High Volume Fraction SiCp/Al Composites Prepared by Pressureless Melt Infiltration: Processing, Properties and Applications

摘要

In this paper, a cost effective near-net-shape fabrication technology based on the pressureless infiltration of Al alloy melt into SiC preform was systematically investigated, the basic mechanical and physical properties of the high volume fraction (～70vol%) SiCp/Al composites were characterized. The advantages of the composites over traditional materials used as the optomechanical components for space-based optical systems and electronic packages for avionics systems were analyzed. By developing and using a series of novel techniques including the precise hot injection moulding for SiC perform and melt infilitration restrictive coating for SiC preform surface, the composites were fabricated to highly near net-shape under no external pressure and high temperature mould. In details, taking a typical component of the high volume fraction SiCp/Al composites with complex and thin wall structure as illustration, its dimension deviation and configuration precision were controlled to 0.2%, the surface smoothness (Ra) came up to 1.6 μm, and furthermore, its metallurgical quality was excellent. The properties of the SiCp/Al composites were noted for their high thermal conductivity of 200W/m-K or so, low coefficient of thermal expansion (7.0x10~(-6)/K) and high specific stiffness (more than 3 times that of Al alloys).