Preparation Of SiCp/ZL101 Composites By High-intensity Ultrasonic Treatment

SiCp/ZL101 composites are used extensive in aviation, military affairs, automotive industry, electronic device, athletic sports and many other industrial fields, due to their unique properties such as high wear-resistance, low expansion coefficient, lightweight, specific strength and specific modular. In this paper, the SiC/Al composite precast block with high SiC volume fraction is prepared by infiltrating process, and the technology for fabricating SiCp/ZL101 composite by high intensity ultrasound treatment were studied. The microstructure, hardness, friction wear behavior of the SiCp/ZL101 composites were also studied.Firstly, the SiCp/ZL101 composites precast block with high SiCp volume fraction have been prepared by using pressure infiltration method. The factor such as the surface treatment process for the SiC particles, preheating temperature of SiC particles and mold, the temperature of molt, infiltration pressure were controlled in order to ob obtain a composite block of high quality. It is indicated that when the preheating temperature of SiC particles and mold is 580℃-620℃, the poring temperature of alloy is 700℃-720℃and the infiltrating pressure is 1×105^-3×10⁵N/m², a precast composite block with a homogeneous structure can be obtained. SiC particles are distributed homogeneously in the precast block, and a well bounding between the SiC particle and matrix is observed in the block. The density of the block isρ_预= 2.93g/cm³ corresponding to the SiC volume fraction of 51% by measureing its weight and volume. The size of SiC particle is in the range of 80μm to120μm.Secondly, the technology for fabricating SiCp/ZL101 composite by adding precast block in the semisolid using intensity ultrasound treatment is studied, and the microstructure as well as properties of the composite is also investigated. Under semi-solid condition, the precast composite block was added into the molten Al alloy and stirred by using intensity ultrasound, as a result, a composite with different SiC content were prepared. It is indicated by the results that a homogeneous dispersion of SiCp particles is discovered in the microstructure of the SiCp/ZL101 composite. The mechanics for the high intensity ultrasound to make the particles dispersing homogeneously result from the cooperation of acoustic cavitation and high speed acoustic streaming effects. In addition, high intensity ultrasound treatment can also meliorate the microcosmic appearance of aluminium alloy'basal body and the primary phase can be changed into the spherical grain configuration by the thickset fir-tree crystal.Thirdly, the hardness of the composites is measured and increased by increasing SiCp volume fraction. The Brinell hardness of the composite is increased from HB62.2 to HB78.7 by increasing the SiC volume fraction from 5 to 20 percents. Comparing with the basal body, 20 percents of SiCp/ZL101 composites'macrohardness enhanced nearly 33%.Lately, wear-resistance of SiCp/ZL101 composites were studied. With increasing of SiCp volume fraction, the wear-resistance can be improved significantly. It is incated by SEM analyze that abrasion mechanism are made up of tiny cutting abrasion and desquamating outside in addition of dry friction, it is the synthesis effect with grain-abrasion, oxidation- abrasion and a spot of adhesion-abrasion.