Application of Coatings to Hydrodynamic Deflection Pad Bearings

Implant Sciences Corporation (ISC) proposes a 6-month, Phase I program to evaluate promising, affordable, low friction coatings for use in deflection pad thrust bearings to protect against frequent engine start-stops and potential oil-out conditions. The coatings selected all exhibit a smooth surface finish, high wear resistance, high temperature capability and thermal transparency. They include doped/undoped diamond-like carbon, TiN, multilayered TiCN/TiN, Teflon-filled electroless nickel, silver-fluoride eutectic in a metal bonded chromium carbide matrix and two polymer based coatings (phenolic and polyimide) with solid lubricant additions. Phosphor bronze, Cu-Be and AISI 4340 steel pads have been selected for coating. Also, the coatings on the steel runner will be evaluated. In addition, the influence of ion implantation on pad and runner performance will be investigated. Tribological properties of the coatings will be determined under boundry lubricated and oil-out conditions from ambient to 500 degrees F in an ISC pin-on-disk tribometer capable of rotational speeds up to 10,000 rpm. Coatings also will be characterized in terms of thickness, smoothness, hardness, microstructure and adhesion (both as-deposited and after thermal cycling). KMC and AlliedSignal have expressed interest in the program and will service as technical advisors.