Thermally-stabilized thermal barrier coating and process therefor

A thermal barrier coating (TBC 26 ) and method for forming the TBC ( 26 ) on a component ( 10 ) characterized by a stabilized microstructure that resists grain growth, sintering and pore coarsening or coalescence during high temperature excursions. The TBC ( 26 ) contains elemental carbon and/or a carbon-containing gas that increase the amount of porosity ( 32 ) initially within the TBC ( 26 ) and form additional fine closed porosity ( 32 ) within the TBC ( 26 ) during subsequent exposures to high temperatures. A first method involves incorporating elemental carbon precipitates by evaporation into the TBC microstructure. A second method is to directly incorporate an insoluble gas, such as a carbon-containing gas, into an as-deposited TBC ( 26 ) and then partially sinter the TBC ( 26 ) to entrap the gas and produce fine stable porosity within the TBC ( 26 ).