Abstract: A method for forming a composite having a matrix which is stronger and which is resistant to cracking is disclosed. The composite is reinforced by silicon carbide fibers. The silicon carbide fibers are first RF plasma-spray coated with a niobium metal and the matrix metal of titanium base alpha-2 crystal structure is next RF plasma-spray deposited over the niobium coated SiC fibers to form a layer of Ti base metal reinforced by SiC fibers. A plurality of layered structures are consolidated by heat and pressure into a composite structure.

Abstract: A method for improved HIPing of filament reinforced metal matrix composite samples is disclosed. The method departs from conventional HIPing practice in that it does not rely on the heating of the HIPing gas in order to increase pressure. Rather, the temperature of the article and of the HIPing gas is first to the HIPing temperature and the pressure of the gas and the pressure on the sample is then raised to the HIPing pressure. Benefits are derived in that a lower level of filament fracture results.

Abstract: A method of altering the crystal form of an alloy is disclosed. To accomplish this change in crystal form, the concentrations of the more volatile constituents of the alloy are reduced and the concentration of the less volatile constituents is increased on a relative basis. The process may be carried out in forming a reinforced structure. For this purpose, an improved reinforced matrix and a method of forming it are taught. The reinforcement may be silicon carbide filaments or other reinforcing filaments. The matrix is a titanium 1421 alloy nominally containing 14 weight percent of aluminum and 21 weight percent of niobium. The matrix is formed by plasma-spray forming a powder of the alloy to impart to the alloy particles a superheat during the plasma-spraying as the particles traverse the plasma plume. As a result of the superheat, the alloy is changed in its composition to reduce the aluminum concentration and to increase the niobium and titanium concentrations on a relative basis.

Abstract: An RF plasma gun has a metal annular support ring at the gun's nozzle exit port. The ring is conductively mounted to a metal tank containing a substrate to be processed. The substrate is connected to a manipulator which is electrically isolated from the tank. A DC voltage is impressed between the tank, which contains an inert atmosphere at a pressure below that of ambient atmosphere, and the manipulator. The tank is placed at ground potential and the manipulator at a negative potential relative to the tank. The DC voltage creates an electric arc which flows from the exit port ring via the plasma to the substrate for cleaning the substrate.

Abstract: A method for forming a titanium metal foil is provided. The titanium metal may be essentially any titanium alloy. The alloy is first provided in powder form. The powder is sprayed through a low pressure RF plasma deposition apparatus onto a preformed foil mounted onto a rotating drum. The preformed foil is removed from the drum after plasma deposit of the layer of titanium alloy and the preformed foil is removed from the plasma deposit foil to leave a free standing foil of the titanium alloy.

Abstract: An improved method of forming titanium alloy in sheet form is taught. The sheet is formed by plasma spraying larger particles of greater than 100 .mu.m diameter onto a receiving surface to form a sheet having a rough surface due to the larger particles. An RF powered gun is employed to form the deposit using the larger particles. The formed sheet is separated from the substrate and rolled to reduce the sheet thickness as well as to render the rough surface smoother and more even.

Abstract: A method of forming a composite of fibers having high strength at high temperatures in a high temperature metal matrix is taught. The high strength fibers may be silicon carbide fibers. The fibers are aligned and disposed on a substrate surface. A metal to serve as a matrix is provided in powder form with relatively larger particles of the order of more than 100 .mu.m. The powder is plasma spray deposited on the fiber coated substrate surface to cause the metal to at least partially envelop the fibers. The composite is then separated from the substrate.

Abstract: A number of individual silicon carbide filaments are assembled to form a tape. The tape is passed across a drum in a low pressure plasma deposition apparatus where the surface of the drum is formed of a polished and cooled refractory metal. The tape is sprayed with a plasma spray of the titanium base alloy metal to form a sheet of such metal on the tape and on the surface of the drum. The deposited sheet including the silicon carbide reinforcement tape is removed from the drum surface by peeling. The peeled product is a composite of titanium base sheet metal which is impregnated with the filaments of silicon carbide, i.e. a metal impregnated tape.

Abstract: The preparation of multilayer filament reinforced consolidated articles is found to be possible because of the unique properties of RF plasma sprayed deposits. Pursuant to this method, a first layer of plasma deposited foil is made with a rough upper surface. A layer of closely spaced aligned reinforcing filaments is positioned on the rough surface. A second foil of RF plasma deposited metal is formed in and on the layer of filaments. A second layer of filaments is positioned on the second foil and a third foil is formed in and on the second layer. The three foils are integrated because of the strong tendency of the RF plasma sprayed metal to penetrate through, wet the fibers, and bond to the layer underneath.

Abstract: A ring is formed having alternating segments of ferromagnetic and paramagnetic materials. The ring is formed by first providing an annular ring of a high strength magnetic steel. Teeth are formed on the outer surface of the ring by forming troughs of the ferromagnetic material. Low pressure plasma deposition is used to fill in the troughs with a high strength paramagnetic material. The excess steel and excess plasma deposited material is removed to leave the finished ring of alternating segments of ferromagnetic and paramagnetic material.

Abstract: The present invention provides a gun capable of operating at relatively higher temperatures. The barrel of the gun is made up of at least two layers. The inner layer is of a refractory material which may be a metal refractory or a non-metal refractory. The liner is bonded to an outer jacket material formed of an alloy of nickel, aluminum and molybdenum. The coefficient of expansion of the liner and of the jacket are relatively low so that the gun does not expand extensively when heated by intensive use. The jacket metal is of higher strength at elevated temperature than is the conventional gun barrel steel.

Abstract: A ring is formed having alternating segments of ferromagnetic and paramagnetic materials. The ring is formed by first providing an annular ring of a high strength magnetic steel. Teeth are formed on the outer surface of the ring by forming troughs of the ferromagnetic material. Low pressure plasma deposition is used to fill in the troughs with a high strength paramagnetic material. The excess steel and excess plasma deposited material is removed to leave the finished ring of alternating segments of ferromagnetic and paramagnetic material.

Abstract: A method of forming a generally planar part for a jet engine is provided. The part is adapted for withstanding high thermal stress but not high mechanical stress. A preformed strip of a superalloy is mounted around a drum shaped mandrel. A low pressure plasma deposit of a different superalloy is formed on the preformed strip. The strip is demounted and mechanically straightened.

Abstract: Substantially homogeneous, substantially spherical interdiffused metallic oxide particles, especially useful in plasma spraying applications, are readily and economically prepared from constituent metal oxide powders by the method of this invention which includes the step of heating a mass of discrete agglomerated particles under conditions of temperature and time sufficient to interdiffuse the constituent metallic oxides within the agglomerates, but insufficient to sinter the agglomerates together.

Abstract: A gun barrel is produced by vacuum plasma spray depositing an inner layer of a refractory metal as a gun barrel liner on a mandrel, followed by deposit of successive layers of dense gun barrel jacket material to build up a structure from the inside out. The outermost layer can include attachment means for fixing the barrel into a gun mechanism.

Abstract: A method is provided for forming articles from difficult to fabricate materials with precise internal dimensions. The article is first formed to approximate dimensions as a body using the material in powdered form. Plasma spray forming is proposed. The powder formed body is then brought to its final dimensions by consolidating and densifying the body about a densifying mandrel having a coefficient of expansion which is higher and outer dimensions which are slightly smaller than that of the body.

Abstract: A method is provided for improving the corrosion resistance of superalloy substrates, such as gas turbine blades, by initially coating the superalloy with an intermediate bonding alloy, followed by plasma spraying the resulting treated surface with cerium oxide or a sprayable blend of cerium oxide and zirconium oxide. The resulting metal oxide-super alloy composite has been found to be resistant to vanadium and sulfur dioxide corrosion.

Abstract: A plasma or flame spraying method is provided for applying a ceramic or metallic UV sensitive indicating coating onto a metal substrate. Particle size control of the ingredients used in the plasma or flame sprayable mixture has been found to enhance the fluorescence of the resulting indicating coating.

Abstract: High temperature resistant turbine engine shrouds are formed of an amphoteric refractory oxide, a phosphate binding agent and optionally a stabilizer, reinforcement and/or porosity controller.