High temperature oxidation resistance of surfacing /spraying NiCr/Al composite coatings
High temperature oxidation resistance of surfacing /spraying NiCr/Al composite coatings
Wednesday, May 13, 2015
Exhibit Halls A&B (Long Beach Convention and Entertainment Center)
NiCr coating was prepared on a cast-iron substrate by TIG surfacing welding, and pure Al coating was then sprayed on it using arc spraying method. The NiCr/Al composite coatings were heated under constant temperature of 800 ℃ until 50h. The phase constitution and microstructure characterization of the coatings were investigated by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and energy dispersive analysis of X-rays(EDAX) techniques, respectively. The coating oxidation resistance was also studied in this paper. It was found that NiCr coating and the substrate formed well metallurgical combination. In the process of oxidation, Al element existed internal diffusion to NiCr layer and formed Al2O3 protective layer outside. The isothermal oxidation kinetic curve was accord with Wagner rule, the composite coating has good resistance to high temperature.