A Comprehensive Review of High-Temperature Ceramic Abradable Coatings used in Aero and Industrial Gas Turbines

As global efforts intensify to curb carbon emissions, optimizing fuel efficiency has become increasingly crucial. Abradable coatings, utilized in aero and industrial gas turbines, play a significant role in enhancing fuel efficiency by minimizing the clearance between turbine blade tip and the casing. This reduction in clearance leads to lower Specific Fuel Consumption (SFC), translating into substantial fuel savings and decrease in carbon emissions. While there are different types of abradable coatings, those used in the high-pressure turbine (HPT) section should have a friable structure and be mechanically stable in the high temperatures (> 1,100 ? C) of the turbine. These coatings are based on modified ceramic that can withstand these extreme requirements. Despite their critical role, there is a lack of comprehensive reviews about these coatings. This literature review addresses this gap by presenting an overview of current advancements in high temperature abradable ceramic coatings. It explores recent developments in material systems, examines various thermal spray deposition techniques, and discusses testing methodologies for evaluating coating performance. A particular emphasis will be placed on the abradability and wear mechanisms of these coatings. This study aims to provide a consolidated understanding of the state-of-the-art in high-temperature ceramic adradable coatings.