The effect of Si content on the microstructures and growth kinetics of intermetallic compounds(IMCs)formed during the initial interfacial reaction(<10 s)between solid steel and liquid aluminum was investigated by a...The effect of Si content on the microstructures and growth kinetics of intermetallic compounds(IMCs)formed during the initial interfacial reaction(<10 s)between solid steel and liquid aluminum was investigated by a thermophysical simulation method.The influence of Si addition on interfacial mechanical properties was revealed by a high-frequency induction brazing.The results showed that IMCs layers mainly consisted ofη-Fe_(2)Al_(5)andθ-Fe_(4)Al_(13).The addition of Si reduced the thickness of the IMCs layer.The growth of theηphase was governed by the diffusion process when adding 2 wt.%Si to the aluminum melt.When 5 wt.%or 8 wt.%Si was added to aluminum,the growth was governed by both the diffusion process and interfacial reaction,and ternary phaseτ1/τ9-(Al,Si)_(5)Fe_(3)was formed in theηphase.The apparent activation energies of theηphase decreased gradually with increasing Si content.The joint with pure aluminum metal had the highest tensile strength and impact energy.展开更多
The correlation between Si content （0.1%-0.5%, mass fraction） and pulse laser welding performance of AI-Mn-Mg aluminum alloy sheets was studied. The sheets were fabricated in the laboratory, with gauge of 0.45 mm, H...The correlation between Si content （0.1%-0.5%, mass fraction） and pulse laser welding performance of AI-Mn-Mg aluminum alloy sheets was studied. The sheets were fabricated in the laboratory, with gauge of 0.45 mm, H16 temper by pulse laser welding. It was found that no cracking existed in the welding pool as Si content was below 0.34%. However, when the Si content increased to 0.47%, cracking formed in the welding pool. Microstructure observations indicated that residual eutectic phases distributed at the grain boundaries were discontinuous and appeared to be small particles in lower Si content alloys; the residual eutectic phases distributed at the grain boundaries were partially continuous and appeared to be films in higher Si content alloys. These phenomena could explain why Si content adversely affected the laser welding performance.展开更多
It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and mi...It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.展开更多
By means of scanning electron microscopy(SEM), energy dispersive spectrum(EDS), X-ray diffractometry(XRD) and metallographic analysis, the effects of variation of magnesium content on phase constituents of Al-Mg-Si-Cu...By means of scanning electron microscopy(SEM), energy dispersive spectrum(EDS), X-ray diffractometry(XRD) and metallographic analysis, the effects of variation of magnesium content on phase constituents of Al-Mg-Si-Cu alloys were investigated. The results indicate that the constituents formed during casting alloys are main Al1.9CuMg4.1Si3.3,Al4(MnFe)3Si2 and Mg2Si, while pure Si is only present in the alloy containing lower magnesium content. Increasing Mg content leads to increasing the amount of Mg2Si, but decreasing the amount of Al1.9CuMg4.1Si3.3 and Al4(MnFe)3Si2. During the following homogenization process, Al1.9CuMg4.1Si3.3 is completely dissolved, Al4(MnFe)3Si2 and pure Si remain unchanged. After rolling and final heat treatment, the constituents in the alloys change no longer.展开更多
Implementing high-performance silicon(Si)anode in actual processing and application is highly desirable for next-generation,high-energy Li-ion batteries.However,high content of inactive matrix(including conductive age...Implementing high-performance silicon(Si)anode in actual processing and application is highly desirable for next-generation,high-energy Li-ion batteries.However,high content of inactive matrix(including conductive agent and binder)is often indispensable in order to ensure local conductivity and suppress pulverization tendency of Si particles,which thus cause great capacity loss based on the mass of whole electrode.Here,we designed an accordion-structured,high-performance electrode with high Si content up to 95%.Si nanoparticles were well anchored into the interlayer spacings of accordion-like graphene arrays,and free-standing electrode was prepared via a simple filtration process without any binder.Conductive accordion framework ensures strong confinement effect of Si nanoparticles and also provides direct,non-tortuous channels for fast electrochemical reaction kinetics.As a consequence,the accordion Si electrodes exhibit ultrahigh,electrode-based capacities up to 3149 mAh g^(-1)(under Si content of 91%),as well as long-term stability.Also,the accordion electrode can bear extreme condition of over-lithiation and maintains stable in full-cell test.This design provides a significant stride in high Si content toward realistic,high-performance electrodes.展开更多
In order to investigate whether an air–water plasma jet is beneficial to improve the efficiency of inactivation, a series of experiments were done using a ring-needle plasma jet. The water content in the working gas...In order to investigate whether an air–water plasma jet is beneficial to improve the efficiency of inactivation, a series of experiments were done using a ring-needle plasma jet. The water content in the working gas（air） was accurately measured based on the Karl Fischer method. The effects of water on the production of OH（A;Σ;–X;Π;） and O（3p;P–3s;S） were also studied by optical emission spectroscopy. The results show that the water content is in the range of 2.53–9.58 mg l;, depending on the gas/water mixture ratio. The production of OH（A;Σ;–X;Π;） rises with the increase of water content, whereas the O（3p;P–3s;S） shows a declining tendency with higher water content. The sterilization experiments indicate that this air–water plasma jet inactivates the P. digitatum spores very effectively and its efficiency rises with the increase of the water content. It is possible that OH（A;Σ;–X;Π;） is a more effective species in inactivation than O（3p;P–3s;S） and the water content benefit the spore germination inhibition through rising the OH（A;Σ;–X;Π;） production. The maximum of the inactivation efficacy is up to 93% when the applied voltage is -6.75 kV and the water content is 9.58 mg l;.展开更多
Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R（R = F, OH, NH2） have been systematically carried out by combined density functional theory（...Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R（R = F, OH, NH2） have been systematically carried out by combined density functional theory（DFT） and ab initio quantum chemical calculations. The geometries of all stationary points for these reactions were optimized using the B3 LYP method and then the QCISD method was used to calculate the single-point energies. The calculated results indicate that, there are one precursor complex（Q）, one transition state（TS）, and one intermediate（IM） which connect the reactants and the products along the potential energy surface. The insertion reactions of three-membered-ring silylenoid with Ge H3 R proceed in a concerted manner, forming H2RSi-Ge H3 and Li F. The calculated potential energy barriers of the three reactions are 29.17, 30.90, and 54.07 k J/mol, and the reaction energies for the three reactions are –127.05, –116.91, and –103.31 k J/mol, respectively. The insertion reactions in solvents are similar to those in vacuum. Under the same situation, the insertion reactions should occur easily in the following order： GeH 3-F GeH 3-OH GeH 3-NH2. The elucidations of the mechanism of these insertion reactions provided a new mode of silicon-germanium bond formation.展开更多
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51875037)the Beijing Municipal Natural Science Foundation,China(No.3192021)the Fundamental Research Funds for the Central Universities,China(No.FRF-GF-18-004B).
文摘The effect of Si content on the microstructures and growth kinetics of intermetallic compounds(IMCs)formed during the initial interfacial reaction(<10 s)between solid steel and liquid aluminum was investigated by a thermophysical simulation method.The influence of Si addition on interfacial mechanical properties was revealed by a high-frequency induction brazing.The results showed that IMCs layers mainly consisted ofη-Fe_(2)Al_(5)andθ-Fe_(4)Al_(13).The addition of Si reduced the thickness of the IMCs layer.The growth of theηphase was governed by the diffusion process when adding 2 wt.%Si to the aluminum melt.When 5 wt.%or 8 wt.%Si was added to aluminum,the growth was governed by both the diffusion process and interfacial reaction,and ternary phaseτ1/τ9-(Al,Si)_(5)Fe_(3)was formed in theηphase.The apparent activation energies of theηphase decreased gradually with increasing Si content.The joint with pure aluminum metal had the highest tensile strength and impact energy.
基金Project(2011KJZD04)supported by the CHINALCO Science and Development Foundation,China
文摘The correlation between Si content （0.1%-0.5%, mass fraction） and pulse laser welding performance of AI-Mn-Mg aluminum alloy sheets was studied. The sheets were fabricated in the laboratory, with gauge of 0.45 mm, H16 temper by pulse laser welding. It was found that no cracking existed in the welding pool as Si content was below 0.34%. However, when the Si content increased to 0.47%, cracking formed in the welding pool. Microstructure observations indicated that residual eutectic phases distributed at the grain boundaries were discontinuous and appeared to be small particles in lower Si content alloys; the residual eutectic phases distributed at the grain boundaries were partially continuous and appeared to be films in higher Si content alloys. These phenomena could explain why Si content adversely affected the laser welding performance.
基金This work is supported by the National Natural Science Foundation of China （Grant Nos. 60336010 ＆ 90401001）973 Program （Grant No. TG 2000036603）the Student Innovation Program of CAS （No. 1731000500010）.
文摘It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.
基金Project(2002AA331050) supported by Hi-tech Research and Development Program of China project(0208) supported by Science and Technology Research of Ministry of Education of China
文摘By means of scanning electron microscopy(SEM), energy dispersive spectrum(EDS), X-ray diffractometry(XRD) and metallographic analysis, the effects of variation of magnesium content on phase constituents of Al-Mg-Si-Cu alloys were investigated. The results indicate that the constituents formed during casting alloys are main Al1.9CuMg4.1Si3.3,Al4(MnFe)3Si2 and Mg2Si, while pure Si is only present in the alloy containing lower magnesium content. Increasing Mg content leads to increasing the amount of Mg2Si, but decreasing the amount of Al1.9CuMg4.1Si3.3 and Al4(MnFe)3Si2. During the following homogenization process, Al1.9CuMg4.1Si3.3 is completely dissolved, Al4(MnFe)3Si2 and pure Si remain unchanged. After rolling and final heat treatment, the constituents in the alloys change no longer.
基金supported by Shaanxi Yanchang Petroleum Co.,Ltd.(18529)Yiwu Research Institute of Fudan University(21557)+1 种基金the National Science Foundation of China(22075048)the Shanghai International Collaboration Research Project(19520713900).
文摘Implementing high-performance silicon(Si)anode in actual processing and application is highly desirable for next-generation,high-energy Li-ion batteries.However,high content of inactive matrix(including conductive agent and binder)is often indispensable in order to ensure local conductivity and suppress pulverization tendency of Si particles,which thus cause great capacity loss based on the mass of whole electrode.Here,we designed an accordion-structured,high-performance electrode with high Si content up to 95%.Si nanoparticles were well anchored into the interlayer spacings of accordion-like graphene arrays,and free-standing electrode was prepared via a simple filtration process without any binder.Conductive accordion framework ensures strong confinement effect of Si nanoparticles and also provides direct,non-tortuous channels for fast electrochemical reaction kinetics.As a consequence,the accordion Si electrodes exhibit ultrahigh,electrode-based capacities up to 3149 mAh g^(-1)(under Si content of 91%),as well as long-term stability.Also,the accordion electrode can bear extreme condition of over-lithiation and maintains stable in full-cell test.This design provides a significant stride in high Si content toward realistic,high-performance electrodes.
基金supported by National Natural Science Foundation of China (NSFC) under Grants No. 51407020National Key Technology Research and Development Program of the Ministry of Science and Technology of China under Grants No. 2014BAC13B05Visiting Scholarship of State Key Laboratory of Power Transmission Equipment & System Security and New Technology (Chongqing University) No. 2007DA10512716404
文摘In order to investigate whether an air–water plasma jet is beneficial to improve the efficiency of inactivation, a series of experiments were done using a ring-needle plasma jet. The water content in the working gas（air） was accurately measured based on the Karl Fischer method. The effects of water on the production of OH（A;Σ;–X;Π;） and O（3p;P–3s;S） were also studied by optical emission spectroscopy. The results show that the water content is in the range of 2.53–9.58 mg l;, depending on the gas/water mixture ratio. The production of OH（A;Σ;–X;Π;） rises with the increase of water content, whereas the O（3p;P–3s;S） shows a declining tendency with higher water content. The sterilization experiments indicate that this air–water plasma jet inactivates the P. digitatum spores very effectively and its efficiency rises with the increase of the water content. It is possible that OH（A;Σ;–X;Π;） is a more effective species in inactivation than O（3p;P–3s;S） and the water content benefit the spore germination inhibition through rising the OH（A;Σ;–X;Π;） production. The maximum of the inactivation efficacy is up to 93% when the applied voltage is -6.75 kV and the water content is 9.58 mg l;.
基金supported by the National Natural Science Foundation Committee of China(No.21103145)the Natural Science Foundation of Shandong Province(No.ZR2009BQ006)+3 种基金the Fund for Doctor of Yantai University(No.HY05B30)the Special Foundation of Youth Academic Backbone of Yantai Universitysupport by the Open fund(sklssm201418)of the State Key Laboratory of Supramolecular Structure and Materials,Jilin Universitythe Graduate Innovation Foundation of Yantai University,GIFYTU
文摘Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R（R = F, OH, NH2） have been systematically carried out by combined density functional theory（DFT） and ab initio quantum chemical calculations. The geometries of all stationary points for these reactions were optimized using the B3 LYP method and then the QCISD method was used to calculate the single-point energies. The calculated results indicate that, there are one precursor complex（Q）, one transition state（TS）, and one intermediate（IM） which connect the reactants and the products along the potential energy surface. The insertion reactions of three-membered-ring silylenoid with Ge H3 R proceed in a concerted manner, forming H2RSi-Ge H3 and Li F. The calculated potential energy barriers of the three reactions are 29.17, 30.90, and 54.07 k J/mol, and the reaction energies for the three reactions are –127.05, –116.91, and –103.31 k J/mol, respectively. The insertion reactions in solvents are similar to those in vacuum. Under the same situation, the insertion reactions should occur easily in the following order： GeH 3-F GeH 3-OH GeH 3-NH2. The elucidations of the mechanism of these insertion reactions provided a new mode of silicon-germanium bond formation.
