Corrosion fatigue behavior of epoxy-coated Mg–3Al–1Zn alloy in NaCl solution

The corrosion fatigue behavior of epoxy-coated Mg–3Al–1Zn alloy was investigated in air and 3.5 wt%NaCl solution. Epoxy coating as a new method was used to improve the corrosion fatigue property of the material.Results show that the fatigue limit(FL) of the coated specimens is higher than that of the uncoated specimens in3.5 wt% NaCl solution because of the strengthening and blocking functions of the epoxy coating. The FL of the coated specimens in 3.5 wt% NaCl solution is as high as that in air. It implies that the coated specimens are not as sensitive to the environment as the magnesium alloy. The low tensile strength and the short elongation of the pure epoxy coating lead to that the fatigue crack of the coated specimen is always initiated from the epoxy-coating film Pores and pinholes accelerate the fatigue crack initiation process. Pinholes are caused by the corrosion reactions between the epoxy coating and the NaCl solution.     

Cerium-Based Sealing Treatment of Mg–Al Hydrotalcite Film on AZ91D Magnesium Alloy

An environment-friendly cerium-based sealing treatment was developed to improve the surface integrity and corrosion resistance of Mg–Al hydrotalcite film on AZ91D magnesium alloy. The cerium dioxide was generated through three stages namely nucleation, growth and dissolution, modifying the surface of AZ91D Mg alloy, and the hydrotalcite film became integral after being treated for 30 min. The results of polarization curves showed that the anti-corrosive performance of the hydrotalcite film was enhanced by the sealing treatment. Moreover, the immersion tests and electrochemical impedance spectrum measurements also demonstrated that the sealed hydrotalcite film provided a longer-term protection of magnesium alloy from corrosion as compared to the unsealed one.     

Improvement of electrochemical and electrical properties of LiFePO_4 coated with citric acid

LiFePO_4 was synthesized using hydrothermal method and coated with different amounts of citric acid as carbon source.The samples were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscope(TEM),surface area measurement—Brunauer–Emmett–Teller(BET),discharge capability,cyclic voltammetry(CV),and electrochemical impedance spectroscopy(EIS).The results show that the quality and thickness of the carbon coating on the surface of LiFePO_4 particles are very important.The optimum carbon content(about 30 wt%)can lead to a more uniform carbon distribution.Electrochemical results show that the samples containing 20 wt%,30 wt%,40 wt%,and50 wt% carbon deliver a discharge capacity of 105,167,151,and 112 mAhg~(-1),respectively,at the rate of 0.1C.The increase of carbon content leads to the decrease of discharge capacity of LiFePO_4/C,owing to the fact that excess carbon delays the diffusion of Li~+ through the carbon layers during charge/discharge procedure.The LiFePO_4/C with low carbon content exhibits poor electrochemical performance because of its low electrical conductivity.Therefore,the amount of carbon must be optimized in order to achieve excellent electrochemical performance of LiFePO_4/C for its application in a lithium ion battery.     

Enhanced Strength and Corrosion Resistance of Mg–2Zn–0.6Zr Alloy with Extrusion

The microstructure, mechanical properties and corrosion behavior of Mg–2 Zn–0.6 Zr alloy under the as-cast and asextruded conditions were investigated. Microstructure analysis indicated the remarkable grain refinement by extrusion, as well as notable reductions in volume fraction and size of precipitate phases. As compared with the as-cast alloy, the asextruded alloy exhibited better mechanical performance, especially in yield strength which was promoted from 51 to 194 MPa. Refined grains, dispersive precipitate phases and texture were thought to be the main factors affecting the improved performance in strength. The electrochemical measurement and immersion test revealed the corrosion rate of Mg–2 Zn–0.6 Zr alloy by extrusion decreased from 1.68 to 0.32 mm/year. The reasons for the enhanced corrosion resistance were mainly attributed to the decreased volume fraction and Volta potential of the precipitate phases, the refinement of the grain size, as well as the formation of more protective corrosion film.     

Corrosion behavior of Cu-Ni-Ag-Al alloy anodes in aluminium electrolysis

The behavior of Cu-Ni-Ag-Al alloy used as anode for aluminum electrolysis was directly visualized in a two-compartment see-through cell during electrolysis, and its performances were tested at 850℃ in acidic electrolyte molten salts consisting of 39.3%NaF-43.7%AlF3-8%NaCl-5?F2-4%Al2O3 for 40 h in a laboratory cell. The results show that nascent oxygen oxidizes the anodic surface to form oxide film at the beginning of electrolysis. X-ray diffraction analysis of alloy surface show that the oxide film on the anodic surface consists of CuO, NiO, Al2O3,CuAl2O4 and NiAl2O4. However, SEM image shows the oxide film is porous, loose and easy to fall into electrolyte and to contaminate aluminum. The corrosion mechanism of metal anodes was analyzed.     

Dual impact of superior SEI and separator wettability to inhibit lithium dendrite growth

Lithium metal battery(LMB)is regarded as the most potential energy storage system.However,unfortunately,its large-scale commercial development is hindered due to the uncontrollable dendrite growth problem on its Li-metal anode.The utilization of electrolyte additives is one of the promising strategies to solve the problem mentioned above.An electrolyte additive based on heptafluorobutyric anhydride(HFA)is used to solve the dendrite problem by forming robust inorganic-rich solid electrolyte interphase(SEI)and enhancing the separator wettability.     

Performance of electrolyte with dimethyl methyl phosphonate as flame-retardant additive

To improve the safety of lithium-ion batteries, dimethyl additive in a LiPF6 electrolyte solution. The flammability and thermal methyl phosphonate（DMMP） was used as a flame-retardant stability of DMMP-containing electrolyte was investigated by means of burning test and accelerating rate calorimeter. It was found that the flammability and self-heat rate of the electrolyte can be reduced by the addition of DMMP. On the other hand, the electrochemical performances of graphite/LiCoO2 cells become slightly worse after using DMMP additive in the electrolyte. This alleviated trade-off between electrolyte flammability, thermal stability, and cell performance provides a possibility to formulate a nonflammable electrolyte containing DMMP and improve the electrolyte thermal stability with a minimal sacrifice in performance.     

Numerical Approach for Atmospheric Corrosion Monitoring Based on EIS of a Weathering Steel

Electrochemical impedance spectroscopy(EIS) and film thickness measurement have been employed to study the atmospheric corrosion of a weathering steel covered with a thin electrolyte layer in a simulated coastal–industrial atmosphere. The results indicate that the corrosion rate is a function of the covered electrolyte thickness and the wet/dry cycle. Within each wet/dry cycle, the increased corrosion rate is related to the increased Cl-and SO2-4concentration and an enhancement of oxygen diffusion rate with the evaporation of the electrolyte. In addition, the corrosion rate increases during the initial corrosion stage and then decreases as the wet/dry cycle proceeds. Moreover, one mathematical approach based on the numerical integration method to obtain corrosion mass loss of steel from the measurements of EIS has been developed, and this would be useful for the development of indoor simulated atmospheric corrosion tests.     

Effect of pulse time on surface characteristics and corrosion resistance during pulse electrochemical polishing

Pulse electrochemical polishing (PECP) was used to improve the mechanical properties,such as surface roughness and corrosion resistance,of conductive metallic materials.PECP can provide a smooth,bright,reflective,and deburred surface that exhibits superior corrosion resistance.In this work,stainless steel was used as the anode,and copper was used as the cathode due to their low electrical resistances.The surface roughness of the PECP sample was measured by atomic force microscopy (AFM).A scanning electron microscope (SEM) was used to observe surface characteristics,and an Auger electron spectroscope (AES) was used to analyze the metallurgical composition and thickness of the passive film.The aim of this research was to compare the corrosion resistance rates of the unprocessed and PECP-processed stainless steel.     

Realizing simultaneously enhanced energy and power density fullcell construction using mixed hard carbon/Li_4Ti_5O_(12) electrode

Practical applications of lithium-ion batteries(LIBs) with both high energy and power density are urgently demanded,which require suitable charge/discharge platform,fast charge-transfer kinetics,as well as optimal solid electrolyte interphase(SEI) layer of electrode materials.In this work,a high-performance lithium-ion battery(LIB) full cell was assembled by using commercial LiNi_(0.33)Co_(0.33)Mn_(0.33)O_2(NCM111) as the positive electrode and mixed Li_4 Li_5 O_(12)(LTO)/hard carbon(HC) as the negative electrode.It reveals that the component ratio between LTO and HC plays a critical role in manipulating the electric conductivity and the electro-reaction platform.The electrochemical test results show that when the content of HC is 10 wt%,the as-constructed full cell demonstrates the best electrochemical,with a maximum energy density of 149.2 Wh·kg~(-1) and a maximum power density of2195 W·kg~(-1) at 10 A·g~(-1)(30 C).This outperforms all the assembled systems within our work range and the state-ofthe-art literatures.The NCM//Li_4 Ti_5 O_(12)+10 wt% HC battery system also exhibits a good capacity retention after1000 cycles at the current density of 1 A·g~(-1).This work provides a new approach to enhance the full-cell performance by mixing electrode materials with different charge potentials and reaction kinetics.     

铸态及退火态Mg66Al34阳极镁空气电池的性能

制备了铸态及退火态Mg66Al34共晶合金,通过研究该合金的腐蚀及放电行为,考察了该合金作为镁空气电池阳极的放电性能。结果表明:在3.5 mass%NaCl溶液中,铸态合金具有较低的腐蚀速率及放电活性,退火态合金具有高的腐蚀速率及放电活性。在NaCl溶液中加入水溶性石墨烯后,铸态合金具有低的腐蚀速率及较高放电活性。铸态合金低的腐蚀速率是由于在β-Mg17Al12层间形成了黑色富铝氧化物腐蚀产物。     

Al-Mg-Sn基阳极材料在含ZnO碱性溶液中的电化学性能研究

研究了Al-0.5Mg-0.1Sn-0.1Si-0.02In (质量分数,%) 合金作为铝空气电池的阳极材料,在2 mol/L NaCl,4 mol/L NaOH,4 mol/L NaOH-0.2 mol/L ZnO,7 mol/L KOH 和 7 mol/L KOH-0.2 mol/L ZnO溶液中的腐蚀行为及电化学性能。结果表明,该合金在4 mol/L NaOH-0.2 mol/L ZnO和7 mol/L KOH-0.2 mol/L ZnO溶液中具有较好的综合电化学性能。该合金在2 mol/L NaCl,4 mol/L NaOH及7 mol/L KOH溶液中的溶解由电荷转移步骤控制,在4 mol/L NaOH-0.2 mol/L ZnO和7 mol/L KOH-0.2 mol/L ZnO溶液中的溶解由电荷转移及质量转移混合控制。相比于Zn在7 mol/L KOH溶液中的电化学性能,以该合金作为阳极材料,以4 mol/L NaOH-0.2 mol/L ZnO或7 mol/L KOH-0.2 mol/L ZnO溶液作为电解液的铝空气电池是可行的。     

织构对基于Mg-3Al-1Zn合金的镁空气电池性能的影响

在本论文中,商用AZ31镁合金板材被用为实验材料。为了研究织构对镁空气电池性能的影响,分别制备了基于板材轧面和截面的镁空气电池。与已经报道过的关于织构对镁合金电化学性能的影响的研究不同,本文所用实验材料的表面粗糙度与实际应用中镁合金板材的表面粗糙度相似。通过电化学阻抗谱研究了试样的电化学性能,结果表明轧面比截面更耐腐蚀。通过恒流放电测试研究了电池的放电性能,结果表明基于截面阳极的镁空气电池和基于轧面阳极的镁空气电池相比具有更高的阳极效率（两种电池的阳极效率分别为71.3%和65.7%）。放电24小时之后,通过扫描电子显微镜研究了镁合金阳极基体的表面形貌。轧面阳极显示出一个具有更多孔洞和沟壑的阳极表面,这可能是导致它具有低阳极利用率的原因。因此,被(10-10)、 (11-20) 和(10-11)取向晶粒所主导的轧面阳极更合适于被运用于镁空气电池。     

Discharge performance of Mg-Al-Pb-La anode for Mg-air battery

The discharge performance of Mg-Al-Pb-La anode was investigated by electrochemical techniques and compared with that of Mg-Al-Pb alloy. The results indicate that the Mg-Al-Pb-La anode provides enhanced corrosion resistance at open circle potential, and exhibits better discharge activity than the Mg-Al-Pb alloy. The utilization efficiency of Mg-Al-Pb-La anode is higher than that of commercial Mg-Al-Zn (AZ) and Mg-Al-Mn (AM) alloys. A single Mg-air battery with Mg-Al-Pb-La alloy as the anode and air as the cathode has an average discharge potential of 1.295 V and a discharge capacity of 1370 mA·h/g during discharge at 10 mA/cm², which is higher than that of batteries using Mg-Li anodes. The enhancement in discharge performance of the Mg-Al-Pb-La anode is caused by its modified microstructure, which reduces the self-corrosion and accelerates the spalling of oxidation products during battery discharge. Furthermore, the dissolution mechanism of Mg-Al-Pb-La anode during the discharge process was analyzed.     

硅酸盐体系电解液中添加Na2WO4对LY12铝合金陶瓷膜性能的影响

通过SEM、XRD、硬度试验、电化学腐蚀试验研究了在硅酸盐体系电解液中加入不同浓度的Na2WO4对LY12铝合金微弧氧化陶瓷膜表面形貌及性能的影响.结果表明,添加Na2WO4改变了膜层的微观结构,使微弧氧化膜层硬度增加,表面平滑,呈现出小而少的孔洞结构,且表面堆积少量形状不规则的白色质点;随着Na2WO4添加量的增加,...     

Effect of Different Calcination Temperatures on the Structure and Properties of Zirconium-Based Coating Layer Modified Cathode Material Li1.2Mn0.54Ni0.13Co0.13O2

Lithium-rich manganese-based oxides have the advantages of high discharge specific capacity, so they are potential candidates for advanced lithium battery cathode materials. However, they also have drawbacks to be solved such as serious irreversible loss of capacity and voltage decay in the cycling process. Surface coating method was used in this paper to modify the lithium-rich manganese-based oxide (LRMO, Li_1.2Mn_0.54Ni_0.13Co_0.13O₂) to improve its electrochemical properties. Zirconium-based compounds coated LRMO materials (ZBC@LRMO) were obtained via the reaction of lithium hydroxide with zirconium n-butanol and subsequent thermal treatment at different temperatures. The results of X-ray diffraction and transmission electron microscopy confirm that the crystal structure and composition of the ZBC coating layer vary with the calcination temperature. The coating layer obtained at 600 ℃ is composed of tetragonal ZrO₂ and Li₂ZrO₃. The ZBC@LRMO sample with tetragonal ZrO₂ and Li₂ZrO₃ composite exhibits the best electrochemical performance: the discharge capacity of ZBC@LRMO can reach 296 mAh g^-1 at 0.1 C and 120 mAh g^-1 at high rate of 5 C.     

In对Al-Mg-Ga-Sn-(In)铝合金阳极组织及电化学性能的影响

在Al基体中添加Mg、Ga、Sn、In合金元素,通过正交试验设计了9组铝-空气电池阳极材料。采用动电位极化试验、析氢试验和恒电流放电试验对铝合金阳极的电化学性能进行优化,通过扫描电镜和能谱测试仪观察了合金的显微组织及成分。结果表明,没有添加In元素的1号合金(Al-0.5Mg-0.05Sn-0.05Ga)、5号合金(Al-Mg-0.1Sn-0.2Ga)和9号合金(Al-2Mg-0.2Sn-0.1Ga)铝阳极具有较差的放电性能和较高的自腐蚀速率,而添加0.05wt% In元素的7号铝阳极(Al-2Mg-0.05Sn-0.2Ga-0.05In)具有最好的放电电压(平均电位-1.968 V)和抗腐蚀性能 (自腐蚀速率0.193 mL·cm^-2·min^-1)。对比去腐蚀产物后的合金表面形貌,发现5号合金的腐蚀表面布满较深的腐蚀坑,这增加了铝合金的自腐蚀,而7号合金的表面具有较浅的腐蚀坑,这减缓了电解液中离子传递和自腐蚀速率。 因此,7号铝合金适合用作铝-空气电池阳极材料。     

Al-Mg-Sn-Si-In铝合金在不同溶液中的腐蚀与电化学性能研究

研究了Al-0.5Mg-0.1Sn-0.1Si-0.02In合金作为铝空气电池的阳极材料,在2 mol/L NaCl,4 mol/L NaOH乙醇-10%水,4 mol/L NaOH溶液中的腐蚀行为及电化学性能。结果表明,该合金在4 mol/L NaOH乙醇-10%水溶液中性能优良,具有较高的阳极利用率及较低的自腐蚀速率。腐蚀形貌及电化学阻抗谱测试结果与合金腐蚀特性一致。通过对比Zn在4 mol/L NaOH溶液中的电化学性能,Al-0.5Mg-0.1Sn-0.1Si-0.02In合金在4 mol/L NaOH乙醇-10%水介质中作为铝空气电池的阳极材料具有可行性。     

瓷质氧化预处理对6061铝合金弱酸性介质中微弧氧化膜的影响

以6061铝合金为研究对象,对其在弱酸性介质中的微弧氧化膜的成分及性能进行了分析,探讨瓷质氧化预处理对微弧氧化膜的影响.结果表明:在弱酸性介质中,6061铝合金瓷质氧化预处理+微弧氧化膜的主要成分是γ-Al2 O3和α-Al2 O3,同时由于残留的瓷质氧化膜,无定型的Al2 O3也存在于氧化膜中;其厚度和硬度分别为25...     

Characterization of anodic films formed on AZ91D magnesium alloy

Anodization of die-casted AZ91D magnesium alloy was performed in 3 M KOH+0.21 M Na₃PO₄+0.6 M KF base electrolyte with and without Al(NO₃)₃ addition. The anodic film was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the various anodized alloys was then evaluated in 3.5 wt % NaCl solution using electrochemical impedance spectroscopy (EIS) and immersion testing. The results showed that the anodic film was mainly composed of MgO. The addition of Al(NO₃)₃ into the base electrolyte results in the formation of Al₂O₃ and Al(OH)₃ in the anodic film. The maximum amount of Al₂O₃ was found in the anodic film when the alloy was anodized in the electrolyte containing 0.15 M Al(NO₃)₃. The results of EIS analysis and morphological examination showed that the MgO anodic film modified with Al₂O₃ exhibited the superior corrosiom resistance for AZ91D Mg alloy.