Development status of surface treatment technology for copper and its alloys for metallurgical equipment

Copper and its alloys have various applications in the metallurgical industry due to their good thermal conductance. Continuous casting mold, blast furnace tuyere cooler, and converter oxygen lance’s nozzle are the core components to ensure normal steel production. With increasingly severe service conditions and the goal of long component life, there is an urgent need to improve the surface properties of copper alloy components to curb premature component failure due to surface abrasion, corrosion, or oxidation. Therefore, the effective surface treatment of copper alloy parts is of great significance to the development of the steel industry, which combines the high thermal conductivity of copper alloys and the high strength, heat resistance, or corrosion resistance of the protective layer. There have been numerous attempts to apply surface technologies to metallurgical equipment and more reports on surface treatment technologies for copper and copper alloys. However, fewer reports have systematically sorted out the failure forms of key metallurgical components of copper alloys and the current state of research on surface treatment technology for copper alloys. Therefore, this paper first reviews the main surface failures of three key copper alloy components, namely the continuous casting crystallizer, the blast furnace air outlet bushing, the converter oxygen lance head, and the current technical methods to improve the overall performance of these components. Second, this paper reviews the current research and development status of several surface treatment technologies in the field of copper alloy surface modification, such as electroplating, thermal spraying and cold spraying, surface fusion coating, laser treatment, and alloy co-infiltration. Moreover, it highlights the emerging thermal spraying, cold spraying, surface fusion coating technology, and laser surface treatment technology; contrasts and analyzes the advantages and disadvantages of these surface treatment technologies; and provides an overview of the physical vapor deposition refractory high-entropy alloy film technology. The potential application of physical vapor deposition of refractory high-entropy alloy films in surface strengthening of copper alloys is prospected. Developing new coating materials, optimizing the physical vapor deposition technology coating process, and combining various surface treatment technologies (such as laser surface treatment and surface coating technology) are possible directions to improve surface properties and bond strength. They will enable a longer life of copper alloy components for metallurgical equipment.