Study On Processes And Equipment For Preparation Of Copper Matrix Composites Reinforced By Sic Particles

CuAl10 alloy, as one member of aluminum bronze, is widely used in modern industrial manufacturing because of its high strength, corrosion resistance, powerful resistance to oxidation at high temperature, good wearability and so on. Also, Silicon carbide (SiC) is an ideal reinforcement material with high strength, modulus, hardness and low coefficient of expansion, can further improve the mechanical properties of copper-based alloys. So, the SiC particles reinforced copper matrix composites have broad application prospects.In this paper, copper matrix composites which is reinforced by SiC particles (5um) are prepared by power metallurgy method, mainly research the effects of different treatments on silicon carbide to the organization, structure and properties of copper matrix composites and optimize the parameters of electroless nickel plating. Finally, the copper matrix composites which were strengthened by SiC particles of different treatment methods and mass fraction will be characterized by Metallurgical Microscopy, Field Emission Scanning Electron Microscope (SEM), Energy Disperse Spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Vickers (VH-5LAC).Testing results shows the SiO2 protective layer with a certain thickness is generated on the surface of original SiC particles after the high temperature oxidation treatment (1000?,10h). The SiC particles are treated in alcoholic solution of organic nickel (nickel acetate, C4H6O4·4H2O) and sodium borohydride (NaBH4), On the basis of pre-plated solution, the optimal parameters are established (pH:9-9.5, bath temperature:40 ?,the maxiun addition amount of SiC:5g/L), the surface of SiC particles can be covered completely on this occasion. Otherwise, the result of the thermal shock analysis shows that the small binding force between Ni and SiC particles, by reason of the falling off of Ni from SiC particles after quenching many times. The XRD results of nickel SiC particles which were annealing at 500 ? for 4h show that Ni transformed into NiO and Ni grains become larger.Furthermore, SEM and EDS results showed that SiC particles distributed uniformly in the CuAl10 matrix and have no signs of agglomeration, Ni which originally located on the surface of SiC particles diffused and distributed in the surrounding matrix. Metallograph confirmed that the addition of SiC particles can significantly refine grains of the matrix, and grain refinement is one of the most prominent effect on reinforcement. Moreover, the TEM results showed that grain boundary between original SiC and matrix is clean and straight without precipitation and interface reaction layer. The holes appeared on the boundary declare the low intensity of the combination. Nevertheless, a large number of small nanocrystals formed on the boundaries of those two phases with totally different morphology from grains of SiC and matrix. Besides, Vickers test is applied to samples of composites which had different mass fraction (1wt.%,3wt.%,5wt.%) and treatment methods (original, high temperature oxidation, electroless nickel plating) of SiC particles, the matrix of CuAl10 alloy becomes harder than before by reason of the addition of SiC particles and strengthening effect of nickel plated SiC particles, being a strengthening phase, is most obvious, the original one is worst relatively.Lastly, the results of testing of the Continuous Casting Equipment shows a great potential in materials production, the metallograph semi-solid casting of ZA27 alloy shows the grains are quite smaller than conventional casting. The equipment runs normally.