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.

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.

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.

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.

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.

Abstract: A CVD outwardly grown platinum aluminide diffusion coating on a nickel or cobalt base superalloy substrate wherein the platinum modified aluminide diffusion coating is modified to include silicon, hafnium, and optionally zirconium and/or other active elements (e.g. Ce, La, Y, etc.) each in a concentration of about 0.01 weight % to about 8 weight % of the outer additive (Ni,Pt)(Al,Si) layer of the coating. A particular coating includes about 0.01 weight % to less than 2 weight % of each of silicon, hafnium, and zirconium in the outer additive layer, preferably with a Hf/Si ratio less than about 1 and, when Zr also is present, a Hf+Zr/Si ratio of less than about 1. A coating microstructure is provided characterized by an inner diffusion zone or region adjacent the substrate and the outer additive (Ni,Pt)(Al,Si) layer including hafnium silicide second phase particles or regions dispersed throughout the outer additive layer of the coating.

Abstract: A CVD outwardly grown platinum aluminide diffusion coating on a nickel or cobalt base superalloy substrate wherein the platinum modified aluminide diffusion coating is modified to include silicon, hafnium, and optionally zirconium and/or other active elements (e.g. Ce, La, Y, etc.) each in a concentration of about 0.01 weight % to about 8 weight % of the outer additive (Ni,Pt)(Al,Si) layer of the coating. A particular coating includes about 0.01 weight % to less than 2 weight % of each of silicon, hafnium, and zirconium in the outer additive layer, preferably with a Hf/Si ratio less than about 1 and, when Zr also is present, a Hf+Zr/Si ratio of less than about 1. A coating microstructure is provided characterized by an inner diffusion zone or region adjacent the substrate and the outer additive (Ni,Pt)(Al,Si) layer including hafnium silicide second phase particles or regions dispersed throughout the outer additive layer of the coating.

Abstract: A method of improving the oxidation resistance of a platinum modified aluminide coating formed on a nickel base superalloy substrate, comprises providing a platinum layer on the substrate, heating the substrate in a coating retort to a temperature of at least about 1000.degree. C., forming external of the coating retort a high purity coating gas comprising hydrogen and aluminum trichloride, and introducing the coating gas into the coating retort to contact the heated substrate to form an outwardly grown, single phase [(Ni,Pt)]Al] platinum modified aluminide coating having reduced concentration of at least one of a substrate substitutional alloying element and a surface active tramp element selected from at least one of B, P, and S in said coating as compared to a platinum modified aluminide coating formed at a lower temperature.

Abstract: A chemical vapor deposition (CVD) apparatus comprises a reactor having a coating chamber at elevated temperature, means for supporting substrates to be coated at different zones in the coating chamber, and means for supplying a gaseous reactant stream to the chamber for distribution to the coating zones in a manner that the stream is heated to substantially different temperatures at different coating zones. Reactivity-altering material is disposed at the coating zones for contact by the reactant stream supplied thereto before the reactant stream contacts a substrate at the zones. The reactivity-altering material includes a composition that differs between coating zones in dependence on the reactant stream temperatures at the coating zones as necessary to alter the reactivity of the reactant (i.e., activity of a particular chemical specie of the reactant stream) stream at the coating zones in a manner to provide substantially the same reactant reactivity at all coating zones.

Abstract: Chemical vapor deposition apparatus comprises a reactor having a chamber with a coating region for coating a substrate and an exhaust region communicating with the coating region. The coating region includes an inlet for introduction of a gaseous reactant stream to pass over the substrate to react therewith to form a coating thereon and a spent gas stream. The exhaust region includes an outlet for exhausting the spent gas stream from the coating region. The substrate is supported in the coating region and heated to an elevated reaction temperature by suitable support means and heating means. A condensing assembly is disposed in the exhaust region for condensing excess, unreacted gaseous reactant from the spent gas stream before entry into the outlet. The condensing assembly includes a high surface area, apertured structure disposed in the exhaust region where the temperature of the spent gas stream is sufficiently reduced to condense excess, unreacted gaseous reactant therefrom.

Abstract: A chemical vapor deposition (CVD) method utilizing an apparatus comprising a reactor having a coating chamber at elevated temperature, means for supporting substrates to be coated at different zones in the coating chamber, and means for supplying a gaseous reactant stream to the chamber for distribution to the coating zones in a manner that the stream is heated to substantially different temperatures at different coating zones. Reactivity-altering material is disposed at the coating zones for contact by the reactant stream supplied thereto before the reactant stream contacts a substrate at the zones. The reactivity-altering material includes a composition that differs between coating zones in dependence on the reactant stream temperatures at the coating zones as necessary to alter the reactivity of the reactant (i.e., activity of a particular chemical specie of the reactant stream) stream at the coating zones in a manner to provide substantially the same reactant reactivity at all coating zones.

Abstract: Chemical vapor deposition apparatus comprises a reactor having a chamber with a coating region for coating a substrate and an exhaust region communicating with the coating region. The coating region includes an inlet for introduction of a gaseous reactant stream to pass over the substrate to react therewith to form a coating thereon and a spent gas stream. The exhaust region includes an outlet for exhausting the spent gas stream from the coating region. The substrate is supported in the coating region and heated to an elevated reaction temperature by suitable support means and heating means. A condensing assembly is disposed in the exhaust region for condensing excess, unreacted gaseous reactant from the spent gas stream before entry into the outlet. The condensing assembly includes a high surface area, apertured structure disposed in the exhaust region where the temperature of the spent gas stream is sufficiently reduced to condense excess, unreacted gaseous reactant therefrom.