Investigation of the effect of V₂O₅ and Na₂SO₄ melted salts on thermal barrier coatings under cyclic conditions

Thermal barrier coatings (TBCs), which are used in high temperature applications of gas turbines, are damaged due to fuels and airborne minerals under working conditions. Stable zirconia coatings, which are usually used as topcoat materials in TBCs, are damaged by interacting at high temperatures with elements such as vanadium and sulfur from low quality fuels. The purpose of this paper is to see the failure mechanism of TBC systems after hot corrosion damages.

CoNiCrAlY metallic bond coatings of TBC samples were produced by cold gas dynamic spray method which is a new trend production method and stabilized zirconia ceramic top coating was produced by atmospheric plasma spray method. In total, 50% by weight of V₂O₅ and 50% Na₂SO₄ salt mixtures were placed on TBC samples and subjected to hot corrosion test at 1000°C.

Hot corrosion behaviors of TBC samples were examined by scanning electron microscopy, elemental mapping analysis, energy dispersive X-ray spectrometry analysis and X-ray diffraction analysis. TBC samples were damaged at the end of 12-h cycles.

The paper provides to understand the mechanism of hot corrosion of TBCs with cold sprayed metallic bond coat.