Lanthanum dialkyldithiophosphate (LaDDP) was synthesized. Its tribological behavior was evaluated with a four-ball machine. The results show that LaDDP possesses very good antiwear and friction reduction capacities. T...Lanthanum dialkyldithiophosphate (LaDDP) was synthesized. Its tribological behavior was evaluated with a four-ball machine. The results show that LaDDP possesses very good antiwear and friction reduction capacities. The boundary film composition, characterized by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), reveals that the antiwear and friction reduction layer containing metallic La, La_2O_3, phosphate, sulphate, tribopolmer and lanthanum tribodiffusion layer prevent the rubbing pairs from contacting directly and result in better extreme pressure and antiwear behavior. The microhardness of frictional surface increases by 25%. It indicates that the frictional surface is strengthened by La tribodiffusion layer. The tribological decomposition reactions of LaDDP are simulated through mass spectroscopy. Its tribological mechanism was suggested.展开更多
Neodymium dialkylthiophosphate (NdDDP) with alkyls of isopropyl and isooctyl were synthesized by exchanged reaction respectively. The structures of the two NdDDPs were determined using IR and XRD. Properties of anti...Neodymium dialkylthiophosphate (NdDDP) with alkyls of isopropyl and isooctyl were synthesized by exchanged reaction respectively. The structures of the two NdDDPs were determined using IR and XRD. Properties of anti-wear and friction-reducing of the two additives were investigated with four ball experiment and the commercial anti-wear additive ZDDP was selected as control. The elemental analysis of the wear scars after 10 s friction at low stress were investigated by EDXA (Energy Dispersion Analysis of X-ray). Primary results showed that the NdDDPs possess better lubrication ability than ZDDP. This might mainly be contributed to the formation of a boundary film containing Nd2O3, FeS and sulphate, phosphate, organo-sulfide, etc., and a neodymium-rich diffused layer which changes the crystal structure of the surface of friction materials.展开更多
Two polymeric complexes, [Cd(BTP)2]n 1 and [Cd(i-BTP)2]n 2, were prepared and investigated by solid 31P and 113Cd NMR spectroscopies. The crystal structure of 2 was determined by X-ray diffraction.
Organic molybdenum lubricant additive like molybdenum dialkyl dithiocarbamate(MoDTC)can cause wear acceleration of diamond-like carbon(DLC)coating coupled with steel under boundary lubrication,which hinders its indust...Organic molybdenum lubricant additive like molybdenum dialkyl dithiocarbamate(MoDTC)can cause wear acceleration of diamond-like carbon(DLC)coating coupled with steel under boundary lubrication,which hinders its industrial application.Therefore,polyisobutylene succinimide(PIBS),an organo molybdenum amide,was adopted to modify molybdenum oxide affording molybdenum polyisobutylene succinimidemolybdenum oxide nanoparticles(MPIBS-MONPs)with potential to prevent the wear acceleration of DLC coating.The thermal stability of MPIBS-MONPs was evaluated by thermogravimetric analysis.Their tribological properties as the additives in di-isooctyl sebacate(DIOS)were evaluated with MoDTC as a control;and their tribomechanism was investigated in relation to their tribochemical reactions and synergistic tribological effect with zinc dialkyldithiophosphate(ZDDP)as well as worn surface characterizations.Findings indicate that MPIBS-MONPs/ZDDP added in DIOS can significantly reduce the friction and wear of DLC coating,being much superior to MoDTC.This is because MPIBS-MONPs and ZDDP jointly take part in tribochemical reactions to form a composite tribofilm that can increase the wear resistance of DLC coating.Namely,the molybdenum amide on MPIBS-MONPs surface can react with ZDDP to form MoS2 film with excellent friction-reducing ability;and MPIBS-MONPs can release molybdenum oxide nanoparticle to form deposited lubrication layer on worn surfaces.The as-formed composite tribofilm consisting of molybdenum oxide nanocrystal,amorphous polyphosphate,and molybdenum disulfide as well as a small amount of Mo2C accounts for the increase in the wear resistance of DLC coating under boundary lubrication.展开更多
This study reports the influence of methyl isopropyl ketone, which often kept in com-mercial zinc dialkyldithiophosphate (ZDDP) as a residue, on the tribological performance of ZDDP.The lubricity test of 500 SN neutra...This study reports the influence of methyl isopropyl ketone, which often kept in com-mercial zinc dialkyldithiophosphate (ZDDP) as a residue, on the tribological performance of ZDDP.The lubricity test of 500 SN neutral base stock oil containing ZDDP with methyl isopropyl ketonewas carried out by MQ--800 four-ball thbometer. The experimental results show that the methylisopropyl ketone results in the decrement of the wear resistance of ZDDP. The ketone compounddecreases greatly the load-carry capacity of ZDDP. The fact that the antiwear performance ofZDDP reduces with the addition of methyl isopropyl ketone could be partly attributed to a nucleo-philic substitution reaction, which retards the formation of phosphate antiwear films.展开更多
Laser surface texturing(LST)has been proven to improve the tribological performance of machine elements.The micro-scale patterns manufactured by LST may act as lubricant reservoirs,thus supplying oil when encountering...Laser surface texturing(LST)has been proven to improve the tribological performance of machine elements.The micro-scale patterns manufactured by LST may act as lubricant reservoirs,thus supplying oil when encountering insufficient lubrication.However,not many studies have investigated the use of LST in the boundary lubrication regime,likely due to concerns of higher contact stresses that can occur with the increasing surface roughness.This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication.A series of periodic patterns were produced on the thrust rolling bearings,using two geometrically different designs,namely cross and dimple patterns.Base oil ISO VG 100 mixed with 0.05 wt%P of zinc dialkyldithiophosphate(ZDDP)was supplied.The bearings with cross patterns reduce the wear loss by two orders of magnitude.The patterns not only retain lubricant in the textured pockets but also enhance the formation of an anti-wear tribofilm.The tribofilm generation may be improved by the higher contact stresses that occur when using the textured surface.Therefore,in contrast to the negative concerns,the ball bearings with cross patterns were instead found to increase the fatigue life by a factor of three.展开更多
Molybdenum dialkyldithiocarbamate(MoDTC)is widely used as a friction modifier in engine lubricating oil.Under MoDTC lubrication,the friction and wear behaviors of tungsten-doped diamond-like carbon(W-DLC)films anneale...Molybdenum dialkyldithiocarbamate(MoDTC)is widely used as a friction modifier in engine lubricating oil.Under MoDTC lubrication,the friction and wear behaviors of tungsten-doped diamond-like carbon(W-DLC)films annealed at 100-400℃were discussed and evaluated using scanning electron microscopy(SEM),atomic force microscopy(AFM),and Raman spectroscopy.Under(polymerized alpha olefin)PAO+MoDTC lubrication,the coefficient of friction of all samples decreased,but the wear rates of the W-DLC films annealed at 300℃increased significantly.By interacting with zinc dialkyldithiophosphate(ZDDP),the wear rates of W-DLC films annealed at different temperatures declined significantly owing to the formation of dense phosphate tribofilms on the worn surfaces.展开更多
基金Project supported by the National Natural Science Foundation of China (59875083)
文摘Lanthanum dialkyldithiophosphate (LaDDP) was synthesized. Its tribological behavior was evaluated with a four-ball machine. The results show that LaDDP possesses very good antiwear and friction reduction capacities. The boundary film composition, characterized by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), reveals that the antiwear and friction reduction layer containing metallic La, La_2O_3, phosphate, sulphate, tribopolmer and lanthanum tribodiffusion layer prevent the rubbing pairs from contacting directly and result in better extreme pressure and antiwear behavior. The microhardness of frictional surface increases by 25%. It indicates that the frictional surface is strengthened by La tribodiffusion layer. The tribological decomposition reactions of LaDDP are simulated through mass spectroscopy. Its tribological mechanism was suggested.
文摘Neodymium dialkylthiophosphate (NdDDP) with alkyls of isopropyl and isooctyl were synthesized by exchanged reaction respectively. The structures of the two NdDDPs were determined using IR and XRD. Properties of anti-wear and friction-reducing of the two additives were investigated with four ball experiment and the commercial anti-wear additive ZDDP was selected as control. The elemental analysis of the wear scars after 10 s friction at low stress were investigated by EDXA (Energy Dispersion Analysis of X-ray). Primary results showed that the NdDDPs possess better lubrication ability than ZDDP. This might mainly be contributed to the formation of a boundary film containing Nd2O3, FeS and sulphate, phosphate, organo-sulfide, etc., and a neodymium-rich diffused layer which changes the crystal structure of the surface of friction materials.
基金financial support of Chinese Scholarship Council.
文摘Two polymeric complexes, [Cd(BTP)2]n 1 and [Cd(i-BTP)2]n 2, were prepared and investigated by solid 31P and 113Cd NMR spectroscopies. The crystal structure of 2 was determined by X-ray diffraction.
基金support provided by the National Natural Science Foundation of China(Nos.51875172 and 52105180)Zhongyuan Science and Technology Innovation Leadership Program(No.214200510024).
文摘Organic molybdenum lubricant additive like molybdenum dialkyl dithiocarbamate(MoDTC)can cause wear acceleration of diamond-like carbon(DLC)coating coupled with steel under boundary lubrication,which hinders its industrial application.Therefore,polyisobutylene succinimide(PIBS),an organo molybdenum amide,was adopted to modify molybdenum oxide affording molybdenum polyisobutylene succinimidemolybdenum oxide nanoparticles(MPIBS-MONPs)with potential to prevent the wear acceleration of DLC coating.The thermal stability of MPIBS-MONPs was evaluated by thermogravimetric analysis.Their tribological properties as the additives in di-isooctyl sebacate(DIOS)were evaluated with MoDTC as a control;and their tribomechanism was investigated in relation to their tribochemical reactions and synergistic tribological effect with zinc dialkyldithiophosphate(ZDDP)as well as worn surface characterizations.Findings indicate that MPIBS-MONPs/ZDDP added in DIOS can significantly reduce the friction and wear of DLC coating,being much superior to MoDTC.This is because MPIBS-MONPs and ZDDP jointly take part in tribochemical reactions to form a composite tribofilm that can increase the wear resistance of DLC coating.Namely,the molybdenum amide on MPIBS-MONPs surface can react with ZDDP to form MoS2 film with excellent friction-reducing ability;and MPIBS-MONPs can release molybdenum oxide nanoparticle to form deposited lubrication layer on worn surfaces.The as-formed composite tribofilm consisting of molybdenum oxide nanocrystal,amorphous polyphosphate,and molybdenum disulfide as well as a small amount of Mo2C accounts for the increase in the wear resistance of DLC coating under boundary lubrication.
文摘This study reports the influence of methyl isopropyl ketone, which often kept in com-mercial zinc dialkyldithiophosphate (ZDDP) as a residue, on the tribological performance of ZDDP.The lubricity test of 500 SN neutral base stock oil containing ZDDP with methyl isopropyl ketonewas carried out by MQ--800 four-ball thbometer. The experimental results show that the methylisopropyl ketone results in the decrement of the wear resistance of ZDDP. The ketone compounddecreases greatly the load-carry capacity of ZDDP. The fact that the antiwear performance ofZDDP reduces with the addition of methyl isopropyl ketone could be partly attributed to a nucleo-philic substitution reaction, which retards the formation of phosphate antiwear films.
基金The present work is supported by Deutsche Forschungsgemeinschaft(DFG)in the priority program SPP 1551“Resource efficient machine elements”(GA 1706/2-2,Ja1940/2-2)This work is also supported by the government of Lower Austria for the endowed professorship tribology at TU Vienna(No.WST3-F-5031370/001-2017)The authors also acknowledge the support by“Austrian COMET-Programme”(Project InTribology,No.872176)under the scope of K2 XTribology and were developed in collaboration with the“Excellence Centre of Tribology”(AC2T research GmbH).
文摘Laser surface texturing(LST)has been proven to improve the tribological performance of machine elements.The micro-scale patterns manufactured by LST may act as lubricant reservoirs,thus supplying oil when encountering insufficient lubrication.However,not many studies have investigated the use of LST in the boundary lubrication regime,likely due to concerns of higher contact stresses that can occur with the increasing surface roughness.This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication.A series of periodic patterns were produced on the thrust rolling bearings,using two geometrically different designs,namely cross and dimple patterns.Base oil ISO VG 100 mixed with 0.05 wt%P of zinc dialkyldithiophosphate(ZDDP)was supplied.The bearings with cross patterns reduce the wear loss by two orders of magnitude.The patterns not only retain lubricant in the textured pockets but also enhance the formation of an anti-wear tribofilm.The tribofilm generation may be improved by the higher contact stresses that occur when using the textured surface.Therefore,in contrast to the negative concerns,the ball bearings with cross patterns were instead found to increase the fatigue life by a factor of three.
基金This research was financially supported by the National Natural Science Foundation of China(Nos.51875537 and 41872183)the Pre-Research Program in National 14th Five-Year Plan(No.61409230614)the Fundamental Research Funds for the Central University(No.2652018094).
文摘Molybdenum dialkyldithiocarbamate(MoDTC)is widely used as a friction modifier in engine lubricating oil.Under MoDTC lubrication,the friction and wear behaviors of tungsten-doped diamond-like carbon(W-DLC)films annealed at 100-400℃were discussed and evaluated using scanning electron microscopy(SEM),atomic force microscopy(AFM),and Raman spectroscopy.Under(polymerized alpha olefin)PAO+MoDTC lubrication,the coefficient of friction of all samples decreased,but the wear rates of the W-DLC films annealed at 300℃increased significantly.By interacting with zinc dialkyldithiophosphate(ZDDP),the wear rates of W-DLC films annealed at different temperatures declined significantly owing to the formation of dense phosphate tribofilms on the worn surfaces.