Air foil thrust and journal bearing coatings: A review

Abstract

Surfaces of air foil thrust and journal bearings in high-speed turbomachinery are coated to improve their operational integrity, particularly when the aerodynamic load carrying capacity is reduced during instances of startup and shutdown. Surface coatings, as protective barriers in air foil bearings, can mitigate the adverse effects of direct surface interactions on such occasions. This paper provides an in-depth review of the body of important research conducted for study of coated air foil thrust and journal bearings, highlighting the state of the art in coating technology. The review features the role of composite coatings, designed to provide favourable thermal, mechanical, and frictional characteristics. The paper also highlights the trends in selection of coatings for air foil bearings pertinent to desired thermomechanical performance.