Ceramic matrix composite component, turbine system and fabrication process

Abstract

A ceramic matrix composite component, turbine system and fabrication process are disclosed. The ceramic matrix composite (CMC) component includes a CMC material, an environmental barrier coating (EBC) on the CMC material, and a hard wear coating applied over the EBC. The turbine system includes a rotatable CMC component having a hard wear coating, and a stationary turbine component, the stationary turbine component having an abradable coating arranged and disposed to be cut by the silicon carbide material. The fabrication process includes positioning the rotatable CMC a pre-determined distance from the stationary turbine component and rotating the rotatable CMC component. The hard wear coating on the rotatable CMC component cuts the abradable coating on the stationary turbine component.

What is claimed is: 
     
         1 . A ceramic matrix composite component, comprising:
 a ceramic matrix composite material;   an environmental barrier coating applied over the ceramic matrix composite material; and   a hard wear coating applied over the environmental barrier coating.   
     
     
         2 . The ceramic matrix composite component of  claim 1 , wherein the hard wear coating further comprises silicon carbide. 
     
     
         3 . The ceramic matrix composite component of  claim 1 , wherein the hard wear coating is the outermost layer. 
     
     
         4 . The ceramic matrix composite component of  claim 1 , wherein the hard wear coating coats an outer surface of the component. 
     
     
         5 . The ceramic matrix composite component of  claim 1 , wherein the hard wear coating is applied by physical vapor deposition. 
     
     
         6 . The ceramic matrix composite component of  claim 1 , wherein the hard wear coating is applied by chemical vapor deposition. 
     
     
         7 . A turbine system, comprising:
 a rotatable ceramic matrix composite bucket attached to a disc, the rotatable ceramic matrix composite bucket having a ceramic matrix composite material, an environmental barrier coating applied over the ceramic matrix composite material, and a hard wear coating applied over the environmental barrier coating; and   a stationary turbine shroud, the stationary turbine shroud having an abradable coating arranged and disposed to be cut by the hard wear coating of the rotatable ceramic matrix composite bucket.   
     
     
         8 . The turbine system of  claim 7 , wherein the stationary turbine shroud forms a perimeter around the rotatable bucket. 
     
     
         9 . The turbine system of  claim 7 , wherein a plurality of rotatable ceramic matrix composite buckets are attached circumferentially to the turbine disc. 
     
     
         10 . A fabrication process, comprising:
 positioning a rotatable ceramic matrix composite component a pre-determined distance from a stationary turbine component, the stationary turbine component having an abradable coating and the rotatable component having a hard wear layer applied over an environmental layer; and   rotating the rotatable ceramic matrix composite component;   wherein, the hard wear layer on the rotatable ceramic matrix composite component cuts the abradable coating on the stationary turbine component.   
     
     
         11 . The fabrication process of  claim 10 , wherein power transients cause the rotatable ceramic matrix composite component to contact the abradable coating. 
     
     
         12 . The fabrication process of  claim 10 , wherein the cut by the rotatable ceramic matrix composite component forms a pathway in the abradable coating. 
     
     
         13 . The fabrication process of  claim 10 , wherein the process further comprises a break-in period. 
     
     
         14 . The fabrication process of  claim 13 , wherein the break-in period is up to about 100 hours. 
     
     
         15 . The fabrication process of  claim 13 , wherein the break-in period is at least 100 hours. 
     
     
         16 . The fabrication process of  claim 10 , wherein the hard wear layer volatilizes after predetermined exposure to elevated temperature. 
     
     
         17 . The fabrication process of  claim 16 , wherein the elevated temperature comprises at least 1,500° F. 
     
     
         18 . The fabrication process of  claim 16 , wherein the elevated temperature is at least 2,900° F. 
     
     
         19 . The fabrication process of  claim 16 , wherein the hard wear coating volatilization exposes the environmental barrier coating. 
     
     
         20 . The fabrication process of  claim 10 , wherein the environmental barrier coating has a hardness value of less than that of the hard wear coating.