Abstract: A method of coating a metal substrate such as the components in second and third stages of gas turbine engines in order to increase the oxidation and corrosion resistance of the metal substrate under high temperature operating conditions, the method including the steps of forming a powdered mixture of a high-melt superalloy or MCrAlY component, where M comprises Fe, Ni and/or Co, and a low-melt component containing about 2-5 wt. % silicon, boron or hafnium, applying the powdered mixture to the surface of the metal substrate at room temperature using an atomized spray to form a uniform surface coating, and then heating the coated substrate surface under vacuum conditions to a temperature in the range of about 1900° F. to 2275° F. to obtain a uniform coating composition providing oxidation resistance to the underlying substrate.

Abstract: A method for depositing material on a turbine airfoil having a tip wall extending past a tip cap, wherein the tip wall includes a first alloy with a single crystal microstructure. The method includes: depositing a second alloy on at least a portion of the tip wall to form a repair structure, wherein a high temperature oxidation resistance of the second alloy is greater than a high temperature oxidation resistance of the first alloy, and wherein the repair structure has a crystallographic orientation that is substantially the same as a crystallographic orientation of the tip wall.

Abstract: A method of coating a metal substrate such as the components in second and third stages of gas turbine engines in order to increase the oxidation and corrosion resistance of the metal substrate under high temperature operating conditions, the method including the steps of forming a powdered mixture of a high-melt superalloy or MCrAlY component, where M comprises Fe, Ni and/or Co, and a low-melt component containing about 2-5 wt. % silicon, boron or hafnium, applying the powdered mixture to the surface of the metal substrate at room temperature using an atomized spray to form a uniform surface coating, and then heating the coated substrate surface under vacuum conditions to a temperature in the range of about 1900° F. to 2275° F. to obtain a uniform coating composition providing oxidation resistance to the underlying substrate.

Abstract: A method for depositing material on a turbine airfoil having a tip wall extending past a tip cap, wherein the tip wall includes a first alloy with a single crystal microstructure. The method includes: depositing a second alloy on at least a portion of the tip wall to form a repair structure, wherein a high temperature oxidation resistance of the second alloy is greater than a high temperature oxidation resistance of the first alloy, and wherein the repair structure has a crystallographic orientation that is substantially the same as a crystallographic orientation of the tip wall.

Abstract: Various braze alloy compositions are described, along with methods for using them. In one instance, a boron-free, high-temperature braze alloy includes selected amounts of chromium, hafnium, and nickel. The braze alloy can be used, for example, as a component in a wide gap braze mixture where a higher or lower melting point superalloy and/or brazing powder is used. The braze alloys may permit joining or repairing of superalloy articles with complex shapes, and may be used in high temperature applications. In some other braze alloy embodiments, a nickel- or cobalt-based braze composition can contain selected amounts of boron, but includes restricted amounts of chromium.

Abstract: A process for diffusion bonding of cracks and other gaps in high-temperature nickel and cobalt alloy components is described. The gap is filled with alloy powder matching the substrate alloy, or with an alloy of superior properties, such as MAR-M 247, MAR-M 247LC, or CM 247LC. A braze containing a melting point depressant is either mixed into the alloy powder or applied over it. The depressant is preferably hafnium, zirconium, or low boron. The component is heated for 15-45 minutes above the melting point of the braze, which fills the spaces between the alloy powder particles. The component is diffused at a temperature above or below the liquidus of the braze and solution heat-treated and aged at a temperature at which the braze and alloy mixture in the gap is solid, but the depressant diffuses away.