Study on effect of calcium sulfonate on friction characteristics of paper-based friction materials under low sliding velocity

The purpose of this research is to elucidate the friction mechanism between paper-based friction materials and steel and to characterize the effect of lubricant composition on frictional properties at low sliding velocity. Effect of calcium sulfonate on wet clutch frictional properties was determined with a modified SAE No.2 machine and a reciprocating tribometer. A close correlation was observed between the results with the SAE No.2 machine and those with the reciprocating tribometer. The results showed friction reduction with both the basic and neutral calcium sulfonate for the combination of paper friction material and steel. A similar effect was also found for the combination of phenol resin and steel. The neutral calcium sulfonate (that is, soap) shows only a very small friction reduction effect when compared to the base oil because the neutral calcium sulfonate adsorbs so weakly to the paper friction material and steel. When the basic calcium carbonate is dispersed in oil, a calcium carbonate film forms on the friction surface that has a friction reduction effect greater than that of the neutral calcium sulfonate. When the basic components increase, the calcium carbonate particles dispersed in oil increase the friction, resulting in a higher friction coefficient.