Silica-forming articles having engineered surfaces to enhance resistance to creep sliding under high-temperature loading
An article includes a silicon-containing region; at least one outer layer overlying a surface of the silicon-containing region; and a constituent layer on the surface of the silicon-containing region and between and contacting the silicon-containing region and the at least one outer layer, the constituent layer being formed by constituents of the silicon-containing region and being susceptible to creep within an operating environment of the article, wherein the silicon-containing region defines a plurality of channels and a plurality of ridges that interlock within the plurality of channels are formed in the silicon-containing region to physically interlock the at least one outer layer with the silicon-containing region through the constituent layer.
1. An article, comprising:
a substrate that contains silicon carbide, silicon nitride, a silicide and/or silicon as a reinforcement phase and/or a matrix phase;
a bondcoat overlying the substrate, wherein the bondcoat is formed of a material containing elemental silicon; silicon with one or more additional metal, intermetallic and/or ceramic phases; and/or one or more silicon alloys or compounds;
at least one outer layer overlying the bondcoat, wherein the at least one outer layer contains rare earth silicates and/or aluminosilicates; and
a constituent layer on the surface of the bondcoat and between and contacting the bondcoat and the at least one outer layer, the constituent layer being formed by constituents of the bondcoat and being susceptible to creep within an operating environment of the article, wherein the bondcoat defines a plurality of channels and a plurality of ridges that interlock within a plurality of channels formed in the at least one outer layer to physically interlock the at least one outer layer with the bondcoat through the constituent layer and the ridges have a height of from about 50 to about 200 μm, a wavelength of from about 250 to about 1,000 μm, a ratio of a span of each ridge to the wavelength of the ridges of about 0.2 to about 0.8 and a thickness of the constituent layer is between about 4 to about 40 μm.
2. The article according to claim 1 , wherein the ridges have a height of from about 75 to about 125 μm.
3. The article according to claim 1 , wherein the bondcoat consists essentially of elemental silicon.
4. The article according to claim 1 , wherein the bondcoat consists essentially of silicon with one or more additional ceramic phases chosen from the group consisting of silicon carbide and silicon nitride.
5. The article according to claim 1 , wherein the aluminosilicates comprise mullite and/or an alkaline earth aluminosilicate.
6. The article according to claim 5 , wherein the alkaline earth aluminosilicate comprises BSAS.
7. The article according to claim 1 , wherein the substrate is a ceramic matrix composite material containing silicon carbide as a reinforcement phase and/or a matrix phase.
8. The article according to claim 1 , wherein the silicide is a refractory metal silicide or a transition metal silicide.
9. The article according to claim 1 , wherein the constituent layer comprises amorphous silica or crystalline silica or mixtures thereof.
10. The article according to claim 1 , wherein the article is a rotating component of a turbine engine and the ridges extend in a direction substantially perpendicular to a shear load applied to the article during rotation of the article.
11. The article according to claim 10 , wherein a thickness of the constituent layer varies from a leading edge thickness to a trailing edge thickness with respect to the direction of the applied shear load.