The Synthesis And Studies On Tribo-performance Of N-containing Long Alkyl Chain Phenylboronic Ammonium Derivative As Lubricant Additives

With the improving requirements of environmental protection andindustrial equipments for the lubricating oil, the new standards forlubricating oil were put forward to satisfy the increasing requirements.The use of traditional lubricant additives such as zincdialkyl-dithiophosphate (ZDDP) and sulfurized olefins have beenseriously challenged due to the environmental pollution and mechanicalcorrosion.A series of novel environmentally friendly S, P free long alkylchain phenylboronic ammonium derivatives were prepared and used aslubricant additives. The tribological behaviors of the additives in amineral oil (HVI WH150,5CST) were evaluated by a four-ball tester.Furthermore, DBBOM and DBBT as well as their combinations withZDDP were further studied in tribological properties and mechanism. Thescanning electron microscopy (SEM) was used to observe of the worn surface topographies lubricated by DBBOM, DBBT, DBBOM-ZDDP andDBBT-ZDDP respectively. The X-ray absorption near-edge structurespectroscopy (XANES) was used to characterize the chemical nature ofthe tribofilms and thermal films generated by the additives. The mainresults are summarized as follows:1. The synthesized N-containing long alkyl chain phenylboronicammonium derivatives possess good oil solubility. The anti-wearperformance increases with the length of the alkyl chain in the aminegroup and the additives without branched alkyl chain performed betterthan that with branched alkyl chain when the amine group contains thesame number of carbon atoms. All the additives can increase the PBvalueof the base oil.2. The synthesized additives DBBOM and DBBT possess goodthermal stability and anti-wear performance, and DBBOM has betteranti-wear performance and friction reducing property than that of DBBTunder high loads. According to the surface analysis, protective filmsgenerated from the two additives mainly consist of B2O3, increasing theanti-wear performance of the base oil effectively. And a small amount ofboron nitride can be found in tribofilm when the additive concentration ofDBBOM is relatively high, improving its anti-wear and friction-reducingperformance.3. The two combinations of DBBOM-ZDDP and DBBT-ZDDP possess good anti-wear property. DBBOM-ZDDP exhibits better frictionreducing property than DBBT-ZDDP while the extreme pressureperformance is opposite. DBBOM and ZDDP do not show significantlysynergistic effect, but they show obviously complementary advantages inanti-wear, frication reducing performance as well as extreme pressureperformance. When the concentration ratio of DBBT and ZDDP is1:1,the combination showes great synergistic performance under high loads.According to the surface analysis, the B in the combination mainly formB2O3during the rubbing processes, which can help to improve theanti-wear performance, while the S in the combination mainly form FeS2,,sulfite and sulfate, which can help to improve the extreme pressureperformance.