An article comprises a body and a conformal protective layer on at least one surface of the body. The conformal protective layer is a plasma resistant rare earth oxide film having a thickness of less than 1000 μm, wherein the plasma resistant rare earth oxide is selected from a group consisting of YF.sub.3, Er.sub.4Al.sub.2O.sub.9, ErAlO.sub.3, and a ceramic compound comprising Y.sub.4Al.sub.2O.sub.9 and a solid-solution of Y.sub.2O.sub.3—ZrO.sub.2.

An article comprises a body and a conformal protective layer on at least one surface of the body. The conformal protective layer is a plasma resistant rare earth oxide film having a thickness of less than 1000 μm, wherein the plasma resistant rare earth oxide film is selected from a group consisting of an Er—Y composition, an Er—Al—Y composition, an Er—Y—Zr composition, and an Er—Al composition.

An article comprises a body and a conformal protective layer on at least one surface of the body. The conformal protective layer is a plasma resistant rare earth oxide film having a thickness of less than 1000 μm, wherein the plasma resistant rare earth oxide film is selected from a group consisting of an Er—Y composition, an Er—Al—Y composition, an Er—Y—Zr composition, and an Er—Al composition.

A heat treated ceramic article includes a ceramic substrate and a ceramic coating on the ceramic substrate. The ceramic coating is a non-sintered ceramic coating that has a different composition than the ceramic substrate. The heat treated ceramic article further includes a transition layer between the ceramic substrate and the ceramic coating, the transition layer comprising first elements from the ceramic coating that have reacted with second elements from the ceramic substrate, wherein the transition layer has a thickness of about 0.1 microns to about 5 microns.

A heat treated ceramic article includes a ceramic substrate and a ceramic coating on the ceramic substrate. The ceramic coating is a non-sintered ceramic coating that has a different composition than the ceramic substrate. The heat treated ceramic article further includes a transition layer between the ceramic substrate and the ceramic coating, the transition layer comprising first elements from the ceramic coating that have reacted with second elements from the ceramic substrate, wherein the transition layer has a thickness of about 0.1 microns to about 5 microns.

An outer periphery coating material being coated onto an outer peripheral surface of a ceramic honeycomb structure to form an outer periphery coated layer. The outer periphery coating material comprises: a particle mixture containing cordierite particles and amorphous silica particles in a mass ratio of from 40:60 to 80:20; and from 10 to 30% by mass of crystalline inorganic fibers in an outer percentage relative to the particle mixture. An average particle diameter of the cordierite particles is different from an average particle diameter of the amorphous silica particles.

A multi-layer coating arrangement includes an environmental barrier coating (EBC) over a substrate; and at least one dense vertically cracked (DVC) coating layer over the EBC. The at least one DVC layer is resistant to erosion, water vapor corrosion and to calcium-magnesium-aluminum-silicate (CMAS).

A multi-layer coating arrangement includes an environmental barrier coating (EBC) over a substrate; and at least one dense vertically cracked (DVC) coating layer over the EBC. The at least one DVC layer is resistant to erosion, water vapor corrosion and to calcium-magnesium-aluminum-silicate (CMAS).

A heat treated ceramic article includes a ceramic substrate and a ceramic coating on the ceramic substrate. The ceramic coating is a non-sintered ceramic coating that has a different composition than the ceramic substrate. The heat treated ceramic article further includes a transition layer between the ceramic substrate and the ceramic coating, the transition layer comprising first elements from the ceramic coating that have reacted with second elements from the ceramic substrate, wherein the transition layer has a thickness of about 0.1 microns to about 5 microns.

A heat treated ceramic article includes a ceramic substrate and a ceramic coating on the ceramic substrate. The ceramic coating is a non-sintered ceramic coating that has a different composition than the ceramic substrate. The heat treated ceramic article further includes a transition layer between the ceramic substrate and the ceramic coating, the transition layer comprising first elements from the ceramic coating that have reacted with second elements from the ceramic substrate, wherein the transition layer has a thickness of about 0.1 microns to about 5 microns.