Multi-environmental barrier coating, processes for coating articles, and their coated articles

Abstract

A coated article including an article having a surface; an oxidation resistant bond coat layer deposited on the surface, the oxidation resistant bond coat layer comprising a metal silicide phase, a crystalline ceramic phase and an amorphous ceramic phase, wherein the metal silicide phase has an aspect ratio greater than 1:1 but less than 50:1.

1 - 9 . (canceled) 
     
     
         10 . A process for applying a coating to an article, comprising:
 mixing a silicide powder, a ceramic powder, and a glass powder to form a mixed powder feedstock;   injecting the mixed powder feedstock into a plasma torch that is directed at a surface of the article to at least partially melt the silicide powder, the ceramic powder, and the glass powder; and   controlling a particle diameter of the silicide powder, the ceramic powder, and the glass powder to control the extent of the melting to form an oxidation resistant bond coat layer.   
     
     
         11 . The process as recited in  claim 10 , wherein a volume fraction of the metal silicide phase ranges between 20-80 vol.%, a volume fraction of the crystalline ceramic phase is 25-75 vol.%, and a volume fraction of the amorphous ceramic phase ranges between 1-30 vol.%. 
     
     
         12 . The process as recited in  claim 10 , wherein a volume fraction of the metal silicide phase is 60 vol.% MoSi2, a volume fraction of the crystalline ceramic phase is 25 vol.% HfSiO4, and a volume fraction of the amorphous ceramic phase is 15 vol.% boro-silicate glass where the glass has the composition (Si0.75B0.15A10.05Na0.05)O2 with porosity less than 10%. 
     
     
         13 . The process as recited in  claim 10 , wherein a volume fraction of the metal silicide phase is 60 vol.% MoSi2, a volume fraction of the crystalline ceramic phase is 25 vol.% HfSiO4, and 5% HfB2; and a volume fraction of the amorphous ceramic phase is 10 vol.% boro-silicate glass where the glass has the composition (Si0.75B0.15Al0.05Na0.05)O2 with porosity less than 10%. 
     
     
         14 . The process as recited in  claim 10 , wherein the particle diameter of the ceramic powder is greater than the particle diameter of the silicide powder and the glass powder. 
     
     
         15 . The process as recited in  claim 10 , wherein the ceramic powder is melted less than that of the silicide powder and the glass powder. 
     
     
         16 . The process as recited in  claim 10 , further comprising depositing an environmental protective top coat layer upon the oxidation resistant bond coat layer, whereby the oxidation resistant bond coat layer is operable to repair a crack in the environmental protective top coat layer during operation of the coated article. 
     
     
         17 . A process for applying a coating to an article, comprising:
 injecting a silicide powder into a plasma torch that is directed at a surface of the article to at least partially melt the silicide powder;   injecting a ceramic powder into the plasma torch that is directed at the surface of the article to at least partially melt the ceramic powder;   injecting a glass powder into the plasma torch that is directed at the surface of the article to at least partially melt the glass powder; and   controlling a particle diameter of the silicide powder, the ceramic powder, and the glass powder to control the extent of the melting to form an oxidation resistant bond coat layer.   
     
     
         18 . The process as recited in  claim 17 , wherein injecting the silicide powder, the ceramic powder, and the glass powder occurs simultaneously. 
     
     
         19 . The process as recited in  claim 17 , wherein the silicide powder is injected upstream of the ceramic powder. 
     
     
         20 . The process as recited in  claim 19 , wherein the ceramic powder is injected upstream of the glass powder.