Abstract: A substrate is protected by a multilayer protective coating having an oxide layer, and a phosphate/organic binder layer initially overlying the oxide layer. The multilayer protective coating is cured by first degassing the multilayer protective coating in a pre-cure degassing temperature range of from about 250° F. to about 500° F. for a time of at least about 30 minutes. The multilayer protective coating is thereafter heated to a curing temperature range of from about 1200° F. to about 1400° F. for a time of at least about 30 minutes.

Abstract: A protective coating system and method for protecting a thermal barrier coating from CMAS infiltration. The coating system comprises inner and outer alumina layers and a platinum-group metal layer therebetween. The outer alumina layer is intended as a sacrificial layer that reacts with molten CMAS, forming a compound with a melting temperature significantly higher than CMAS. As a result, the reaction product of the outer alumina layer and CMAS resolidifies before it can infiltrate the TBC. The platinum-group metal layer is believed to serve as a barrier to infiltration of CMAS into the TBC, while the inner alumina layer appears to enhance the ability of the platinum-group metal layer to prevent CMAS infiltration.

Abstract: A method for forming a thermal barrier coating system on an article subjected to a hostile thermal environment, such as the hot gas path components of a gas turbine engine. The coating system is generally comprised of a ceramic layer and an environmentally resistant beta phase nickel aluminum intermetallic (&bgr;-NiAl) bond coat that adheres the ceramic layer to the component surface. A thin aluminum oxide scale forms on the surface of the &bgr;-NiAl during heat treatment. An additional layer of diffusion aluminide may can be formed underlying the ceramic layer. The &bgr;-NiAl may contain alloying elements in addition to nickel and aluminum in order to increase the environmental resistance of the &bgr;-NiAl. These elements include hafnium, chromium and zirconium and increase the oxidation resistance of the &bgr;-NiAl. The &bgr;-NiAl is supplied as a powder having a size in the range of 20-80 microns.

Abstract: Improved adhesion of thermal barrier coating systems to nonmetallic substrates using a layer of silica on an underlying nonmetallic substrate that includes a silicon containing material is described. The improved adhesion occurs because the improved thermal barrier system improves the temperature capability of the system by providing a layer adjacent the substrate that has improved thermal performance and that is not subject to deterioration. The application of a silica layer of predetermined thickness adjacent the substrate also forms a diffusion barrier for oxygen while eliminating the need to transform an external layer of the substrate by a pre-oxidation step. This diffusion barrier prevents any oxidizable component of the substrate from decomposing.

Abstract: A method for forming a thermal barrier coating system on an article subjected to a hostile thermal environment, such as the hot gas path components of a gas turbine engine. The coating system is generally comprised of a ceramic layer and an environmentally resistant beta phase nickel aluminum intermetallic (&bgr;-NiAl) bond coat that adheres the ceramic layer to the component surface. A thin aluminum oxide scale forms on the surface of the &bgr;-NiAl during heat treatment. The &bgr;-NiAl may contain alloying elements in addition to nickel and aluminum in order to increase the environmental resistance of the &bgr;-NiAl. The &bgr;-NiAl powder having a size in the range of 20-50 microns is applied using air plasma spray techniques to produce a surface having a roughness of 400 microinches or rougher. The ceramic top coat can be applied using inexpensive thermal spray techniques to greater thicknesses than achievable otherwise because of the rough surface finish of the underlying &bgr;-NiAl bond coat.

Abstract: A thermal barrier coating (TBC) system and method for forming the coating system on a component. The method generally entails forming a TBC on the surface of the component so that the TBC has at least an outer portion that is resistant to infiltration by CMAS. The TBC is formed by co-depositing first and second ceramic compositions by physical vapor deposition so that the entire TBC has columnar grains and at least the outer portion of the TBC is a mixture of the first and second ceramic compositions. The outer portion is preferably a continuation of the inner portion, such that the TBC is not characterized by discrete inner and outer coatings. The second ceramic composition serves to increase the resistance of the outer portion of the TBC to infiltration by molten CMAS. A platinum-group metal may be co-deposited with the first and second ceramic compositions, or deposited before the TBC and then diffused into the outer portion as a result of the parameters employed in the deposition process.

Abstract: An anti-stick coating that inhibits the adhesion of contaminants that form deposits on the internal cooling passages of gas turbine engine components. The anti-stick coating is formed as an outer coating of the internal cooling passages, and preferably overlies an environmental coating such as a diffusion aluminide coating formed on the passage surfaces. The outer coating has a thickness of not greater than three micrometers, and is resistant to adhesion by dirt contaminants as a result of comprising at least one layer of tantala, titania, hafnia, niobium oxide, yttria, silica and/or alumina. The outer coating is preferably deposited directly on the environmental coating by chemical vapor deposition.

Abstract: A multilayer thermal barrier coating (TBC) having a low thermal conductivity that is maintained or even decreases as a result of a post-deposition high temperature exposure. The TBC comprises an inner layer and an insulating layer overlying the inner layer. The inner layer is preferably yttria-stabilized zirconia (YSZ), while the insulating layer contains barium strontium aluminosilicate (BSAS). After deposition, the TBC is heated to a temperature and for a duration sufficient to cause a decrease in the thermal conductivity of the BSAS-containing layer and, consequently, the entire TBC.

Abstract: A gas turbine component, such as a turbine disk or a rotating seal, is fabricated by furnishing a substrate shaped as a gas turbine component made of a nickel-base superalloy, and oxidizing the substrate to produce an oxidized substrate having thereon a layer comprising an oxide and having a thickness of at least about 500 Angstroms. The step of oxidizing is performed prior to entry of the component into service and in an atmosphere that does not contain combustion gas. The oxidized gas turbine component is thereafter placed into service.

Abstract: A gas turbine component, such as a turbine disk or a rotating seal, is fabricated by furnishing a substrate shaped as a gas turbine component made of a nickel-base superalloy, and oxidizing the substrate to produce an oxidized substrate having thereon a layer comprising an oxide and having a thickness of at least about 500 Angstroms. The step of oxidizing is performed prior to entry of the component into service and in an atmosphere that does not contain combustion gas. The oxidized gas turbine component is thereafter placed into service.

Abstract: An article protected by a protective coating has a substrate and a protective coating having an outer layer deposited upon the substrate surface and a diffusion zone formed by interdiffusion of the outer layer and the substrate. The protective coating includes platinum, aluminum, no more than about 2 weight percent hafnium, and substantially no silicon. The outer layer is substantially a single phase.

Abstract: An article having a substrate is protected by a thermal barrier coating system. An interfacial layer contacts the upper surface of the substrate. The interfacial layer may comprise a bond coat only, or a bond coat and an overlay coat. The interfacial layer has on its upper surface a preselected, controllable pattern of three-dimensional features, such as grooves in a parallel array or in two angularly offset arrays. The features are formed by an ablation process using an ultraviolet laser such as an excimer laser. A ceramic thermal barrier coating is deposited over the pattern of features on the upper surface of the interfacial layer.

Abstract: A multilayer thermal barrier coating (TBC) having a low thermal conductivity that is maintained or even decreases as a result of a post-deposition high temperature exposure. The TBC comprises an inner layer and an insulating layer overlying the inner layer. The inner layer is preferably yttria-stabilized zirconia (YSZ), while the insulating layer contains barium strontium aluminosilicate (BSAS). After deposition, the TBC is heated to a temperature and for a duration sufficient to cause a decrease in the thermal conductivity of the BSAS-containing layer and, consequently, the entire TBC.

Abstract: Improved adhesion of thermal barrier coating systems to nonmetallic substrates using a layer of silica on an underlying nonmetallic substrate that includes a silicon containing material is described. The improved adhesion occurs because the improved thermal barrier system improves the temperature capability of the system by providing a layer adjacent the substrate that has improved thermal performance and that is not subject to deterioration. The application of a silica layer of predetermined thickness adjacent the substrate also forms a diffusion barrier for oxygen while eliminating the need to transform an external layer of the substrate by a pre-oxidation step. This diffusion barrier prevents any oxidizable component of the substrate from decomposing.

Abstract: An anti-stick coating that inhibits the adhesion of contaminants that form deposits on the internal cooling passages of gas turbine engine components. The anti-stick coating is formed as an outer coating of the internal cooling passages, and preferably overlies an environmental coating such as a diffusion aluminide coating formed on the passage surfaces. The outer coating has a thickness of not greater than three micrometers, and is resistant to adhesion by dirt contaminants as a result of comprising at least one layer of tantala, titania, hafnia, niobium oxide, yttria, silica and/or alumina. The outer coating is preferably deposited directly on the environmental coating by chemical vapor deposition.

Abstract: An improved thermal barrier coating for metal substrates such as superalloys is disclosed. The coating is a slurry composition, comprising spheres of zirconia, at least some of which are hollow, contained within a porous oxide matrix, such as aluminosilicate. The slurry composition can be applied by slurry casting or similar techniques to the desired surface. Coating methods are also described. In general, they involve the application of successive layers of variations of the slurry composition, with various curing techniques used between layers and after the final coating is applied. Another embodiment of this invention embraces a composite coating, comprising (i) an oxide matrix phase; (ii) zirconia spheres embedded in the oxide matrix; and (iii) a porous phase.

Abstract: An improved thermal barrier coating for metal substrates such as superalloys is provided. The coating is a slurry composition, comprising spheres of zirconia, at least some of which are hollow, contained within a porous oxide matrix, such as aluminosilicate. The slurry composition can be applied by slurry casting or similar techniques to the desired surface. Coating methods involve the application of successive layers of variations of the slurry composition, with various curing techniques used between layers and after the final coating is applied. Another embodiment of this invention embraces a composite coating, comprising (i) an oxide matrix phase; (ii) zirconia spheres embedded in the oxide matrix; and (iii) a porous phase.