High temperature mechanical characterization of innovative ceramic materials for thermal barrier coatings

This study investigates the thermo-mechanical properties of three different solutions for top coat of plasma-sprayed thermal barrier coatings, in order to comprehend their behavior over a wide range of temperatures. The studied materials are a conventional PSZ, a nanostructured PSZ and a lanthanum zirconate-based material. While the nanostructured PSZ shows a different sintering behaviour, keeping its original porosity at high temperatures [1], lanthanum zirconate does not suffer from the allotropic transformations experienced by the PSZ. On the other hand, previous analyses show that lanthanum zirconate-based materials appear to be less tough than the conventional PSZ, while the nanostructured one is slightly tougher. [2, 3] Four-points bend tests were carried out at different temperatures in order to evaluate and compare their Young modulus, modulus of rupture and deformation at break, while dilatometric analysis provided information about their CTE over a wide range of temperatures. In order to better understand the effects of the sintering process, some lanthanum zirconate samples were previously heat treated.