Ceramic coatings with sintering agents

A method of preparing a coated substrate comprising:

• providing ceramic matrix composite substrate comprising ceramic fiber tows within a ceramic matrix or a superalloy substrate;
• and
• applying a protective layer to the substrate by thermal spraying a powder composition containing:
• (a) hafnium silicate, hafnium oxide, zirconium silicate, a rare earth phosphate (REPO4), a rare earth oxide (RE2O3), alumina, an aluminosilicate,, zirconia, or combinations thereof, wherein RE is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu, and
• (b) 0.1 to 10 wt. % of a metal oxide selected from Al2O3, SiO2, Nb2O3, MgO, CaO, SrO, and BaO, and combinations thereof.

A jet engine component comprising:

• a ceramic matrix composite substrate comprising ceramic fiber tows within a ceramic matrix, or a superalloy substrate;
• and
• a coating system applied to the substrate wherein the coating system comprises a layer comprising hafnium silicate, zirconium silicate, a rare earth phosphate (REPO4), a rare earth oxide (RE2O3), alumina, an aluminosilicate, hafnia, HfO2—SiO2-rare earth (RE) oxide, hafnia partially or fully stabilized by an alkaline or rare earth (RE) metal, zirconia partially or fully stabilized by an alkaline or rare earth (RE) metal, a rare earth zirconate (RE2Zr2O7), and a rare earth hafnate (RE2Hf2O7), which in each case may be stoichiometric or non-stoichiometric, and combinations thereof, wherein RE is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu;
• wherein the layer further contains 0.1 to 10 wt. % of a metal oxide selected from Al2O3, SiO2, Nb2O3, MgO, CaO, SrO, and BaO, and combinations thereof,
• wherein said component is a turbine blade, turbine airfoil, blade outer air seal, or combustor liner.