.ni-co-p/wc (nm) Composite Coating And The Silicon Surface Of The Metal

In this paper, the electro-deposition technology of Ni-Co-P/WC(nm) coating on hyper-eutectic Al-Si casting alloy and the chemical-deposition technology of Ni-P coating on single crystal silicon were studied. The morphology, structure, and properties of the two kinds of coatings were analyzed by the method of XRD, SEM, metallographic microscope, etc. The single factor which effects the coatings deposition was explored. The mechanical properties and corrosion resistance of Ni-Co-P/WC(nm) coating, the properties of electric conduction of the chemical-deposition Ni-P coating were tested. The chief experimental contents and results included:(1)By the method of electro-deposition, Ni-Co-P/WC(nm) coating on hyper-eutectic Al-Si casting alloy has been first acquired and the technology of elecfro-deposition has been optimized: the consistency of CoSO4 is 6OglL; the electric current density is 6 A/dm2~ the temperature is 70?IJ ;the rate of agitation is 1100rpm; PH is 1.5.(2)The single factor which effects the content of cobalt in the coating was explored, the experimental results show that the concentration of CoSO4 and electric current density effect strongly on the cobalt content in coating. The effect of two kinds of factor on cobalt content is different, cobalt content in the coating increases as the concentration of CoSO4 rises; but when electric current density rises up will make the cobalt content will decrease.(3)The mechanical test shows that the properties of Ni-Co-P/WC (nm) coating are better than these of Ni-PIWC (nm) coating, for the former, the hardness and wear resistance were improved. From the testing for corrosion resistance, this coating has high requirements for surface quality; otherwise, the corrosion resistance of the coating will get bad.(4)The morphology, structure, and properties of the two kinds of coatings were analyzed by the method of XRD, SEM, metallographic microscope, etc. it has been found that, most part of nano-crystalline WC particles are distributed dispersedly over the matrix. But there has small part of nano-crystalline WC particles is congregate in the coating. The coating morphology is similar to Ni-P/WC (nm) coating, and the cystiform morphology petaliod appears on the surface of coating.?II ?(5)Different factors in the chemical-depositing Ni-P alloy which affect on the content of phosphorus and the rate of deposition have been discussed. It has been shown that the content of NaH2PO2 affects on content of phosphorus and the rate of deposition much stronglier than other factors.(6)The morphology, structure of the chemical-deposition Ni-P coating was analyzed. It was found that the chemical-deposition Ni-P alloy is typical petaliod feature.(7)The property of electric-conduct of the chemical-deposition Ni-P alloy has been analyzed qualitatively. The result shows that the specific resistance of Ni-P alloy rises rapidly with the increasing of phosphorus content.