Sinter resistant abradable thermal barrier coating

摘要

An abradable thermal barrier coating material (10) formed of a highly defective fluorite ceramic matrix (16) having a desired degree of porosity (18) created in part by the addition of a fugitive material (19). The ceramic material has a concentration of a stabilizer sufficiently high that the oxygen vacancies created by the stabilizer interact within the matrix to form multi-vacancies, thereby improving the sintering resistance of the material. Such a concentration of stabilizer results in a material that is softer than prior art materials having lower concentrations of stabilizer, and that will be more resistive to sintering than prior art materials. Embodiments include a fluorite matrix of zirconia stabilized by at least 30 wt. % yttria, or stabilized by at least 30 wt. % ytterbia, and with porosity of 10-40%. In one embodiment, a metallic gas turbine seal ring segment is coated with a bond coat layer, then with a layer of porous 8 wt. % YSZ material, and finally with a layer of 33 mole % YbSZ (61.3 wt. % YbSZ) material having porosity of 10-40%.