Microstructure and properties of Ni-SiC-CaF2 composite coatings on aluminum alloy surface
Ni-SiC-CaF2 composite coating was prepared on the surface of 1060 aluminum alloy with NiSO4·6H2O,NiCl2·6H2O,H3BO3 and PVP as plating solution under the conditions of pH=4.The effects of plating temperature,current density and SiC concentration in plating solution on the microstructure of Ni-SiC-CaF2 composite coating were studied.The surface,cross section morphology,microstructure and properties of the coatings were detected and analyzed by scanning electron microscope,X-ray diffractometer,energy spectrometer,microhardness tester and friction and wear testing machine.Meanwhile,the friction and wear properties of pure Ni coating,Ni-SiC and Ni-SiC-CaF2 composite coating were compared.The results show that the stable composite coatings containing 8.26 at.％-8.95 at.％SiC and 0.46 at.％-0.62 at.％CaF2 can be formed when the plating temperature is 35-50 ℃,the current density is 5 A/dm2 and the content of SiC in the plating solution is 60-80 g/L.Under the same process conditions,the prepared Ni-SiC-CaF2 composite coating shows a 67.50％and 35.00％decrease in friction coefficient,and a 41.27％and 26.14％decrease in wear rate compared to pure Ni coating and Ni-SiC composite coating,respectively.
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