Thermal barrier coatings technology: critical review, progress update, remaining challenges and prospects

TLDR

The review covers materials systems, processes, applications, durability issues, technical approaches, and progress in understanding the science and technology of thermal barrier coatings. The authors aim to provide a comprehensive review of TBCs for turbine components and to pursue further reduction of the top layer’s thermal conductivity through composition and processing modifications. They discuss design methodologies, new bond compositions, morphology, performance data, and modeling efforts to improve durability and reduce thermal conductivity in TBCs. TBC performance is limited by particle impact erosion and low‑melting eutectic spallation, which restricts maximum surface temperature, and the review highlights processing, stability, and durability challenges.

Abstract

A comprehensive and integrated review of thermal barrier coatings (TBCs) applied to turbine components is provided. Materials systems, processes, applications, durability issues, technical approaches and progress for improved TBC, and our understanding of the science and technology are discussed. Thermal barrier coating prime reliance and further advances have been hampered by TBC loss by particle impact and erosion in certain locations of the turbine blades. Accumulation of low melting eutectic containing calcia, magnesia, alumina and silica resulting in TBC spallation limits maximum surface temperature. Design methodologies to address durability and data scatter issues are discussed. Compositions, morphology, characteristics and performance data for new bonds to achieve longer TBC life are described. Further reduction in the thermal conductivity of the top layer to minimise the parasitic mass of the coating on the component is being sought via top layer composition and processing modifications as well as by alternate ceramic compositions. The progress in these areas is critically reviewed including processing, stability and durability limitations. The paper also describes effort to understand various failure mechanisms including modelling and simulation.