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Galvanostatic anodic polarisation of WE43

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Journal of Magnesium and Alloys 2014年第3期2卷 197-202页

作者： Zhiming Shi Jimmy Xueshan Jia Andrej Atrens The University of Queensland Queensland Centre for Advanced Materials Processing and Manufacturing(AMPAM)Department of Mechanical and Mining EngineeringBrisbaneQld 4072Australia The University of Queensland Defence Materials Technology CentreBrisbaneQld 4072Australia The University of Queensland Division of MaterialsDepartment of Mechanical and Mining EngineeringBrisbaneQld 4072 Australia

The Mg corrosion mechanism was explored using galvanostatic polarisation curves,hydrogen evolution and weight *** data(a)were consistent with the existence of the uni-positive Mg+ion,(b)indicated that some hydrogen dissolved in the WE43 metal,and(c)indicated that self corrosion was more important than the applied current density in causing weight loss.

关键词： Magnesium Galvanostatic polarisation SEM Weight loss Hydrogen adsorption Negative difference effect

Influence of Component Size on the Corrosion Behavior of Ti6Al4V Alloy Fabricated by Electron Beam Powder Bed Fusion

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 159-168页

作者： Hongyu Zheng Xin Gai Yun Bai Wentao Hou Shujun Li Yulin Hao R.D.K.Misra Rui Yang Institute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China Nuclear Power Institute of China Chengdu610213China Department of Metallurgical Materialsand Biomedical EngineeringThe University of Texas at El Paso500WUniversity AvenueEl PasoTX79968USA

The electrochemical behavior of Ti-6Al-4V with 1 mm and 16 mm thickness prepared by electron beam powder bed fusion(EB-PBF)was investigated in phosphate buffered *** results showed that EB-PBF Ti-6Al-4V with a larger component size was more resistant to corrosion compared to the smaller component,because of less acicularαʹphase content and moreβphase *** a non-equilibrium phase in the“high-energy state”,αʹphase has a greater susceptibility to corrode and reduces the corrosion resistance of the material,whileβphase improves corrosion resistance of titanium *** results show that the phase composition has a more significant effect on the corrosion performance than the grain size.

关键词： Electron beam powder bed fusion Ti6Al4V alloy Corrosion resistance Component size polarisation

Inhibition of Zinc Corrosion by Fucoidan in Natural Sea water

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Acta Metallurgica Sinica(English Letters) 2017年第6期30卷 594-600页

作者： Cui Wang Jie Zhang Xiao-Lin Chen Bin Xiang Ji-Zhou Duan Bao-Rong Hou College of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China Key Laboratory of Marine Environmental Corrosion and Biofouling Institute of OceanologyChinese Academy of SciencesQingdao 266071China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China

Research on corrosion behaviour of zinc in natural sea water without and with fucoidan was carried out by potentiodynamic polarisation test and electrochemical impedance spectroscopy （EIS）. The results revealed that fucoidan serves as a good inhibitor for zinc in sea water. polarisation curves suggested that corrosion potential values shifted to the positive ones after adding inhibitor and fucoidan retards anodic reaction more. Thus, fucoidan can be acted as anodic inhibitor. EIS results showed two phenomena including a charge transfer and an adsorption film. The corrosion inhibition of fucoidan was further confirmed by the scanning electron microscope （SEM） and atomic force microscope （AFM） analysis. Langmuir＇s adsorption isotherm was found the appropriate adsorption model.

关键词： Zinc polarisation EIS AFM XRD Anodic protection

Linearly polarised three-colour lasing emission from an evanescent wave pumped and gain coupled fibre laser

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Chinese Physics B 2010年第5期19卷 313-319页

作者：普小云江楠韩德昱冯永利任一涛 Department of Physics Yunnan University

A novel Whispering-Gallery-Mode （WGM） fibre laser, emitting linearly polarised three-colour light, is demonstrated by pumping and gain coupling with evanescent waves. The pump light is longitudinally coupled into a bare optical fibre immersed in a dye solution of lower refractive index. The dye molecules around the bare fibre are excited by the evanescent waves of pump light when they propagate along the fibre in a total internal reflection. When the pump beam within the fibre is a meridian beam, the WGM lasing emission from the fibre laser is a linearly polarised transverse electric wave, while it is a mixed wave of the linearly polarised transverse electric and magnetic waves if the pump beam is a skew beam within the fibre. Because the excited molecules are located within the evanescent field of WGM, a good spatial overlap between the dye gain and the evanescent field leads to a high pumping efficiency and a longer gain distance along the fibre. Once the bare fibre is inserted into three glass capillaries filled with Rhodamine 6G, 610 and 640 dye solutions, respectively, WGM laser oscillations at the wavelengths of 567-575, 605-614 and 656-666 nm occur simultaneously, and a linearly polarised three-colour lasing emission is achieved in a single optical fibre.

关键词： fibre laser Whispering-Gallery-Mode evanescent wave polarisation

A hybrid model for the charging process of the amorphous SiO_2 film in radio frequency microelectromechanical system capacitive switches

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Chinese Physics B 2011年第3期20卷 426-432页

作者：王立峰黄庆安唐洁影廖小平 Key Laboratory of MEMS of the Ministry of Education Southeast University

Charging is one of the most important reliability issues in radio frequency microelectro- mechanical systems （RF MEMS） capacitive switches since it makes the actuation voltage unstable. This paper proposes a hybrid model to describe the transient dielectric charging and discharging process in the defect-rich amorphous SiO2 RF MEMS capacitive switches and verifies experimentally. The hybrid model contains two parts according to two different charging mechanisms of the amorphous SiO2, which are the polarisation and charge injection. The models for polarisation and for charge injection are established, respectively. Analysis and experimental results show that polarisation is always effective, while the charge injection has a threshold electric field to the amorphous SiO2 film. Under different control voltage conditions, the hybrid model can accurately describe the experimental data.

关键词： modeling polarisation charge injection amorphous SiO2

A Comparative Study on the Corrosion Behaviour of Hard Anodic Coatings on AA 6061 Obtained Using DC and Pulsed DC Power Sources

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Acta Metallurgica Sinica(English Letters) 2013年第6期26卷 647-656页

作者： Franco M. Hari Krishna T. Anju M.Pillai A.Rajendra A.K.Sharma Thermal Systems Group ISRO Satellite Centre

The corrosion behaviour of the hard anodic coatings prepared by three different methods viz., conventional hard anodizing （C-HA）, pulse hard anodizing （P-HA） and low voltage room temperature pulse hard anodizing （LVP- HA） on AA 6061 was compared using electrochemical impedance spectroscopy （EIS） and linear polarisation. Scanning electron microscope （SEM） was used to study the surface morphology before and after corrosion. EIS data revealed that no significant difference in corrosion resistance was observed among three types. Rp, Icorr and Ecorr were found to be highly stable over the exposure period up to 72 h which confirms the excellent corrosion resistance. The studies indicate that the corrosion resistance of LVP-HA and P-HA, which are processed at lower voltage and at relatively higher temperatures, are comparable to that of C-HA which is processed at sub-zero temperatures and high operating voltages. The corrosion resistance of all coatings was found to be improved after hydrothermal sealing.

关键词： Aluminium Anodic films EIS polarisation SEM

Two-dimensional non-spatial filtering based on holographic Bragg gratings

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Chinese Physics B 2010年第7期19卷 327-332页

作者：何焰蓝郑浩斌谭吉春丁道一郑光威王晓东王逍 Science College National University of Defense Technology Research Center of Laser Fusion China Academy of Engineering Physics

The filter made up of two gratings performs as a two-dimensional non-spatial filtering. This paper reports that the volume Bragg gratings are fabricated by interfering two collimated coherent laser beams in photopolymer. Diffraction efficiency of a single grating is up to 78% in Bragg＇s condition, then a two-dimensional non-spatial filter, which consists of two volume Bragg gratings and a half-wave plate, enables the laser beam filtered in two dimensions with the diffraction efficiency of 54%. The Bragg＇s condition and effect of polarisation on performances of the two-dimension filter are also discussed.

关键词： spatial filter Bragg gratings two-dimensional filtering polarisation

Finite size effect of ions and dipoles close to charged interfaces

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Chinese Physics B 2010年第4期19卷 469-477页

作者：童朝晖诸跃进 Department of Physics Ningbo University

The modified dipolar Poisson-Boltzmann （MDPB） equation, where the electrostatics of the dipolar interactions of solvent molecules and also the finite size effects of ions and dipolar solvent molecules are explicitly taken into account on a mean-field level, is studied numerically for a two-plate system with oppositely charged surfaces. The MDPB equation is solved numerically, using the nonlinear Multigrid method, for one-dimensional finite volume meshes. For a high enough surface charge density, numerical results of the MDPB equation reveal that the effective dielectric constant decreases with the increase of the surface charge density. Furthermore, increasing the salt concentration leads to the decrease of the effective dielectric constant close to the charged surfaces. This decrease of the effective dielectric constant with the surface charge density is opposite to the trend from the dipolar Poisson Boltzmann （DPB） equation. This seemingly inconsistent result is due to the fact that the mean-field approach breaks down in such highly charged systems where the counterions and dipoles are strongly attracted to the charged surfaces and form a quasi two-dimensional layer. In the weak-coupling regime with the electrostatic coupling parameter （the ratio of Bjerrum length to Gouy-Chapman length） Ξ 〈 1, where the MDPB equation works, the effective dielectric constant is independent of the distance from the charged surfaces and there is no accumulation of dipoles near the charged surfaces. Therefore, there are no physical and computational advantages for the MDPB equation over the modified Poisson-Boltzmann （MPB） equation where the effect of dipolar interactions of solvent dipoles is implicitly taken into account in the renormalised dielectric constant.

关键词： dipole Poisson Boltzmann equation charged interface polarisation

Corrosion Behaviours of Copper Alloy in Solutions Containing Na_2SO_4 and NaCl with Different Concentrations

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Journal of Materials Science & Technology 2002年第6期18卷 549-551页

作者： A.A.El-Meligi Chem. Dept. Durham Univ. DH1 3LE South Road Durham United Kingdom

Potentiodynamic polarisation, potential-time measurements, X-ray diffraction (XRD) and infrared spectroscopy (IR) have been used to investigate the effect of different concentrations of Na2SO4 in the absence and presence of NaCI, on the corrosion of Cu-alloy. The electrochemical measurements showed that the increase of Na2SO4 concentration led to increase the corrosion current density of Cu alloy and vice versa. The presence of NaCI shifted the potential to more cathodic potential, which had a great influence on the protectiveness of the Cu oxide layer formed on the surface in presence of Na2SO4. The spectrometric measurements indicated the constituents of the film formed on the alloy surface were mainly Cu2O, in addition to the oxides, NiO and Fe2O3, which were traced by XRD analysis.

关键词： Cu-alloy polarisation X-ray diffraction Na2SO4 NaCl Oxide film