Surface gas discharge(SGD)plasmas have potential applications in the fields of active flow control,gas purification,heat transfer enhancement,etc.In order to obtain a uniform,stable and large-area SGD at atmosphere,a ...Surface gas discharge(SGD)plasmas have potential applications in the fields of active flow control,gas purification,heat transfer enhancement,etc.In order to obtain a uniform,stable and large-area SGD at atmosphere,a multi-electrode SGD plasma generator is designed in this paper.The major features of this newly-designed SGD plasma generator is as follows:the air-exposed upper grounded electrodes are made of nine tungsten wires and flush mounted on the dielectric PTFE barrier layer,while the lower powered electrode is made of a copper foil and encapsulated inside the PTFE material to avoid the ignition of the gas discharges below the dielectric barrier layer.The measurements on the electrical characteristics,fast imaging of discharges and the preliminary numerical analysis on the electric field distributions suggest that the multi-electrode configuration of the plasma generator plays a crucial role in enhancing the local electrical field,and subsequently,leads to the stable,quasi-uniform and large-area surface discharges.展开更多
Lanthanum-doped muscovite(MC) composite particles(hereinafter abbreviated as La-MC) were prepared by the mechanical solid-state-chemistry-reaction method, followed by surface modification with oleic acid. The microstr...Lanthanum-doped muscovite(MC) composite particles(hereinafter abbreviated as La-MC) were prepared by the mechanical solid-state-chemistry-reaction method, followed by surface modification with oleic acid. The microstructure of materials was characterized by SEM, XRD, EDS and FTIR. Furthermore, the friction-reduction and anti-wear properties of MC and La-MC as lubricant additives in lithium grease were evaluated using a four-ball friction and wear tester. The results showed that La(OH)_3 nanoparticles were coated on the surface of muscovite. Both MC and La-MC can effectively improve the friction-reduction and anti-wear properties of lithium grease and La-MC presents better tribological properties than MC. The excellent tribological properties of La-MC can be attributed to the formation of the adsorbed La-MC film and the chemical reaction film mainly composed of Fe_2O_3 and SiO_2 on the worn surface, as well as the catalysis of lanthanum element during the friction process.展开更多
Since the 1990 s, the kerosene fuel(code: JP-8) had been applied in the ground equipment provided with direct injection compression ignition engines in the U.S. Army, resulting in increased occurrence of injection pum...Since the 1990 s, the kerosene fuel(code: JP-8) had been applied in the ground equipment provided with direct injection compression ignition engines in the U.S. Army, resulting in increased occurrence of injection pump failures. Anti-wear additives must be used in the single fuel due to its poor lubricity. In the present work, lubricity improvers were selected on the basis of molecular simulation theoretically and these agents were evaluated to improve the lubricity of jet fuel using the high frequency reciprocating rig(HFRR) apparatus and the ball-on-cylinder lubricity evaluator(BOCLE). It was revealed that dimer acid with higher value of adsorption energy on the Fe(110) plane surface had more efficient lubricity promoting properties than that of naphthenic acid. The experimental results suggested that the dimer acid had a better tribological behavior compared with that of naphthenic acid used as lubricity improver of jet fuel. And addition of anti-wear additives at a dosage of 15 μg/g was able to promote the lubricity of jet fuel to a required level on BOCLE, while a higher concentration over 80 μg/g was needed to improve the lubricity to a demanded value of diesel on HFRR.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 series of functionalized ionic liquids （ILs） containing ester-group were synthesized and their tribological prop- erties as lubricants for steel-steel contact were studied and compared with a non-functionalized io...A series of functionalized ionic liquids （ILs） containing ester-group were synthesized and their tribological prop- erties as lubricants for steel-steel contact were studied and compared with a non-functionalized ionic liquid and perfluo- ropolyethers （PFPE）. The morphology and chemical composition of the worn scars were analyzed by scanning electron mi- croscopy and X-ray photoelectron spectroscopy, respectively, and the possible lubrication mechanism of ILs was discussed. As a result, all ILs demonstrated a better lubricity and a much higher load-carrying capacity than PFPE used as lubricants for the steel-steel tribomates system. The functionalized ILs with ester-group showed slightly worse friction reducing abil- ity than their nonfunctionalized counterparts at relatively lower loads owing to their higher viscosity, but then exhibited better antiwear ability because the ester group they contained had not only physical but also strong chemical reactions with the freshly exposed steel surface and formed chemical adsorption boundary films on the worn surface during friction pro- cess. Under high loads, some triboehemical reactions took place between the active elements, such as fluorine which were released from the ILs, and fresh metal surfaces of rubbing pairs to form the admixture reaction films, which were mainly composed of ferric fluoride mixed with ferric oxide, leading to lower friction coefficients and good wear resistance.展开更多
Cu-doped muscovite（Mu） composite particles, abbreviated as Mu/Cu, were prepared via liquid phase reduction method. The morphologies, phase composition and elementary distribution of the as-prepared Mu/Cu and raw mus...Cu-doped muscovite（Mu） composite particles, abbreviated as Mu/Cu, were prepared via liquid phase reduction method. The morphologies, phase composition and elementary distribution of the as-prepared Mu/Cu and raw muscovite particles were characterized by means of scalmmg electron microscope（SEM）, X-ray diffraction（XRD） and energy dispersive spectrometry（EDS）. The tirbological properties of Mu/Cu and Mu as lubricant additives in lithium grease were evaluated on a block-ring tribomachine. The roughness, 2D and 3D morphologies and elementary distribution of block worn surface were analyzed to explore the tribogical mechanism. The results show that muscovite are evenly coated by the cubic Cu nanoparticles in composite particles. Both Mu/Cu and Mu can effectively improve the tirbological properties of lithium grease and Mu/Cu exhibits better tribological performance than Mu. The friction coefficient of Mu/Cu is decreased by 69.2% as compared to that of lithium grease. The layer structure of muscovite is synergistic with Cu nanoparticles in contribution to the formation of lubricant film mainly consisting of O, Si, Fe, Cu as well as Al elements on the block worn surface thereby further reducing the friction and wear.展开更多
It has been found that under favorable friction conditions some antiwear elements inlubricating additives can permeate into subsurface of metal which can strengthens the friction sur-faces and improves anti-wear capac...It has been found that under favorable friction conditions some antiwear elements inlubricating additives can permeate into subsurface of metal which can strengthens the friction sur-faces and improves anti-wear capacity of frication pairs. It is in many ways similar to chemical heattreatment. A new concept, technology of on-line strengthening, was logically put forward. Based oncurrent gear surface treatment technology, the on-line strengthen of gear surface is proposed. Itsdesign method is established. Based on it, the on-line strengthen of gear is achieved on CL-100gear test machine. A new method is put forward for strengthen treatment of gear surface. Andthree kinds of surface film were suggested.展开更多
基金Project supported by National Natural Science Foundation of China （10972119 61104204）.
文摘Surface gas discharge(SGD)plasmas have potential applications in the fields of active flow control,gas purification,heat transfer enhancement,etc.In order to obtain a uniform,stable and large-area SGD at atmosphere,a multi-electrode SGD plasma generator is designed in this paper.The major features of this newly-designed SGD plasma generator is as follows:the air-exposed upper grounded electrodes are made of nine tungsten wires and flush mounted on the dielectric PTFE barrier layer,while the lower powered electrode is made of a copper foil and encapsulated inside the PTFE material to avoid the ignition of the gas discharges below the dielectric barrier layer.The measurements on the electrical characteristics,fast imaging of discharges and the preliminary numerical analysis on the electric field distributions suggest that the multi-electrode configuration of the plasma generator plays a crucial role in enhancing the local electrical field,and subsequently,leads to the stable,quasi-uniform and large-area surface discharges.
基金supported by the Postdoctoral Science Foundation of China(XM2013018)Logistics Project Foundation of China(Oil 20070209)
文摘Lanthanum-doped muscovite(MC) composite particles(hereinafter abbreviated as La-MC) were prepared by the mechanical solid-state-chemistry-reaction method, followed by surface modification with oleic acid. The microstructure of materials was characterized by SEM, XRD, EDS and FTIR. Furthermore, the friction-reduction and anti-wear properties of MC and La-MC as lubricant additives in lithium grease were evaluated using a four-ball friction and wear tester. The results showed that La(OH)_3 nanoparticles were coated on the surface of muscovite. Both MC and La-MC can effectively improve the friction-reduction and anti-wear properties of lithium grease and La-MC presents better tribological properties than MC. The excellent tribological properties of La-MC can be attributed to the formation of the adsorbed La-MC film and the chemical reaction film mainly composed of Fe_2O_3 and SiO_2 on the worn surface, as well as the catalysis of lanthanum element during the friction process.
文摘Since the 1990 s, the kerosene fuel(code: JP-8) had been applied in the ground equipment provided with direct injection compression ignition engines in the U.S. Army, resulting in increased occurrence of injection pump failures. Anti-wear additives must be used in the single fuel due to its poor lubricity. In the present work, lubricity improvers were selected on the basis of molecular simulation theoretically and these agents were evaluated to improve the lubricity of jet fuel using the high frequency reciprocating rig(HFRR) apparatus and the ball-on-cylinder lubricity evaluator(BOCLE). It was revealed that dimer acid with higher value of adsorption energy on the Fe(110) plane surface had more efficient lubricity promoting properties than that of naphthenic acid. The experimental results suggested that the dimer acid had a better tribological behavior compared with that of naphthenic acid used as lubricity improver of jet fuel. And addition of anti-wear additives at a dosage of 15 μg/g was able to promote the lubricity of jet fuel to a required level on BOCLE, while a higher concentration over 80 μg/g was needed to improve the lubricity to a demanded value of diesel on HFRR.
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.
基金the Natural Science Foundation Project of CQ CSTC, 2010BB0201
文摘A series of functionalized ionic liquids （ILs） containing ester-group were synthesized and their tribological prop- erties as lubricants for steel-steel contact were studied and compared with a non-functionalized ionic liquid and perfluo- ropolyethers （PFPE）. The morphology and chemical composition of the worn scars were analyzed by scanning electron mi- croscopy and X-ray photoelectron spectroscopy, respectively, and the possible lubrication mechanism of ILs was discussed. As a result, all ILs demonstrated a better lubricity and a much higher load-carrying capacity than PFPE used as lubricants for the steel-steel tribomates system. The functionalized ILs with ester-group showed slightly worse friction reducing abil- ity than their nonfunctionalized counterparts at relatively lower loads owing to their higher viscosity, but then exhibited better antiwear ability because the ester group they contained had not only physical but also strong chemical reactions with the freshly exposed steel surface and formed chemical adsorption boundary films on the worn surface during friction pro- cess. Under high loads, some triboehemical reactions took place between the active elements, such as fluorine which were released from the ILs, and fresh metal surfaces of rubbing pairs to form the admixture reaction films, which were mainly composed of ferric fluoride mixed with ferric oxide, leading to lower friction coefficients and good wear resistance.
文摘Cu-doped muscovite（Mu） composite particles, abbreviated as Mu/Cu, were prepared via liquid phase reduction method. The morphologies, phase composition and elementary distribution of the as-prepared Mu/Cu and raw muscovite particles were characterized by means of scalmmg electron microscope（SEM）, X-ray diffraction（XRD） and energy dispersive spectrometry（EDS）. The tirbological properties of Mu/Cu and Mu as lubricant additives in lithium grease were evaluated on a block-ring tribomachine. The roughness, 2D and 3D morphologies and elementary distribution of block worn surface were analyzed to explore the tribogical mechanism. The results show that muscovite are evenly coated by the cubic Cu nanoparticles in composite particles. Both Mu/Cu and Mu can effectively improve the tirbological properties of lithium grease and Mu/Cu exhibits better tribological performance than Mu. The friction coefficient of Mu/Cu is decreased by 69.2% as compared to that of lithium grease. The layer structure of muscovite is synergistic with Cu nanoparticles in contribution to the formation of lubricant film mainly consisting of O, Si, Fe, Cu as well as Al elements on the block worn surface thereby further reducing the friction and wear.
文摘It has been found that under favorable friction conditions some antiwear elements inlubricating additives can permeate into subsurface of metal which can strengthens the friction sur-faces and improves anti-wear capacity of frication pairs. It is in many ways similar to chemical heattreatment. A new concept, technology of on-line strengthening, was logically put forward. Based oncurrent gear surface treatment technology, the on-line strengthen of gear surface is proposed. Itsdesign method is established. Based on it, the on-line strengthen of gear is achieved on CL-100gear test machine. A new method is put forward for strengthen treatment of gear surface. Andthree kinds of surface film were suggested.
