High temperature corrosion studies of a zirconia coating: Implications for waste-to-energy (WTE) plants

Corrosion of functional parts within waste-to-energy (WTE) plants significantly reduces their efficiency with respect to maintenance costs. Currently, nickel-based alloy claddings, several millimeters thick, are the state of the art as anti-corrosion coating. Another approach is to utilize thermally sprayed multilayer coatings with a zirconia top-coat. Lab-scale experiments under simulated WTE plant conditions and in situ tests within a WTE plant revealed a partially reduced porosity of the zirconia top-coat after the experiments, enabling the coating to act as a barrier against aggressive gases. In a lab-scale experiment sample the pores are filled up with zirconia, while the pores of the in situ samples are filled up with newly formed metal (Cr, Ni, Fe) oxides.