Comparative study on corrosion resistance and lubrication function of lithium complex grease and polyurea grease

In this study,lithium complex grease(LCG)and polyurea grease(PUG)were synthesized using mineral oil(500 SN)and polyalphaolefin(PAO40)as base oil,adsorbed onto lithium complex soap and polyurea as thickeners,respectively.The effects of grease formulation(thickener and base oil with different amounts(80,85,and 90 wt%)on the corrosion resistance and lubrication function were investigated in detail.The results have verified that the as-prepared greases have good anti-corrosion ability,ascribed to good salt-spray resistance and sealing function.Furthermore,the increase in the amount of base oil reduces the friction of the contact interface to some extent,whereas the wear resistance of these greases is not consistent with the friction reduction,because the thickener has a significant influence on the tribological property of greases,especially load-carrying capacity.PUG displays better physicochemical performance and lubrication function than LCG under the same conditions,mainly depending on the component/structure of polyurea thickener.The polyurea grease with 90 wt%PAO displays the best wear resistance owing to the synergistic lubrication of grease-film and tribochemical film,composed of Fe_(2)O_(3),FeO(OH),and nitrogen oxide.

Improving the lubrication and anti-corrosion performance of polyurea grease via ingredient optimization

Thickener formulation plays a significant role in the performance characteristics of grease.The polyurea greases(PUGs)were synthesized using mineral oil(500SN)as the base oil,and by regulating the reaction of diphenylmethane diisocyanate(MDI)and different organic amines.The as‐prepared PUGs from the reaction of MDI and cyclohexylamine/p‐toluidine exhibit the optimum physicochemical and friction‐wear properties,confirming that the regulation of thickener formulation can improve the performance characteristics of grease,including friction reduction,wear,corrosion resistance,and load‐carrying capacity.The anticorrosion and lubrication properties of as‐prepared PUGs depend on good sealing functions and a boundary lubrication film(synergy of grease‐film and tribo‐chemical reaction film),as well as their chemical components and structure.