Improvement of mechanical properties in RBSC by boron carbide addition

摘要

High temperature resistant ceramics have the potential to have a significant influence on the improvement of energy efficiency. The use of lightweight ceramic material can result in energy savings in many applications such as in the power, automobile, environmental or chemical industry [1]. Silicon carbide (SiC) is a high temperature resistant material used in refractories, mechanical seals, nozzles and bearings (2, 3]. However, high costs due to its high sintering temperature, >2000 ℃ in the case of conventional solid state sintering, and expensive diamond machining have restricted wider applications. On the other hand, reaction-boned silicon carbide (RBSC) has an economical advantage because of lower sintering temperature and almost no dimensional change [4,5]. However, one of the critical problems is that the mechanical properties of RBSC are still inferior to those of conventional sintered products, mostly due to free silicon in the final products [6,7]. In the present study, we added boron carbide (B_4C) with higher mechanical properties to RBSC for the purpose of improving the properties such as strength, hardness and toughness. Metal silicon (Si) was infiltrated to the green body, which consists of SiC, B_4C and C powder mixtures, producing fully dense SiC-B_4C composites with free silicon (Si). In particular, we evaluated the damage characteristics of B_4C added RBSC composites by spherical indentation to characterize the damage tolerance [8].