| 简介 |
An article 12 comprising a silicon-containing substrate 30 a silicide-containing bond coat layer 42 overlying the substrate and an environmental barrier coating 50 overlaying the bond coat layer. An article is also provided wherein the environmental barrier coating comprises : (1) an optional inner silica scale layer 58 overlaying the bond coat layer; (2) intermediate layer 66 overlaying the inner silica scale layer, or the bond coat layer in the absence of the inner silica scale layer, and comprising mullite, or a combination of mullite with a barium strontium aluminosilicate, a yttrium silicate, or a calcium aluminosilicate; and (3) an outer steam-resistant barrier layer 74 overlaying the intermediate layer and consisting essentially of an alkaline earth silicate/aluminosilicate. Processes are also provided for forming the silicide-containing bond coat layer over the substrate, followed by forming the environmental barrier coating over the bond coat layer. The bond coat can be a metal silicide such as Cr, Mo, Nb, Ta, Ti, W, Zr or rare earth metal silicides. |
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