Characterization of the strain in the thermal barrier coatings caused by molten CaO-MgO-Al2O3-SiO2 using a digital image correlation technique

The strain field of the thermal barrier coatings (TBCs) corroded by molten CaO-MgO-Al2O3-SiO2 (CMAS) is investigated using the digital image correlation (DIC) techniques. The results indicate that the strain in TBCs is compressive and it increases during cooling from 1250 to 25 °C. The cracks induced by CMAS form at the YSZ/BC interface at 300-400 °C. These cracks can be observed even without CMAS as temperature decreases to 100 °C. The DIC measurements show that the critical strains for the failure of TBCs with and without CMAS are − 0.7% and − 1.6%, respectively, and these results can be predicted by using a theoretical model.