| This study was aimed to investigate influence of microstructure, abrasive heat affected zone(AHAZ), primary silicon and eutectic silicon on abrasive characteristics of AC8A/SiC_p composite fabricated by the squeeze casting under various conditions. The abrasive characteristics was improved by addition of Mg and Ca elements because of improvement of SiC_p wettability and hardness in matrix. It is general theory that abrasive amount is decreased with increase of squeezing pressure. In this study, however, as squeezing pressure applies over a certain limit value(220MPa), the abrasive resistance under the condition of the high abrasive speed(3.67 ㎧) is not increased with increase of squeezing pressure. This is due to the crack by the generation of abrasive heat and fatigue below abrasive surface under the condition of high abrasive speed(3.67 ㎧). In abrasive heat affected zones of AC8A and AC8A/SiC_p composite fabricated by same squeezing pressure(220MPa), eutectic Si of directly below abrasive surface is finer than that of matrix, and abrasive heat affected zone of AC8A/SiC_p composite is thinner than that of AC8A. These reasons are that abrasive heat makes α dendrite and eutectic Si fine in AC8A/SiC_p composite. Therefore, the hardness of heat affected zone of directly below abrasive surface was increased sharply owing to abrasive heat. |
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