Composite article and method therefor

Abstract

A composite article includes a substrate and a multilayer coating on the substrate. The multilayer coating includes an inner layer near the substrate, and outermost layer on the inner layer, and an intermediate layer between the inner layer and the outermost layer. The inner layer and outermost layer are boron-containing materials, and the intermediate layer is a silicon-containing ceramic material.

1 . A composite article comprising:
 a substrate; and   a multilayer coating on the substrate, the multilayer coating including an inner layer near the substrate, an outermost layer on the inner layer, and an intermediate layer between the inner layer and the outermost layer, the inner layer and the outermost layer are boron-containing materials and the intermediate layer is a silicon-containing ceramic material.   
     
     
         2 . The composite article as recited in  claim 1 , wherein the inner layer and the outermost layer are boron nitride. 
     
     
         3 . The composite article as recited in  claim 1 , wherein the silicon-containing ceramic material is silicon nitride. 
     
     
         4 . The composite article as recited in  claim 1 , wherein the substrate is a fiber structure. 
     
     
         5 . The composite article as recited in  claim 4 , wherein the fiber structure is selected from a group consisting of carbon fibers, silicon carbide fibers, aluminum silicate fibers, alumina fibers, silicon oxynitride fibers, and combinations thereof. 
     
     
         6 . The composite article as recited in  claim 4 , wherein the fiber structure includes fibers of a material selected from a group consisting of oxides, nitrides, carbides, borides, and combinations thereof. 
     
     
         7 . The composite article as recited in  claim 4 , wherein the fiber structure includes silicon carbide fibers. 
     
     
         8 . The composite structure as recited in  claim 1 , wherein the inner layer has a first thickness and the outermost layer has a second thickness that is greater than the first thickness. 
     
     
         9 . The composite article as recited in  claim 1 , wherein the inner layer and the outermost layer each have a thickness of 50-150 nanometers, and the intermediate layer has a thickness of 100-500 nanometers. 
     
     
         10 . The composite article as recited in  claim 1 , wherein the multilayer coating is approximately 200 nanometers thick. 
     
     
         11 . The composite article as recited in  claim 1 , wherein the multilayer coating has a thickness ratio t 1  of the intermediate layer to the inner layer and a thickness ratio t 2  of the intermediate layer to the outermost layer that are each 0.67-10. 
     
     
         12 . The composite article as recited in  claim 11 , wherein the thickness ratios t 1  and t 2  are 1-4. 
     
     
         13 . The composite article as recited in  claim 1 , further comprising a ceramic matrix material interfaced with the outermost layer. 
     
     
         14 . A composite article comprising:
 a ceramic matrix;   reinforcement fibers dispersed within the ceramic matrix; and   a triplex coating between the reinforcement fibers and the ceramic matrix, the triplex coating including a boron nitride layer interfaced with the reinforcement fibers, a boron-containing layer interfaced with the ceramic matrix, and an intermediate silicon-containing layer between the boron nitride layer and the boron-containing layer.   
     
     
         15 . The composite article as recited in  claim 14 , wherein the intermediate silicon-containing layer is silicon nitride. 
     
     
         16 . The composite article as recited in  claim 14 , wherein the ceramic matrix is silicon carbonitride and the reinforcement fibers are silicon carbide. 
     
     
         17 . The composite article as recited in  claim 14 , wherein the boron-containing layer contains borosilicate glass.