Modified atmosphere melt infiltration

Abstract

A ceramic matrix composite component for use in a gas turbine engine and method for making the same are described herein. The component comprising a body and an outer region. The body having a silicon containing ceramic composite. The outer region on an outer surface of the body.

What is claimed is: 
     
         1 . A ceramic matrix composite component for use in a gas turbine engine, the component comprising
 a body comprising a silicon containing ceramic composite; and   an outer region on an outer surface of the body, the outer region comprising whiskers embedded in a matrix, the whiskers comprising silicon carbide, and the matrix comprising a majority of silicon metal.   
     
     
         2 . The component of  claim 1 , wherein the outer region further comprises precipitates selected from a group consisting of silicon carbide, iron-rich silicides, silicon borides, and any combination thereof. 
     
     
         3 . The component of  claim 1 , wherein the outer region has a substantially flat external surface. 
     
     
         4 . The component of  claim 1 , wherein the ceramic composite of the body is a silicon carbide-silicon carbide composite. 
     
     
         5 . The component of  claim 1 , wherein the whiskers have a diameter of between about 0.5 μm and about 25 μm. 
     
     
         6 . The component of  claim 1 , wherein the outer region has a thickness of between about 5 μm and about 300 μm. 
     
     
         7 . The component of  claim 1 , wherein the matrix consists essentially of silicon metal. 
     
     
         8 . The component of  claim 7 , wherein the silicon metal of the outer region is wetted to the silicon carbide whiskers. 
     
     
         9 . The component of  claim 1 , further comprising an environmental barrier coating bonded to the outer region such that the outer region is sandwiched between the body the and environmental barrier coating. 
     
     
         10 . The component of  claim 9 , wherein the environmental barrier coating is selected from a group consisting of mullite, barium strontinum aluminosilicate, strontinum aluminosilicate, barium aluminosilicate, rare earth disilicates, rare earth monosilicate, and any combination thereof. 
     
     
         11 . The component of  claim 10 , further comprising an abradable bonded to the environmental barrier coating such that the environmental barrier is sandwiched between the ceramic matrix composite component and the abradable coating. 
     
     
         12 . The component of  claim 11 , wherein the abradable is selected from a group consisting of barium strontinum aluminosilicate, strontinum aluminosilicate, barium aluminosilicate, rare earth disilicates, rare earth monosilicates, and combinations thereof. 
     
     
         13 . An in situ method for forming a silicon rich outer region along a ceramic matrix composite component for use in a gas turbine engine, the method comprising
 melt infiltrating a silicon metal or alloy into a ceramic preform to form a body;   cooling the component after the melt infiltrating;   adding hydrocarbon gas to an atmosphere in contact with the body during at least a portion of the melt infiltrating, the cooling or any combination thereof; and   chemically reacting the hydrocarbon gas with silicon in the body to form silicon carbide on an outer region of the body.   
     
     
         14 . The method of  claim 13 , wherein the silicon carbide on the outer region of the body comprise whiskers. 
     
     
         15 . The method of  claim 13 , further comprising wetting a silicon metal or alloy, formed from silicon of the body, to the whiskers to form the outer region, wherein the outer region has a silicon concentration greater than a silicon concentration of the body. 
     
     
         16 . The method of  claim 13 , wherein the hydrocarbon gas is selected from a group consisting of methane, propane, or a combination thereof. 
     
     
         17 . The method of  claim 16 , further comprising adding hydrogen gas to the step of adding hydrocarbon gas in a ratio of hydrocarbon gas to hydrogen gas of between about 4:1 and about 1:20. 
     
     
         18 . The method of  claim 13 , further comprising depositing an environmental barrier coating along an external surface of an outer region. 
     
     
         19 . The method of  claim 18 , further comprising depositing a porous abradable such that the environmental barrier coating is sandwiched between the outer region of the body and the abradable. 
     
     
         20 . The method of  claim 13 , further comprising adding a catalyst comprising nickel, molybdenum, cobalt, or any combination thereof during the step of melt infiltration.