Effect of sol gel coating on wettability and interfacial reaction in Al-SiC MMC

Abstract

The control of the interfacial reaction between the matrix and the SiC reinforcement in Al-SiC metal matrix composites (MMCs) is an important production parameter. The reaction causes degradation of the reinforcement, weakening of the interface and a decrease of the mechanical properties of the products. Much recent work has been carried out to characterize the Al/SiC interface and to control the interfacial reaction. The present paper describes and compares the effects of surface coatings on two interface properties, the wettability of SiC in pure A1 and the interface reaction of the same SiC reinforcement particulates in the presence of controlled amounts of Si pre-alloyed in the matrix. The results suggest that a treated particulate with lower wettability has better resistance to molten A1 attack, and that 4 wt% Si in the matrix is sufficient to protect a coated particulate while 7-9 wt% is needed for uncoated SiC particles.