LUBRICATING EFFECTIVENESS OF OIL-SOLUBLE ADDITIVES AND MOLYBDENUM-DISULFIDE DISPERSED IN MINERAL-OIL

The influence of molybdenum disulfide on the lubricating effectiveness of some oil-soluble additives has been investigated. In order to vary the test variables in a wide range, three different test devices have been used, which all simulated the conditions of mixed-film lubrication. During the first part of this research program, the mutual behavior of MoS//2 and some antiwear and extreme-pressure additives was studied under conditions of loads below the transition point. Generally, the addition of the solid lubricant to the mixture of mineral oil and chemical additive caused an improvement of the antiwear behavior. Especially in the case of tricresylphosphate and dibenzyldisulfide, synergistic behavior has been found. The results point out the tendency that neutral or even negative effects of MoS//2 could occur with those chemical substances, which exhibit a highly effective behavior themselves. In the course of the second part of this research program, the transition load on the ball-on-cylinder device was studied as a function of sliding speed and oil sump temperature. Results obtained with the mineral oil, MoS//2 and n-C//8CnDDP indicate that, in most cases, the solid-lubricant additive raises the load-carrying capacity of the liquid lubricant.