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
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.
