Pre-oxidization of SiC on interfacial structure and mechanical properties of SiCp/Al composites prepared by vacuum-pressure infiltration

Abstract

SiC particle reinforced Al matrix (SiCp/Al) composites is one of the most representative metal matrix composites and its properties depend on the interfacial structure between SiC and Al matrix. In this paper, SiCp/Al composite with pre-oxidized SiC perform was fabricated by a vacuum-pressure infiltration method. A layer of SiO2 was formed on the surface of SiC particles by pre-oxidization treatment, which then reacted with molten Al to form Al2O3 layer during the infiltration process. The formation of SiC/Al2O3 and Al2O3/Al interface improved interfacial bonding strength and enhanced bonding strength of composites. The formation of an Al2O3 continuous phase between Al and oxidized-SiC results in an improvement of interfacial bonding strength, a 16.8% improvement in bending strength (378.4Mpa) was obtained for the pre-oxidization of SiC performs at 1200 °C. However, higher oxidized temperature (1600 °C) results in thicker SiO2 layer which cannot fully transformed into Al2O3 during the infiltration processes, residual SiO2 layer becomes the source of crack initiation and propagation which lead to a decrease in bending strength (319.2Mpa) of SiCp/Al composites.