Study On The Nano-SiO₂/Ni-P-Co Composite Coatings

In this paper, the method of electrochemistry plates is applied to depositing Ni-P-Co alloy coatings and nano-SiO2/Ni-P-Co composite coatings on the surface of steel. The effects of NaH2PO2 content, the current density, CoSO4 content and temperature on the Ni-P-Co alloy coatings were investigated. Based research on Ni-P-Co alloy coatings, adding the nano-SiO2 to the electroless plating solution, the effects of nano-SiO2 content on the structure and properties of the composite coatings. The shape of the composite coatings and the grow up mechanism of plating layer were studied by SEM analysis. The results show that nano-SiO2/Ni-P-Co composite coatings has a high hardness, its micro-hardness is up to 502HV, the corrosion resistance and wear resistance of the nano-SiO2/Ni-P-Co composite coatings is higher than Ni-P-Co coatings. The study shows that the optimal components of the electroless plating solution were 50~60g/L NaH2PO2 and 70~80g/L CoSO4. Plating temperature is 50~60℃. The nano-SiO2 conformable content in plating layer is 6g/L. The current density chooses 6A/dm2 when the velocity of electroless plating is clipping. It is choosed to 3A/dm2 when glabrous degree of plating layer is well.