Study On The Technology Of SiC/6066Al Composites Prepared By Composite Casting

SiC Particle reinforced aluminum matrix composites are widely used in aerospace, sports equipment, automotive and other industrial fields because of their high specific strength, specific modulus, good thermal conductivity and wear resistance. In this paper, the SiC/6066Al composites were prepared by composite casting. The surface morphology of SiC particles, microstructures and phase structure of the composites were analysed by OM, SEM, XRD. Using Brinell hardness tester measured the hardness of the composites, the effects of SiC particles surface treatment and stirring parameters on the microstructures and hardness of composites were studied, and the stirring parameters were optimized by orthogonal experiment. The main results obtained are as follows:(1) After pickling and high temperature oxidation treatment, the surface of SiC particles have amorphous SiO2 film, the edges and corners were passive; after treatment, the surface of SiC particles becomes rough, and some K2ZrF6 salt precipitation; after alkaline cleaning and pickling treatment, the surface of SiC particles becomes clean, the edges were passive a little.(2) The surface treatment of SiC particles have a greater impact on its distribution in the matrix and hardness of the composites. SiC treated by alkaline cleaning and fluoride salts have a best distribution, the hardness of composites reach maximum; the original state SiC without any treatment have a worst distribution, the hardness of composites reach minimum.(3) Under the same conditions, when stirring temperature is 620℃or the stirring speed is 600r/min, particles distribute uniform, if temperature or speed is too low, particles are difficult to disperse, agglomeration serious, too high, particles are difficult to enter the melt or melt suck Gas serious; at the experimental conditions, with the stirring time grows, the dispersion of particles increasing. Stirring temperature, stirring speed and stirring time on the hardness of composites showed a similar pattern to microstructure. (4) Orthogonal experimental results show that : in 620℃, 600r/min, 45min conditions, composites get the lowest porosity which is about 3.9%.(5) The interfacial bond strength between SiC particles and the matrix is moderate, the main fracture mode of composites are the fracture of SiC particles, debonding of SiC/Al interfacial, matrix ductile fracture.