Processing of SiC/Mg Composites by Pressureless Infiltration Technique

AZ91 magnesium on SiC poroues preform and interfacial reaction between SiC and AZ91 magnesium were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), friction and wear testers and micro-hardness testers. The results indicate that magnesium has a good wettability on SiC and can spontaneously infiltrate the porous SiC/starch preform after a 5h infiltration at 750 degrees C. Moreover, interface reaction at the front of magnesium melt was found between the SiC and AZ91 magnesium, which improves wettability between each other. The massive oxidized SiC powders have uniform distribution in AZ91 magnesium metal matrix. The micro-hardness of SiC/Mg composites is 383HV(0.2) and more than 5 times higher than that of AZ91 magnesium (72HV(0.2)). Under the conditions of dry sliding wear and 4N loads, compared with the unreinforced AZ91 magnesium matrix, the friction curve of the SiC/Mg composite fabricated by pressureless infiltration is much lower than that of AZ91 magnesium, which means SiC/Mg composites have a better wear resistance.