ENHANCEMENT OF PERFLUOROPOLYETHER BOUNDARY LUBRICATION PERFORMANCE

A ball bearing simulator operating under starved conditions was used t o perform screening tests to evaluate the boundary lubrication perform ance of a branched perfluoropolyether (PFPE), K-143 AB. Several approa ches to enhance boundary lubrication were studied. These included solu ble boundary additives, bearing surface modifications, ''run-in'' surf ace films and ceramic bearing components. In addition, results were co mpared with two nonperfluorinated liquid lubricant formulations. Based on these tests, the following tentative conclusions can be made: 1. S ubstantial improvements in boundary lubrication performance were obser ved with a beta-diketone boundary additive and a tricresyl phosphate ( TCP) liquid surface pretreatment. 2. The use of rough Si3N4 balls (R-a = 40 mu in) also provided increases in test duration, but with concom itant abrasive wear. 3. Moderate improvements were seen with two bound ary additives (a phosphine and a phosphatriazine) and a neat (100%) fl uid (a carboxylic acid terminated PFPE). Small improvements occurred w ith surface pretreatments with synthetic hydrocarbons, a polytetrafluo roethylene (PTFE) coating, and TiC-coated 440C and smooth Si3N4 balls (R-a = 1 mu in). 4. Two non-PFPE lubricant formulations (a polyalphaol efin (PAO) and a synthetic hydrocarbon) yielded substantial improvemen ts.