Microstructure, microhardness and corrosion resistance of laser cladding Ni−WC coating on AlSi5Cu1Mg alloy
The microstructure, microhardness, and corrosion resistance of laser cladding Ni−WC coating on the surface of AlSi5Cu1Mg alloy were investigated by scanning electron microscopy, X-ray diffraction, microhardness testing, immersion corrosion testing, and electrochemical measurement. The results show that a smooth coating containing NiAl, Ni3Al, M7C3, M23C6 phases (M=Ni, Al, Cr, W, Fe) and WC particles is prepared by laser cladding. Under a laser scanning speed of 120 mm/min, the microhardness of the cladding coating is 9−11 times that of AlSi5Cu1Mg, due to the synergistic effect of excellent metallurgical bond and newly formed carbides. The Ni−WC coating shows higher corrosion potential (−318.09 mV) and lower corrosion current density (12.33 μA/cm2) compared with the matrix. The crack-free, dense cladding coating obviously inhibits the penetration of Cl− and H+, leading to the remarkedly improved corrosion resistance of cladding coating.
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万方数据
维普
