A microstructural study and high-temperature oxidation behaviour of plasma sprayed NiCrAlY based composite coatings

Abstract

In this study, the development and performance evaluation of plasma sprayed NiCrAlY based coatings, such as NiCrAlY, NiCrAlY + Al?O? and NiCrAlY + YSZ on T91 steel substrates for high temperature applications is carried out. Microstructural features, phase composition and oxidation resistance under cyclic oxidation at 800 °C of the coatings were characterized. Analysis of the XRD confirmed the formation of protective phases such as Cr?O?, Ni?Al and NiAl, and the improvement observed in the coating's performance was due to the addition of Al?O? and YSZ. Oxidation resistance was improved for the NiCrAlY + Al?O? coating through the formation of a dense Al?O? oxide layer, but the NiCrAlY + YSZ coating was superior in terms of thermal stability and spallation resistance, because YSZ has low thermal conductivity and high thermal shock resistance. Composite coatings showed improved cyclic oxidation behavior and microstructural analysis revealed reduced porosity and enhanced integrity. The results demonstrate that the addition of Al?O? and YSZ in the NiCrAlY coatings leads to capability of tailoring NiCrAlY–based coatings for high temperature industrial applications with improved durability and oxidation protection. © 2025 The Author(s)