An oxidation protection system disposed on a substrate is provided, which may comprise a boron layer comprising a boron compound disposed on the substrate; a silicon layer comprising a silicon compound disposed on the boron layer; and at least one sealing layer comprising monoaluminum phosphate and phosphoric acid disposed on the silicon layer.

An oxidation protection system disposed on a substrate is provided, which may comprise a boron layer comprising a boron compound disposed on the substrate; a silicon layer comprising a silicon compound disposed on the boron layer; and at least one sealing layer comprising monoaluminum phosphate and phosphoric acid disposed on the silicon layer.

An environmental barrier coating, comprising a substrate containing silicon; an environmental barrier layer applied to said substrate; said environmental barrier layer comprising a rare earth composition.

An environmental barrier coating, comprising a substrate containing silicon; an environmental barrier layer applied to said substrate; said environmental barrier layer comprising a rare earth composition.

An oxidation protection system disposed on a substrate is provided, which may comprise a boron layer comprising a boron compound disposed on the substrate; a silicon layer comprising a silicon compound disposed on the boron layer; and at least one sealing layer comprising monoaluminum phosphate and phosphoric acid disposed on the silicon layer.

An oxidation protection system disposed on a substrate is provided, which may comprise a boron layer comprising a boron compound disposed on the substrate; a silicon layer comprising a silicon compound disposed on the boron layer; and at least one sealing layer comprising monoaluminum phosphate and phosphoric acid disposed on the silicon layer.

Provided is a C/C composite having a long life in an environment including a heating process and a cooling process and having less adverse effects on surrounding facilities and the quality of treatment objects. A C/C composite in which, in measurement for open pores by mercury porosimetry, an open porosity for open pores with a radius of not less than 0.4 μm and less than 10 μm in the C/C composite is 2.0% or less.

The present disclosure provides a method for coating a composite structure comprising the steps of applying a first slurry of a first phosphate glass composition on an outer surface of the composite structure. The first slurry comprises a first additive including at least one of molybdenum disulfide or tungsten disulfide. The method may further include heating the composite structure to a temperature sufficient to form a base layer adhered to the composite structure.

The present disclosure provides a method for coating a composite structure comprising the steps of applying a first slurry of a first phosphate glass composition on an outer surface of the composite structure. The first slurry comprises a first additive including at least one of molybdenum disulfide or tungsten disulfide. The method may further include heating the composite structure to a temperature sufficient to form a base layer adhered to the composite structure.

The present disclosure provides a method for coating a composite structure, comprising forming a first slurry by combining a first pre-slurry composition with a first carrier fluid, applying the first slurry on a surface of the composite structure, and heating the composite structure to a temperature sufficient to form a base layer on the composite structure. The first pre-slurry composition may comprise a first phosphate glass composition and a low coefficient of thermal expansion material, wherein the low coefficient of thermal expansion material is a material with a coefficient of thermal expansion of less than 10×10.sup.−6° C..sup.−1.