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The U.S. Department of Energy has a program to develop fuel cell technology for automotive applications. For maximum efficiency, a fuel cell system requires a compact, light-weight, and highly efficient air compressor to provide a stream of clean air to the fuel cell stack. Meruit, Inc., is developing a turbocompressor for this application. Journal and thrust air bearings are two critical components of the turbocompressor that require low friction and excellent wear resistance. These components were coated with Argonne's new low-friction amorphous carbon coating and tested in an air bearing test rig. Results to date show that the coating provides the required friction reduction, as indicated by reduction in time to lift-off of the radial journal bearing during cyclic start/stop testing. The coating also prevented wall climbing which can cause bearing instability.

Amorphous carbon coatings with very low friction properties were recently developed at Argonne National Laboratory. These coatings have shown good promise in mitigating excessive wear and scuffing problems associated with low-lubricity diesel fuels. To reduce the negative effect of sulfur and other lubricant additives in poisoning the after-treatment catalyst, a lubricant formulation with a low level of sulfur may be needed. Exclusion of proven sulfur-containing extreme pressure (EP) and antiwear additives from oils will require other measures to ensure durability of critical lubricated components. The low-friction carbon coating has the potential for such applications. In the present study, we evaluated the friction and wear attributes of three variations of the coating under a boundary lubrication regime. Tests were conducted with both synthetic and mineral oil lubricants using a ball-on-flat contact configuration in reciprocating sliding.

Increased use of higher-efficiency compression ignition direct injection (CIDI) diesel fueled engines instead of today's gasoline engines will result in reduced fuel consumption and greenhouse gases emissions. However, nitrogen oxides (NOx) and particulate exhaust emissions from diesel engines must be significantly reduced due to their possible adverse health effects. Exhaust gas recirculation (EGR) is an effective way to reduce NOx emissions from diesel engines, but the particulates and acidic exhaust products in the recirculated gas will contaminate engine lubricant oil by increasing the soot content and total acid number (TAN). These factors will increase the wear rate in many critical engine components and seriously compromise engine durability. We have investigated the use of commercially available thin and hard coatings (TiN, TiCN, TiAlN, and CrN) to mitigate the negative effects of EGR on wear.