Hot Corrosion Resistance of ZrO2-5%CaO Thermal Barrier Coating (TBC) System

Abstract

Thermal barrier coatings (TBCs) provide thermal and corrosive protection to metallic substrate materials under high temperature conditions. TBC systems applied to hot part components of workpieces are exposed to oxidation and hot corrosion damage. Hot corrosion, in particular, causes destructive damage earlier than oxidation. In this study, NiCoCrAlY powders were sprayed on 316L stainless steel substrate material using High Velocity Oxygen Fuel (HVOF) technique. Calcia-stabilized zirconia (ZrO<inf>2</inf>-5% CaO, CSZ) was deposited as a top coating material by the atmospheric plasma spray technique (APS) on the substrate with the bond coat. The produced TBC system was subjected to 25 hours cyclic hot corrosion tests with a mixture of 50% V<inf>2</inf>O<inf>5</inf>-50% Na<inf>2</inf>SO<inf>4</inf> at 900 °C. At the end of the hot corrosion tests, as a result of the reaction of CaO with hot corrosion salts, phase transformation has occurred in the top coating. It has been found that the molten corrosion salts penetrate through the top coating, but have not yet seriously damaged the coating under these test conditions. © 2020, TUBITAK. All rights reserved.