Crystallinity, Stresses, and Cracks of YSZ Coatings Characterized by SEM-EBSD-Raman Spectroscopy

Yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) were prepared by atmospheric plasma spraying (APS). SEM-EBSD-Raman spectroscopy evaluated the relationship between the crystallinity, stresses, and cracks in YSZ coatings. Cracks were more likely to form in locations having poor crystallinity, due to the tensile stresses. Analysis between the formation of cracks and stresses shows that transgranular cracks are more likely created in areas with poor crystallinity. Moreover, intergranular cracks are more likely to occur around columnar grains, because the tensile stresses of columnar grains are greater than those of equiaxed grains. Resultantly, the formation and propagation of cracks can be controlled by controlling the cooling rate and grain shape.