CVD codeposition of A1 and one or more reactive (gettering) elements to form protective aluminide coating
AssigneeHowmet Research Corporation
InventorsBruce M. Warnes, David C. Punola, Jeffery S. Smith, Daniel L. Near
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Abstract
CVD aluminide coatings including a small concentration of a reactive, gettering element for surface active impurities dispersed therein are formed for improved oxidation resistance. The aluminide coatings are formed by CVD codeposition of Al and the gettering element on the substrate using coating gases for the gettering element generated either outside or inside the coating retort depending on the chlorination temperature needed for the particular gettering element.
Claims22
A method of forming by chemical vapor deposition on a substrate an aluminide diffusion coating including an additive element, comprising flowing a first halide precursor gas in a carrier gas in contact with a first source comprising aluminum disposed outside a coating retort to generate an aluminum halide first coating gas, flowing a second halide precursor gas in a carrier gas in contact with a second source comprising the additive element disposed outside the coating retort to generate a second halide coating gas, and introducing the first and second coating gases concurrrently into a coating retort in which the substrate at coating temperature is disposed to codeposit aluminum and the additive element on said substrate at the coating temperature for a time to form thereon an aluminide diffusion coating including said additive element.
A method of chemical vapor deposition on a substrate of first and second metallic elements, comprising flowing a halide precursor gas in a carrier gas in contact with a first source comprising a first element disposed outside a coating retort to generate a first halide coating gas, flowing the first halide coating gas into the coating retort in contact with a second source comprising a second element disposed inside the coating retort to convert a portion of the first halide coating gas to a second halide coating gas of the second element, and contacting the first and second halide coating gases concurrently with the substrate in the coating retort to codeposit thereon the first and second metallic elements at a substrate coating temperature to form a diffusion coating including said first and second metallic elements.
A method of forming by chemical vapor deposition on a substrate an aluminide diffusion coating including an additive element, comprising flowing a halide precursor gas in a carrier gas in contact with a first source comprising aluminum disposed outside a coating retort to generate an aluminum halide coating gas, flowing the first coating gas into the coating retort in contact with a second source comprising the additive element disposed inside the coating retort to convert a portion of the first coating gas to a halide coating gas of additive element, and contacting the coating gases concurrently with the substrate at coating temperature for a time in the coating retort to form thereon an aluminide diffusion coating including the additive element.
A method of forming by chemical vapor deposition on a substrate an aluminide diffusion coating including an additive element, comprising flowing a halide precursor gas in a carrier gas in contact with a first source comprising aluminum disposed outside a coating retort to generate an aluminum halide coating gas, flowing the first coating gas into the coating retort in contact with a second source comprising the additive element disposed inside the coating retort to convert a portion of gas to a halide coating gas of the additive element, flowing the unconverted portion of the first coating gas in contact with a secondary source comprising aluminum in the coating retort downstream of said second source to increase the activity of aluminum therein, and contacting the coating gases concurrently with the substrate at coating temperature for a time in the coating retort to form thereon an aluminide diffusion coating including the additive element.
Dependencies are inferred from the claim text.