A porous support includes a base body, a supporting layer, and a topmost layer. The supporting layer is disposed between the base body and the topmost layer, and makes contact with the topmost layer. A ratio of a porosity of the topmost layer to a porosity of the supporting layer is greater than or equal to 1.08. A ratio of a thickness of the topmost layer to a thickness of the supporting layer is less than or equal to 0.9.

A porous support includes a base body, a supporting layer, and a topmost layer. The supporting layer is disposed between the base body and the topmost layer, and makes contact with the topmost layer. A ratio of a porosity of the topmost layer to a porosity of the supporting layer is greater than or equal to 1.08. A ratio of a thickness of the topmost layer to a thickness of the supporting layer is less than or equal to 0.9.

A UAV surface coating includes at least a bonding layer, an antioxidant layer, an oxygen-blocking propagation layer and a heat-insulation cooling layer. The coating is fabricated on a surface of a UAV machine body or covers on the surface of the UAV machine body through a composite material matrix. The UAV machine body is made of lightweight material, and the composite material matrix includes a resin-based composite matrix and a ceramic-based composite matrix. Wherein, a thickness of the bonding layer is from 20 ?m to 200 ?m, a thickness of the oxygen-blocking propagation layer is from 20 ?m to 200 ?m, and a thickness of the heat-insulation cooling layer is from 80 ?m to 1000 ?m.

Coating systems on a surface of a CMC component, such as a CMC shroud, are provided. The coating system can include an environmental barrier coating on the surface of the CMC component and an abradable coating on the environmental barrier coating and defining an external surface opposite of the environmental barrier coating. The abradable coating includes a compound having the formula: Ln.sub.2ABO.sub.8, where Ln comprises scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, or mixtures thereof; A comprises Si, Ti, Ge, or a combination thereof; and B comprises Mo, W, or a combination thereof. In one embodiment, the abradable coating has a first coefficient of thermal expansion at an interface with the environmental barrier coating that changes to a second coefficient of thermal expansion at its external surface. Methods are also provided for applying an abradable coating onto a CMC component.

Coating systems on a surface of a CMC component, such as a CMC shroud, are provided. The coating system can include an environmental barrier coating on the surface of the CMC component and an abradable coating on the environmental barrier coating and defining an external surface opposite of the environmental barrier coating. The abradable coating includes a compound having the formula: Ln.sub.2ABO.sub.8, where Ln comprises scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, or mixtures thereof; A comprises Si, Ti, Ge, or a combination thereof; and B comprises Mo, W, or a combination thereof. In one embodiment, the abradable coating has a first coefficient of thermal expansion at an interface with the environmental barrier coating that changes to a second coefficient of thermal expansion at its external surface. Methods are also provided for applying an abradable coating onto a CMC component.

Environmental barrier coatings for high temperature ceramic components including a bond coat layer; an optional silica layer; and at least one transition layer including: from about 85% to about 100% by volume of the transition layer of a primary transition material including a rare earth disilicate, or a doped rare earth disilicate; and from 0% to about 15% by volume of the transition layer of a secondary material selected from Fe.sub.2O.sub.3, iron silicates, rare earth iron oxides, Al.sub.2O.sub.3, mullite, rare earth aluminates, rare earth aluminosilicates, TiO.sub.2, rare earth titanates, Ga.sub.2O.sub.3, rare earth gallates, NiO, nickel silicates, rare earth nickel oxides, Lnb metals, Lnb.sub.2O.sub.3, Lnb.sub.2Si.sub.2O.sub.7, Lnb.sub.2SiO.sub.5, borosilicate glass, alkaline earth silicates, alkaline earth rare earth oxides, alkaline earth rare earth silicates, and mixtures thereof; where the transition layer is applied to the component as a slurry including at least an organic solvent, the primary transition material and at least one slurry sintering aid, and where a reaction between the slurry sintering aid and the primary transition material results in the transition layer having a porosity of from 0% to about 15% by volume of the transition layer.

Environmental barrier coatings for high temperature ceramic components including a bond coat layer; an optional silica layer; and at least one transition layer including: from about 85% to about 100% by volume of the transition layer of a primary transition material including a rare earth disilicate, or a doped rare earth disilicate; and from 0% to about 15% by volume of the transition layer of a secondary material selected from Fe.sub.2O.sub.3, iron silicates, rare earth iron oxides, Al.sub.2O.sub.3, mullite, rare earth aluminates, rare earth aluminosilicates, TiO.sub.2, rare earth titanates, Ga.sub.2O.sub.3, rare earth gallates, NiO, nickel silicates, rare earth nickel oxides, Lnb metals, Lnb.sub.2O.sub.3, Lnb.sub.2Si.sub.2O.sub.7, Lnb.sub.2SiO.sub.5, borosilicate glass, alkaline earth silicates, alkaline earth rare earth oxides, alkaline earth rare earth silicates, and mixtures thereof; where the transition layer is applied to the component as a slurry including at least an organic solvent, the primary transition material and at least one slurry sintering aid, and where a reaction between the slurry sintering aid and the primary transition material results in the transition layer having a porosity of from 0% to about 15% by volume of the transition layer.

Disclosed is a method for producing coated substrates, wherein a first aqueous suspension and a second aqueous suspension are produced, a layer of the first aqueous suspension is applied onto a substrate, a layer of the second aqueous suspension is applied onto the layer of the first aqueous suspension applied onto the substrate, and the resulting substrate coated is sintered. The first and second aqueous suspensions each contains a refractory metal carbide, a sinter additive and water. Additionally, the second aqueous suspension can contain a sinter additive, wherein the content by weight percentage of the sinter additive in the second aqueous suspension, based on the total weight of the second aqueous suspension, is less than the content by weight percentage of the sinter additive in the first aqueous suspension, based on the total weight of the first aqueous suspension. Also disclosed are a coated substrate produced using the method and the use of the coated substrate.

A method may include applying a layer comprising a carbon source on a surface of a substrate including silicon; applying a layer comprising silicon on the layer comprising elemental carbon; and heat treating at least the layer comprising the carbon source to cause carbon from the layer comprising the carbon source to react with at least one of silicon from the substrate or silicon from the layer comprising silicon to form silicon carbide.

This disclosure concerns methods of fabricating porous ceramic supports and supported ceramic membranes, comprising mixing a ceramic powder, a clay powder and a binder to form a mixture, kneading the mixture in an aqueous or non-aqueous medium and a humectant to form a ceramic paste, and aging the ceramic paste for at least 24 h. The ceramic powder is about 70 wt % to about 80 wt % in the ceramic paste. The clay powder is about 5 wt % to about 15 wt % in the ceramic paste. The ceramic powder has an average particle size of about 5 ?m to about 20 ?m. This disclosure also concerns porous ceramic supports and supported ceramic membranes thereof.