Tribological Characteristics of Zinc Diakyldithio Phosphates Blended with Pongamia Biodiesel

The present research deals with study of pongamia oil methyl ester as a lubricant by blending with anti-wear additive ZDDP. The experimental work carried in this work aims to investigates the friction and wear characteristics by blending zinc diakyldithio phosphates (ZDDP) with pongamia oil methyl ester as lubricant under various loading conditions and temperatures. The coefficient of friction and wear scar depth were determined using pongamia biodiesel blended with 0.3%, 0.6% and 1 % ZDDP by concentration through high frequency reciprocating wear testing machine for 2 h duration. The reciprocating wear tests were performed on an engine liner-piston ring contact under the loads of 40 N, 60 N and 80 N for 2 h duration at temperatures of 100°C, 125°C 150° C with 10 Hz oscillation frequency. The addition of ZDDP with pongamia biodiesel showed marginal reduction in friction coefficient and wear scar depth under all loads and temperatures. The coefficient of friction was found to be higher in the initial stages due to running-in for all testing conditions. In addition, the SEM images of tested specimens were also examined. The presence of deep grooves at certain locations on the specimens was observed that might have caused due to simultaneous effect of fatigue and adhesive wear. Further, the addition of ZDDP with pongamia biodiesel has not affected the formation of an antiwear tribofilm.