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AssigneeSurface Engineered Products Corporation
InventorsGary Anthony Fisher, Robert Prescott, Yan Chen, Hang Zheng, Chinnia Subramanian, Andrew George Wysiekierski
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A method for protecting high temperature stainless steel from coking and corrosion at elevated temperatures in corrosive environments, such as during ethylene production, by coating the stainless steel with an overlay coating of MCrAlX in which M is nickel, cobalt, iron or a mixture thereof and X is yttrium, hafnium, zirconium, lanthanum or combination thereof. The overlay coating and stainless steel substrate are heat-treated to metallurgically bond the overlay coating to the substrate and to form a multiphased microstructure. The overlay coating preferably is aluminized by depositing a layer of aluminum thereon and subjecting the resulting coating to oxidation to form an alumina surface layer. An intermediary aluminum-containing diffusion coating may be deposited directly onto the stainless steel substrate prior to deposition of the overlay coating to form a protective interlayer between the stainless steel substrate and overlay coating.
A method for providing a protective and inert coating on high temperature stainless steel comprising depositing onto a high temperature stainless steel substrate a continuous overlay coating having a thickness of about 50 to 350 μm of a MCrAlX alloy, where M=nickel, cobalt or iron or mixture thereof and X=yttrium, hafnium, zirconium, lanthanum or combination thereof, having about 10 to 25 wt % chromium, about 8 to 15 wt % aluminum and up to about 3 wt % X, the balance M, by physical vapour deposition or thermal spray at a temperature in the range of about 200 to 1000° C., or by slurry coating, and heat-treating the overlay coating and substrate at a soak temperature in the range of about 1000 to 1160° C. for about 20 minutes to 24 hours to provide a multiphased microstructure change and to metallurgically bond the overlay coating to the substrate.
Dependencies are inferred from the claim text.