| Modifying the antiwear and lubricating property of material has an important effectboth on the energy, resources savings and environmental protection. It not only satisfiesthe tendency of higher speed，heavier load and higher accuracy of the machine inventedwith modern scientific technology, but also lengthens their service life. According to theshortcomings of the current extreme pressure-antiwear additives product, two kinds ofextreme pressure-antiwear additives (surface modified lanthanum borate andmolybdenum disulfide) were prepared to realize material with the property of antiwearand anti friction and in-situ tribochemical treatment. A borate-molybdenum (B-Mo)agent was finally prepared and the application of the agent was investigated.Phosphorus pentasulfide, octadecanol and pyridine were used as basic material tosynthesize the main surface modifying agent of this paper: pyridinium dialkyldithiophosphate (PyDDP). The technological conditions were thoroughly studied andfonfirmed. Using stearic acid and PyDDP, respectively, as modifying agent, borax andlanthanum nitrate as raw material, the stearic acid and PyDDP modified lanthanumborate nanoparticles were synthesized, respectively, in mixed alcohol-water solvents.Using PyDDP as the modifying agent, sodium molybdate, hydroxylamine hydrochloride,sodium sulfide and dilute sulfuric acid as raw material, the surface modifiedmolybdenum disulfide (MoS2) nanoparticles were synthesized. The technologicalparameters of the proceses were optimized. Infrared spectrum (IR), thermal gravity anddiffertial thermal analysis (TG-DTA), X-ray diffraction (XRD), Ultraviolet spectrum (UV)were used to characterize the structure of the three kind nanoparticles. The formationmechanism of the surface modified nanoparticles was initially analyzed and proposedand results showed that the three kinds of nanoparticles were modified by a layer oforganic material with an inorganic core. The tribological properties of three synthesizednanoparticles were studied by four-ball test. The surface morphology and elements wereanalyzed by SEM and EDXA. The tribological mechanism was discussed and impliedthat all synthesized nanoparticles had good extreme pressure property.The tribological properties showed that all synthesized stearic acid and PyDDPmodified lanthanum borate nanoparticles had good extreme pressure characteristics. BothSt-and DDP-can react with La3+ions to form thermol stable LaSt3or LaDDP3. The mainelements which affect on the friction properties might be owing to La，B and Mo. Thechemical reacted film and the physical penetrated layer formed by La and B in thefriction surface is the main contribution to the extreme pressure properties of themodified lanthanum borate nanoparticles. But for surface modified molybdenum disulfide (MoS2), the transformation of roll friction to sliding friction might be the mostimportant effect which induced good friction abilities even in low agent concentration.Four ball experiments were used to investigate the extreme pressure properties ofthe particles. Compared with steric acid modified lanthanum borate, PyDDP modifiedlanthanum borate possessed better anti-friction ability even in lower content in base oil.Further more, it was founded that PyDDP modified lanthanum borate and molybdenumdisulfide were favored on extreme pressure properties and friction reducing propertiesrespectively both in lower contents. So a new agent of B-Mo was formed with bi-component and possesses satisfied extream pressure properties and lower frictioncoefficient.Taking PyDDP modified PyDDPBMo with good extreme pressure property asextreme pressure-antiwear additive, the tribological properties of engine oil product werestudied. Results indicated that PyDDPBMo could improve the abrasion resistance andanti-friction of engine oil. The engine oil complex additive was prepared usingPyDDPBMo as one compoment. Laboratory test showed that the abrasion resistance andcarrying capacity of PyDDPBMo was also equivalent to that of other similar products inmarket. |
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