FORMATION OF WEAR-RESISTANT AL-SIC SURFACE COMPOSITE BY LASER MELT-PARTICLE INJECTION PROCESS

The microstructural and mechanical properties (hardness and wear resis tance) of the metal-SiC composite formed on the surface of the cast Al alloy A-S7G0.3 by SiC particle injection assisted laser treatment wer e studied. The upper part of the laser treated zone had a very fine mi crostructure, characterised by needles of various sizes and high micro hardness values (250 HV(30 g)) compared with that of the substrate (60 HV(30 g)). The SiC particles had partially reacted with the matrix. I n the lower part of the zone, the SiC particles remained completely un reacted and had only mechanical adhesion with the matrix. Wear tests r evealed that extremely high wear resistance (90 times higher than that of the untreated surface) was provided by this laser surface treatmen t technique when a load of 35 N was applied.