Effect of graphite particle size on wear property of graphite and Al_2O_3 reinforced AZ91D-0.8%Ce composites

The graphite particles and Al2O3 short fibers reinforced AZ91D-0.8%Ce composites were fabricated by squeeze-infiltration technique.The researches about the effects of different graphite particle sizes on the microstructure and wear property of the composites were performed under the condition of constant contents of graphite particles and Al2O3 short fibers.The results reveal that the grain size of the composites changes less when the graphite particle size descends.Moreover,Ce enriches around the graphite particle and Al2O3 short fibers and forms Al3Ce phase with A1 element.The graphite that works as lubricant decreases the wear loss.The wear resistance of the composites increases as the graphite particle size increases.At low load the composites have similar wear loss;at high load the composite with the largest graphite particle size has the best wear resistance.The wear mechanism of all the composites at low load is abrasive wear and oxidation wear;at high load,except the composites with the particle size of 240 μm whose wear mechanism is still abrasive wear and oxicIation wear,the wear mechanism of othcrs changes to delamination wear.