Advanced Ground Vehicle Propulsion Technology - High Temperature Tribological Considerations

The primary roadblock to the success of the high output Low Heat Rejection (LHR) diesel engine requiring little or no water cooling is the lack of effective liquid lubrication where target top ring reversal (TRR) temperatures between the cylinder liner and piston ring approach 1000 degrees F. Adiabatics, Inc. has developed a Thermo-sealed plasma sprayed Fe2O3 tribological coating which provides excellent wear characteristics on a hot wear tribometer developed under privous U.s. Army Controact No. DAAE07-85-C-R166. The combined wear rate and friction coefficient Mf~0.18 provides one of the bet state of the art coatings known today. The thermo-seal and plasma spray processing requirethe Fe2O3 to pass through extreme temperatures where a second stable phase Fe3O4 may come into play be attracting graphitic lubricating carbon from the liquid lubricant to form a temporary solid lubricant film. From our experience with catalytic reactions between lubriant and coating constitutents, along with nowledge of other researchers in the field, we believe a solution in this high temperature tribology obstacle is at hand. Our intent in this Phase I effort is to demonstrate a feasible apporach of this combined concept to catalytically generate solid lubricant films with a dynamic friction coefficient Mf <0.10.