This paper presents a comparative study of the influence of nanometer-CeO_2（nano-CeO_2） and temperature on tribological and lubricating properties of lithium grease. The morphology and structure of nanocrystals were...This paper presents a comparative study of the influence of nanometer-CeO_2（nano-CeO_2） and temperature on tribological and lubricating properties of lithium grease. The morphology and structure of nanocrystals were characterized by means of transmission electron microscopy（TEM） and X-ray diffraction（XRD）, respectively. Friction and wear tests were conducted on the friction and wear tester.Results show that the lithium grease with addition of nanometer-CeO_2 has much better friction-reducing and anti-wear performance than that of base grease. When the additive in grease is 0.6 wt%, the friction coefficient（COF） and wear scar diameter（WSD） decrease by 28% and 13% comparing with base grease,respectively. The base grease and grease with 0.6 wt% nanometer-CeO_2 both possess the lowest average COF and wear width at 50 ℃. The worn surface morphology after friction test was analyzed by scanning electron microscopy（SEM） and NANOVEA three-dimensional profilometer. Under the lubrication of the lithium grease containing 0.6 wt% nano-CeO_2. few shallow furrows can be observed on the quite smoothed surface and the WSD decreased. Moreover, It was found that the nano-CeO_2 has been incorporated into the surface protective and lubricious layer by energy dispersive spectrometer（EDS） analysis.展开更多
Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.1...Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.15Ce were prepared through reduction, iso- static pressing, sintering, and drawing. Tensile properties, second phase microstructure and fracture surface appear- ance of wires were analyzed. The better refining effect for Mo alloy powder can be gotten after two kinds of nano- particle oxide doped into MoO2 than only one doped. Nano-Y2O3 and nano-CeO2 have different influences on sintering process. For nano-CeO2, the constraining effect of grain growth focuses on the initial sintering stage, nano- Y2O3 plays refining grains roles in the later densification stage. Nano-Y2O3 is undistorted and keeps intact in the process of drawing; and nano-CeO2 is elongated and bro- ken into parts in the drawing direction. The strengthening effect of nano-Y2O3 and nano-CeO2 keeps the finer grains and superior tensile properties for Mo-0.15Y-0.15Ce wire.展开更多
Aggregates of cerium dioxide nanoparticles(nano-CeO_2) were successfully prepared via a facile solvothermal process in this study. The crystallographic information and morphological information of nano-CeO_2 were syst...Aggregates of cerium dioxide nanoparticles(nano-CeO_2) were successfully prepared via a facile solvothermal process in this study. The crystallographic information and morphological information of nano-CeO_2 were systematically studied by X-ray diffraction(XRD),transmission electron microscopy(TEM), laser particle size analyzer(LA) and specific surface area and pore size analyzer during the solvothermal process. Among all the obtained samples, the 18-h solvothermal-prepared nano-CeO_2 aggregates show the best crystallinity and the largest specific surface area of 110.92 m^2·g^(-1). Owing to the high activity derived from the high specific surface area of the aggregates, the application as arsenic(As) adsorption was also studied. The adsorption efficiency of arsenic by nano-CeO_2 aggregates was established as the function of adsorbent dose, then pH value and at last adsorption time.The results indicate that the nano-CeO_2 aggregates show a high efficiency in removing arsenic from low As concentration solution, from which the nano-CeO_2 adsorbent could be easily separated. In addition, the adsorption kinetics is best fitted to pseudo-second-order model(R^2 = 0.99999).展开更多
基金Project supported by the Natural Science Foundation of the Henan Province(152102210196)the Foundation of the Henan Educational Committee(16A460001)
文摘This paper presents a comparative study of the influence of nanometer-CeO_2（nano-CeO_2） and temperature on tribological and lubricating properties of lithium grease. The morphology and structure of nanocrystals were characterized by means of transmission electron microscopy（TEM） and X-ray diffraction（XRD）, respectively. Friction and wear tests were conducted on the friction and wear tester.Results show that the lithium grease with addition of nanometer-CeO_2 has much better friction-reducing and anti-wear performance than that of base grease. When the additive in grease is 0.6 wt%, the friction coefficient（COF） and wear scar diameter（WSD） decrease by 28% and 13% comparing with base grease,respectively. The base grease and grease with 0.6 wt% nanometer-CeO_2 both possess the lowest average COF and wear width at 50 ℃. The worn surface morphology after friction test was analyzed by scanning electron microscopy（SEM） and NANOVEA three-dimensional profilometer. Under the lubrication of the lithium grease containing 0.6 wt% nano-CeO_2. few shallow furrows can be observed on the quite smoothed surface and the WSD decreased. Moreover, It was found that the nano-CeO_2 has been incorporated into the surface protective and lubricious layer by energy dispersive spectrometer（EDS） analysis.
基金financially supported by the National Tungsten and Molybdenum Value-added Utilization Tech-nology Industry Development(No.2012BAE06B02)Shanxi Province Science and Technology Innovation Plan(No.2012KTCQ01-08)
文摘Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.15Ce were prepared through reduction, iso- static pressing, sintering, and drawing. Tensile properties, second phase microstructure and fracture surface appear- ance of wires were analyzed. The better refining effect for Mo alloy powder can be gotten after two kinds of nano- particle oxide doped into MoO2 than only one doped. Nano-Y2O3 and nano-CeO2 have different influences on sintering process. For nano-CeO2, the constraining effect of grain growth focuses on the initial sintering stage, nano- Y2O3 plays refining grains roles in the later densification stage. Nano-Y2O3 is undistorted and keeps intact in the process of drawing; and nano-CeO2 is elongated and bro- ken into parts in the drawing direction. The strengthening effect of nano-Y2O3 and nano-CeO2 keeps the finer grains and superior tensile properties for Mo-0.15Y-0.15Ce wire.
基金financially supported by the Sichuan Province Science and Technology Support Program (No. 2014GZ0090)
文摘Aggregates of cerium dioxide nanoparticles(nano-CeO_2) were successfully prepared via a facile solvothermal process in this study. The crystallographic information and morphological information of nano-CeO_2 were systematically studied by X-ray diffraction(XRD),transmission electron microscopy(TEM), laser particle size analyzer(LA) and specific surface area and pore size analyzer during the solvothermal process. Among all the obtained samples, the 18-h solvothermal-prepared nano-CeO_2 aggregates show the best crystallinity and the largest specific surface area of 110.92 m^2·g^(-1). Owing to the high activity derived from the high specific surface area of the aggregates, the application as arsenic(As) adsorption was also studied. The adsorption efficiency of arsenic by nano-CeO_2 aggregates was established as the function of adsorbent dose, then pH value and at last adsorption time.The results indicate that the nano-CeO_2 aggregates show a high efficiency in removing arsenic from low As concentration solution, from which the nano-CeO_2 adsorbent could be easily separated. In addition, the adsorption kinetics is best fitted to pseudo-second-order model(R^2 = 0.99999).
