Adaptive High-Temperature Lubrication through Nanopore Channels

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

This research effort focuses on a new approach to high-temperature self-lubrication, using wear-resistant nanoporous coatings. The key idea is to control and guide the flow of easily-sheared solid lubricant inclusions through nanopore channels within the hard matrix of a composite coating towards its sliding contact surface. It is envisioned that the lubricant flow can be controlled by (i) the original lubricant agglomerate size, (ii) the channel width, and (iii) a thin barrier-layer that allows diffusion only exactly where wear indicates lubricant depletion. The primary advantage of this approach over isotropic or multilayered adaptive composite coatings is the much smaller amount of wear that is required to initiate the supply of additional lubricant to the surface, resulting in less abrasive wear debris and, in turn, greatly enhanced coating life-time. While specifically exploring silver solid lubricant inclusions within a chromium nitride nanoporous matrix, this new strategy is applicable to a range of coating systems and has the potential to become a true breakthrough technology by providing low friction surfaces in various environments and during multiple temperature cycles ranging from 0 to ~1000°C. Applications include hard wear-resistant lubricious coatings for high-temperature bearings in fuel-efficient jet-engines and gas-turbines, solid-lubrication in cyclic air-vacuum environments for space applications, and oil-free air-foil bearings in gas compressors for fuel cells and hydrogen storage. The research effort will also provide the dissertation experience of one graduate student through completion of the doctoral degree, as well as a mind-broadening experience for several undergraduate students to also be involved in the research laboratories. Finally, a hands-on friction and wear sliding test involving solid lubricant-containing materials will be performed by over 200 mechanical engineering undergraduate students per year in their required junior-level Mechanical Systems Laboratory course, providing them direct exposure to the field of engineered multi-functional adaptive materials.