Abstract: To repair a failed PVC plastic extruder mold, Cu-Al₂O₃ coating was prepared on the surface of the 2Cr13 steel by low-pressure cold spray technology. By simulating the forming process of coating particles, it is found that the higher the inner energy of the coating closer to the substrate, the better the binding effect. In order to ensure the wear and corrosion resistance of the repaired mold, the coating were ground and polished to different thickness, and then the propertieswere compared. Scanning electron microscopy was used to observe morphology of the coating, immersion mass loss method and salt spray corrosion test were used to analyze the corrosion resistance of coatings, static indentation method was used to test the hardness of the coating, friction and wear testing machine was used to test the wear resistance of the coatings. The results show that the coating has a uniform structure, the porosity of the coating increases with the increase of the distance from the jointing surface, the corrosion resistance of the coating in HCl is better than that of the substrate, however in the salt spray test, the coating is obviously corroded, and AlCl₃ and CuO products are formed. The closer the coating position is to the joining surface, the higher the hardness of the coating, the more obvious the work hardening effect, the smaller the wear amount when rubbing with hard alloy, and the wear resistance is gradually improved. When the thickness of the polished coating is 1 mm, the wear resistance of the coating is the best, and the extruder mold can be effectively repaired.

Key words: cold spraying, simulation analysis, corrosion resistance, micro morphology, frictional properties