Hydrodynamic air lubricated compliant surface bearing for an automotive gas turbine engine. II. Materials and coatings

Abstract

Part III of a technology program performed for the NASA Lewis Research Center for the development of hydrodynamic air lubricated journal bearings for an automotive gas turbine engine is described. Part I of the program had focused on advancing compliant surface journal bearing technology by providing design information through an experimental and analytical effort. Part II of the program has investigated and tested materials and coatings for compliant surface bearings and journals good to either 540/sup 0/C or 650/sup 0/C environment. The most promising combination (Kaman DES) was tested at 35 kPa (5 psi) loading in partial-arc bearing form. This coating combination successfully completed 2000 start-stop cycles. Some of the coating was worn under the loaded area. There was some coating left on the grain boundaries, and the remaining area was oxidized during exposure to higher temperature. This combination was further tested at 14 kPa (2 psi) loading as a complete bearing. It completed 1000 start-stop cycles. A considerable amount of loose wear debris collected at the interface and, apparently, could not easily escape. As a result, it damaged the surfaces.