Comparison of method and performance in tantalum coating prepared by molten salt electroplating and glow infiltration

Abstract

Tantalum as a rare refractory metal is mainly used for temperature-resistant and wear-resistant surfaces of rocket engines and aerospace structures. In this paper, two preparation methods of metal tantalum coating were discussed, and the performance testing and application of the coating were studied. The results show the thickness of tantalum coating (S-Ta coating) formed by glow infiltration method is about 12 μm, the grain growth of coating is compact and the bonding strength with the matrix is about 65 N. The thickness and bonding strength of the S-Ta coating are better than those of the tantalum coating (D-Ta coating) obtained by molten salt electroplating method. The two coatings mainly exist in α-Ta phase and the crystal plane (211) preferred orientation appears. Compared with the matrix, the wear resistance and friction reduction of two coatings are obviously improved at room temperature. The friction coefficient is further reduced by 42% and 57%, and the wear rates are 2.65 × 10−4 and 2.45 × 10−4 mm3/N·m respectively, with the combination of tantalum and oxygen to form a self-lubricating oxide (Ta2O5) at 600 °C. Tantalum can be used as high temperature protective coating material to achieve sustainable development of rare metal resources by reducing costs and improving performance.