Thermal Stability of Novel Multilayer Lanthanum Zirconate Based Thermal Barrier Coatings

Abstract

This chapter discusses the thermal stability of SCL and DCL porous La2Zr2O7 coats by depositing three types of SCL and DCL La2Zr2O7 and 8YSZ structures in an experiment. Heat treatment, cyclic furnace cycle test and jet engine thermal shock test were conducted for the thermal barrier coatings (TBC) samples. The heating and cooling cycles were repeated until cracks or spallation were spotted on the TBC surface. Both the front and back surface temperatures were measured using pyrometer. The delamination is caused by the thermal residual stress induced by CTE difference between La2Zr2O7 and 8YSZ. All the La2Zr2O7 coats were delaminated in the furnace cycle test in less than 20 cycles. This is because residual thermal stresses accumulated during thermal cycling. Microstructure images of heat treated samples were taken using a scanning electron microscope.