THERMAL BARRIER COATING SYSTEMS AND PROCESSES THEREFOR

摘要

Coating systems and processes by which the coating systems can be deposited to be resistant to contaminants, and particularly resistant to infiltration and damage caused by CMAS. The coating systems include inner and outer ceramic layers. The inner ceramic layer consists essentially of zirconia stabilized by about 6 to about 9 weight percent yttria and optionally contains greater than 0.5 to 10 weight percent hafnium oxide. The outer ceramic layer overlies and contacts the inner ceramic layer to define the outermost surface of the coating system. The outer ceramic layer consists essentially of zirconia stabilized by about 25 to about 75 weight percent yttria, has a thickness that is less than the thickness of the inner ceramic layer and further contains greater than 0.5 to 10 weight percent hafnium oxide and optionally 1 to 10 weight percent tantalum oxide. The outer ceramic layer has a porosity level that is lower than that of the inner ceramic layer.