Composite article and method of making same

Abstract

A method of making a composite article and a composite article specifically adapted for use in high temperature, corrosive and errosive environments comprising a carbon fibrous substrate, including a pyrolytic carbon sheath formed about each fiber of the substrate; a metallic carbide, oxide, or nitride compliant coating over the coated fibers of the substrate; and an impermeable metallic carbide, oxide or nitride outer protective layer formed about the entire periphery of the coated substrate. In accordance with the method of the invention, the compliant metallic coating is applied to the fibers in a manner such that any mechanical stresses built-up in the substrate due to a mismatch between the coefficient of thermal expansion of the fibrous substrate and the coating are effectively accomodated.

I claim: .[.1. A carbon-silicon composite anisotropic article comprising a multiplicity of carbon fibers forming a shaped article, a coating of pyrolytic carbon extending over each of said fibers, a reaction formed diffusion coating of silicon extending substantially over each of said pyrolytic carbon coated fibers and substantially over the outer periphery of the article, said pyrolytic carbon coating and side silicon coating having been applied to said fibers in a manner whereby said fibers are free to move relative to said coatings, said carbon fibers and said silicon coating having a different coefficient of thermal expansion..]. .[.2. A carbon-silicon composite article as defined in claim 1 in which said reaction formed diffusion coating consists of silicon carbide..]. .[.3. A carbon-silicon composite article as defined in claim 1 in which said reaction formed diffusion coating consists of silicon nitride..]. .[.4. A carbon-silicon composite article as defined in claim 1 in which said reaction formed diffusion coating consists of silicon oxide..]. 
     
        .[.    A carbon-silicon composite article as defined in claim 1 in which a coating of chemical vapor deposited silicon carbide extends substantially over each of said coated fibers and substantially over the outer periphery of said article..]. .[.6. A carbon-silicon composite article as defined in claim 1 wherein the density of said article is between 0.3 gm/cc and 3.0 gm/cc..]. .[.7. A carbon-silicon composite article as defined in claim 1 wherein said multiplicity of carbon fibers forming the shaped article are in the form of a woven material having a multiplicity of interwoven carbon fibers..]. .[.8. A carbon-silicon composite article as defined in claim 1 wherein said multiplicity of carbon fibers forming the shaped article are in the form of a felt material having a multiplicity of randomly oriented fibers..]. .[.9. A carbon-silicon composite article as defined in claim 1 wherein said multiplicity of carbon fibers forming the shaped article are in the form of a macerated material having a multiplicity of randomly oriented fibers..]. .[.10. A carbon-silicon composite article as defined in claim 1 in which said carbon fibers forming said shaped article are pyrolyzed rayon..]. .[.11. A carbon-silicon composite article as defined in claim 1 in which said carbon fibers forming said shaped article are pyrolyzed polyacrylonitrile..]. .[.12. A carbon-silicon composite article as defined in claim 1 in which said carbon fibers forming said shaped article are wool..]. .[.13. A carbon-silicon composite article as defined in claim 1 in which said carbon fibers forming said shaped article are 
     
     
        pitch fibers..]. .Iadd.14.  A carbon-silicon composite anisotropic article comprising a multiplicity of carbon fibers forming a shaped article, a coating of pyrolytic carbon extending over each of said fibers, a reaction formed diffusion coating of silicon extending substantially over each of said pyrolytic carbon coated fibers and substantially over the outer periphery of the article, said pyrolytic carbon coating and said silicon coating having been applied to said fibers in a manner whereby said fibers are free to move relative to said coatings, said carbon fibers and said silicon coating having a different coefficient of thermal expansion. .Iaddend. .Iadd.15. A carbon-silicon composite article as defined in claim 14 in which said reaction formed diffusion coating consists of silicon 
     
     
        carbide. .Iaddend. .Iadd.16.  A carbon-silicon composite article as defined in claim 14 in which said reaction formed diffusion coating consists of silicon nitride. .Iaddend. .Iadd.17. A carbon-silicon composite article as defined in claim 14 in which said reaction formed diffusion coating consists of silicon oxide. .Iaddend..Iadd.18. A carbon-silicon composite article as defined in claim 14 in which a coating of chemical vapor deposited silicon carbide extends substantially over each of said coated fibers and substantially over the outer periphery of said article. .Iaddend. .Iadd.19. A carbon-silicon composite article as defined in claim 14 wherein the density of said article is between 0.3 gm/cc and 3.0 gm/cc. .Iaddend. .Iadd.20. A carbon-silicon composite article as defined in claim 14 wherein said multiplicity of carbon fibers forming the shaped article are in the form of a woven material having a 
     
     
        multiplicity of interwoven carbon fibers. .Iaddend. .Iadd.21.  A carbon-silicon composite article as defined in claim 14 wherein said multiplicity of carbon fibers forming the shaped article are in the form of a felt material having a multiplicity of randomly oriented fibers. .Iaddend. .Iadd.22. A carbon-silicon composite article as defined in claim 14 wherein said multiplicity of carbon fibers forming the shaped article are in the form of a macerated material having a multiplicity of randomly oriented fibers. .Iaddend. .Iadd.23. A carbon-silicon composite article as defined in claim 14 in which said carbon fibers forming said shaped article are pyrolized rayon. .Iaddend. .Iadd.24. A carbon-silicon composite article as defined in claim 14 in which said carbon fibers forming said shaped article are pyrolyzed polyacrylonitrile. .Iaddend. .Iadd.25. A carbon-silicon composite article as defined in claim 14 in which said carbon fibers forming said shaped article are pyrolyzed wool. .Iaddend. .Iadd.26. A carbon-silicon composite article as defined in claim 14 in which said carbon fibers forming said shaped article are pyrolyzed 
     
     
        pitch fibers. .Iaddend. .Iadd.27.  In combination, a fibrous substrate formed from a plurality of anisotropic discrete members defining a porous relationship, the substrate having anisotropic properties and having a first coefficient of thermal expansion, the substrate being formed from a material selected from the group consisting of carbon and a ceramic,   means for promoting a load transfer between the discrete elements in the substrate, and   a matrix disposed on the load transfer means and having a second coefficient of thermal expansion different from the first coefficient of thermal expansion and providing for a free movement of the matrix relative to the fibrous substrate to accommodate the different coefficients of thermal expansion of the fibrous substrate and the matrix, the matrix being formed from a refractory material including a first metallic element having refractory properties and a second element chemically bound to the   
     
     
        first element. .Iaddend. .Iadd.28.  A combination as set forth in claim 27 wherein the load transfer means encases the discrete members and   the matrix encases the load transfer means and wherein   the matrix is porous and is formed from a material selected from the group consisting of metallic oxides, nitrides and carbides. .Iaddend. .Iadd.29. A combination as set forth in claim 28 wherein   the matrix is formed from a material providing positive ions and a   
     
     
        non-organic gas. .Iaddend. .Iadd.30.  A combination as set forth in claim 27 wherein the matrix is formed from a material selected from the group consisting of the oxide, nitride and carbide of silicon and the substrate is formed from a material selected from the group consisting of carbon and a ceramic. .Iaddend. .Iadd.31. A combination as set forth in claim 28 wherein   the load transfer means is formed from a material selected from the group   
     
     
        consisting of pyrolyzed carbon and a ceramic. .Iaddend. .Iadd.32.  A combination as set forth in claim 27 wherein the fibrous substrate is formed from a plurality of anisotropic fibers and the matrix is formed from a material selected from the group consisting of silicon carbide, silicon nitride and silicon oxide. .Iaddend. .Iadd.33. In combination,   a fibrous substrate formed from a plurality of discrete elements defining a porous relationship and having anisotropic properties and having a first coefficient of thermal expansion, the substrate being formed from a material selected from the group consisting of carbon and a ceramic,   means associated with the substrate for promoting a load transfer between the discrete elements in the substrate, and   a matrix formed from a material selected from the group consisting of a metallic oxide, a metallic carbide and a metallic nitride and having a second coefficient of thermal expansion different from the first coefficient of thermal expansion and disposed on the load transfer means to accommodate stresses between the substrate and the matrix as a result of the differences in their coefficients of thermal expansion. .Iaddend.   
     
     
        .Iadd.34.  A combination as set froth in claim 20, including, an impermeable coating disposed on the matrix and formed from a material selected from the group consisting of a metallic oxide, a metallic carbide and a metallic nitride, the impermeable coating being impermeable to corrosion and erosion caused by high temperatures and exposure to hostile   
     
     
        fluid environments. .Iaddend. .Iadd.35.  The combination set forth in claim 33 wherein the matrix is freely movable relative to the fibrous substrate. .Iaddend. .Iadd.36. A combination as set forth in claim 33 wherein   the load transfer means is bound to the discrete elements in the fibrous substrate and are formed from a pyrolitic carbon. .Iaddend. .Iadd.37. A combination as set forth in claim 36 wherein   an impermeable coating is disposed on the matrix and formed from a material selected from the group consisting of a metallic oxide, a metallic carbide and a metallic nitride, the impermeable coating being impermeable to corrosion and erosion caused by high temperatures and exposure to hostile   
     
     
        fluid environments. .Iaddend. .Iadd.38.  A combination as set forth in claim 36 wherein the fibers in the fibrous substrate are selected from the group consisting of carbon, ceramic, pyrolyzed wool, pyrolyzed rayon, pyrolyzed   
     
     
        polyacrylonitrile and pyrolyzed pitch fibers. .Iaddend. .Iadd.39.  In combination, a substrate formed from a plurality of discrete elements having anisotropic properties and having a first coefficient of thermal expansion and providing the substrate with porous characteristics,   an intermediate layer of a refractory material disposed on the substrate, and   means including a matrix disposed on the intermediate layer of refractory material and having a different coefficient of thermal expansion than the discrete members and providing for a free movement relative to the substrate to accommodate the different coefficients of thermal expansion of the matrix and the substrate, the matrix being formed from a material including a first metallic element having refractory properties and a   
     
     
        second element chemically bound to the first element. .Iaddend. .Iadd.40. A combination as set forth in claim 39 wherein the matrix is porous. .Iaddend. .Iadd.41. A combination as set forth in claim 40, including   an impermeable coating covering the matrix and having a coefficient of thermal expansion compatible with that of the matrix, the impermeable coating being impermeable to corrosion and erosion caused by high temperature and exposure to hostile fluid environment. .Iaddend. .Iadd.42. A combination as set forth in claim 41 wherein   the impermeable coating is resistant to corrosion. .Iaddend. .Iadd.43. A combination as set forth in claim 41 wherein   the matrix is formed from material selected from the group consisting of metallic oxide, nitride and carbide, and   the impermeable coating is formed from a material selected from the group consisting of the metallic oxide, nitride and carbide. .Iaddend.   
     
     
        .Iadd.     A combination as set forth in claim 43 wherein the discrete members in the substrate are formed from a material selected from the group consisting of carbon, ceramic, pyrolyzed wool, pyrolyzed rayon, pyrolyzed polyacrylonitrile and pyrolyzed pitch fibers. .Iaddend. .Iadd.45. A combination as set forth in claim 44 wherein   the metallic element in the metallic oxide, nitride and carbide is silicon.   
     
     
        .Iaddend. .Iadd.46.  In combination, a fibrous substrate formed a plurality of discrete elements having anisotropic properties and having a first coefficient of thermal expansion, the substrate defining a porous relationship, the discrete elements being formed from a material selected from the group consisting of carbon and a ceramic,   an intermediate layer of a refractory material disposed on the substrate, and   a matrix formed from a refractory material and encasing the discrete members and the intermediate layer of refractory material and having a different coefficient of thermal expansion than the substrate and providing for a free movement relative to the substrate to provide for adjustments in the relative positions of the substrate and the matrix in accordance with their different coefficients of thermal expansion, the refractory material of the matrix including a first metallic element having refractory properties and a second element chemically bound to the   
     
     
        first element. .Iaddend. .Iadd.47.  A combination as set forth in claim 46 wherein the matrix is formed from a material selected from the group consisting of metallic oxides, nitrides and carbides and wherein   an impermeable coating is provided on the matrix, the impermeable coating being impermeable to corrosion and erosion caused by high temperatures and   
     
     
        exposure to hostile fluid environments. .Iaddend. .Iadd.48.  A combination as set forth in claim 46 wherein the substrate is formed form a material selected from the group consisting of carbon, ceramic, pyrolyzed rayon, pyrolyzed polyacrylonitrile, pyrolyzed wool and carbonized polyacrylonitrile and   the matrix is formed from a material selected from the group consisting of   
     
     
        silicon carbide, silicon nitride and silicon oxide. .Iaddend. .Iadd.49.  A combination as set forth in claim 48 wherein an impermeable coating is provided on the matrix and is formed from a material selected from the group consisting of silicon carbide, silicon nitride and silicon oxide, the impermeable coating being impermeable to corrosion and erosion caused by high temperatures and exposure to hostile   
     
     
        fluid environments. .Iaddend. .Iadd.50.  A combination as set forth in claim 46 wherein the matrix encases the discrete members. .Iaddend. .Iadd.51. A combination as set forth in claim 50 wherein   an impermeable coating encases the matrix, the impermeable coating being permeable to corrosion and erosion caused by high temperatures and exposure to hostile fluid environments. .Iaddend. .Iadd.52. A combination as set forth in claim 51 wherein   
     
     
       the discrete members in the substrate are fibrous. .Iaddend. .Iadd.53.  In combination in a composite material, a fibrous substrate having a first coefficient of thermal expansion and defining porous characteristics and formed from discrete elements having anisotropic properties, and   an intermediate pyrolitic layer disposed on the substrate, and   a matrix formed from a refractory material and having a second coefficient of thermal expansion different from the first coefficient of thermal expansion and disposed on the intermediate pyrolitic layer, the matrix accommodating the substrate, as a result of changes in temperature, to relieve stresses between the matrix and the substrate in accordance with the differences in their coefficients of thermal expansion, the refractory material of the matrix including a first metallic element having refractory properties and a second element chemically bound to the first elements, and   an impermeable coating on the matrix, the impermeable coating being impermeable to corrosion and erosion caused by high temperatures and   
     
     
        exposure to hostile fluid environments. .Iaddend. .Iadd.54.  A combination as set forth in claim 53, including a coating between the porous substrate and the matrix to promote superior load transfer between the discrete elements in the substrate and the matrix upon the stressing of the composite material and to enhance the toughness and flow resistance of the composite material. .Iaddend. .Iadd.55. A combination as set forth in claim 54 wherein   the intermediate pyrolitic layer is a pyrolitic carbon and   the matrix is formed from a material selected from the group consisting of   
     
     
        silicon carbide, silicon nitride and silicon oxide. .Iaddend. .Iadd.56.  A combination as set forth in claim 54 wherein the substrate is formed from a material selected from a group consisting of carbon, ceramic, pyrolyzed wool, pyrolyzed rayon, pyrolyzed polyacrylonitrile and pyrolyzed pitch fibers. .Iaddend. .Iadd.57. A combination as set forth in claim 53 wherein   the substrate is formed from a material selected from the group consisting of carbon, ceramic, pyrolyzed wool, pyrolyzed rayon, pyrolyzed polyacrylonitrile and pyrolyzed pitch fibers, and   the impermeable layer is formed from a material selected from the group consisting of silicon carbide, silicon nitride and silicon oxide, and   the matrix is formed from a material selected from the group consisting of   
     
     
        silicon oxide, silicon nitride and silicon carbide. .Iaddend. .Iadd.58.  A combination as set forth in claim 57 wherein the intermediate pyrolitic layer is formed from the group consisting of pyrolitic carbon and ceramic. .Iaddend. .Iadd.59. A combination as set forth in claim 46 wherein   the intermediate layer of refractory material encases the discrete members and wherein the matrix encases the intermediate layer of refractory material. .Iaddend.