Fabrication, characterization and application of functional coatings on nickel foam to resist hydrogen sulfide corrosion and metal dusting at high temperature.

摘要

Electrodeposition and co-electrodeposition methods were used to prepare: (1) copper coated nickel foam; (2) copper-ceria coated nickel foam. Both of these coatings formed a copper-nickel alloy after heat treatment in reducing atmosphere. These coatings have low, stable resistance when exposed to 500 ppm H2S-syngas at 750 °C. The copper-ceria coated nickel foam showed better resistance to H2S corrosion compared to copper coated nickel foam. This was because ceria acted as sulfur adsorbent which reduced the sulfidation rate. However, for the copper-ceria coating, cracks were formed and dense layer of coating could not be obtained thus making it unsuitable for use as an anode current collector in SOFCs applications. In contrast, for uncoated nickel foams exposed to either syngas or 500 ppm H2S-syngas, the bare nickel was severely cracked, causing loss of mechanical strength and large increase in resistance.;Electrophoretic deposition was used as the coating technique for the ceramic coating. This coating is used to resist H2S corrosion for H2S level up to 5000 ppm. Titanium oxide was first used as the coating material since it can be commercially obtained and was used to help understand the process. The optimum suspension used for deposition contained 2 wt% titanium oxide, 2 wt% triethanolamine (TEA) and 1 wt% poly(vinyl butral-co-vinyl) (PVB). Cracks-free coating can be obtained after deposition. However, cracks were present when the titanium oxide coated samples were heated at high temperature.