Methods for tape deposition of a sacrificial coating on a CMC substrate are provided. The method comprises: applying a matrix material onto a surface of a film; drying the matrix material to remove the solvent; and transferring the dried matrix material from the film to the CMC substrate. The matrix material comprises a mixture of a rare earth silicate powder, a sintering aid, and a solvent.

Methods for tape deposition of a sacrificial coating on a CMC substrate are provided. The method comprises: applying a matrix material onto a surface of a film; drying the matrix material to remove the solvent; and transferring the dried matrix material from the film to the CMC substrate. The matrix material comprises a mixture of a rare earth silicate powder, a sintering aid, and a solvent.

A coating includes: at least 34.9 percent by mass silicon dioxide; at least 9.1 percent by mass aluminum oxide; and at least 16.1 percent by mass yttrium oxide.

A coating includes: at least 34.9 percent by mass silicon dioxide; at least 9.1 percent by mass aluminum oxide; and at least 16.1 percent by mass yttrium oxide.

An article includes a ceramic-based substrate and a barrier layer on the ceramic-based substrate. The barrier layer includes a matrix of SiO2 and a dispersion of silicon oxycarbide particles in the matrix. The silicon oxycarbide particles have Si, O, and C in a covalently bonded network, and a dispersion of barium-magnesium alumino-silicate particles in the matrix. The barium-magnesium alumino-silicate particles have an average maximum dimension that is between about 10-40% of an average maximum dimension of the silicon oxycarbide particles. A composite material and a method of applying a barrier layer to a substrate are also disclosed.

An article includes a ceramic-based substrate and a barrier layer on the ceramic-based substrate. The barrier layer includes a matrix of SiO2 and a dispersion of silicon oxycarbide particles in the matrix. The silicon oxycarbide particles have Si, O, and C in a covalently bonded network, and a dispersion of barium-magnesium alumino-silicate particles in the matrix. The barium-magnesium alumino-silicate particles have an average maximum dimension that is between about 10-40% of an average maximum dimension of the silicon oxycarbide particles. A composite material and a method of applying a barrier layer to a substrate are also disclosed.

A method of cementing a wellbore comprises injecting into the wellbore a cement slurry comprising an aqueous carrier, a swellable nanoclay, and a solid delayed releasing divalent inorganic salt comprising calcined magnesium oxide, calcined calcium oxide, calcium magnesium polyphosphate, a borate, a nitride, a silicate, an agent having a cation of Ba.sup.2+, Sr.sup.2+, Fe.sup.2+, Ni.sup.2+, or a combination comprising at least one of the foregoing; and allowing the cement slurry to set.

A method of cementing a wellbore comprises injecting into the wellbore a cement slurry comprising an aqueous carrier, a swellable nanoclay, and a solid delayed releasing divalent inorganic salt comprising calcined magnesium oxide, calcined calcium oxide, calcium magnesium polyphosphate, a borate, a nitride, a silicate, an agent having a cation of Ba.sup.2+, Sr.sup.2+, Fe.sup.2+, Ni.sup.2+, or a combination comprising at least one of the foregoing; and allowing the cement slurry to set.

A method for producing an alumina sintered body, including: a step of applying an alkaline earth metal compound onto a surface of an alumina raw material which is an unsintered alumina compact or an alumina sintered body; and a step of subjecting the alumina raw material to which the alkaline earth metal compound has been applied to heat treatment at a temperature of 1200 C. or more for 5 minutes or more and 300 minutes or less.

A method for producing an alumina sintered body, including: a step of applying an alkaline earth metal compound onto a surface of an alumina raw material which is an unsintered alumina compact or an alumina sintered body; and a step of subjecting the alumina raw material to which the alkaline earth metal compound has been applied to heat treatment at a temperature of 1200 C. or more for 5 minutes or more and 300 minutes or less.