Articles may be protected against halide plasma, by applying a rare earth-containing glaze to the surface of the article. The glaze may be a coating comprising; 20 to 90 mol % SiO.sub.2, 0 to 60 mol % Al.sub.2O.sub.3, 10 to 80 mol % rare earth oxides and/or rare earth fluorides (REX), wherein SiO.sub.2+Al.sub.2O.sub.3+REX60 mol %.

Articles may be protected against halide plasma, by applying a rare earth-containing glaze to the surface of the article. The glaze may be a coating comprising; 20 to 90 mol % SiO.sub.2, 0 to 60 mol % Al.sub.2O.sub.3, 10 to 80 mol % rare earth oxides and/or rare earth fluorides (REX), wherein SiO.sub.2+Al.sub.2O.sub.3+REX60 mol %.

A glass-ceramic article is at least partly coated with at least one layer of enamel, including a glass frit. The frit includes, expressed by weight, SiO.sub.2, 45-60%; Al.sub.2O.sub.3, 12-22%; B.sub.2O.sub.3, 12-22%; Li.sub.2O, 0-5%; Na.sub.2O, 0-2%; K.sub.2O, >2%; CaO, 0-4%; MgO, 0-4%; ZnO, 0-4%; BaO, 0-4%; ZrO.sub.2, 0-4%; and TiO.sub.2, 0-1%. The sum of oxides CaO+MgO+BaO+SrO+ZnO is at most 10%, preferably from 2 to 8%. A process can be used to obtain the article.

An example method may include applying a bond coat comprising silicon or a silicon alloy on a surface of a ceramic or ceramic matrix composite substrate, where the bond coat comprises a plurality of pores; infiltrating a precursor into at least some pores of the plurality of pores; and heat-treating the bond coat and the precursor, where after heat-treating a porosity of the bond coat is less than about 5 vol. %, and where after heat-treating, the bond coat is substantially free of continuous porosity extending through a thickness of the bond coat.

An example method may include applying a bond coat comprising silicon or a silicon alloy on a surface of a ceramic or ceramic matrix composite substrate, where the bond coat comprises a plurality of pores; infiltrating a precursor into at least some pores of the plurality of pores; and heat-treating the bond coat and the precursor, where after heat-treating a porosity of the bond coat is less than about 5 vol. %, and where after heat-treating, the bond coat is substantially free of continuous porosity extending through a thickness of the bond coat.

The present disclosure provides a method for coating a composite structure, comprising applying a first slurry onto a surface of the composite structure, wherein the first slurry is a sol gel comprising a metal organic salt, a first carrier fluid, and a ceramic material, and heating the composite structure to a first sol gel temperature sufficient to form a sol gel-derived base layer on the composite structure.

Lithium silicate glass ceramics and glasses are described which can advantageously be applied to zirconium oxide ceramics in particular by pressing-on in the viscous state and form a solid bond with these.

According to the present invention, there is provided a ceramic product in which damage to a decorative film during washing with an alkali can be reduced. In a ceramic product 1 disclosed here, a decorative film 30 is formed on the surface of a ceramic substrate 10. Here, the decorative film 30 of the ceramic product includes a noble metal region 32 containing a noble metal element as a main component and an amorphous region 34 containing matrix-forming elements containing at least Si as a main component. Here, in the ceramic product 1 disclosed here, crystalline particles 35 containing a crystalline oxide of at least one metal element selected from among the matrix-forming elements as a main component are dispersed in the amorphous region 34. Since such crystalline particles 35 are difficult for alkaline components to penetrate, it is possible to prevent the alkaline components from entering the amorphous region 35 and reduce damage to the decorative film 30 during washing with an alkali.

A method for forming an oxidation protection system on a composite structure are provided. The method includes applying a composite slurry to the composite structure, wherein the composite slurry comprises boron carbide, silicon carbide, borosilicate glass, an oxygen reactant compound including a silica forming component, and a carrier fluid and heating the composite structure to a temperature sufficient to form a boron-silicon-glass-oxygen reactant layer on the composite structure.

Systems and methods for forming an oxidation protection system on a composite structure. An oxidation protection system disposed on an outer surface of a substrate includes a boron layer disposed over the outer surface, the boron layer comprising a boron compound and a first glass compound. The oxidation protection system further includes a silicon layer disposed on the boron layer, the silicon layer comprising a silicon compound and a second glass compound.