Surfactants are used for formulation metal working fluids. These fluids are applied to the interface between a cutting tool and the metal working piece to provide friction reduction. In the present paper, poly aromati...Surfactants are used for formulation metal working fluids. These fluids are applied to the interface between a cutting tool and the metal working piece to provide friction reduction. In the present paper, poly aromatic ammonium sulphonate and polyaromatic benzyl triethanolamsonium ethoxylate with 6 ethylene oxide units were synthesized and blended with coupling agent like dodecyl alcohol and oleic acid to produce cutting fluid and evaluate as antiwear. Values of surface tension of these additives were measured in oil phase and consequently CMC was determined for all additives and their mixtures in oil phase. The efficiency of these additives depends on their chemical structure and the presence of ether oxygen brings about the association of the surfactant with metal surface, hence very good wetting properties. The antiwear characteristic of surfactants increases with increasing polar linkages in the aromatic moieties forming chelated and coordinated layer. This is due to the increase in the number of sites to chemisorption on the metal surface. The films formed are highly condensed ring aromatic layered structures. These films provide lower wear and depend on the type of surfactants concentration and sliding speed. The surface of metal was analyzed by SEM/EDX techniques. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the surfactants and their film forming. More confirmation for suggested mechanism was investigated by measuring the area occupied per molecule of the surfactant in oil phase. The results indicate that the sulphonate group is less efficient than ethoxylate group. At the same time, the micelle of surfactants acts as oil dispersant and improves adsorption of oil on the metal surface.展开更多
Surfactants used for formulation metal working fluids. In the present paper, the inhibitive effect of synthesized anionic surfactant P-decyloxy p-sodium sulphonateazobenzene with chemical structure H21C10O-Ph-N=N-Ph-S...Surfactants used for formulation metal working fluids. In the present paper, the inhibitive effect of synthesized anionic surfactant P-decyloxy p-sodium sulphonateazobenzene with chemical structure H21C10O-Ph-N=N-Ph-SO3Na and 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine on the corrosion of carbon steel in sulphuric acid solution is measured by the weight loss method. The relationships between the concentrations of these inhibitors and their surface properties, thermodynamic properties, surface coverage and inhibiting efficiency, have been investigated. The results indicate that P-decyloxy p-sodium sulphonate azobenzene is superior to 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine at high acid concentration. These inhibitors blend with coupling agent to produce water miscible cutting fluid. Values of surface tension of these additives were measured in water phase and consequently CMC was determined for all inhibitors. The efficiency of these inhibitors depends on their chemical structure and the presence of hydrophilic group to association of the surfactant with metal surface, hence very good wetting properties. The anti-corrosion characteristic of surfactants increases with increasing polar linkages in the aromatic moieties forming chelated and coordinated layer. This is due to the increase in number of sites to chemisorption on the metal surface. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the surfactants and their efficiency. More confirmation for suggested mechanism was investigated by measuring the area occupied per molecule of the surfactant at aqueous phase. The results indicate that the amphoteric surfactant more efficient than anionic surfactant. The antioxidants activities of different dosages of inhibitors were evaluated and suggested mechanism according to their thermodynamics parameters. The oxidation of the oil has been carried for different time intervals. The degradation of the oil has been monitored by total acid formation.展开更多
Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicat...Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicated that, compared with petrodiesel, biodiesel was more liable to promote oxidation degradation of diesel oils, leading to worse oxidative stability, detergency and antiwear ability of the oils.展开更多
To improve the tribological behavior of biodiesel soot(BDS) in liquid paraffin(LP), the order of biodiesel soot was increased through thermally oxidized treatment at 500 ℃, and the oil solubility was then improved th...To improve the tribological behavior of biodiesel soot(BDS) in liquid paraffin(LP), the order of biodiesel soot was increased through thermally oxidized treatment at 500 ℃, and the oil solubility was then improved through a modification using oleylamine(OLA). The BDS and thermally oxidized oleylamine-modified BDS(T-BDS-OLA)were characterized through various methods including the use of TG, FETEM, Raman spectroscopy, FTIR, and a zeta potentiometer. The tribological properties and mechanisms of the BDS before and after the thermally oxidized treatment modification were investigated using a ball-on-disc reciprocating tribometer, FESEM, 3 D laser-scanning microscopy, and Raman spectroscopy. The results showed that T-BDS-OLA has a higher degree of order than the BDS, with an onion-like microstructure. BDS and T-BDS-OLA can both improve the antifriction and antiwear properties of LP at a soot content of 0.1%-0.4%, while T-BDS-OLA in LP shows better antifriction and antiwear properties than BDS. The tribological mechanisms can be attributed to both types of soot acting as spacing and roll bearing between the friction surfaces. In addition, the exfoliated graphitic sheets from T-BDS-OLA can form a carbon lubrication layer providing easy sliding.展开更多
A four-ball machine was employed to investigate the tribological performances and the synergetic function of organo-molybdenum compounds (molybdenum dialkyl-dithiophosphate and molybdenum dithiophosphate, coded as MoD...A four-ball machine was employed to investigate the tribological performances and the synergetic function of organo-molybdenum compounds (molybdenum dialkyl-dithiophosphate and molybdenum dithiophosphate, coded as MoDDP and MoDTP, respectively) as additives in liquid paraffin. The morphologies of the worn surfaces and elemental distributions were observed and determined by means of scanning electron microscopy and energy dispersive spectrometry. The chemical states of some typical elements on the worn surface were analyzed on X-ray photoelectron spectroscope. The results show that MoDDP and MoDTP additives in liquid paraffin have excellent antiwear and friction-reduction properties, which are attributed to the reaction film composed of MoS2, FeS and MoO2, and the deposited film composed of phosphate on the worn surface. Moreover, these two additives have synergetic friction-reducing and antiwear effect, which is closely related to the chemical states of S on the worn surface.展开更多
The tribological behaviors of the nano-diamond particles including the nano- diamond and the nano-diamond modified were studied at high temperature using SRV multifunctional test system. The worn steel surfaces were a...The tribological behaviors of the nano-diamond particles including the nano- diamond and the nano-diamond modified were studied at high temperature using SRV multifunctional test system. The worn steel surfaces were analyzed by means of X-ray photoelectron spectroscopy (XPS). The results show that nano-diamond particles can obviously improve the antiwear and friction reducing properties of the base oil at high temperature and the high load. The friction coefficient of the nano-diamond is very low at 200 ℃ when the test load is not more than 20 N. This tribological behaviors should attributed to the similarly to “ball bearing” lubrication action of the nano-diamond particles, so the movement between tribological pairs become sliding/rolling. The nano-diamond modified by dimer ester possesses excellent antiwear and friction reducing performance at 500 ℃ and load 500 N. The tribochemical reaction film between the nano-diamond particles and the renascent wear surface plays dominating lubrication role and the presence of the dimer ester on the rubbing surface can be propitious to form lubrication film containing nano- diamond on the worn surface at high temperature and high load.展开更多
A heterocyclic derivative of (2 sulphurone benzothiazole) 3 methyl dodecanoate was synthesized. Its tribological performance when added to liquid paraffin was evaluated on a four ball tester and a ring on block machin...A heterocyclic derivative of (2 sulphurone benzothiazole) 3 methyl dodecanoate was synthesized. Its tribological performance when added to liquid paraffin was evaluated on a four ball tester and a ring on block machine. Results indicate that compared with the base oil the wear resistance and load carrying capacities of the oil with novel additive are improved, and the friction coefficient is decreased. There is an optimal content of the novel compound, at which the corresponding oil gives the highest maximum non seizure load. Above the content, the load carrying capacity of the oil is not increased but decreased. The nature of the film formed on the rubbed surface was investigated by X ray photoelectron spectroscopy (XPS) analysis, and the action mechanism of the novel compound was discussed. [展开更多
Global economic and pollution concerns are having a major impact on how modern engine oils are being formulated.Modern engine oil specifications mandate reduced levels of phosphorus and sulfur to protect the efficacy ...Global economic and pollution concerns are having a major impact on how modern engine oils are being formulated.Modern engine oil specifications mandate reduced levels of phosphorus and sulfur to protect the efficacy of pollution control devices.In addition,modern engine oil must also be more fuel efficient than earlier generations to reduce greenhouse gas emissions and the impact of high priced gasoline and diesel fuel to the consumer.At the same time,oxidation,wear,and corrosion performance of the oil must not be compromised.Multifunctional additives are useful formulation tools that help formulators meet these tough new challenges.One such additive is the organo-borate ester/amide.Originally conceived as an organic friction modifier,this patented technology is really a multifunctional additive that addresses the global economic and pollution concerns.With the addition of boron,this unique commercial organic friction modifier also imparts antioxidancy,antiwear and anticorrosion properties to engine oil.In addition,the organo-borate ester/amide is compatible with pollution control devices because it does not contain sulfur or phosphorus.Work is on going to uncover additional beneficial properties of this chemistry.展开更多
A series of high performance lubricants of water-soluble polymers with telechelic or star structures has been studied. Their average molecular weights (M) over bar are 1800-6000. The chemical structures of the lubrica...A series of high performance lubricants of water-soluble polymers with telechelic or star structures has been studied. Their average molecular weights (M) over bar are 1800-6000. The chemical structures of the lubricants are characterized by their hydrophilic groups (-CH2CH2O-), -COOH, -OH, -CONH2 and antiwear active elements (S,P,Zn and Mo). The results of assessing for the anti-wear property indicate that this kind of water-soluble polymeric lubricants possesses excellent watersolubility, lubricity and anti-wear property. A preliminary study on the anti-wear mechanism of the polymers is performed by means of electron probe and scanning electron microscopy (SEM).展开更多
CeF3. CaF2, (CF)n, SbF3, and CeO2 were selected as the high temperature solid additives in a lithium grease, and their friction, wear, and extreme pressure properties were evaluated on an Optimol-SRV wear tester. The ...CeF3. CaF2, (CF)n, SbF3, and CeO2 were selected as the high temperature solid additives in a lithium grease, and their friction, wear, and extreme pressure properties were evaluated on an Optimol-SRV wear tester. The effect of additive on the fiber structure of soap was studied by means of the transmission electron microscopy(TEM). The corrosive property of grease containing additive was evaluated by copper strip corrosion test. Thermal decomposition behaviors of the additives were studied by thermogravimetry(TG) tester. The adhesive strength of rubbing surface film was measured by automatic scratch tester and the wear surface was detected by means of X-ray photoelectron spectroscopy (XPS). The test results showed that the grease containing CeF3 has good anti-wear, anti-friction, and EP performances, and has high adhesive strength of rubbing surface film.The greases containing CaF2 or (CF)n are good in antiwear and anti-friction properties, but poor in extreme pressure function. The tribological properties of the grease containing SbF3 are decreased.And the addition of CeO2 in grease was useless. Finally the mechanism of fluoride additive was proposed in this paper.展开更多
The oil-soluble cadmium dipropyldithiophosphate additive was synthesized. A four-ball tester was used to evaluate the tribological performance of the additive in a mineral oil under different loads and lubricant greas...The oil-soluble cadmium dipropyldithiophosphate additive was synthesized. A four-ball tester was used to evaluate the tribological performance of the additive in a mineral oil under different loads and lubricant grease synthesized compared with some commercial additives. The results show that it exhibits excellent antiwear and load-carrying capacities and is better than other additives. The surface analytical tools such as scanning electron microscope (SEM) with energy dispersive X-ray (EDX), X-ray photoelectron spectrometer (XPS) were used to investigate the topography, the compositions, and chemical states of some typical elements on the rubbing surface of worn scar.Smooth and light topography of worn scar further confirms that the additive shows good antiwear capacities. The results of EDX and XPS analyses indicate that tribochemical mixed protective films consisting of atomic cadmium, sulphides, sulphates and phosphates are formed on the rubbing surface, which contribute to improving the tribological properties of lubricant and grease. Particularly, the soft cadmium film formed plays an important role in improving antiwear properties of oils. Finally, antiwear mechanism of the additive and formation scheme of atomic cadmium was proposed.展开更多
Simulated adsorptive experiments using the axletree and lubricating oil containing anticorrosion additive were conducted,and the UV absorbance of the lubricating oil before and after the adsorptive experiments was mea...Simulated adsorptive experiments using the axletree and lubricating oil containing anticorrosion additive were conducted,and the UV absorbance of the lubricating oil before and after the adsorptive experiments was measured.Through the UV spectral measurements the difference in UV absorbance of the lubricating oil before and after the adsorptive experiments was identified,the adsorbed quantity of anticorrosion additive in the interfacial film between lubricating oil and bearing was calculated using the Lambert-Bell principle to verify the adsorption of corrosion inhibitor on the surface of friction pairs.Adsorption experiments on lubricating oil containing both antiwear and anticorrosion additives were carried out and the UV absorbance of lubricating oil samples before and after the experiments was measured to determine the difference in the UV absorbance among lubricating oil samples with the same mass fraction of anticorrosion additive and different mass fractions of antiwear additive.By measuring the ultraviolet spectral absorbance of lubricating oil samples and calculating the adsorbed quantity of anticorrosion additive in the interfacial film it was possible to determine the influence of antiwear additive on the quantity of adsorbed anticorrosion additive on the surface of friction pairs and verify the competitive adsorption relationship between the antiwear additive and the anticorrosion additive.展开更多
A new method for the preparation of dinuclear molybdenum dithiocarbamates(MoDDCs) is reported.This new method allows for the control of the amount of sulfurization of the Mo2SxO4-x core(x = 1 to 4) in the dinuclear Mo...A new method for the preparation of dinuclear molybdenum dithiocarbamates(MoDDCs) is reported.This new method allows for the control of the amount of sulfurization of the Mo2SxO4-x core(x = 1 to 4) in the dinuclear MoDDCs.This control assists in the tailoring of specific tribological properties of the MoDDCs in both greases and lubricating oils.展开更多
Cryogenic treatment has been increasingly applied to enhance the hardness, antiwear ability and fatigue performance of die steel. On the basis of reading a large number of research papers and references across the wor...Cryogenic treatment has been increasingly applied to enhance the hardness, antiwear ability and fatigue performance of die steel. On the basis of reading a large number of research papers and references across the world, the author makes a detailed analysis and brief summary of the influence of cryogenic treatment on microstructure after quenching process or quenching plus tempering process, on first and second carbides, on content of retained austenite, on surface hardness, on mechanical properties and antiwear ability of die steels. It’s proved that cryogenic treatment on die steel significantly improves its hardness, antiwear capacity and service life. It’s the cryogenic process to make die steel have higher hardness, better antiwear ability, better ductility and longer service life because cryogenic process actually has a good influence on die steel of its microstructure, retained austenite volume and amount and size of the second carbide.展开更多
In this study,the nanocomposites of MoS_(2) nanoparticles(NPs)grown on carbon nanotubes(MoS_(2)@CNT),graphene(MoS_(2)@Gr),and fullerene C60(MoS_(2)@C60)were synthesized,characterized,and evaluated for potential use as...In this study,the nanocomposites of MoS_(2) nanoparticles(NPs)grown on carbon nanotubes(MoS_(2)@CNT),graphene(MoS_(2)@Gr),and fullerene C60(MoS_(2)@C60)were synthesized,characterized,and evaluated for potential use as lubricant additives.By using the benefit of the synergistic effect between MoS_(2) and carbon nanomaterials(CNMs),these nanocomposites can be well dispersed in polyalkylene glycol(PAG)base oil and show superior stability compared with pure MoS_(2) NPs.Moreover,the dispersions of MoS_(2)@CNT,MoS_(2)@Gr,and MoS_(2)@C60 added in PAG have noticeably improved friction reducing and antiwear(AW)behaviors at elevated temperature for comparison with that of PAG and PAG containing CNT,Gr,C60,and M0S2 NPs,respectively.The enhanced lubricating properties of these nanocomposites were also elucidated by exploring the tribofilm formed on the disc.展开更多
Quantitative structure-activity relationship methods are used to study the quantitative structure tribo-ability relationship (QSTR), which refers to the tribology capability of a compound from the calculation of struc...Quantitative structure-activity relationship methods are used to study the quantitative structure tribo-ability relationship (QSTR), which refers to the tribology capability of a compound from the calculation of structure descriptors. Here, we used the Bayesian regularization neural network (BRNN) to establish a QSTR prediction model. Two-dimensional (2D) BRNN-QSTR models can flexibly and easily estimate lubricant-additive antiwear properties. Our results show that electron transfer and heteroatoms (such as S, P, O, and N) in a lubricant-additive molecule improve the antiwear ability. We also found that molecular connectivity indices are good descriptors of 2D BRNN-QSTR models.展开更多
Comparative molecular field analysis and comparative molecular similarity indices analysis were employed to analyze the antiwear properties of a series of 57 esters as potential lubricant-based oils. Predictive 3D-qua...Comparative molecular field analysis and comparative molecular similarity indices analysis were employed to analyze the antiwear properties of a series of 57 esters as potential lubricant-based oils. Predictive 3D-quantitative structure tribo-ability relationship models were established using the SYBYL multifit molecular alignment rule with a training set and a test set. The optimum models were all shown to be statistically significant with cross-validated coefficients q^2 > 0.5 and conventional coefficients r^2 > 0.9, indicating that the models are sufficiently reliable for activity prediction, and may be useful in the design of novel ester-based oils.展开更多
Three kind of water-soluble additives, 3-(N, N- dialkyl dithiocarbamate-y1) propionicacid, were synthesized. Their tribological performances when added to water were evaluated on afour-ball tester and a ring-on-block ...Three kind of water-soluble additives, 3-(N, N- dialkyl dithiocarbamate-y1) propionicacid, were synthesized. Their tribological performances when added to water were evaluated on afour-ball tester and a ring-on-block machine. Results indicate that the hydrocarbon chain length ofthese compounds has significant influence on their tribological properties. When the number ofcarbon atom in alkyl group is equal to (or more than) 4, the compounds exhibit excellentload-carrying capacity, antiwear property and weld load. The antiwear action mechanisms of thepropionic acid compounds can be ascribed to the formation of adsorption film and chemical reac-tion film. The cooperation action of these films plays an important role in the prevention of tri-bological failure.展开更多
文摘Surfactants are used for formulation metal working fluids. These fluids are applied to the interface between a cutting tool and the metal working piece to provide friction reduction. In the present paper, poly aromatic ammonium sulphonate and polyaromatic benzyl triethanolamsonium ethoxylate with 6 ethylene oxide units were synthesized and blended with coupling agent like dodecyl alcohol and oleic acid to produce cutting fluid and evaluate as antiwear. Values of surface tension of these additives were measured in oil phase and consequently CMC was determined for all additives and their mixtures in oil phase. The efficiency of these additives depends on their chemical structure and the presence of ether oxygen brings about the association of the surfactant with metal surface, hence very good wetting properties. The antiwear characteristic of surfactants increases with increasing polar linkages in the aromatic moieties forming chelated and coordinated layer. This is due to the increase in the number of sites to chemisorption on the metal surface. The films formed are highly condensed ring aromatic layered structures. These films provide lower wear and depend on the type of surfactants concentration and sliding speed. The surface of metal was analyzed by SEM/EDX techniques. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the surfactants and their film forming. More confirmation for suggested mechanism was investigated by measuring the area occupied per molecule of the surfactant in oil phase. The results indicate that the sulphonate group is less efficient than ethoxylate group. At the same time, the micelle of surfactants acts as oil dispersant and improves adsorption of oil on the metal surface.
文摘Surfactants used for formulation metal working fluids. In the present paper, the inhibitive effect of synthesized anionic surfactant P-decyloxy p-sodium sulphonateazobenzene with chemical structure H21C10O-Ph-N=N-Ph-SO3Na and 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine on the corrosion of carbon steel in sulphuric acid solution is measured by the weight loss method. The relationships between the concentrations of these inhibitors and their surface properties, thermodynamic properties, surface coverage and inhibiting efficiency, have been investigated. The results indicate that P-decyloxy p-sodium sulphonate azobenzene is superior to 1-ethyl-1-dodecyl-2-sulphonate-4-(hydroxyl ethyl)-piprazine at high acid concentration. These inhibitors blend with coupling agent to produce water miscible cutting fluid. Values of surface tension of these additives were measured in water phase and consequently CMC was determined for all inhibitors. The efficiency of these inhibitors depends on their chemical structure and the presence of hydrophilic group to association of the surfactant with metal surface, hence very good wetting properties. The anti-corrosion characteristic of surfactants increases with increasing polar linkages in the aromatic moieties forming chelated and coordinated layer. This is due to the increase in number of sites to chemisorption on the metal surface. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the surfactants and their efficiency. More confirmation for suggested mechanism was investigated by measuring the area occupied per molecule of the surfactant at aqueous phase. The results indicate that the amphoteric surfactant more efficient than anionic surfactant. The antioxidants activities of different dosages of inhibitors were evaluated and suggested mechanism according to their thermodynamics parameters. The oxidation of the oil has been carried for different time intervals. The degradation of the oil has been monitored by total acid formation.
基金the financial support from the Natural Science Foundation of Chongqing(Project NO. CSTC, 2011JJA90020)the Science Foundation for Young Teachers of Logistical Engineering University
文摘Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicated that, compared with petrodiesel, biodiesel was more liable to promote oxidation degradation of diesel oils, leading to worse oxidative stability, detergency and antiwear ability of the oils.
基金supported by the National Natural Science Foundation of China (Grant No. 51675153)the Major Science and Technology Special Project in Anhui (Grant No. 17030901084)
文摘To improve the tribological behavior of biodiesel soot(BDS) in liquid paraffin(LP), the order of biodiesel soot was increased through thermally oxidized treatment at 500 ℃, and the oil solubility was then improved through a modification using oleylamine(OLA). The BDS and thermally oxidized oleylamine-modified BDS(T-BDS-OLA)were characterized through various methods including the use of TG, FETEM, Raman spectroscopy, FTIR, and a zeta potentiometer. The tribological properties and mechanisms of the BDS before and after the thermally oxidized treatment modification were investigated using a ball-on-disc reciprocating tribometer, FESEM, 3 D laser-scanning microscopy, and Raman spectroscopy. The results showed that T-BDS-OLA has a higher degree of order than the BDS, with an onion-like microstructure. BDS and T-BDS-OLA can both improve the antifriction and antiwear properties of LP at a soot content of 0.1%-0.4%, while T-BDS-OLA in LP shows better antifriction and antiwear properties than BDS. The tribological mechanisms can be attributed to both types of soot acting as spacing and roll bearing between the friction surfaces. In addition, the exfoliated graphitic sheets from T-BDS-OLA can form a carbon lubrication layer providing easy sliding.
基金Project(50235030)supported by the National Natural Science Foundation of China project(G1999065009)supported by the National Basic Research Program of China
文摘A four-ball machine was employed to investigate the tribological performances and the synergetic function of organo-molybdenum compounds (molybdenum dialkyl-dithiophosphate and molybdenum dithiophosphate, coded as MoDDP and MoDTP, respectively) as additives in liquid paraffin. The morphologies of the worn surfaces and elemental distributions were observed and determined by means of scanning electron microscopy and energy dispersive spectrometry. The chemical states of some typical elements on the worn surface were analyzed on X-ray photoelectron spectroscope. The results show that MoDDP and MoDTP additives in liquid paraffin have excellent antiwear and friction-reduction properties, which are attributed to the reaction film composed of MoS2, FeS and MoO2, and the deposited film composed of phosphate on the worn surface. Moreover, these two additives have synergetic friction-reducing and antiwear effect, which is closely related to the chemical states of S on the worn surface.
文摘The tribological behaviors of the nano-diamond particles including the nano- diamond and the nano-diamond modified were studied at high temperature using SRV multifunctional test system. The worn steel surfaces were analyzed by means of X-ray photoelectron spectroscopy (XPS). The results show that nano-diamond particles can obviously improve the antiwear and friction reducing properties of the base oil at high temperature and the high load. The friction coefficient of the nano-diamond is very low at 200 ℃ when the test load is not more than 20 N. This tribological behaviors should attributed to the similarly to “ball bearing” lubrication action of the nano-diamond particles, so the movement between tribological pairs become sliding/rolling. The nano-diamond modified by dimer ester possesses excellent antiwear and friction reducing performance at 500 ℃ and load 500 N. The tribochemical reaction film between the nano-diamond particles and the renascent wear surface plays dominating lubrication role and the presence of the dimer ester on the rubbing surface can be propitious to form lubrication film containing nano- diamond on the worn surface at high temperature and high load.
文摘A heterocyclic derivative of (2 sulphurone benzothiazole) 3 methyl dodecanoate was synthesized. Its tribological performance when added to liquid paraffin was evaluated on a four ball tester and a ring on block machine. Results indicate that compared with the base oil the wear resistance and load carrying capacities of the oil with novel additive are improved, and the friction coefficient is decreased. There is an optimal content of the novel compound, at which the corresponding oil gives the highest maximum non seizure load. Above the content, the load carrying capacity of the oil is not increased but decreased. The nature of the film formed on the rubbed surface was investigated by X ray photoelectron spectroscopy (XPS) analysis, and the action mechanism of the novel compound was discussed. [
文摘Global economic and pollution concerns are having a major impact on how modern engine oils are being formulated.Modern engine oil specifications mandate reduced levels of phosphorus and sulfur to protect the efficacy of pollution control devices.In addition,modern engine oil must also be more fuel efficient than earlier generations to reduce greenhouse gas emissions and the impact of high priced gasoline and diesel fuel to the consumer.At the same time,oxidation,wear,and corrosion performance of the oil must not be compromised.Multifunctional additives are useful formulation tools that help formulators meet these tough new challenges.One such additive is the organo-borate ester/amide.Originally conceived as an organic friction modifier,this patented technology is really a multifunctional additive that addresses the global economic and pollution concerns.With the addition of boron,this unique commercial organic friction modifier also imparts antioxidancy,antiwear and anticorrosion properties to engine oil.In addition,the organo-borate ester/amide is compatible with pollution control devices because it does not contain sulfur or phosphorus.Work is on going to uncover additional beneficial properties of this chemistry.
基金This study is supported by the National Natural Science Foundation of China
文摘A series of high performance lubricants of water-soluble polymers with telechelic or star structures has been studied. Their average molecular weights (M) over bar are 1800-6000. The chemical structures of the lubricants are characterized by their hydrophilic groups (-CH2CH2O-), -COOH, -OH, -CONH2 and antiwear active elements (S,P,Zn and Mo). The results of assessing for the anti-wear property indicate that this kind of water-soluble polymeric lubricants possesses excellent watersolubility, lubricity and anti-wear property. A preliminary study on the anti-wear mechanism of the polymers is performed by means of electron probe and scanning electron microscopy (SEM).
文摘CeF3. CaF2, (CF)n, SbF3, and CeO2 were selected as the high temperature solid additives in a lithium grease, and their friction, wear, and extreme pressure properties were evaluated on an Optimol-SRV wear tester. The effect of additive on the fiber structure of soap was studied by means of the transmission electron microscopy(TEM). The corrosive property of grease containing additive was evaluated by copper strip corrosion test. Thermal decomposition behaviors of the additives were studied by thermogravimetry(TG) tester. The adhesive strength of rubbing surface film was measured by automatic scratch tester and the wear surface was detected by means of X-ray photoelectron spectroscopy (XPS). The test results showed that the grease containing CeF3 has good anti-wear, anti-friction, and EP performances, and has high adhesive strength of rubbing surface film.The greases containing CaF2 or (CF)n are good in antiwear and anti-friction properties, but poor in extreme pressure function. The tribological properties of the grease containing SbF3 are decreased.And the addition of CeO2 in grease was useless. Finally the mechanism of fluoride additive was proposed in this paper.
文摘The oil-soluble cadmium dipropyldithiophosphate additive was synthesized. A four-ball tester was used to evaluate the tribological performance of the additive in a mineral oil under different loads and lubricant grease synthesized compared with some commercial additives. The results show that it exhibits excellent antiwear and load-carrying capacities and is better than other additives. The surface analytical tools such as scanning electron microscope (SEM) with energy dispersive X-ray (EDX), X-ray photoelectron spectrometer (XPS) were used to investigate the topography, the compositions, and chemical states of some typical elements on the rubbing surface of worn scar.Smooth and light topography of worn scar further confirms that the additive shows good antiwear capacities. The results of EDX and XPS analyses indicate that tribochemical mixed protective films consisting of atomic cadmium, sulphides, sulphates and phosphates are formed on the rubbing surface, which contribute to improving the tribological properties of lubricant and grease. Particularly, the soft cadmium film formed plays an important role in improving antiwear properties of oils. Finally, antiwear mechanism of the additive and formation scheme of atomic cadmium was proposed.
文摘Simulated adsorptive experiments using the axletree and lubricating oil containing anticorrosion additive were conducted,and the UV absorbance of the lubricating oil before and after the adsorptive experiments was measured.Through the UV spectral measurements the difference in UV absorbance of the lubricating oil before and after the adsorptive experiments was identified,the adsorbed quantity of anticorrosion additive in the interfacial film between lubricating oil and bearing was calculated using the Lambert-Bell principle to verify the adsorption of corrosion inhibitor on the surface of friction pairs.Adsorption experiments on lubricating oil containing both antiwear and anticorrosion additives were carried out and the UV absorbance of lubricating oil samples before and after the experiments was measured to determine the difference in the UV absorbance among lubricating oil samples with the same mass fraction of anticorrosion additive and different mass fractions of antiwear additive.By measuring the ultraviolet spectral absorbance of lubricating oil samples and calculating the adsorbed quantity of anticorrosion additive in the interfacial film it was possible to determine the influence of antiwear additive on the quantity of adsorbed anticorrosion additive on the surface of friction pairs and verify the competitive adsorption relationship between the antiwear additive and the anticorrosion additive.
文摘A new method for the preparation of dinuclear molybdenum dithiocarbamates(MoDDCs) is reported.This new method allows for the control of the amount of sulfurization of the Mo2SxO4-x core(x = 1 to 4) in the dinuclear MoDDCs.This control assists in the tailoring of specific tribological properties of the MoDDCs in both greases and lubricating oils.
文摘Cryogenic treatment has been increasingly applied to enhance the hardness, antiwear ability and fatigue performance of die steel. On the basis of reading a large number of research papers and references across the world, the author makes a detailed analysis and brief summary of the influence of cryogenic treatment on microstructure after quenching process or quenching plus tempering process, on first and second carbides, on content of retained austenite, on surface hardness, on mechanical properties and antiwear ability of die steels. It’s proved that cryogenic treatment on die steel significantly improves its hardness, antiwear capacity and service life. It’s the cryogenic process to make die steel have higher hardness, better antiwear ability, better ductility and longer service life because cryogenic process actually has a good influence on die steel of its microstructure, retained austenite volume and amount and size of the second carbide.
基金supported by the National Key Research and Development Program of China(2018YFB2000601)and National Natural Science Foundation of China(Nos.51875553 and 51775536).
文摘In this study,the nanocomposites of MoS_(2) nanoparticles(NPs)grown on carbon nanotubes(MoS_(2)@CNT),graphene(MoS_(2)@Gr),and fullerene C60(MoS_(2)@C60)were synthesized,characterized,and evaluated for potential use as lubricant additives.By using the benefit of the synergistic effect between MoS_(2) and carbon nanomaterials(CNMs),these nanocomposites can be well dispersed in polyalkylene glycol(PAG)base oil and show superior stability compared with pure MoS_(2) NPs.Moreover,the dispersions of MoS_(2)@CNT,MoS_(2)@Gr,and MoS_(2)@C60 added in PAG have noticeably improved friction reducing and antiwear(AW)behaviors at elevated temperature for comparison with that of PAG and PAG containing CNT,Gr,C60,and M0S2 NPs,respectively.The enhanced lubricating properties of these nanocomposites were also elucidated by exploring the tribofilm formed on the disc.
基金the National Basic Research (973) Program of China，the National Natural Science Foundation of China
文摘Quantitative structure-activity relationship methods are used to study the quantitative structure tribo-ability relationship (QSTR), which refers to the tribology capability of a compound from the calculation of structure descriptors. Here, we used the Bayesian regularization neural network (BRNN) to establish a QSTR prediction model. Two-dimensional (2D) BRNN-QSTR models can flexibly and easily estimate lubricant-additive antiwear properties. Our results show that electron transfer and heteroatoms (such as S, P, O, and N) in a lubricant-additive molecule improve the antiwear ability. We also found that molecular connectivity indices are good descriptors of 2D BRNN-QSTR models.
基金supported by the National Nature Science Foundation of China (NSFC, No. 51675395)
文摘Comparative molecular field analysis and comparative molecular similarity indices analysis were employed to analyze the antiwear properties of a series of 57 esters as potential lubricant-based oils. Predictive 3D-quantitative structure tribo-ability relationship models were established using the SYBYL multifit molecular alignment rule with a training set and a test set. The optimum models were all shown to be statistically significant with cross-validated coefficients q^2 > 0.5 and conventional coefficients r^2 > 0.9, indicating that the models are sufficiently reliable for activity prediction, and may be useful in the design of novel ester-based oils.
文摘Three kind of water-soluble additives, 3-(N, N- dialkyl dithiocarbamate-y1) propionicacid, were synthesized. Their tribological performances when added to water were evaluated on afour-ball tester and a ring-on-block machine. Results indicate that the hydrocarbon chain length ofthese compounds has significant influence on their tribological properties. When the number ofcarbon atom in alkyl group is equal to (or more than) 4, the compounds exhibit excellentload-carrying capacity, antiwear property and weld load. The antiwear action mechanisms of thepropionic acid compounds can be ascribed to the formation of adsorption film and chemical reac-tion film. The cooperation action of these films plays an important role in the prevention of tri-bological failure.
