Micro arc oxidation(MAO) and electrophoretic deposition(EPD) process are employed to fabricate a dense coating on magnesium alloy to protect it from corrosion in engineering application. The EPD film changes the dampi...Micro arc oxidation(MAO) and electrophoretic deposition(EPD) process are employed to fabricate a dense coating on magnesium alloy to protect it from corrosion in engineering application. The EPD film changes the damping characteristic of magnesium alloy, and both the MAO and EPD process change the bending stiffness of samples being treated. Damping loss factor(DLF) test and sound transmission experiments were carried out for AZ31 B magnesium alloy with coating fabricated by MAO and EPD processes. The results indicate that DLF is improved in frequency range from 0-850 Hz. Bending stiffness of the samples is improved with MAO and EPD treatment. As a result, the sound transmission loss(LST) is improved in the stiffness control stage of the sound transmission verse frequency curve. To the samples by electrophoresis process, the LST is improved in frequency range from 2500-3200 Hz, because the damping loss factor is improved with EPD process. The results are useful for the surface treatment to enhance the damping loss factor, LST and widespread application of magnesium alloy while improving the corrosion resistance.展开更多
For the purpose of evaluating the role of ligand exchange of sulfate ions in retarding the rate of acidification of variable charge soils, the changes in pH after the addition of different amounts of HNO_3 or H_2SO_4 ...For the purpose of evaluating the role of ligand exchange of sulfate ions in retarding the rate of acidification of variable charge soils, the changes in pH after the addition of different amounts of HNO_3 or H_2SO_4 to representative soils of China were measured. A difrerence between pH changes caused by the two kinds of acids was observed only for variable charge soils and kaolinite, but not for consted charge soils and bentonite. The larger the proportion of H_2SO_4 in the HNO_3-H_2SO_4 mixture, the lower the calculated H￣+ ion activities remained in the suspension. The difference in H￣+ ion activities between H_2SO_4 systems and HNO_3 systems was larger for soils with a low base-saturation (BS) percentage than those with a high BS percentage. The removal of free iron oxides from the soil led to a decrease in the difference, while the coating of Fe_2O_3 ona bentonite resulted in a remarkable appearance of the difference. The effect of ligand exchange on the acidity status of the soil varied with the soil type. SurfaCe soils with a hash organic matter content showed a less pronounced effect of ligand exchange than subsoils did. It was estimated that when acid rain chiefly containing H_2SO_4 was deposited on variable charge soils the acidilication rate might be slower by 20%-40% than that when the acid rain chiefly contained HNO_3 for soils with a high organic matter content, and that the rate might be half of that caused by HNO_3 for soils with a low organic matter content, especially for latosols.展开更多
LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2, LiMn_2O_4 and LiCoO_2 are paired to make the blended materials for the cathode of lithium-ion batteries. The factors impacting on the characteristics of blended materials are studied usi...LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2, LiMn_2O_4 and LiCoO_2 are paired to make the blended materials for the cathode of lithium-ion batteries. The factors impacting on the characteristics of blended materials are studied using constant current charge/discharge measurement and electrochemical impedance spectroscopy. The results show that the three pairs of blended materials exhibit very different synergetic effects in high C-rate discharging. The mechanism of particle synergetic effect has a physical root on the compensating material property of blending components, which fundamentally correlates with their similarity and difference in crystalline and electronic structures. The AC impedance show the obvious changes that alternate the high C-rate performance, due to reduced particle impedance in blended materials. The pairs of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2-LiMn_2O and LiCoO_2-LiMn_2O_4 present obvious increases in high C-rate reversible capacities than does the pair LiCoO_2-LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2.展开更多
基金Project(2011BAE22B05)supported by National Technology R&D Program in the 12th Five year Plan of ChinaProject(2011DFA50900)supported by the Canada-China-USA Collaborative Research&Development ProjectProject(51071121)supported by the National Natural Science Foundation of China
文摘Micro arc oxidation(MAO) and electrophoretic deposition(EPD) process are employed to fabricate a dense coating on magnesium alloy to protect it from corrosion in engineering application. The EPD film changes the damping characteristic of magnesium alloy, and both the MAO and EPD process change the bending stiffness of samples being treated. Damping loss factor(DLF) test and sound transmission experiments were carried out for AZ31 B magnesium alloy with coating fabricated by MAO and EPD processes. The results indicate that DLF is improved in frequency range from 0-850 Hz. Bending stiffness of the samples is improved with MAO and EPD treatment. As a result, the sound transmission loss(LST) is improved in the stiffness control stage of the sound transmission verse frequency curve. To the samples by electrophoresis process, the LST is improved in frequency range from 2500-3200 Hz, because the damping loss factor is improved with EPD process. The results are useful for the surface treatment to enhance the damping loss factor, LST and widespread application of magnesium alloy while improving the corrosion resistance.
文摘For the purpose of evaluating the role of ligand exchange of sulfate ions in retarding the rate of acidification of variable charge soils, the changes in pH after the addition of different amounts of HNO_3 or H_2SO_4 to representative soils of China were measured. A difrerence between pH changes caused by the two kinds of acids was observed only for variable charge soils and kaolinite, but not for consted charge soils and bentonite. The larger the proportion of H_2SO_4 in the HNO_3-H_2SO_4 mixture, the lower the calculated H￣+ ion activities remained in the suspension. The difference in H￣+ ion activities between H_2SO_4 systems and HNO_3 systems was larger for soils with a low base-saturation (BS) percentage than those with a high BS percentage. The removal of free iron oxides from the soil led to a decrease in the difference, while the coating of Fe_2O_3 ona bentonite resulted in a remarkable appearance of the difference. The effect of ligand exchange on the acidity status of the soil varied with the soil type. SurfaCe soils with a hash organic matter content showed a less pronounced effect of ligand exchange than subsoils did. It was estimated that when acid rain chiefly containing H_2SO_4 was deposited on variable charge soils the acidilication rate might be slower by 20%-40% than that when the acid rain chiefly contained HNO_3 for soils with a high organic matter content, and that the rate might be half of that caused by HNO_3 for soils with a low organic matter content, especially for latosols.
基金supported by the National Research Program of China (Grant No. 2013AA050901)the National Young Scholar Natural Science Foundation of China (Grant No. 201303235)+3 种基金the Public Projects of Zhejiang Province (Grant No. 2015C31122)Zhejiang Natural Science Foundation(Grant No. LY16B030007)Ningbo Natural Science Foundation (Grant No.2015A610240)Zhejiang Province Key Science and Technology InnovationTeam (Grant No. 2013PT16)
文摘LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2, LiMn_2O_4 and LiCoO_2 are paired to make the blended materials for the cathode of lithium-ion batteries. The factors impacting on the characteristics of blended materials are studied using constant current charge/discharge measurement and electrochemical impedance spectroscopy. The results show that the three pairs of blended materials exhibit very different synergetic effects in high C-rate discharging. The mechanism of particle synergetic effect has a physical root on the compensating material property of blending components, which fundamentally correlates with their similarity and difference in crystalline and electronic structures. The AC impedance show the obvious changes that alternate the high C-rate performance, due to reduced particle impedance in blended materials. The pairs of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2-LiMn_2O and LiCoO_2-LiMn_2O_4 present obvious increases in high C-rate reversible capacities than does the pair LiCoO_2-LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2.
