Microstructures and corrosion behaviors of nickel-based coating prepared by laser cladding and electroplated hard chromium coating

Electroplated hard chromium (EHC) coating owing to bad service life and serious environment pollution was seemed to replace by Ni based laser cladding (NBLC) coating in aircraft. The microstructures and corrosion behaviors of NBLC coating and EHC coating were studied by the electrochemical methods and micro-analysis technique. The results displayed that NBLC coating exhibited dendrite structure and EHC coating showed lamellar structure, which indicated that the NBLC coating expressed metallurgical adhesion and the EHC coating manifested physical cohesion. The micro-hardness results indicated that the NBLC coating was more homogenous and more compact than the EHC coating. Electrochemist results showed that the NBLC sample exhibited more obvious polarization phenomenon and higher polarization resistance than EHC sample, which indicated that the NBLC coating showed more excellent protection ability than the EHC coating in 5% NaCl solution. That was related to the synthetic effects of coating composition and surface process technology.