The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed ...The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed that the polymer formed in plasma is amorphous crosslinked polymer, and its backbone is made of carbon atoms. The surface energy of the polymer film is independent of the polymerization conditions. No addition reaction has taken place in the carbonyl group of butylaldehyde in the plasma condition. The result of the wettability measurements showed that the polymer film is generally hydrophobic and the surface energy of the film is about 41 dyn/cm, in which the dispersion force contribution is the majority. The electron diffraction proved that some crystal substance, even the single crystals were present in the polymer. X-ray diffraction also proved the presence of crystal and showed about 15% crystaUinity fraction.展开更多
The films deposited at low temperature（LT-films） have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited ...The films deposited at low temperature（LT-films） have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited at room temperature.Studies on the tribological properties of LT-films are rarely reported in available literatures.In this paper,the structure,morphology and tribological properties of Ag films,deposited at LT（166 K） under various Ar pressures on AISI 440C steel substrates by arc ion plating（AIP）,are studied by X-ray diffraction（XRD）,atomic force microscopy（AFM） and a vacuum ball-on-disk tribometer,and compared with the Ag films deposited at RT（300 K）.XRD results show that（200） preferred orientation of the films is promoted at LT and low Ar pressure.The Crystallite sizes are 70 nm-80 nm for LT-Ag films deposited at 0.2 Pa and 0.8 Pa and larger than 100 nm for LT-Ag films deposited at 0.4 Pa and 0.6 Pa,while they are 55 nm-60 nm for RT-Ag films deposited at 0.2 Pa-0.6 Pa and 37 nm for RT-Ag films deposited at 0.8 Pa.The surfaces of LT-Ag films are fibre-like at 0.6 Pa and 0.8 Pa,terrace-like at 0.4 Pa,and sphere-like at 0.2 Pa,while the surfaces of RT-Ag films are composed of sphere-like grains separated by voids.Wear tests reveal that,due to the compact microstructure LT-Ag films have better wear resistances than RT-Ag film.These results indicate that the microstructure and wear resistance of Ag films deposited by AIP can be improved by low temperature deposition.展开更多
A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-...A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.展开更多
The experiments were carried out to measure the mechanical properties ofthree grades of structural steels (Q235A, 16Mn and Q390E steel) at low temperature. It was shownthat the strength of the steels increases while t...The experiments were carried out to measure the mechanical properties ofthree grades of structural steels (Q235A, 16Mn and Q390E steel) at low temperature. It was shownthat the strength of the steels increases while the plasticity and toughness decrease as temperaturedrops. In the transitional area the toughness drops rapidly with temperature. Among the threestructural steels, Q390E steel has the best toughness and the lowest sensitivity.展开更多
La15Fe77B8 hydrogen storage alloys were prepared using a vacuum induction-quenching furnace. The results of X-ray dif-fraction （XRD） and scanning electron microscopy （SEM） suggested that La15-xSmxFe2Ni76Mn5B2（x=0...La15Fe77B8 hydrogen storage alloys were prepared using a vacuum induction-quenching furnace. The results of X-ray dif-fraction （XRD） and scanning electron microscopy （SEM） suggested that La15-xSmxFe2Ni76Mn5B2（x=0, 2, 4, 6） alloys had multiphase structure including the main LaNi5 phase, La3Ni13B2 phase and （Fe, Ni） phase. With the increasing substitution of Sm for La, the main phase structure of alloys did not change, while the unit cell volumes decreased, the cycle stability was improved and the maximum discharge capacity decreased, but the low temperature maximum discharge capacity of the same substitution alloy was gradually ap-proaching the maximum discharge capacity at room temperature, which showed that La15Fe77B8 hydrogen storage alloys of the partial substitution of Sm for La had better low-temperature dischargeability （LTD）. For the same substitution alloys, self-discharge charac-teristics and cycle stability at low temperature were better than that at room temperature. Furthermore, the high-rate dischargeability （HRD） and the exchange current densityI0 first increased and then decreased with the increasing of Sm content, whereas the hydro-gen diffusion coefficientD in alloy bulk decreased gradually, which indicated that appropriate substitution of Sm for La improved the electrochemical kinetics properties of the alloys. The HRD was mainly dominated by the charge-transfer rate on the alloy surface.展开更多
Based on the two-dimensional three-temperature （2D3T） radiation diffusion equations and its discrete system, using the block diagonal structure of the three-temperature matrix, the reordering and symbolic decomposit...Based on the two-dimensional three-temperature （2D3T） radiation diffusion equations and its discrete system, using the block diagonal structure of the three-temperature matrix, the reordering and symbolic decomposition parts of the RSMF method are replaced with corresponding block operation in order to improve the solution efficiency. We call this block form method block RSMF （in brief, BRSMF） method. The new BRSMF method not only makes the reordering and symbolic decomposition become more effective, but also keeps the cost of numerical factorization from increasing and ensures the precision of solution very well. The theoretical analysis of the computation complexity about the new BRSMF method shows that the solution efficiency about the BRSMF method is higher than the original RSMF method. The numerical experiments also show that the new BRSMF method is more effective than the original RSMF method.展开更多
Lamellar tearing and crack-induced brittle failures along steel plates in the through-thickness direction seriously threaten the safety and reliability of steel thick plate structures in construction and service, espe...Lamellar tearing and crack-induced brittle failures along steel plates in the through-thickness direction seriously threaten the safety and reliability of steel thick plate structures in construction and service, especially at low ambient temperatures. Three kinds of tests, including uniaxial tensile tests, Charpy V-Notch impact tests, and three-point bending （TPB） tests were performed at normal and low temperatures to investigate the through-thickness mechanical properties, impact and fraclure toughness of Q345B structural steel plates with thicknesses from 60 to 165 mm. The test specimens were mainly sampled along the through-thickness direction of the plate, but transverse specimens along the rolling direction were also involved. The ductility index （percentage reduction of area）, impact toughness index （Charpy impact energy）, and fracture toughness index （critical crack tip opening displacement （CTOD） values） all decrease as the temperature declines. All the mechanical properties and the impact and fracture toughness along the through-thickness direction are worse than those along the rolling direction. The results also offer experimental support for the determination of an evaluation indicator for structural steel thick plates with through-thickness characteristics.展开更多
基金Project sponsored by the National Natural Science Foundation of China.
文摘The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed that the polymer formed in plasma is amorphous crosslinked polymer, and its backbone is made of carbon atoms. The surface energy of the polymer film is independent of the polymerization conditions. No addition reaction has taken place in the carbonyl group of butylaldehyde in the plasma condition. The result of the wettability measurements showed that the polymer film is generally hydrophobic and the surface energy of the film is about 41 dyn/cm, in which the dispersion force contribution is the majority. The electron diffraction proved that some crystal substance, even the single crystals were present in the polymer. X-ray diffraction also proved the presence of crystal and showed about 15% crystaUinity fraction.
基金supported by National Basic Research Program of China(973 Project,Grant No.2007CB607601)National Natural Science Foundation of China (Grant No. 50301015)
文摘The films deposited at low temperature（LT-films） have increasingly attracted theoretical and technical interests since such films exhibit obvious difference in structure and performances compared to those deposited at room temperature.Studies on the tribological properties of LT-films are rarely reported in available literatures.In this paper,the structure,morphology and tribological properties of Ag films,deposited at LT（166 K） under various Ar pressures on AISI 440C steel substrates by arc ion plating（AIP）,are studied by X-ray diffraction（XRD）,atomic force microscopy（AFM） and a vacuum ball-on-disk tribometer,and compared with the Ag films deposited at RT（300 K）.XRD results show that（200） preferred orientation of the films is promoted at LT and low Ar pressure.The Crystallite sizes are 70 nm-80 nm for LT-Ag films deposited at 0.2 Pa and 0.8 Pa and larger than 100 nm for LT-Ag films deposited at 0.4 Pa and 0.6 Pa,while they are 55 nm-60 nm for RT-Ag films deposited at 0.2 Pa-0.6 Pa and 37 nm for RT-Ag films deposited at 0.8 Pa.The surfaces of LT-Ag films are fibre-like at 0.6 Pa and 0.8 Pa,terrace-like at 0.4 Pa,and sphere-like at 0.2 Pa,while the surfaces of RT-Ag films are composed of sphere-like grains separated by voids.Wear tests reveal that,due to the compact microstructure LT-Ag films have better wear resistances than RT-Ag film.These results indicate that the microstructure and wear resistance of Ag films deposited by AIP can be improved by low temperature deposition.
文摘A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50078029).
文摘The experiments were carried out to measure the mechanical properties ofthree grades of structural steels (Q235A, 16Mn and Q390E steel) at low temperature. It was shownthat the strength of the steels increases while the plasticity and toughness decrease as temperaturedrops. In the transitional area the toughness drops rapidly with temperature. Among the threestructural steels, Q390E steel has the best toughness and the lowest sensitivity.
基金Project supported by National Natural Science Foundation of China(51061001)the Projects in International Science and Technology Cooperation from Ministry of Science and Technology of the PRC(2010DFB63510)
文摘La15Fe77B8 hydrogen storage alloys were prepared using a vacuum induction-quenching furnace. The results of X-ray dif-fraction （XRD） and scanning electron microscopy （SEM） suggested that La15-xSmxFe2Ni76Mn5B2（x=0, 2, 4, 6） alloys had multiphase structure including the main LaNi5 phase, La3Ni13B2 phase and （Fe, Ni） phase. With the increasing substitution of Sm for La, the main phase structure of alloys did not change, while the unit cell volumes decreased, the cycle stability was improved and the maximum discharge capacity decreased, but the low temperature maximum discharge capacity of the same substitution alloy was gradually ap-proaching the maximum discharge capacity at room temperature, which showed that La15Fe77B8 hydrogen storage alloys of the partial substitution of Sm for La had better low-temperature dischargeability （LTD）. For the same substitution alloys, self-discharge charac-teristics and cycle stability at low temperature were better than that at room temperature. Furthermore, the high-rate dischargeability （HRD） and the exchange current densityI0 first increased and then decreased with the increasing of Sm content, whereas the hydro-gen diffusion coefficientD in alloy bulk decreased gradually, which indicated that appropriate substitution of Sm for La improved the electrochemical kinetics properties of the alloys. The HRD was mainly dominated by the charge-transfer rate on the alloy surface.
基金supported by the National Natural Science Foundation of China(GrantNos.61202098,61033009,61170309,91130024,and 11171039)the China Tianyuan Mathematics Youth Fund(GrantNo.11226337)
文摘Based on the two-dimensional three-temperature （2D3T） radiation diffusion equations and its discrete system, using the block diagonal structure of the three-temperature matrix, the reordering and symbolic decomposition parts of the RSMF method are replaced with corresponding block operation in order to improve the solution efficiency. We call this block form method block RSMF （in brief, BRSMF） method. The new BRSMF method not only makes the reordering and symbolic decomposition become more effective, but also keeps the cost of numerical factorization from increasing and ensures the precision of solution very well. The theoretical analysis of the computation complexity about the new BRSMF method shows that the solution efficiency about the BRSMF method is higher than the original RSMF method. The numerical experiments also show that the new BRSMF method is more effective than the original RSMF method.
基金the National Natural Science Foundation of China，the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘Lamellar tearing and crack-induced brittle failures along steel plates in the through-thickness direction seriously threaten the safety and reliability of steel thick plate structures in construction and service, especially at low ambient temperatures. Three kinds of tests, including uniaxial tensile tests, Charpy V-Notch impact tests, and three-point bending （TPB） tests were performed at normal and low temperatures to investigate the through-thickness mechanical properties, impact and fraclure toughness of Q345B structural steel plates with thicknesses from 60 to 165 mm. The test specimens were mainly sampled along the through-thickness direction of the plate, but transverse specimens along the rolling direction were also involved. The ductility index （percentage reduction of area）, impact toughness index （Charpy impact energy）, and fracture toughness index （critical crack tip opening displacement （CTOD） values） all decrease as the temperature declines. All the mechanical properties and the impact and fracture toughness along the through-thickness direction are worse than those along the rolling direction. The results also offer experimental support for the determination of an evaluation indicator for structural steel thick plates with through-thickness characteristics.
