Process of thermal fatigue crack formation and expansion of WC/ iron matrix surface composites

In order to provide a theoretic direction for design of surface composites with high thermal fatigue performance , the thermal fatigue performance of WC/ iron mat rix surface composites obtained by the V2EPC casting
2 penet rating technology and mechanics of thermal fatigue crack formation and expansion in the  composites were studied by the thermal shock test . The result s show that , with the increase of the volume f raction of WC particles ,the thermal fatigue performance of the composites increases until reaching the maximum when the volume f raction of WC particles is 52 %. The sample is undamaged af ter 10 times thermal cycling. The interaction of thermal st ress of WC particles and alternating pulsating st ress in the interface between WC particles and mat rices causes the thermal fatigue crack formation and expansion in the composites. The thermal fatigue performance of the composites can beimproved by using the ceramic particles with high heat conductivity as reinforcement , bet tering microscopic quality of the ceramic particles and selecting the mat rices with coefficient of thermal expansion closing that of the ceramic particles , and so on.