Abstract: A coating composition is described, containing (a) a metallic matrix based on nickel, cobalt, iron; or combinations thereof; (b) a ceramic phase, containing at least one metal boride or metal silicide compound; and (c) a lubricant phase. Methods of providing wear-resistance and low-friction characteristics to an article (e.g., a gas turbine) are also described, using the coating composition. Related structures are also discussed.

Abstract: A bearing assembly mounted in an x-ray tube includes a bearing race and a bearing ball positioned adjacent to the bearing race. A lubricant is deposited on a first portion of a bare metal of one of the bearing race and the bearing ball, and a metal matrix deposited on a second portion of the bare metal.

Abstract: A bearing assembly mounted in an x-ray tube includes a bearing race and a bearing ball positioned adjacent to the bearing race. A coating is deposited on one of the bearing race and the bearing ball includes a lubricant and a hard material having a hardness greater than a base material of the bearing race and a base material of the bearing ball.

Abstract: Erosion resistant coating processes and material improvements for line-of-sight applications. The erosion resistant coating composition includes nanostructured grains of tungsten carbide (WC) and/or submicron sized grains of WC embedded into a cobalt chromium (CoCr) binder matrix. A high velocity air fuel thermal spray process (HVAF) is used to create thick coatings in excess of about 500 microns with high percentages of primary carbide for longer life better erosion resistant coatings. These materials and processes are especially suited for hydroelectric turbine components.

Abstract: A method for coating a substrate is presented. The method comprises providing a substrate; attaching a preform to the substrate, the preform comprising braze alloy and wear-resistant particles; and bonding the preform to the substrate to form a wear-resistant coating.

Abstract: A method for mitigating crack initiation and propagation on a surface of a metal component due to susceptibility to corrosion comprises depositing a metallic material on the surface of the component to form a coating, and then converting at least an outer layer of the coating to an electrically insulating material. The deposition of the metallic material is carried out by a method selected from the group consisting of wire-arc spraying, physical vapor deposition, and chemical vapor deposition. Electrochemical corrosion potential less than −0.23 VSHE based on the standard hydrogen electrode can be achieved with the method of coating of the present invention. This method is applied to produce coated structural components of water-cooled nuclear reactor.

Abstract: A method for mitigating crack initiation and propagation on a surface of a metal component due to susceptibility to corrosion comprises depositing a metallic material on the surface of the component to form a coating, and then converting at least an outer layer of the coating to an electrically insulating material. The deposition of the metallic material is carried out by a method selected from the group consisting of wire-arc spraying, physical vapor deposition, and chemical vapor deposition. Electrochemical corrosion potential less than −0.23 VSHE based on the standard hydrogen electrode can be achieved with the method of coating of the present invention. This method is applied to produce coated structural components of water-cooled nuclear reactor.

Abstract: A thermal barrier coating for an article, such as a component of a turbine assembly. The thermal barrier coating comprises a ceramic material and has a plurality of substantially vertical cracks therein and a porosity that is within a predetermined range. The ratio of tensile adhesion strength to modulus of elasticity of the thermal barrier coating has a value of between about 6×10−3 and about 15×10−3. The thermal barrier coating is formed by air spraying the ceramic material onto a metallic bond coat which has been previously applied to a substrate and heating the coated article to between about 1040° C. and about 1200° C. for a predetermined time.

Abstract: A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described.

Abstract: A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described.

Abstract: A stuck locking pin is removed from a turbine rotor by forming an aperture in the locking pin. The diameter of the aperture is less than the diameter of the locking pin, such that a thin shell portion remains in the locking pin receiving slot of the rotor. The locking pin then can be easily removed by any suitable means, such as by driving a high-strength metal rod into the aperture. The driving force stretches the thin shell portion, which easily separates from the rotor.

Abstract: A stuck locking pin is removed from a turbine rotor by forming an aperture in the locking pin. The diameter of the aperture is less than the diameter of the locking pin, such that a thin shell portion remains in the locking pin receiving slot of the rotor. The locking pin then can be easily removed by any suitable means, such as by driving a high-strength metal rod into the aperture. The driving force stretches the thin shell portion, which easily separates from the rotor.

Abstract: A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described.

Abstract: An article having a spallation resistant TBC comprises a metal substrate, such as a high temperature superalloy, and a TBC, such as a coating of yttria stabilized zirconia. The TBC comprises a plurality of plasma-sprayed layers. The TBC has a coherent, continuous columnar grain microstructure, wherein at least one layer has a plurality of continuous columnar grains which have been extended by directional solidification into an adjacent layer.

Abstract: An article is described, which includes a metal-based substrate, such as a superalloy; a dense, primary bond layer; and a spongy secondary bond layer. A thermal barrier coating is applied over the secondary bond layer. The spongy layer has a microstructure which includes an open network of interconnected pores. A process is also described. It includes the step of applying a spongy, metallic bond layer over the substrate, followed by the application of a thermal barrier coating. A dense, primary bond layer may optionally be applied before the application of the spongy layer.

Abstract: An article having a spallation resistant TBC comprises a metal substrate, such as a high temperature superalloy, and a TBC, such as a coating of yttria stabilized zirconia. The TBC comprises a plurality of plasma-sprayed layers. The TBC has a coherent, continuous columnar grain microstructure, wherein at least one layer has a plurality of continuous columnar grains which have been extended by directional solidification into an adjacent layer. In a preferred embodiment, the coherent, continuous columnar microstructure comprises substantially all of the volume of TBC. A coherent, continuous columnar grain microstructure is also taught wherein at least some of the plurality of coherent, continuous columnar grains which comprise a TBC extend through essentially the entire thickness of the coating.

Abstract: A method for providing a substantially-smooth protective coating on a metal-based substrate is disclosed. It comprises the steps of: (a) applying a thermal barrier coating over the substrate by plasma-spraying; (b) plasma-heating the applied coating according to a time- and temperature schedule sufficient to re-melt the surface region of the coating, allowing it to flow and smoothen; and then (c) cooling the surface region to a temperature below its melting point. The thermal barrier coating is often zirconia-based, e.g., yttria-stabilized zirconia. After being cooled, the surface is much smoother than when originally applied, thereby allowing the coating to be used in a higher-temperature environment.

Abstract: An article is described, which includes a metal-based substrate, such as a superalloy; a dense, primary bond layer; and a spongy secondary bond layer. A thermal barrier coating is applied over the secondary bond layer. The spongy layer has a microstructure which includes an open network of interconnected pores. A process is also described. It includes the step of applying a spongy, metallic bond layer over the substrate, followed by the application of a thermal barrier coating. A dense, primary bond layer may optionally be applied before the application of the spongy layer.

Abstract: A method for providing a substantially-smooth protective coating on a metal-based substrate is disclosed. A thermal barrier coating is first applied over the substrate by plasma-spraying. The coating is then plasma-heated according to a time- and temperature schedule sufficient to re-melt its surface region, allowing the coating material to flow and smoothen. The surface region is then allowed to cool to a temperature below its melting point. After being cooled, the surface is much smoother than when originally applied, which allows the coating to be used in a higher-temperature environment. The coating is often zirconia-based, e.g., yttria-stabilized zirconia.

Abstract: A method for improving the quality of a zirconia-based coating deposited on a metal-based substrate is disclosed. The method comprises the step of plasma-spraying zirconia powder of substantially uniform particle size onto the substrate. The disclosure further relates to an improved powder source material for use in a plasma. The source material is zirconia powder having a uniform particle size, and optionally, a uniform particle density. The use of such a material results in improved thermal barrier coatings for various substrates, such as those found in a turbine engine.