PREPARATION OF CAST IRON / CERAMIC PARTICLE COMPOSITES BY COMPOCAST1NG

摘要

There is strong demand for materials such as composites that have both high strength and high wear resistance. The compocasting process invented at MIT is very suitable for preparing composite materials. We tried to make cast iron matrix composites containing hard ceramic particles. We made an apparatus composed of an electric resistant heating furnace and two motors rotating a crucible and a stirrer. The crucible which is made of Al_2O_3 has an inner diameter 95 mm, and is rotated at 0.03 s~(-1). The stirrer is made of SIALON, (one end 40 x 30 x 20 mm), and rotated at 6.7 S~(-1). The stirrer is located eccentrically in the crucible to stir the semi-solid slurry uniformly. The cast iron of the carbon saturation degree of 0.8 is melted. Ceramic particles of Al_2O_3 (100, 50, 20 μm), 92ZrO_2-8Y_2O_3 (26 μm), TiO_2 (20 μm) are added onto / into the cast iron semi-solid slurry (whose fraction solid at 0.1 - 0.4 under the flow of argon) as 1) powders, 2) powders wrapped by iron leaf, 3) pellets made of iron and ceramic powders, and 4) pellets made of iron, ceramic and carbon powders. We can uniformly disperse TiO_2 powders of a good wettability, but having a large density difference with cast iron. However, it is very difficult to disperse not only Al_2O_3 powders of a poor wettability and a large density difference, but also 92ZrO_2-8Y_2O_3 powders of poor wettability but a small density difference. The wettability of ceramic powders with cast iron melt is more important than the density difference.