Lightweight and low thermal expansion composite material

摘要

A method of forming a metallic composite product having a specific gravity no greater than 1.8 and a thermal expansion no greater than 16x10-6 DEG C. in a preheated mold. The portion of the mold between a cavity and the gate has a stainless steel wire gauge for retaining particles. The mold is filled with screened fly ash, glass, hollow spheres having a particle size in the range of 50 to 200 micrometers and a globularness of at least 90%, which has been preheated to the same temperature as the mold. Molten aluminum alloy is injected into the mold at a pressure in the range of from 40 to 80 kgf cm2 at the gate and at a flow velocity in the range of 0.08 to 0.20 m/second.