A method is provided in which a resin coating is applied to a surface of a preform. The resin coating includes a carbonaceous resin and a particulate. The preform is added to a tooling. The preform, which is positioned in the tooling, is cured. The tooling is removed. The resin coating on the surface of the preform is pyrolyzed to form a resin carbon-char layer on the surface of the preform. The preform and the resin carbon-char layer are infiltrated with silicon to form a ceramic matrix composite (CMC) component including a layer of silicon carbide. During the infiltration, the silicon reacts with carbon in the resin carbon-char layer to form the layer of silicon carbide on the preform.

A method of forming a barrier layer on a ceramic matrix composite (CMC) is described. The method includes forming a particulate surface layer comprising silicon particles on an outer surface of a fiber preform. The particulate surface layer is nitrided to convert the silicon particles to silicon nitride particles. After the nitriding, the fiber preform and the particulate surface layer are infiltrated with a molten material comprising silicon. Following infiltration, the molten material is cooled, thereby forming a ceramic matrix composite with a barrier layer thereon, where the barrier layer comprises silicon nitride and less than 5 vol. % free silicon. The barrier layer may also include silicon carbide and/or one or more refractory metal silicides.

A process for manufacturing a composite part includes introducing an adhesion promoter into the pores of a fibrous preform formed by threads covered with a coating having OH groups on its surface, the adhesion promoter including an electron-withdrawing group G1 that is reactive according to a reaction of substitution or of nucleophilic addition with the OH groups, and a reactive group G2; grafting the adhesion promoter to the surface of the coating by a reaction of substitution or nucleophilic addition of the OH groups on the group G1; introducing a ceramic precursor resin into the pores of the fibrous preform; polymerizing the resin introduced and bonding the grafted adhesion promoter to the resin by chemical reaction between these two compounds at the level of the group G2, and forming a ceramic matrix phase in the pores of the fibrous preform by pyrolysis of the polymerized resin.

A member for use in a plasma processing device of the disclosure includes a base material and a film containing yttrium oxide as a main component on the base material. An area occupancy of closed pores of the film is 0.2 area % or less, and a full width at half maximum of a diffraction peak on a (222) plane of yttrium oxide obtained by X-ray diffraction of the film is 0.25 or less. A plasma processing device according to the disclosure includes the member for use in a plasma processing device.

A member for use in a plasma processing device of the disclosure includes a base material and a film containing yttrium oxide as a main component on the base material. An area occupancy of closed pores of the film is 0.2 area % or less, and a full width at half maximum of a diffraction peak on a (222) plane of yttrium oxide obtained by X-ray diffraction of the film is 0.25 or less. A plasma processing device according to the disclosure includes the member for use in a plasma processing device.

A member for use in a plasma processing device of the disclosure includes a base material, and a film of an oxide of a rare earth element on at least a part of the base material. A coefficient of variation of thickness of the film is 0.04 or less. A plasma processing device of the disclosure includes the member for use in a plasma processing device. In the member for use in a plasma processing device according to the disclosure, variation in film thickness is small.

A member for use in a plasma processing device of the disclosure includes a base material, and a film of an oxide of a rare earth element on at least a part of the base material. A coefficient of variation of thickness of the film is 0.04 or less. A plasma processing device of the disclosure includes the member for use in a plasma processing device. In the member for use in a plasma processing device according to the disclosure, variation in film thickness is small.

A method of treating at least one silicon carbide fibre, the method including a) formation of a silica layer at the surface of a silicon carbide fibre having an oxygen content less than or equal to 1% in atomic percentage, the silica layer being formed by contacting this fibre with an oxidizing medium having a temperature greater than or equal to 50 C. and pressure greater than or equal to 1 MPa, and b) removal of the silica layer formed by hydrothermal treatment of the fibre obtained after implementation of step a) in which the fibre is treated with water at a pressure between saturating vapour pressure and 30 MPa and at a temperature less than or equal to 400 C.

Coating systems are provided for positioning on a surface of a substrate, along with the resulting coated components and methods of their formation. The coating system may include a layer having a compound of the formula: A.sub.1bB.sub.bZ.sub.1dD.sub.dMO.sub.6 where: A is Al, Ga, In, Sc, Y, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Fe, Cr, Co, Mn, Bi, or a mixture thereof; b is 0 to about 0.5; Z is Hf, Ti, or a mixture thereof; D is Zr, Ce, Ge, Si, or a mixture thereof; d is 0 to about 0.5; and M is Ta, Nb, or a mixture thereof.

Coating systems are provided for positioning on a surface of a substrate, along with the resulting coated components and methods of their formation. The coating system may include a layer having a compound of the formula: A.sub.1bB.sub.bZ.sub.1dD.sub.dMO.sub.6 where: A is Al, Ga, In, Sc, Y, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Fe, Cr, Co, Mn, Bi, or a mixture thereof; b is 0 to about 0.5; Z is Hf, Ti, or a mixture thereof; D is Zr, Ce, Ge, Si, or a mixture thereof; d is 0 to about 0.5; and M is Ta, Nb, or a mixture thereof.