Microstructures and adhesive strength of functionally gradient coating on crucible substrate sprayed by HVOF

Based on the application of the functionally gradient coating on crucible substrate, the microstructures and bonding strength of CoNiCrAlY+CoCrMoSi coating deposited on CrZrCu substrate by HVOF process and Ni-Co electroplated coating were investigated. Adhesive strength was tested by adhesive stretching method. Microstructures, micro-region composition, phase structure and stress state of section surface of the coatings were investigated by means of SEM, EDS, XRD and X-ray. The results showed that, the bonding strength of gradient coatings was much greater than that of electroplated coating. Stress was compressive residual stress both on the coating surface and at the coating-substrate interface. The surface stress was small, but that was much greater at interface. The elements content and phase structures of electroplated coatings did not change. The main element content of coating was basically consist with original powder, but the contents of C and O element increased obviously.