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.
ATSP Innovations (formed in 2010) and team partner the University of Illinois at Urbana-Champaign (UIUC) developed a new family of polymers (Aromatic Thermosetting coPolyesters, i.e. ATSP) for tribological surfaces in air-conditioning and refrigeration compressors (which could also be applicable to engines and similar applications). The team produced this commercially viable ultra-low wear coating in Phase II and is working with several partners including a major manufacturer and the leading coating companies to commercialize. ATSP Innovations formulates and tailors oligomer blends, which can be applied via solvent or powder routes, to match customer specifications and suit their application needs. The key advantages of ATSP’s polymeric-based coatings are their excellent wear/thermal resistance, relatively low cost, and simple substrate surface conditioning (i.e., no need for expensive surface preparation before coating). In addition, ATSP coatings yield excellent results in terms of thickness uniformity, smoothness, adhesion, and superior tribological performance (low wear rate, low COF) by blending with polytetrafluorethylene (PTFE) compared to the state-of-art coatings (Figure 1) in both lubricated and unlubricated conditions. The use of this high temperature resistant coating could produce many benefits. First and foremost, the ability of the ATSP polymer to withstand higher temperatures is important when high enthalpy refrigerants are used. No polymeric coating currently used in the HVAC&R industry today is known to handle temperatures as high as ATSP. Also, the ability of the coating to lower the frictional properties of moving parts would have the benefit of decreasing power; which translates into energy savings. Also, the expected lower wear rates could result in longer mean-time-to-failure improving reliability and resulting in less field maintenance. The consequence of less field maintenance typically results in less likelihood of accidental release of refrigerant gases into the atmosphere, which directly helps mitigate atmospheric global warming. The impact of this new polymer could also extend into additional applications such as structural composites ranging from launch vehicles to commercial automobiles, as well as low dielectric constant circuit boards for microelectronics, rigid structural foams, and ablative thermal protective systems for reentry vehicles. A further attractive feature of this technology is the potential for recycling, which is very unique for a thermosetting polymer matrix.
