Performance of low friction bio-inspired coatings in hydrodynamic journal bearings

M. Rutkevičius, J. Dong, Y. Sharma, J. Viertel, C. Lipscomb, S. Beckford
ABB Inc.,
United States

Keywords: PTFE coating, bearings, low friction

Summary:

Low friction polymer coatings able to withstand high loadings and continuous operation for many years are difficult to formulate at low cost, but could find many applications in the industry. One common way of polymer-based coating failures is premature delamination from surface due to low adhesion between the substrate and the coating. Here we tested polytetrafluoroethylene (PTFE) based coating, that was co-deposited with polydopamine (PDA), naturally found in sea mussels that are able to “stick” to ocean rocks. Initial tribological studies on flat steel substrates showed low friction and good durability, as the coating did not delaminate, but instead smeared on the surface. This coating was then deposited on a curved cast iron surface of a hydrodynamic journal bearing. The purpose of this bearing is primarily to protect shaft from wear by introducing a thin film of oil between the shaft and the bearing liner, called babbit. We compare results obtained for the PTFE-PDA coating with the current industry standard babbit material.