Korean Journal of Materials Research ISSN:1225-0562(Print) 2287-7258(Online) 한국재료학회지

Properties of coatings produced by warm spray were investigated in order to utilize this technique as a repair method for Al tire molds. Al-(0-10 %)Al₂O₃ composite powder was sprayed on Al substrate by warm spraying, and the microstructure and mechanical properties of the composite coating layer were investigated. For comparative study, the properties of the coating produced by plasma spray, which is a relatively high-temperature spraying process, were also investigated. The composite coating layers produced by the two spray techniques exhibited significantly different morphology, perhaps due to their different process temperatures and velocities of particles. Whereas the Al₂O₃ particles in the warm sprayed coating layer maintained their initial shape before the spray, flattened and irregular shape Al₂O₃ particles were distributed in the plasma sprayed coating layer. The coating layer produced by warm spray showed significantly higher adhesive strength compared to that produced by plasma spray. Hardness was also higher in the warm sprayed coating layer compared to the plasma sprayed one. Moreover, with increasing the fraction of Al₂O₃, hardness gradually increased in both spray coating processes. In conclusion, an Al-Al₂O₃ composite coating layer with good mechanical properties was successfully produced by warm spray.