US 4,863,798 A · Refractory composite material and method of making such material

Abstract

A porous substrate is formed from discrete elements preferably anisotropic and permeable to oxygen and preferably having a first coefficient of thermal expansion. A pyrolytic material permeable to oxygen may be deposited in a thin layer on the discrete elements. A barrier material (e.g. boron carbide or silicon carbide) may be deposited in a thin layer on the pyrolytic material to inhibit diffusion of elements into the pyrolytic material. A material impermeable to oxygen (e.g. boron nitride or silicon nitride) may be deposited in a thin layer on the barrier material. A refractory matrix permeable to oxygen may be deposited on the impermeable material. The matrix may include a metallic element (e.g. silicon, hafnium, tantalum or zirconium) and another element (e.g. oxygen, nitrogen, carbon or boron) chemically bonded to the metallic element. The matrix may have a second coefficient of thermal expansion different from the first coefficient and may have a minimal bond to the substrate. The matrix is accordingly able to move relative to the substrate with changes in temperature, partly because the pyrolytic material contributes to a shear between the matrix and substrate. A refractory material impermeable to oxygen may be deposited in a thin layer on the matrix and may include a metallic element (e.g. silicon, hafnium, tantalum or zirconium) and an element (e.g. oxygen, nitrogen and boron) chemically bonded to the metallic element. The different layers may be deposited on the substrate, each in a substantially uniform thickness, at an elevated temperature and at pressures pulsating at a particular rate, and in reverse directions, between first and second particular limits.

Claims37

Dependent claims

A refractory composite material,

a porous permeable substrate defined by a plurality of discrete elements,
a pyrolytic layer covering the discrete elements in the substrate,
a layer of a material covering the pyrolytic layer and providing a barrier to inhibit diffusion into the pyrolytic layer, and
a layer of a material covering the barrier layer and compatible with the material of the barrier layer and having properties of being impermeable to oxygen.

1 more element

A method of producing a refractory composite material, including the steps of:

forming a plurality of discrete elements into a porous substrate, the discrete elements being permeable to oxygen,
depositing a layer of a pyrolytic material on the discrete elements by chemical vapor infiltration to cover the discrete elements in the substrate, the pyrolytic material being permeable to oxygen,
depositing a layer of a barrier material on the pyrolytic layer by chemical vapor infiltration to cover the pyrolytic layer, and
depositing by a chemical vapor infiltration a layer on the barrier layer of a material impermeable to oxygen to cover the material of the barrier layer,
the barrier material having properties of inhibiting the diffusion of the impermeable material into the pyrolytic

2 more elements

Dependencies are inferred from the claim text.

Refractory composite material and method of making such material

Life of this patent

Refractory composite material and method of making such material

Life of this patent

Abstract

Claims37