The metal ceramic powder with a particle size of 15-45 .Math.m and suitable for thermal spraying is prepared through a combination of mechanical ball milling, spray granulation, and vacuum sintering. The metal ceramic powder is sprayed on a surface of a steel substrate adopting the high velocity oxygen fuel (HVOF) technology with oxygen-propane as fuel and taking oxygen as a combustion improver, propane as fuel, nitrogen as powder feeding carrier gas, and air as a cooling medium to prepare and form the NiCrBSi—ZrB2 composite coating. The present disclosure solves the problem that ZrB.sub.2 ceramic is difficult to compact during sintering and improves powder bonding strength and fluidity. The preparation method is simple, has advantages of high coating deposition efficiency and convenient equipment operation, and is cost-effective. The preparation method can improve thermal corrosion resistance and high-temperature wear resistance of a surface of boiler, and prolonging lifetime of the boiler.

An overlay of a sliding component, such as a sliding component for an engine, may provide a bearing surface against a steel journal, for example. The overlay may include intermetallic particles disposed in a matrix including tin (Sn). The matrix may be formed by electroplating. Examples of intermetallic particles include, but are not limited to, aluminides and nickel aluminides. The matrix may include an electroplated matrix of tin and/or a tin alloy.

A thermally dissipative article and a method of forming a thermally dissipative article are disclosed. The thermally dissipative article includes a component, a porous material formed in a layer on the component. The method of forming a thermally dissipative article includes providing a metal powder mixture and a soluble particulate mixture which forms a porous coating upon sintering and immersion in a solvent to remove the soluble particulate.

An article has a metallic substrate having a plurality of recesses. A first coating is at least at the recesses and has: a splatted layer; and a columnar layer atop the splatted layer. A second coating is away from the recesses and has: a columnar layer atop the substrate without an intervening splatted layer.

An article has a metallic substrate having a plurality of recesses. A first coating is at least at the recesses and has: a splatted layer; and a columnar layer atop the splatted layer. A second coating is away from the recesses and has: a columnar layer atop the substrate without an intervening splatted layer.

A blade outer airseal has a body comprising: an inner diameter (ID) surface; an outer diameter (OD) surface; a leading end; and a trailing end. The airseal body has a metallic substrate and a coating system atop the substrate along at least a portion of the inner diameter surface. At least over a first area of the inner diameter surface, the coating system comprises an abradable layer comprising a metallic matrix and a solid lubricant; and the metallic matrix comprises, by weight, ≧35% nickel, 12.0-20.0% cobalt, 5.0-15.0% aluminum, and 5.0-15.0% chromium.

A blade outer airseal has a body comprising: an inner diameter (ID) surface; an outer diameter (OD) surface; a leading end; and a trailing end. The airseal body has a metallic substrate and a coating system atop the substrate along at least a portion of the inner diameter surface. At least over a first area of the inner diameter surface, the coating system comprises an abradable layer comprising a metallic matrix and a solid lubricant; and the metallic matrix comprises, by weight, ≧35% nickel, 12.0-20.0% cobalt, 5.0-15.0% aluminum, and 5.0-15.0% chromium.

A method to modify the shape of a channel in a metallic substrate is described. The method includes the step of applying at least one metallic coating on selected portions of an interior surface of the channel, so as to alter the heat transfer characteristics of the channel during passage of a coolant fluid therethrough. Related articles that contain the modified channels are also described, such as gas turbine engine components.

A method to modify the shape of a channel in a metallic substrate is described. The method includes the step of applying at least one metallic coating on selected portions of an interior surface of the channel, so as to alter the heat transfer characteristics of the channel during passage of a coolant fluid therethrough. Related articles that contain the modified channels are also described, such as gas turbine engine components.

A component of a gas turbine engine comprises a substrate, a corrosion resistant top layer, and an intermediate corrodible layer disposed between the corrosion resistant top layer and the substrate. When corroding, the intermediate layer has a color contrasting with a color of the top layer. A method of detecting a crack when it penetrated the top layer in a component of a gas turbine engine having a corrosion resistant top layer and an intermediate corrodible layer comprises, in sequence, observing that at least one area of the component has a color contrasting with that of the top layer; determining that the color of the at least one area is a result of corrosion of the intermediate corrodible layer; and determining that the top layer has a crack as a result of determining corrosion of the intermediate layer. A method of facilitating crack detection in a component is also presented.