Bond strength, bond stress and spallation mechanisms of thermal barrier coatings

Five production thermal barrier coatings were thermally cycled between room temperature and 1121 degrees C (2050 degrees F) to determine relative spal lation life. Bond strength measurements were made using a modified ASTM dir ect pull-test. Bond stress measurements were made in the thermally grown ox ide using a laser photoluminescence technique. Bond strength and bond stres s measurements were conducted on two electron beam physical vapor depositio n coatings as a function of thermal cycling. Each coating showed characteri stic values of as-coated strength and stress and changes in strength and st ress with thermal cycling. These variations in strength and stress with the rmal cycling are related to oxidation and micro-debonding effects. (C) 1999 Elsevier Science S.A. All rights reserved.