Abstract: By using double glow plasma surface alloying technology, Ti/Ta composite coating and Ta coating were prepared on the surface of pure copper, where for the preparation of the former a titanium transition layer was added. The microstructure of the Ti/Ta composite coating was analyzed, and the influence of the composite coating on the thermal shock behavior and molten salt corrosion behavior of the copper substrate was studied. The results show that the microstructure of the submicron structured Ti/Ta composite coating is dense and uniform, with a thickness of approximately 14.5 μm, and the surface is α-Ta phase. After 20 thermal shocks at 700 ℃, compared with the single Ta layer, the surface of Ti/Ta composite coating remains relatively flat, dense, and without any micro-cracks, where the gradient distribution of the intermediate Ti layer alleviates the interface stress and significantly improves the thermal shock resistance of the coating. After 10 h of hot corrosion in a mixed salt of NaCl and KCl at 500 ℃, the mass gain of pure copper is 12.89 mg/cm², while that of the Ti/Ta composite coating is only 2.8 mg/cm². The dense Ta₂O₅ oxide film formed on the surface of the Ti/Ta composite coating effectively prevents the penetration of molten salt corrosion, and improves the corrosion resistance of pure copper.

Key words: double glow plasma surface alloying technology, Ti/Ta composite coating, thermal shock, molten salt hot corrosion