Preparation Of Si Particle Reinforced Al Matrix Composites

Particle reinforced aluminum matrix composites (PRAMMCs) show manyexcellent characteristics such as high specific strength, low density, low thermalexpansion coefficient, good wear resistance and thermal stability, simple productionprocess, mature technique, low cost, etc. they are having much rapid development inaviation, spaceflight, automobile, electronics and other fields. Silicon PRAMMCswere prepared by powder metallurgical (P/M) method. The effect of the various factorsin the process was studied in this paper. The research results in this paper providereferences for P/M aluminum matrix composites.Effect of high energy ball milling and general mixing on the spatial distributionof reinforcements in aluminum matrix composites (Al MMCs) was investigated. Theresearch results show that high energy ball milling, which can improve the shape ofsurface of reinforcements, change the particle size and make uniform distribution ofreinforcements, is the effective method for achieving reinforced particles and matrixparticle uniform mixture.The orthogonal optimization design was carried out taking the sintered densityand tensile strength of the sample as objective functions，taking lubricant, thecompacting pressure, sintering temperature and holding time as design variables. Theexperiment shows that, optimal sintered density and mechanical properties areobtained under the condition of the concentration of lubricant for0.4wt.%, thecompacting pressure for500MPa, sintering temperature of575℃and holding timefor1.5h. The research results in this paper provide references for P/M Al MMCs.The reinforcement was distributed by the distortion flows of aluminium matrixcaused by hot extrusion. The PRAMMCs performance was improved by extrusion.The organization was more compact and contributed to improving the hardness andstrength. Performance of the samples under different temperature of hot extrusion hadbeen studied. The experiment shows that the best hardness and strength of the AlMMCs with15wt.%reinforcement are108.0HBS and276.4MPa at480℃of extrusion temperature.The SEM equipment was used to analyze the fracture microstructure of Siparticulate reinforced Al MMCs. Crack was found at interface of reinforcement andmatrix before extrusion. The fracture belonged to brittle fracture. Al MMCsperformance was improved after extrusion and the fracture mechanism was microvoidcoalescence fracture.Research for the performances of reinforcement content between10wt.%~30wt.%of Al MMCs shows that, with the increase of reinforcement content, the hardnessand density increase and the coefficient of linear expansion, wear mass loss, wear ratedecrease. Reinforcement effectively improves the performance of composite materials.