| Because of high strength and excellent wear resistance, particulate reinforced metal matrix composites have been widely developed and researched, and have shown great prospect. SiC particles with high hardness, high wear resistance, low density and low price is widely used to reinforce metal matrix composites. The distribution of the particulate reinforcements in the composites has great effect on particulate reinforced metal matrix composites, so it is indispensable to discuss the effect of high energy ball milling on properties of SiCp/Fe composites. Our research group has conducted a preliminary study on high energy ball milling. This paper mainly studied the effect of high energy ball milling on properties of SiCp/Fe composites with the SiC particles plated by electroless copper plating.The experiment results demonstrate that the optimal process of high energy ball milling is:ball-to-powder ratio was 3:1, the rational speed was 200r/min and the blending time was 3h. The composites prove the best properties in this way.After the using of the optimum high energy ball milling, when the SiC particle size was 21 ?m and without copper plating, the relative density, tensile strength and final elongation of 20vol% SiCp/Fe composites improved 5.6%,13% and 53.3% respectively, compared with conventional method. When the SiC particles was coated by copper, the relative density and tensile strength of SiCp/Fe composites improved 3.3% and 7% respectively, the final elongation of SiCp/Fe composites improved 20%, compared with conventional method. The high energy ball milling had great effect on the properties of the composites after the SiC particles were coated by copper, this fully reflected the importance of the high energy ball milling.On the base of high energy ball milling, effects on the properties of the SiCp/Fe composites reinforced with mixed-sizes particles were studied in the present research. The experiment results demonstrate that when the reinforced particles were coated by copper and the volume fraction of SiC was 30%, the tensile strength of 10?m+21?m mixed-sizes SiC particulates reinforced iron matrix composites improved 70MPa compared with the 21?m single size SiC particles reinforced iron matrix composites. Mixed-sizes particles with copper plating reinforced iron matrix composites showed same improvement on the tensile strength compared with uncoated particles reinforced iron matrix composites.We further studied the wear resistance of SiC particles with copper plating reinforced iron matrix composites. The experiment results demonstrate that the wear properties of the different size particles mixture SiCp/Fe composites could be better than the single size particle SiCp/Fe composites. The 20% SiCp/Fe composites achieved the best wear properties with the 21?m and 45 ?m nominal-sized particles mixed, the wear loss significantly reduced compared with the single-sized particles. With the SiC particle content increased from 20% to 30%, the wear loss of SiCp/Fe composites increased. Due to the high level of SiC particles, the microscopic defects of the material increased with the increasing particle volume, and the wear performance of SiCp/Fe composites significantly decreased.The microstructure of the wear shows that the scratches and furrows is not obvious on the sample surface of 21?m and 45?m size-mixed particles. The material loss and pits is obvious on the sample surface of 45?m single size particles. The wear properties of the different size particles mixture SiCp/Fe composites is better than the single size particle SiCp/Fe composites, this is due to the mixed size particles improved the tensile strength of the composites, reduced interfacial defects, reduced the wear shedding of reinforced particles and could resist the micro-cutting of the friction surface. |
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