REACTION OF CALCIUM ORTHOSILICATE AND BARIUM ZIRCONATE WITH OXIDES AND SULFATES OF VARIOUS ELEMENTS

摘要

Calcium orthosilicate and barium zirconate are being evaluated as the in¬sulating layer of thermal barrier coatings for air-cooled gas turbine compo¬nents. Surface temperatures of such coatings might reach 1300°-i400° C in hot spot locations. Thus chemical stability of these compounds was studied at 1100° and 1300° C in the presence of some oxides and sulfates for times to 400 and 200 hours respectively. The oxides and sulfates studied represent some of the oxidation products of impurities found in either the combustion air, or the fuels as well as the elements in the bond coat alloys. These compounds are listed below in four groups, according to their reactivity with calcium ortho-silicate (actual composition was 1.78 CaO•SiO2) and barium zirconate.