FABRICATION OF HIGH VOLUME FRACTION SiCp / Al METAL MATRIX COMPOSITES

摘要

High volume fraction silicon carbide particle (SiCp) - aluminum metal matrix composites were fabricated for use in a domestic armor application. A SiC powder mixture, consisting of three different average particle size powders (6.3, 2.2 and 0.68 microns), was designed in order to achieve high packing fractions, on the order of 60 to 70%. Near net shape porous SiC preforms were fabricated by die pressing. The preforms were bisque sintered to give them sufficient strength for infiltration. The bisque sintering was conducted either in air to produce an oxide film or by the conversion of a preceramic polymer polycarbosilane (PCS) under an inert atmosphere. The preforms were infiltrated by squeeze casting using 7075 aluminum in a semi-solid state. The infiltrated preforms were given a T6 heat treatment. Polished cross sections and fracture surfaces were observed using optical and electron microscopy to analyze the microstructure. The infiltrated preforms were found to have low residual porosity. Results on mechanical property evaluation and ballistic performance will be reported.