Abstract: A protected article is prepared by providing the article, depositing a bond coat onto an exposed surface of the article, and producing a thermal barrier coating on an exposed surface of the bond coat. The step of producing the thermal barrier coating includes the steps of depositing a primary ceramic coating onto an exposed surface of the bond coat, and depositing a stabilization composition onto an exposed surface of the primary ceramic coating. The stabilization composition includes a first element selected from Group 2 or Group 3 of the periodic table, and a second element selected from Group 5 of the periodic table. The atomic ratio of the amount of the first element to the amount of the second element is at least 1.3, more preferably at least 1:1.

Abstract: A method for preparing a coated nickel-base superalloy article reduces the sulfur content of the surface region of the metallic coating layers to low levels, thereby improving the adhesion of the coating layers to the article. The method includes depositing a first layer of platinum overlying the surface of a substrate, depositing a second layer of aluminum over the platinum, and final desulfurizing the article by heating the article to elevated temperature, preferably in hydrogen, and removing a small amount of material from the surface that was exposed during the step of heating. A ceramic layer may be deposited over the desulfurized article. The article may also be similarly desulfurized at other points in the fabrication procedure.

Abstract: A thermal barrier coating (TBC) system and method for improving the thermal fatigue life of a thermal barrier coating. The invention entails modifying the surface morphology of an aluminide bond coat that adheres the thermal barrier coating to a substrate of a superalloy component. The aluminide bond coat has columnar grains, such that grain boundaries are exposed at the surface of the bond coat and define ridges. The surface of the bond coat is then treated so that a sufficient amount of material is removed from the grain boundary ridges and other surface peaks to flatten the bond coat surface, i.e., the ridges and peaks are replaced with flattened surfaces that are nearly parallel to the diffusion zone of the bond coat. By removing these surface irregularities, it is believed that a more stable bond coat surface is created where the critical alumina-bond coat interface will exist following a thermal treatment, such as TBC deposition.

Abstract: A coating is described for use on a superalloy substrate comprising a diffusion barrier as an intermediate layer overlying the substrate and underlying a protective coating having a high aluminum content. The diffusion barrier layer is characterized by having low interdiffusivity for elements from the substrate and the coating, a minimal impact on the mechanical properties of the article which is coated, and can be achieved readily using existing coating application techniques or post heat treat processes. The diffusion barrier layer is preferably an oxide ceramic.

Abstract: A nickel-base superalloy article substrate has more nickel than any other element, a reactive element that is hafnium, zirconium, yttrium, lanthanum, or cerium, or combinations thereof, and a nominal bulk composition of carbon. A protective layer is deposited overlying the surface of the article substrate. The depositing of the protective layer includes steps of decarburizing locations where the carbon serves as a barrier to the diffusion of the reactive element from the substrate into the protective layer, and depositing an aluminum-containing protective layer overlying the substrate. The decreasing of the carbon concentration may be accomplished by decarburizing the substrate, depositing a platinum-containing layer and then decarburizing, depositing an aluminum-containing layer in a reducing atmosphere, or decarburizing the deposited protective layer. A ceramic thermal barrier coating may be deposited overlying the protective layer.

Abstract: A coating system for Si-containing material, such as those used to form articles exposed to high temperatures, including the hostile thermal environment of a gas turbine engine. The coating system is a compositionally-graded thermal/environmental barrier coating (T/EBC) system that exhibits improved mechanical integrity for high application temperatures that necessitate thick protective coatings. The T/EBC system includes an intermediate layer containing YSZ and BSAS, mullite and/or alumina, which is preferably used in combination with a mullite-containing layer that overlies the surface of the Si-containing material, a layer of BSAS between the mullite-containing layer and the intermediate layer, and a thermal-insulating top coat of YSZ overlying the intermediate layer.

Abstract: A barrier layer for a silicon containing substrate which inhibits the formation of gaseous species of silicon when exposed to a high temperature aqueous environment comprises a barium-strontium alumino silicate.

Abstract: A nickel-base superalloy substrate has an overlying protective coating including a modified aluminum-containing protective layer. The modified aluminum-containing protective layer is formed of nickel, aluminum, calcium in an amount of from about 50 to about 300 parts per million by weight, and, optionally, elements interdiffused into the modified aluminum-containing protective layer from the substrate. Magnesium or barium may be used instead of or in addition to the calcium. A ceramic layer may overlie the modified aluminum-containing protective layer.

Abstract: A barrier layer for a silicon containing substrate which inhibits the formation of gaseous species of silicon when exposed to a high temperature aqueous environment comprises a barium-strontium alumino silicate.

Abstract: A nickel-base superalloy article substrate has more nickel than any other element and a nominal bulk composition of carbon. A protective layer is deposited overlying the surface of the article substrate. The protective layer includes aluminum and one or more of the reactive elements hafnium, zirconium, yttrium, lanthanum, and cerium. The depositing of the protective layer includes steps of decarburizing locations where the carbon may serve as a barrier to the mobility of the reactive elements within the protective layer, and depositing an aluminum-containing protective layer overlying the substrate. The decreasing of the carbon concentration may be accomplished. by decarburizing the substrate, depositing a platinum-containing layer and then decarburizing, depositing an aluminum-containing layer in a reducing atmosphere, and/or decarburizing the deposited protective layer. A ceramic thermal barrier coating may be deposited overlying the protective layer.

Abstract: A coating for use on a superalloy substrate comprising a diffusion barrier as an intermediate layer overlying the substrate and underlying a protective coating having a high aluminum content. The diffusion barrier layer is characterized by having low solubility for aluminum from either the substrate or the protective coating. Further, the diffusion barrier layer has low interdiffusivity for elements from the substrate and the coating, a minimal impact on the mechanical properties of the article which is coated, a minimal thermal expansion mismatch with both the substrate and the high aluminum content protective coating, and can be applied readily using existing coating application techniques. The diffusion barrier is preferably a single phase alloy or intermetallic compound.

Abstract: A process for depositing a mullite coating on a silicon-based material, such as those used to form articles exposed to high temperatures and including the hostile thermal environment of a gas turbine engine. The process is generally to thermally spray a mullite powder to form a mullite layer on a substrate, in which the thermal spraying process is performed so that the mullite powder absorbs a sufficient low level of energy from the thermal source to prevent evaporation of silica from the mullite powder. Processing includes deposition parameter adjustments or annealing to maintain or reestablish phase equilibrium in the mullite layer, so that through-thickness cracks in the mullite layer are avoided.

Abstract: A process for depositing a mullite coating on a silicon-based material, such as those used to form articles exposed to high temperatures and including the hostile thermal environment of a gas turbine engine. The process is generally to thermally spray a mullite powder to form a mullite layer on a substrate, in which the thermal spraying process is performed so that the mullite powder absorbs a sufficient low level of energy from the thermal source to prevent evaporation of silica from the mullite powder. Processing includes deposition parameter adjustments or annealing to maintain or reestablish phase equilibrium in the mullite layer, so that through-thickness cracks in the mullite layer are avoided.

Abstract: A coating system for a substrate containing a silicon-based material, such as silicon carbide-containing ceramic matrix materials containing silicon carbide and used to form articles exposed to high temperatures, including the hostile thermal environment of a gas turbine engine. The coating system includes a layer of barium strontium aluminosilicate (BSAS) as a bond coat for a thermal-insulating top coat. As a bond coat, the BSAS layer serves to adhere the top coat to a SiC-containing substrate. The BSAS bond coat exhibits sufficient environmental resistance such that, if the top coat should spall, the BSAS bond coat continues to provide a level of environmental protection to the underlying SiC-containing substrate.