Mechanical degradation of 3D Cf-SiC composites at elevated temperature

Abstract

Carbon SiC (C_f-SiC) composites are finding increasing applications at elevated temperature because of their unique combination of mechanical and tribological properties. These composites are subjected to various degradation mechanisms during usage because of diverse field of applications. The intention of undertaking the present investigation is to understand and compare the material removal mechanisms of (C_f-SiC) composites subjected to impact abrasion, reciprocating wear at ambient and elevated temperature and hypersonic conditions. The results suggest that material is removed through crack formation and propagation during impact abrasion. As the test temperature is changed from ambient condition to 773 K during impact abrasion, the wear resistance of C_f-SiC composites varies from 48.47 to 41.88 under normal impact and from 7.68 to 9.59 during oblique impact. The formation of smooth self-lubricating tribo-layer governs friction during reciprocating wear. At higher load and higher temperature the formation of carbon dust occurs. The friction coefficient varies between 0.4 and 0.6 at low load. It increases to a high value at higher load and at 773 K. The main material removal mechanism during hypersonic condition is mechanical erosion although marginal ablation also takes place. Total material loss is 6.4 gm for 600 s exposure to hypersonic condition.