Effect of molten glass on degradation of stabilized zirconia thermal barrier coatings

In this study, Ceria Yttria Stabilized Zirconia based alternative Thermal Barrier Coatings those are resistant to molten glass (Ca-Mg-Al-Silicate) have been manufactured. These alternative coatings have been subjected to molten glass and their thermal cycle lifetimes before and after the Ca-Mg-Al-Silicate interaction have been tested. Infiltration of molten glass through the coating is investigated using energy dispersive spectrometry elemental mapping method. Although the life span of coatings without alumina and titania additives has dropped to the quarter of their life span after molten glass contact, the life span of alumina and titania doped Ceria Yttria Stabilized Zirconia coating has decreased lightly. According to the characterization studies, it was observed that the porosity of the Ceria Yttria Stabilized Zirconia coating with Alumina and Titania additives decreased, and the decrease in the porosity caused the molten glass solution to penetrate the coating less. Monoclinic ⇆ tetragonal phase transformations occur during the thermal cycle and plasma spray process. Cracks occur in coatings due to volume changes caused by these phase transformations. These cracks in the coating enable molten glass to penetrate the coating more easily, however, cerium additive reduces the monoclinic ⇆ tetragonal phase transformation. For these reasons, the addition of cerium, alumina and titania makes the coating more resistant to molten glass and thus the thermal cycle life of the coating is improved. In addition, these additives have improved the adhesion strength of the coatings.