Panoramic statistics on porosity and microstructural features of plasma sprayed Y2O3-ZrO2 thermal barrier coatings

An automated procedure, termed as panoramic statistics, was proposed to characterize the microstructure of thermal barrier coatings. An experimental assessment of this approach was conducted by a comparison to mercury intrusion porosimetry (MIP) and Archimedean methods, and the deviations and uncertainties among them were analyzed. Based on the quantification of image contrast and threshold, the overall porosity measured in a panoramic area of 2 mm × 2 mm was much more reproducible than that of MIP, and was in agreement with the result of Archimedean. Large variations of local porosity along the thickness of coatings revealed the non-uniformity of porosity and the importance of applying panoramic statistics. The pore size distribution was consistent with the estimation of MIP. The shape distribution of pores can only be comprehensively analyzed using the present method. This technique will provide a more accurate and reliable estimation of microstructure for coatings and other ceramics.