the point of crack source above 500 ℃.Combined with the analysis of the effect of oxygen in the environment on crack propagation,we can conclude that oxide provides ways for the propagation of the crack,and the composite materials easily craze under the thermal stress.