THERMAL CONDUCTIVITY AND WEAR RESISTANCE OF A359/(SiC + Si3N4) HYBRID COMPOSITES PREPARED BY SQUEEZE CASTING

Thermal parameters and wear are considered with dry sliding for hybrid composites based on an A359 matrix prepared by squeeze casting. Composites are strengthened with addition of 5, 10, and 15 wt.% (SiC + Si3N4). Wear of A359/(SiC + Si3N4) composites proceeds under a load in the range 20 - 60 N with a sliding rate of 2.75 m/sec. It is found that A359/(SiC + Si3N4) composite exhibits relatively low thermal conductivity and better wear resistance than alloy A359. Friction coefficients and surface contact temperature for specimens of composite A359/(SiC + Si3N4) increase as there is an increase in (SiC + Si3N4) content within them. In studying worn surfaces it is detected that A359/(SiC + Si3N4) composite is covered with iron oxide that plays the role of a self-lubricating layer. The better wear resistance index for A359/(SiC + Si3N4) composites makes it possible to use them in the automobile industry.