Effect of alkali cleaning for Ni-P-based metallic glass coating on bearing surface

ABSTRACT A systematic alkali cleaning study has been done on the different bearing component surfaces for subsequent Ni-P alloy coating. The alkali-chemical containing only carbonate and phosphate group shows better surface cleaning efficiency. There is a tendency of silica contamination when silicate containing alkali chemical is used, which is responsible for inferior quality of Ni-P alloy coating on the surface of bearing components. The use of ultrasonic energy further enhances alkali cleaning efficiency and thereby reduces the cleaning time with better properties. Amorphous Ni-P alloy coating is uniformly deposited on the surface of the bearing component. After coating, the surface roughness value drops from 0.05 to 0.025 µm and the hardness value increases from 60 to 63 Rc. The Ni-P alloy-coated bearing shows 250 to 350% improvement in resistance against corrosion, around 5-8% reduction in noise level and improvement in L10 life from 500 h of existing bearing to 1200 h.