HIGH TEMPERATURE CORROSION RESISTANCE OF MODIFIED REACTIVE ELEMENT ALUMINIDE DIFFUSION COATINGS ON IN738 SUPERALLOY

AbstractModified aluminide diffusion coatings on IN738 substrates were produced by a new route using continuously cast, aluminum alloy wires consisting of Al-Y, Al-Si-Y, Al-La and Al-Ce. The cast wires were used as evaporation sources for ion vapour deposition followed by diffusion heat treatments to form nickel aluminide coatings. The ability of the different coatings to resist corrosion was evaluated by conducting experiments during which the coated alloy materials were exposed for prolonged periods to molten sulfates at 900 °C. The results indicated that the Al-Ce modified coating provided the greatest protection against the molten sulphate environment. The other coatings provided less protection and it was concluded that sulfidation followed by oxidation played a major role in their degradation.On a produit des revetements par diffusion a base d’aluminium, modifies, sur des substrats d’IN738 par une nouvelle route utilisant des fils d’alliage d’aluminium coules en continu consistant d’Al-Y, d’Al-Si-Y,...