The friction and wear characteristics of lauroyl glutamine, lauroyl glycine and lauroyl alanine, used as green additives in HVI 350 mineral lubricating oil, were evaluated on a four-ball tribotester. The morphologies ...The friction and wear characteristics of lauroyl glutamine, lauroyl glycine and lauroyl alanine, used as green additives in HVI 350 mineral lubricating oil, were evaluated on a four-ball tribotester. The morphologies and chemical species of the worn surfaces were analyzed by scanning electron microscope （SEM） and X-ray photoelectron spectroscope （XPS）, respectively. The test results indicated that the three fatty acyl amino acids could effectively improve the anti-wear and friction-reducing abilities of the HVI 350 mineral oil. The improvement in anti-wear and friction-reducing abilities of the mineral oil by the related amino acids was mainly ascribed to the formation of a composite boundary lubrication film due to the adsorption of amino acids on the friction surfaces.展开更多
A Cu-50Cr alloy was treated by the high current pulsed electron beam(HCPEB)at 20 and 30 ke V with pulse numbers ranging from 1 to 100.Surface morphologies and microstructures of specimens before and after the treatmen...A Cu-50Cr alloy was treated by the high current pulsed electron beam(HCPEB)at 20 and 30 ke V with pulse numbers ranging from 1 to 100.Surface morphologies and microstructures of specimens before and after the treatments were investigated by employing scanning electron microscopy and X-ray diffraction.Results show that the HCPEB technique is able to induce remarkable surface modifications for the Cu-50Cr alloy.Cracks in Cr phases appear even after one-pulse treatment and their density always increases with the pulse number.Formation reason for these cracks is attributed to quasi-static thermal stresses accumulated along the specimen surface.Craters with typical morphologies are formed due to the dynamic thermal field induced by the HCPEB and they are found to prefer the sites near cracks or boundaries between neighboring Cr phases.Another microstructural characteristic produced by the HCPEB is the fine Cr spheroids,which are determined to be due to occurrence of liquid phase separation in the Cu-50Cr alloy.Finally,a general microstructural evolution profile that incorporates various HCPEB-induced surface features is tentatively outlined.展开更多
A rolled and recrystallized commercially pure Zr sheet was β-solution treated and then cooled at two rates, i.e. air cooling(AC)and furnace cooling(FC). Microstructures and textures of original and β-cooled specimen...A rolled and recrystallized commercially pure Zr sheet was β-solution treated and then cooled at two rates, i.e. air cooling(AC)and furnace cooling(FC). Microstructures and textures of original and β-cooled specimens were characterized by use of electron channeling contrast imaging, electron backscatter diffraction and X-ray diffraction techniques. Results reveal a novel phenomenon, i.e. the concurrent inheritance of microstructure and texture in the FC specimen cooled at a very slow rate. In contrast, for the AC specimen with faster cooling, typical lamellar α phases are obtained with relatively scattered texture.Based on comparatively crystallographic and thermodynamic analyses, reasons accounting for microstructure and texture differences in both cases are discussed, highlighting the significant role played by the variant selection behavior. It is postulated that increasing cooling rates should be more feasible to change the transformed texture in Zr materials.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
基金the financial support from National Natural Science Foundation of China(project No.50975282)Chongqing Science Foundation for Outstanding Youth(project No. CSTC2008,BA4037)
文摘The friction and wear characteristics of lauroyl glutamine, lauroyl glycine and lauroyl alanine, used as green additives in HVI 350 mineral lubricating oil, were evaluated on a four-ball tribotester. The morphologies and chemical species of the worn surfaces were analyzed by scanning electron microscope （SEM） and X-ray photoelectron spectroscope （XPS）, respectively. The test results indicated that the three fatty acyl amino acids could effectively improve the anti-wear and friction-reducing abilities of the HVI 350 mineral oil. The improvement in anti-wear and friction-reducing abilities of the mineral oil by the related amino acids was mainly ascribed to the formation of a composite boundary lubrication film due to the adsorption of amino acids on the friction surfaces.
基金supported by the National Natural Science Foundation of China(Grant Nos.51101177,51401040,51171146 and 51171216)the Natural Science Foundation of Chongqing(Grant No.CSTC2012JJA245)
文摘A Cu-50Cr alloy was treated by the high current pulsed electron beam(HCPEB)at 20 and 30 ke V with pulse numbers ranging from 1 to 100.Surface morphologies and microstructures of specimens before and after the treatments were investigated by employing scanning electron microscopy and X-ray diffraction.Results show that the HCPEB technique is able to induce remarkable surface modifications for the Cu-50Cr alloy.Cracks in Cr phases appear even after one-pulse treatment and their density always increases with the pulse number.Formation reason for these cracks is attributed to quasi-static thermal stresses accumulated along the specimen surface.Craters with typical morphologies are formed due to the dynamic thermal field induced by the HCPEB and they are found to prefer the sites near cracks or boundaries between neighboring Cr phases.Another microstructural characteristic produced by the HCPEB is the fine Cr spheroids,which are determined to be due to occurrence of liquid phase separation in the Cu-50Cr alloy.Finally,a general microstructural evolution profile that incorporates various HCPEB-induced surface features is tentatively outlined.
基金supported by the National Natural Science Foundation of China(Grant Nos.51401040,51371202,51531005,51401039 and51421001)the China Postdoctoral Science Foundation(Grant No.2015M572446)+1 种基金the Postdoctoral Science Foundation of Chongqing(Grant No.Xm2015003)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJ1500901)
文摘A rolled and recrystallized commercially pure Zr sheet was β-solution treated and then cooled at two rates, i.e. air cooling(AC)and furnace cooling(FC). Microstructures and textures of original and β-cooled specimens were characterized by use of electron channeling contrast imaging, electron backscatter diffraction and X-ray diffraction techniques. Results reveal a novel phenomenon, i.e. the concurrent inheritance of microstructure and texture in the FC specimen cooled at a very slow rate. In contrast, for the AC specimen with faster cooling, typical lamellar α phases are obtained with relatively scattered texture.Based on comparatively crystallographic and thermodynamic analyses, reasons accounting for microstructure and texture differences in both cases are discussed, highlighting the significant role played by the variant selection behavior. It is postulated that increasing cooling rates should be more feasible to change the transformed texture in Zr materials.
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.
