Abstract: Abradable coatings are applied to turbine or compressor shroud structures to facilitate reductions in blade tip-to-shroud clearances for improved engine performance or airfoil durability. Coating compositions include a chemically table, soft, burnishable ceramic material (such as CaF.sub.2 or BaF.sub.2) in a ceramic or metallic matrix or honeycomb structure.

Abstract: An abradable ceramic coated turbine shroud structure includes a grid of slant-steps isolated by grooves in a superalloy metal shroud substrate. A thin NiCrAlY bonding layer is formed on the machined slant-steps. A stabilized zirconia layer is plasma sprayed on the bonding layer at a sufficiently large spray angle to cause formation of deep shadow gaps in the zirconia layer. The shadow gaps provide a high degree of thermal strain tolerance, avoiding spalling. The exposed surface of the zirconia layer is machined nearly to the shadow gap ends. The turbine blade tips are treated to minimize blade tip wear during initial abrading of the zirconia layer. The procedure results in very close blade tip-to-shroud tolerances after the initial abrading.

Abstract: A coating for protecting the surfaces of gas turbine components such as single crystal turbine blades and vanes, wherein the coating has a composition (in weight percent) consisting essentially of chromium, 15-35; aluminum, 8-20; tantalum, 0-10; tantalum plus niobium, 0-10; silicon, 0.1-1.5; hafnium, 0.1-1.5; yttrium, 0-1; cobalt, 0-10; and nickel, balance totalling 100 percent. A preferred coating, which is particularly desirable for use with single-crystal turbine blades and vanes, has a composition consisting essentially of chromium, 17-23; aluminum, 10-13; tantalum plus niobium, 3-8; silicon, 0.1-1.5; hafnium, 0.1-1.5; yttrium, 0-0.8; cobalt, 0-trace; and nickel, balance totalling 100 percent. A process for preparing the coated component is also described.

Abstract: The carbon fiber bundles in a carbon-carbon composite are protected against oxidation by coating the fiber bundles with at least one protective layer consisting of an underlayer portion of boron carbide and an overlayer portion of silicon carbide.

Abstract: A coated article and method for producing the coated article are described. The article is coated with a system which provides protection against oxidation and corrosion and which significantly reduces the substrate temperature. An MCrAlY layer is applied to the article to be protected and a columnar grain ceramic is applied by vapor deposition to the MCrAlY coated article. An alumina layer which exists between the MCrAly layer and the columnar ceramic layer provides for the adherence of the columnar layer to the MCrAlY layer.

Abstract: A coated article and method for producing the coated article are described. The article is coated with a system which provides protection against oxidation and corrosion and which significantly reduces the substrate temperature. An MCrAlY layer is applied to the article to be protected and a columnar grain ceramic is applied by vapor deposition to the MCrAlY coated article. An alumina layer which exists between the MCrAly layer and the columnar ceramic layer provides for the adherence of the columnar layer to the MCrAlY layer.

Abstract: A coated article and method for producing the coated article are described. The article is coated with a system which provides protection against oxidation and corrosion and which significantly reduces the substrate temperature. An MCrAlY layer is applied to the article to be protected and a columnar grain ceramic is applied by vapor deposition to the MCrAlY coated article. An alumina layer which exists between the MCrAlY layer and the columnar ceramic layer provides for the adherence of the columnar layer to the MCrAlY layer.

Abstract: The composition and structure of aluminum bearing overlay alloy coatings, such as MCrAlY type overlay coatings, are altered during deposition from a metallic vapor by biasing the substrate at a small negative potential relative to ground while the vapor is at least partially ionized. The coating layer deposited under such conditions is characterized by substantial freedom from leader defects and by a reduced aluminum content and resultant improved ductility. Such coating conditions can be incorporated in a preselected manner into conventional deposition techniques, such as vacuum vapor deposition and sputtering, to produce a variety of coating compositional and structural variations from a single coating alloy ingot source.