SBIR Phase II: Ultra-Low Wear Coatings Based on a Novel Family of Aromatic Thermosetting Copolyesters

This Small Business Innovation Research (SBIR) Phase II project will develop and commercialize a new family of polymers (aromatic thermosetting copolyesters, or ATSP) for application to tribological surfaces for compressors used in air conditioning and refrigeration. Surface treatments/coatings are key to improving wear performance and durability in a wide range of applications. The main advantages of polymeric-based coatings are their relatively low cost and simple substrate surface conditioning. ATSP can be processed into highly effective wear-resistant coatings by blending with polytetrafluoroethylene (PTFE) and other additives. Key features of the new material are: (1) thermal stability at temperatures required to process with PTFE (350-450 deg. C); (2) excellent tribological properties, with several samples of selected compositions evidencing "zero" wear and low friction coefficient values that remained stable during testing - both important attributes for a long-term wear coating. Additional advantages are the ability to undergo interchain transesterification reactions, permitting reincorporation of wear debris into the coating, and good adhesion to metals such as stainless steel and cast iron. Technical objectives in the Phase II include tailoring the polymer backbone to improve powder/coating properties, optimizing thermal spray parameters for this industrially relevant process, and performing both in-house and customer-based evaluations. The broader impact/commercial potential of this project is the potential to realize a new materials family which will permit lower cost and more versatile wear coatings for industry. There is strong customer demand for innovations that significantly improve the performance of the tribopair in compressors for refrigeration and air conditioning. Recent investigation for this specific market segment has shown that the ATSP system exhibits the crucial features of merit: low friction coefficient and an order of magnitude reduction in wear rate compared to state-of-the-art polymeric coatings. With the current societal focus on energy efficiency, more attention is being given to the fact that proper coatings and surface treatments are key to increasing efficiency for a wide range of mechanical surfaces (bearings, seals, turbines blades, etc.). Thus, there are opportunities in the much broader market, with the potential for major societal impact, since engines, pumps, and compressors are common equipment that represent a significant share of U.S. energy demand. ATSP has also shown excellent performance in adhesives, rigid foams, matrices for composites, and dielectrics for microelectronics, all of which suggest additional potential markets.