Creative Preparation of High-oxidation Resistant Coating on Nb-base Heat-resistant Alloys using Molten-salt Electrodeposition and Self-systematization

用熔盐电解液在Nb-W和Nb-W-Mo合金上用熔盐电解液电沉积铝，在Nb-W和Nb-W-Mo合金上制备了Ni-Al/Ni双层涂层。镍层较薄的涂层在初始阶段表现出强烈的氧化行为。相反，镍层较厚的涂层样品具有较高的抗氧化性。对于镍层较厚的涂层，在氧化试验过程中，镍层与合金基材的扩散形成了由Ni-Nb合金组成的中间层。这些中间层有助于维持涂层表层较高的Al浓度，抑制涂层的剥落，从而提高涂层的抗氧化性能。

Coatings of Ni aluminide/Ni bilayer on Nb-W and Nb-W-Mo alloys were prepared by the electrodeposition of Al using a molten salt electrolyte after the Ni electrodeposition. The coating specimen with a thin Ni layer showed a vigorous oxidation during the initial period. On the contrary, the coating specimen with a thick Ni layer showed a high oxidation resistance. For the coating specimen with a thick Ni layer, intermediate layers consisting of Ni-Nb alloys were formed by the diffusion of the Ni layer and the alloy substrate during the oxidation test. These intermediate layers contributed the maintenance of a high concentration of Al in the surface layer and the suppression of spallation of the layers, leading to the improvement in the oxidation resistance of the coating.