Abstract: A coating and method for overcoating a TBC on a component used in a high-temperature environment, such as the combustor section of an industrial gas turbine. The coating defines the outermost surface of the component and is formed of at least two layers having different compositions. An inner layer of the coating contains alumina in a first silica-containing matrix material that is free of zinc titanate. An outer layer of the coating contains alumina, a glass material, and zinc titanate in a second silica-containing matrix material. The outer layer of the coating has a surface roughness of not greater than three micrometers Ra and forms the outermost surface of the component. The coating reduces the component temperature by reducing the convective and radiant heat transfer thereto.

Abstract: A method for manufacturing a machine component is provided. The method includes forming a machine component substrate wherein the substrate has a substrate surface region. The method further includes forming at least one primary thermal barrier layer including a first ceramic thermal barrier material having a first porosity. The method also includes forming at least one secondary thermal barrier layer formed over at least a portion of the plurality of primary thermal barrier layers. Also, the secondary thermal barrier layer further includes a second ceramic thermal barrier material having a second porosity that is greater than the first porosity. The method also includes forming at least one tertiary thermal barrier layer comprising a smooth coat material, wherein the tertiary thermal barrier layer is formed over at least a portion of the secondary thermal barrier layer. The secondary thermal barrier layer facilitates reducing a delamination of the tertiary thermal barrier layer.

Abstract: A compressor forward stub shaft comprising a plurality of axially spaced, annular rows of dovetail grooves, at least a first and a second of the plurality of rows having dovetail slots coated in part with an anti-wear coating.

Abstract: A method for metallurgically bonding a stator bar to a coupling to reduce the incidence of leak paths resulting from corrosion. The stator bar comprises strands through which a liquid coolant can flow. Adjacent ends of the strands are received in an interior cavity of the coupling through an opening in the coupling. A joining material is provided on a first portion of the stator bar within the coupling opening and adjacent the ends of the strands. The first portion is heated to melt the joining material. At essentially the same time, a second portion of the stator bar outside the coupling is also heated. Once the joining material is suitably molten, the first portion is allowed to cool while the second portion remains heated, thereby causing the joining material nearest the ends of the strands to solidify first.

Abstract: A method includes blasting the interior surfaces of the fitting to stator bar strand joint with CO2 pellets to remove loose copper oxide which otherwise would interfere with proper sealing between an epoxy and the copper surfaces of the joint. After cleaning the surfaces and applying air under pressure to remove particulate material, epoxy is applied to the brazed joints followed by an evacuation of the fitting to strand joint. Subsequent release of the vacuum ensures that the epoxy fills in all crevices or cracks at the joint surfaces and minimizes or eliminates any tendency of the epoxy to delaminate.

Abstract: A coating and method for overcoating a TBC on a component used in a high-temperature environment, such as the combustor section of an industrial gas turbine. The coating defines the outermost surface of the component and is formed of at least two layers having different compositions. An inner layer of the coating contains alumina in a first silica-containing matrix material that is free of zinc titanate. An outer layer of the coating contains alumina, a glass material, and zinc titanate in a second silica-containing matrix material. The outer layer of the coating has a surface roughness of not greater than three micrometers Ra and forms the outermost surface of the component. The coating reduces the component temperature by reducing the convective and radiant heat transfer thereto.