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1376 |
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The use of PVD intermediate layers for the improvement of thermal barrier coatings performance |
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Sergi Dosta / Thermal Spray Centre (CPT) - Universitat de Barcelona, SPAIN C.R.C. Lima / UNIMEP - Methodist University of Piracicaba, Brazil N. Cinca/ Thermal Spray Center (CPT), Spain J.M. Guilemany/ Thermal Spray Center (CPT), Spain |
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Some of the well-known problems that cause the degradation of a TBC in service are bond coat delamination due to the infiltration of gases at high temperature through the intrinsic porosity of the ceramic layer, the differences of thermal expansion coefficient between metallic and ceramic layers, the growth of an oxide layer that takes place under specific thermal conditions on the bond coat (TGO-Thermally Grown Oxide) and Al diffusion from the substrate. With this perspective, extensive research has been made to improve the adhesion and high temperature (above 1000ºC) oxidation resistance of the TBCs. Some possibilities have been explored, as the gradation of successive metal-ceramic layers (FGM-Functionally Graded Materials), diffusion barrier layers and intermediate layers with specific functions. In this work, the possibility of using an intermediate layer between the bond coat and the ceramic top coat is evaluated. The intermediate layer is a Cr3C2 applied by PVD (Physical Vapor Deposition). The results are discussed based on the oxidation and microstructural characteristics of the obtained coatings. |