Investigation of stress field and failure mode of plasma sprayed Al2O3-13%TiO2 coatings under thermal shock

The stress field and failure mode of plasma sprayed Al2O3-13%TiO2 coatings under thermal shock were analyzed by experimental and numerical investigations in this paper. Two kinds of nanostructured coatings were derived from reconstituted nanostructured feedstocks and one kind of conventional coating was deposited with commercial fused and crushed feedstock. Testing results showed that the nanostructured coatings exhibited improved thermal shock resistance than the conventional coating. The failure modes of coatings predicted by numerical analysis had a good consistency with the experimental results. The effects of interface morphology and coating defects on thermal stresses were also discussed in this paper. The improved thermal shock resistance of nanostructured coatings was related to their pre-existing spherical pores, reduced cracks and microstructures. (C) 2009 Elsevier B.V. All rights reserved.