Sunflower, corn, rapeseed, olive, and linseed oils were used for investigation. Their fatty-acid compositions have been evaluated by gas chromatography. The tribological properties were determined with a four-ball machine. Flash and set points, static and dynamic viscosity of the oils were estimated by standard methods. The results of tests show that refined plant oils possess better tribotechnical properties than the base mineral oil without additives. It was found that their antiwear and bearing resistance properties correlate with the structure of fatty acids molecules. It is demonstrated that the activation of unsaturated bonds as a result of the triglycerides oxidation has a positive influence on friction due to tribopolymerization and film formation on the contact surfaces.

No abstract

Purpose The purpose of this paper is to report on the tribological properties of beef tallow grease and improvements therein through modification with special processing, polymeric compounds and additives. Design/methodology/approach Pure original beef tallow grease was used as a biological lubricating grease reference material for the tribological research. Beef tallow was modified and synthesized by adding special biological anti-oxidant additives, LZ anti-wear additives, waste polyethylene terephthalate (PET) polymer compounds and thermally processed graphite. Findings Rheometric measurements indicate that the beef tallow grease modification technology used in this study enables control of the synthesis process to produce lubricants with the required microstructure. Investigation results of the tribological properties of differently modified greases show that beef tallow synthesized with polymer additives efficiently operates together with anti-wear additives to reduce friction and wear. The grease compound with thermally processed graphite has good tribological properties at 300 N load levels. The critical load level of lubricating greases could be significantly increased through the use of anti-wear additives and thermally processed graphite. Originality/value Investigation results of the tribological properties of differently modified beef tallow greases show that beef tallow synthesized with polymer additives efficiently operates together with anti-wear additives to reduce friction and wear. The critical load level of lubricating beef tallow greases could be significantly increased using anti-wear additives and thermally processed graphite.

No abstract