High-Temperature Vapor Phase Lubrication Using Carbonaceous Gases

Following the pioneering work of Prof. James Lauer, the ability to provide continuous solid lubrication through vapor phase delivery of carbonaceous gases has been successfully demonstrated on a pin-on-disk contact at the temperatures of 650 °C. Results from tribological experiments under 2 N normal load and 50 mm/s sliding speed showed an over 20× reduction in friction coefficient. The samples were silicon nitride (pin) versus CMSX-4 (disk) and the experiments when run in a nitrogen environment with acetylene admixtures. Two repeat experiments gave average friction coefficients of μ = 0.03 and μ = 0.02. The process was robust and provided low friction for the entire 500 m of sliding. Using focused ion-beam milling, high-resolution transmission electron microscopy, and confocal Raman spectroscopy, the resulting solid lubricant was found to be oriented microcrystalline graphite.