Madan Mohan Rai

Synthesis and performance evaluation of O, O-dialkylphosphorodithioic disulphides as potential antiwear, extreme-pressure and antioxidant additives

Abstract The ashless antiwear/EP additives based on phosphorodithioic acids are preferred to their heavy metal complexes, due to operational problems and enviromental restrictions being enforced in many countries. Four O, O-dialkylphosphorodithioic disulphides with varying alkyl chain length from C5 to C10 have been synthesized and their antiwear, EP and antioxidant performance examined vis-a-vis a commercial ZDDP in a mineral base oil. The synthesized products have been found to exhibit appreciable antiwear and antioxidant properties and mild EP performance, which are comparable to that of commercial ZDDP.

Additive-additive interactions : search for synergistic FM-EP-AW composition

Abstract A recent trend and need is towards formulating energy efficient lubricants as fuel efficiency has become a critical component of industrys operating efficiency. However, compatibility of friction modifiers (FM) with existing additives, specially surface-active types, needs to be examined beforehand. The effect of oil-soluble commercial organomolybdenum compounds on the extreme pressure (EP) and antiwear (AW) properties of most commonly used S-containing EP/AW agents has been investigated on a four-ball machine. While mostly complementary and exclusory interactions were observed in some cases graded response was also noticed. Based on this extensive study, involving three oil-soluble organomolybdenum FM and four EP/AW agents of varying chemistries, the most synergistic FM-AW-EP combination was identified. The selected combination, when incorporated into a fully formulated industrial gear oil formulation, resulted in marked enhancement in EP/AW properties and a substantial improvement in frictional characteristics.

Molybdenum dialkylphosphorodithioates: synthesis and performance evaluation as multifunctional additives for lubricants

Abstract Phosphorodithioate complexes of various metals are used as lubricant additives to impart anti-wear, anti-friction, anti-oxidant and extreme-pressure properties in lubricating oils. Four molybdenum dialkylphosphorodithioate (MoDTP) complexes with varying alkyl chain length from C5 to C10 have been synthesized and their anti-friction, anti-wear and anti-oxidant performance examined vis-a-vis a commercial MoDTP in a mineral oil, base oil and finished engine oil. The synthesized products have been found to exhibit appreciable anti-friction, anti-wear and anti-oxidant properties, which are comparable to that of commercial MoDTP.