| In the modern industrial production, machinery and equipment are often working in relatively poor conditions in a long-term. Mechanical parts are prone to wear and corrosion which lead to failure of mechanical equipment and business losses. Therefore, mechanical equipment and materials should be with high wear resistance, corrosion resistance, high temperature resistance which can be applied in poor working conditions. Thus, changing the surface properties of those materials is the best way to combat this problem. So far it has been a lot of surface modification method, including thermal spray, laser cladding, electroplating, heat diffusion, chemical leakage, casting and other methods. Cast-sintering method is used in the fabrication of metal matrix surface composites technology, which has the advantages of simple, material savings, heat-flow density sintering in a short time, and the fabrication of metal matrix surface composites with the material has an excellent overall performance.This article applies the Self-fluxing alloy Ni60 powder, self-molten Cu powder and self-molten Cu powder +Al powder +CuO powder alloy system by cast-sintering process of pouring molten pure copper exploration, explores the different metal powder sintering system and process parameters influence on the matrix surface composite by cast-sintering of copper layer is formed. By optical microscopy, scanning electron microscopy, energy dispersive spectrometer, micro-x-ray diffraction analysis of cast microstructure of sintered composite layer, phase composition, distribution and morphology, sintered layer and substrate combination are analyzed. Addition of Al2O3 particles on casting was also studied effects of microstructure and mechanical properties of sintered composite layer. Results show that:1) Using self fluxed copper powder preparation of the surface of the copper base composite material wall thickness up to 30 mm above is needed to make its combination with matrix, but the interface does not achieve complete metallurgical bonding. Al + 4CuO mixed powder was added into the molten copper powder melting point of the impact is not big, so the self fluxed sintering promoting effect of copper powder sample is limited. And Al + 4CuO is too high for the amount of powder, its reaction is very sharp, easy to cause metal splash, it will reduce the effectiveness of the combination of sinter layer and matrix and the density of sintered layer.2) Nickel base layer on the surface to substrate surface to realize the combination of metallurgy, sintering layer with high strength and density, casting sintering effect is obviously better than self fluxed copper nickel base layer on the surface. Nickel base layer on the surface obviously divided into two layers: the outer is Ni60 / Al2O3 composite layer, inner layer for the diffusion layer. Composite layer phase composition mainly Ni based solid solution, hard boride CrB, Cr3Ni2 intermetallic compounds3)Ni60- Al2O3 composite material hardness of the sintered to get the relative to the substrate materials have obvious improvement. Join the 10% Al2O3 content reached the maximum hardness. Al2O3 content is 10% when the maximum thermal conductivity composite layer, more conducive to high temperature work, 20% when density is not good enough, the minimum thermal conductivity. Add the right amount of Al2O3 content can improve the wear resistance of nickel base layer on the surface, to wear the best when Al2O3 content is 10%, Al2O3 content reaches 20% abrasion resistance variation; Al2O3 content is 20%, the sintering layer with low bonding strength, friction powder particles will fall off, which seriously affect the sintering layer of abrasion resistance... |
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