Methods of forming sintered coatings are provided, along with the resulting coatings on a substrate. The sintered coating may comprise a rare earth compound and a sintering aid, with the rare earth compound has the formula: A.sub.1−bB.sub.bZ.sub.1−dD.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. The coating may be densified at a sintering temperature, such as 1300° C. to 1600° C.

Methods for forming a coating on a surface of a substrate are provided. The method can include: preheating the surface of the substrate; spraying a slurry suspension onto the surface of the substrate to form a coating, wherein the slurry composition comprises a rare earth compound, a sintering agent, and a solvent, wherein the rare earth compound has the formula: A.sub.1-bB.sub.bZ.sub.1-dD.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 0.5; Z is Hf, Ti, or a mixture thereof; D is Zr, Ce, Ge, Si, or a mixture thereof; d is 0 to 0.5; and M is Ta, Nb, or a mixture thereof; and thereafter, heat treating the coating to densify the coating from an initial porosity to a sintered porosity.

Methods for forming a coating on a surface of a substrate are provided. The method can include: preheating the surface of the substrate; spraying a slurry suspension onto the surface of the substrate to form a coating, wherein the slurry composition comprises a rare earth compound, a sintering agent, and a solvent, wherein the rare earth compound has the formula: A.sub.1-bB.sub.bZ.sub.1-dD.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 0.5; Z is Hf, Ti, or a mixture thereof; D is Zr, Ce, Ge, Si, or a mixture thereof; d is 0 to 0.5; and M is Ta, Nb, or a mixture thereof; and thereafter, heat treating the coating to densify the coating from an initial porosity to a sintered porosity.

An automated preparation method of a SiC.sub.f/SiC composite flame tube, comprising the following steps: preparing an interface layer for a SiC fiber by a chemical vapor infiltration process, and obtaining the SiC fiber with a continuous interface layer; laying a unidirectional tape on the SiC fiber with the continuous interface layer and winding the SiC fiber with the continuous interface layer to form and obtaining a preform of a net size molding according to a fiber volume and a fiber orientation obtained in a simulation calculation; and adopting a reactive melt infiltration process and the chemical vapor infiltration process successively for a densification and obtaining a high-density SiC.sub.f/SiC composite flame tube in a full intelligent way. The SiC.sub.f/SiC composite flame tube prepared by the present disclosure not only has a high temperature resistance, but also has a low thermal expansion coefficient, high thermal conductivity and high thermal shock resistance.

A coating is formed on a surface of a base material of a furnace, and includes a base layer and a sliding material layer that is formed on a surface of the base layer and contains an oxide ceramic and a compound having a layered crystal structure. The sliding material layer causes the collided ashes to be slipped and facilitates the drop off of the adhered ashes. The base material forms a heat transfer tube or a wall surface of the furnace. The coating is also applied to a coal gasification furnace, a pulverized coal fired boiler, a combustion apparatus, or a reaction apparatus containing a furnace.

A coating is formed on a surface of a base material of a furnace, and includes a base layer and a sliding material layer that is formed on a surface of the base layer and contains an oxide ceramic and a compound having a layered crystal structure. The sliding material layer causes the collided ashes to be slipped and facilitates the drop off of the adhered ashes. The base material forms a heat transfer tube or a wall surface of the furnace. The coating is also applied to a coal gasification furnace, a pulverized coal fired boiler, a combustion apparatus, or a reaction apparatus containing a furnace.

A gas turbine engine article includes a silicon-containing ceramic substrate and an environmental barrier coating (EBC) system disposed on the substrate. The EBC system includes, from the substrate, a dense bond coat layer, a porous bond coat layer, and a topcoat layer in contact with the porous bond coat layer. The dense bond coat layer and the porous bond coat layer each include a silica matrix and oxygen-scavenging gas-evolution particles dispersed through the silica matrix. The porous bond coat layer includes engineered pores.

A gas turbine engine article includes a silicon-containing ceramic substrate and an environmental barrier coating (EBC) system disposed on the substrate. The EBC system includes, from the substrate, a dense bond coat layer, a porous bond coat layer, and a topcoat layer in contact with the porous bond coat layer. The dense bond coat layer and the porous bond coat layer each include a silica matrix and oxygen-scavenging gas-evolution particles dispersed through the silica matrix. The porous bond coat layer includes engineered pores.

Methods for forming a coated component, along with the resulting coated components, are provided. The method may include forming a silicon-based bond coating on a surface of a substrate and forming a barrier coating on the silicon-based bond coating. The silicon-based bond coating comprises columnar grains of crystalline silicon. Chemical vapor depositing (CVD) may be used to form the silicon-based bond coating through CVD of a silicon-containing precursor at a deposition temperature and deposition pressure that causes crystallization of the silicon material during the deposition of the silicon-based bond coating. The silicon-containing precursor may be silane, monochlorosilane, dichlorosilane, and/or trichlorosilane.

Methods for forming a coated component, along with the resulting coated components, are provided. The method may include forming a silicon-based bond coating on a surface of a substrate and forming a barrier coating on the silicon-based bond coating. The silicon-based bond coating comprises columnar grains of crystalline silicon. Chemical vapor depositing (CVD) may be used to form the silicon-based bond coating through CVD of a silicon-containing precursor at a deposition temperature and deposition pressure that causes crystallization of the silicon material during the deposition of the silicon-based bond coating. The silicon-containing precursor may be silane, monochlorosilane, dichlorosilane, and/or trichlorosilane.