Assessing Coating Reliability Through Pore Architecture Evaluation
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S. Paul (Submitted July 15, 2009; in revised form December 5, 2009) Plasma-sprayed thermal barrier coatings (TBCs) exhibit many interlamellar pores, voids, and microcracks. These microstructural features are primarily responsible for the low global stiffness and the low thermal conductivity commonly exhibited by such coatings. The pore architecture thus has an important influence on such thermophysical properties. In the present work, the effect of heat treatment (at temperatures up to 1400 C, for times of up to 20 h) on the pore architecture of detached YSZ top coats with different impurity levels have been characterized by mercury intrusion porosimetry and gassorption techniques. Stiffness and thermal conductivity were also monitored to assess the effect of change in pore architecture on properties. While the overall porosity level remained relatively unaffected (at around 10-12%) after the heat treatments concerned, there were substantial changes in the pore size distribution and the (surface-connected) specific surface area. Fine pores (
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