Electrodeposition and the Optimization of Molybdenum Layer on Nb-Ti-Si Based Ultra-High Alloys from Aqueous Solution

Abstract

Depositing a molybdenum layer through electrodeposition is a possible and economical way to prepare Mo layer. It could be a new preparation of MoSi2coating on Nb-Ti-Si based alloys combined with halide pack cementation. In this paper, the effects of pre-coated Re layer on the substrate, pH of the electrolyte, water to acetate ratio and the applied current density on the deposition were investigated and optimized to obtain low oxygen content, adherent molybdenum coating on Nb-Ti-Si based alloys. The surface morphology and cross section were characterized by SEM. The thickness of the deposit is about 6 μm and nodules and cracks were observed on the surface. EDS and EPMA analysis suggested the presence of Mo and its oxides in the deposit; XPS results confirmed the presence of Mo, Mo2O3and MoO3in the as-deposited layer. The crystal structure of as-prepared coating was amorphous by the XRD investigation, and the metallic molybdenum was the main existence form of the molybdenum element in the deposit.