METHOD OF PRODUCING REACTIVE ELEMENT MODIFIED-ALUMINIDE DIFFUSION COATINGS

摘要

There is disclosed a process for forming aluminide diffusion coatings containing reactive elements on metal substrates such as iron, nickel or cobalt based alloys for protection against high temperature oxidation or corrosive environments. The process includes depositing a mixed metal coatin g containing aluminum and at least one reactive element onto the metal substra te and heat treating the coated substrate to induce interdiffusion of elements between the substrate and the deposited metal coating. In one aspect of the invention, the reactive element is yttrium and the metal coating is deposite d by ion plating yttrium-aluminum by thermal evaporation from an yttrium- aluminum source. The coated substrate is heat treated between 500-1200 ~C to form a reactive element modified-aluminide diffusion coating having a thin outer Al2O3 coating formed thereon. An interdiffusion between components of the metal substrate and the deposited metal coating when the coated substrat e is heat treated in an inert or reducing gas atmosphere.