A part includes a substrate having, adjacent to a surface of the substrate, at least a portion that is made of a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including a first layer including at least one first rare earth silicate and presenting grains with a mean size less than or equal to 1 μm; and a second layer covering the first layer, the second layer including at least one rare earth silicate and presenting grains with a mean size greater than 1 μm.

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.

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.

Composites of silicon and various porous scaffold materials, such as carbon material comprising micro-, meso- and/or macropores, and methods for manufacturing the same are provided. The compositions find utility in various applications, including electrical energy storage electrodes and devices comprising the same.

Composites of silicon and various porous scaffold materials, such as carbon material comprising micro-, meso- and/or macropores, and methods for manufacturing the same are provided. The compositions find utility in various applications, including electrical energy storage electrodes and devices comprising the same.

A reaction-bonded silicon carbide (SiC) body is produced by: providing a preform including ceramic elements and carbon, and one or more surface features; providing a powder which includes diamond particles and carbon; locating the powder in the surface feature(s); and infiltrating the preform and the powder with molten silicon (Si) to form reaction-bonded SiC in the preform, and to form reaction-bonded SiC coatings on the diamond particles. The present disclosure also relates to a device/component which includes: a main body portion and discrete elements located at least partially within the main body portion. The main body portion may include reaction-bonded SiC and Si, but not diamond, while the discrete elements include diamond particles, reaction-bonded SiC coatings surrounding the diamond particles, and Si. According to the present disclosure, diamond may be advantageously located only where it is needed.

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.

An article for high temperature service is presented herein. One embodiment is an article including a substrate having a silicon-bearing ceramic matrix composite; and a layer disposed over the substrate, wherein the layer includes silicon and a dopant, the dopant including aluminum. In another embodiment, the article includes a ceramic matrix composite substrate, wherein the composite includes a silicon-bearing ceramic and a dopant, the dopant including aluminum; a bond coat disposed over the substrate, where the bond coat includes elemental silicon, a silicon alloy, a silicide, or combinations including any of the aforementioned; and a coating disposed over the bond coat, the coating including a silicate (such as an aluminosilicate or rare earth silicate), yttria-stabilized zirconia, or a combination including any of the aforementioned.

An article for high temperature service is presented herein. One embodiment is an article including a substrate having a silicon-bearing ceramic matrix composite; and a layer disposed over the substrate, wherein the layer includes silicon and a dopant, the dopant including aluminum. In another embodiment, the article includes a ceramic matrix composite substrate, wherein the composite includes a silicon-bearing ceramic and a dopant, the dopant including aluminum; a bond coat disposed over the substrate, where the bond coat includes elemental silicon, a silicon alloy, a silicide, or combinations including any of the aforementioned; and a coating disposed over the bond coat, the coating including a silicate (such as an aluminosilicate or rare earth silicate), yttria-stabilized zirconia, or a combination including any of the aforementioned.