溅射Ti涂层的Mg-7Y-2.5Zn-2Si/Al合金电化学腐蚀行为研究

为提高镁合金耐电化学腐蚀性能,研究磷化溅射Ti涂层的Mg-7Y-2.5Zn-2Al和Mg-7Y-2.5Zn-2Si两种镁合金在质量分数为3. 5%的NaCl溶液中的电化学腐蚀性能.对两种试样进行电化学腐蚀试验,腐蚀后用扫描电镜(SEM)观测镁合金表面形貌,以及使用维氏硬度计对腐蚀后的镁合金进行硬度分析.磷化后溅射Ti涂层镁合金的电化学实验结果表明:含Si镁合金比含Al镁合金腐蚀膜更加稳定紧凑,通过磷化后溅射Ti涂层工艺处理后的镁合金的腐蚀膜与基体的连接性能较好,耐蚀效果提高较为显著.     

Sn对轧制Mg-Al-Sn-Zn系海水电池用镁阳极材料组织及电性能的影响

针对合金元素Sn对轧制态镁基阳极材料显微组织及电性能的影响,探讨其提高海水电池用镁阳极材料电化学性能的途径.采用金相显微镜、X射线衍射、扫描电镜,结合能谱分析了Sn含量对轧制态镁阳极材料显微组织、相结构、表面形貌及成分分布的影响;通过恒电流法、动电位极化法、排水集气法等研究了该镁合金的腐蚀行为和电性能.研究结果表明:随着Sn含量的增加,合金晶粒愈加细小,且球形颗粒相Mg2Sn析出逐渐增多.轧制处理使大部分β-Mg17Al12相溶解,残留Mg2Sn未溶相;Sn的加入可以提高镁合金放电电压和电流效率,降低析氢率.由于镁合金的"负差数效应"使得析氢率随电流密度的增大而增大;腐蚀产物主要成分为MgO和Al2O3,且疏松,易脱落,使镁合金阳极的工作电极电位负而且稳定,可促进电池反应深入进行.     

La2Mg(Ni1-xAlx)9(x=0.1,0.2)合金的相组成及储氢性能研究

研究了Al替代对AB₃型La₂Mg(Ni_1-xAl_x)₉(x=0.1,0.2)合金相组成、储氢性能和失效行为的影响.表明Al在常温下促进La(Ni, Al)₅相含量的提高和LaMg₂Ni相的形成,并导致合金放氢困难和电化学放电容量的降低.由于La₂MgNi₂和LaMg₂Ni相含量的增加,合金耐KOH的腐蚀性降低.腐蚀产物主要为La(OH)₃,La₂O₃和Mg(OH)₂.通过Al替代改善合金电化学放电和循环稳定性的关键在于优化其中的相组成类型.     

锆基非晶合金在NaOH溶液中的腐蚀行为

用电化学极化曲线研究锆基非晶合金Zr53.5Cu26.5Ni5Al12Ag3在25℃和60℃温度下,在0.01 mol/L和0.1 mol/L的NaOH溶液中腐蚀100 h的腐蚀行为,并用金相显微镜和扫描电镜对腐蚀前后试样的表面形貌进行观察与分析.极化曲线的测试结果表明：锆基非晶合金在25℃下,在浓度为0.01 mol/L和0.1 mol/L的NaOH溶液中浸泡100 h,随着NaOH溶液浓度的升高,非晶合金的耐腐蚀能力下降;锆基非晶合金在25℃和60℃下,在浓度为0.01 mol/L的NaOH溶液中浸泡100 h,随着NaOH溶液温度的升高,非晶合金的耐腐蚀能力下降;锆基非晶合金和晶态合金在60℃下,在浓度为0.1 mol/L的NaOH溶液中浸泡100 h,非晶合金的耐腐蚀性能优于晶态合金.最后根据电化学腐蚀原理,从腐蚀介质温度和浓度方面的性质探讨锆基合金耐蚀性能的因素.     

AZ31镁合金在Hank’s仿生溶液中的电化学腐蚀行为研究

为研究镁合金在人体生理环境下的腐蚀行为,采用阳极极化和电化学交流阻抗谱(EIS)测量技术研究了AZ31镁合金在Hank’s仿生溶液中的电化学腐蚀行为及腐蚀产物形成过程;利用扫描电子显微镜(SEM)和X射线能谱仪(EDS)分析不同浸泡时间腐蚀产物膜的形貌和成分变化。研究结果表明:镁合金AZ31在Hank’s溶液中浸泡最初10min,表面形成新的MgO钝化膜。镁合金的腐蚀经历了点蚀的诱导、点蚀的发展和腐蚀产物层的生成3个阶段,腐蚀过程中除Mg的溶解过程外,还有H2PO-4、HPO2-4、PO3-4、Ca2+在镁合金表面的吸脱附过程。镁合金点蚀处磷酸钙盐沉积较多,表明镁离子的溶解促进了磷酸钙的沉积。     

表面活性剂对镁合金基体上的非铬化镀镍涂层的腐蚀特性的作用

在镁合金AZ91D化学沉积了镍涂层,研究了非铬化预处理及表面活性物质对涂层腐蚀特性的影响。通过盐水试验(1mol/L HCl)和电化学极化试验(3.5%NaCl)检测了腐蚀性能。试验表明:化镀镍溶液中添加的表面活性剂可提高镁合金镍涂层上的抗腐蚀能力。此外,表面平整均匀的纳米和非晶相涂层提高了其抗腐蚀能力。极化试验表明,其腐蚀电位向正方转移,且腐蚀电流密度减低。浸泡试验和电化学极化试验都表明阳离子表面活化剂具有更好的提高抗腐蚀性能的作用。     

Ti_3Al合金的电化学腐蚀研究及涂层防护

利用电化学工作系统,分析了Ti_3Al合金的电化学腐蚀行为。在Ti_3Al基体上制备防护涂层,分析涂层对合金的电化学腐蚀影响。采用电化学工作站三电极系统分别在25%Na_2SO_4+75%K_2SO_4、3.5%NaCl溶液中进行电化学腐蚀实验,利用动电位扫描方式获取Tafel曲线对材料的腐蚀行为进行表征。Ti_3Al合金在室温硫酸盐体系中腐蚀速度较快,添加涂层后,在同样的环境下呈现分级钝化现象,腐蚀速度有所减缓;Ti_3Al合金在室温NaCl体系中阳极快速溶解,添加涂层后,在同样的环境下呈现钝化现象,腐蚀速度有所减缓;升高温度,在70℃的硫酸盐和NaCl体系中,Ti_3Al合金阳极溶解速度更快,添加涂层后同样出现阳极溶解现象。Ti_3Al合金的抗硫酸盐和氯化钠的电化学腐蚀能力较弱,添加涂层后,耐蚀能力有所提高。     

表面渗铝Q235钢在弱酸性卤水中的腐蚀与防护

应用电化学方法及形貌观察研究了表面渗铝Q235钢在弱酸性卤水中的腐蚀行为.结果表明:在Cl-浓度为0.3 mol/L,pH=6的40℃的NaCl溶液中,渗铝层起到了阻止Q235钢基体腐蚀的作用,渗铝层主要是由Al,Fe化合物组成.Q235表面腐蚀产物疏松、容易脱落,渗铝钢表面腐蚀产物致密、均匀.渗铝钢表层形成的Al,Fe化合物连续致密,具有高效保护作用,Al-Fe合金渗层起到阴极保护的作用.     

储氢合金LaNi（4．2＋5x）Mn0．4A10．4Zrx的微观组织及电化学性能研究

研究了x(Zr)及热处理工艺对LaNi(4.2 5x)Mn0.4Al0.4Zrx储氢合金微观组织与电化学性能的影响．结果表明：添加Zr元素后该储氢合金中均出现Zr(Ni，A1，Mn)5第二相，并且第二相的含量随x的增大而增多．当x=0．4时，经热处理后合金中的第二相沿主相晶界呈网状分布，而且其韧性很好．由于第二相对主相起到了防腐蚀保护作用，并降低了充放电过程中晶格畸变引起的合金粉化的速度，从而使循环稳定性显著提高，但由于第二相不是吸氢相，对电化学容量没有贡献，因此它的出现使合金的放电容量降低．     

AZ31D镁合金固溶处理组织的耐蚀性

用金相显微镜(OM)、扫描电镜(SEM)、能量分散谱仪(EDS)和X射线衍射仪(XRD)研究了AZ31D镁合金铸态和固溶组织的特征。为了揭示其腐蚀特征和机理,在NaCl溶液中进行了浸泡试验和极化腐蚀试验。结果显示:由于铸态组织成分不均匀和第二相晶界集中析出,在NaCl溶液中形成了梅花状腐蚀花纹;固溶组织在NaCl溶液中虽具点蚀特征,但耐蚀性仍优于铸态组织。     

Influence of Nd and Y additions on the corrosion behaviour of extruded Mg-Zn-Zr alloys

To improve the corrosion resistance of wrought magnesium alloys through rare earth (RE) additions, the corrosion behaviour of Mg-5Zn-0.3Zr-xNd (x=0, 1, and 2; wt%) and Mg-5Zn-0.3Zr-2Nd-yY (y=0.5 and 1; wt%) alloys in a 5wt% NaCl solution was investigated using immersion test and electrochemical measurements. The results of immersion test show that Mg-5Zn-0.3Zr-2Nd alloy exhibits the best corrosion resistance among the tested alloys. Electrochemical measurements show that secondary phases in RE-containing Mg...     

A new perspective on the 5 V discharge capacity of Li/Al doped manganese spinels

A series of manganese spinels LiMn2-yMeyO4 (Me = Li, Al, Mg) were prepared and examined by XRD and electrochemical methods. The spinels doped with Li or high content of Al can exhibit discharge capacity in the 5 V region, but spinels doped with Mg do not exhibit any 5 V discharge capacity. It is also observed that the 5 V discharge capacity of Li/Al doped spinels will be greatly suppressed once calcinated at temperatures above 900 ℃ in preparation. It is suggested that the 5 V discharge capacity of Li/Al doped spinels may be originated from the special chemical/structural characteristics of spinel phases containing Li or high content of Al prepared at temperatures below 900 ℃.     

A2B7型La0.75Mg0.25Ni3.5-xCrx(x=0～0.3)贮氢合金相结构及电化学性能研究

采用感应熔炼方法制备了La0.75Mg0.25Ni3.5-xCrx(x=0,0.05,0.1,0.2,0.3)四元贮氢合金,系统地研究了合金B端Cr元素对Ni部分替代对合金相结构及电化学性能的影响.X衍射(XRD)分析表明,La0.75Mg0.25Ni3.5合金是由La2Ni7相组成.随着Cr元素的加入,该类合金中出现LaNi5相及LaNi3相,且随着Cr含量的增加而增多.电化学测试表明,随Cr含量的增加,合金电极活化次数变化不大,最大放电容量逐步降低,合金的最大放电容量由x=0.05时的383.43 mAh/g下降到x=0.3时的348.40 mAh/g;而合金的高倍率放电性能呈现先增后减的趋势,当电流密度为900 mA/g时,合金的高倍率放电性能由83.66%(x=0)增加到92.57%(x=0.05)然后减小到83.9%(x=0.3);循环稳定性先增加后下降,当x=0.1时合金电极的循环寿命达到最大(S100=74.71%).     

Co部分替代Ni对La_(0.4)Er_(0.4)Mg_(0.2)Ni_(3.3-x)Co_xAl_(0.2)(0.1≤x≤0.4)储氢合金结构和电化学性能的影响

为了改善储氢合金La0.4Er0.4Mg0.2Ni3.3-xCoxAl0.2(0.1≤x≤0.4)的结构和综合电化学性能,采用Co部分替代Ni的方法,实验采用高频感应炉制备La0.4Er0.4Mg0.2Ni3.3-xCoxAl0.2(0.1≤x≤0.4)储氢合金。通过X射线衍射技术和电化学测量方法研究储氢合金的晶体结构和电化学性能。XRD图谱显示样品储氢合金主要由LaNi5和La2Ni7相组成,电化学实验表明,随着Co含量的增高,储氢合金电极的最大放电容量和50次循环后的容量保持率S50基本呈现增加状态,放电容量从x=0.1时的225mA·h/g升高到x=0.4时的254.9mA·h/g,容量保持率S50从57.11%(x=0.1)增加到66.10%(x=0.4),但高倍率性能不断下降。通过交流阻抗(EIS)和线性扫描(LS)对Co替代Ni的合金动力学性能分析发现,Co替代Ni后合金的表面电荷转移能力先降低后升高。     

Corrosion mechanism and corrosion model of Mg-Y alloy in NaCl solution

Corrosion of Mg–Y alloy was studied using electrochemical evaluations, immersion tests and SEM observations. Corrosion mechanisms of Mg-(0.25 and 2.5) Y alloy and Mg-(5, 8, and 15) Y alloy were uniform corrosion and pitting corrosion respectively, and the content of Mg_(24)Y_5 phases determined its effect acting as cathode to accelerate the corrosion or corrosion barrier to inhibit the corrosion. Corrosion resistance of Mg-(0.25, 2.5, 5, 8, and 15) Y alloys was as follows: Rt(Mg-0.25Y) Rt(Mg-8Y) Rt(Mg-15Y) Rt(Mg-5Y) Rt(Mg-2.5Y). Y could significantly improve the corrosion resistance of the Mg-Y alloy, but the excess of Y deteriorated the corrosion resistance of the Mg-Y alloy. The optimum content of Y in the studied alloys was 2.5%.     

Al-Ce-TM（Fe,Co,Ni）非晶铝合金在NaCl溶液中的耐腐蚀性

使用单辊旋淬技术制备非晶态Al88Ce6TM6（Fe,Co,Ni）薄带,并研究了非晶态铝合金Al88Ce6TM6（Fe,Co,Ni）在中性NaCl溶液的电化学腐蚀行为.采用XRD和TEM对非晶合金的微观结构进行表征.使用直流和交流的电化学分析方法研究非晶态合金在中性0.6M NaCl溶液中的耐腐蚀性,并与纯Al进行比较.结果发现：使用单辊旋淬技术制备的铝基合金Al88Ce6TM6（Fe,Co,Ni）为完全非晶结构,铝基非晶合金在阳极活化过程中均发生了明显的钝化现象,在中性NaCl溶液中铝基非晶合金Al88Ce6TM6（Fe,Co,Ni）均发生点蚀.与纯Al相比,3种非晶合金有更高的抗腐蚀能力和抗点蚀能力.3种铝基非晶合金中Al88Ce6Fe6的耐蚀性最好.     

Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr⁶⁺ and PO ₄ ³⁻ , constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating’s structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgAl₂O₄ and MgO, and the minor phases are Al₂O₃ and SiO₂ when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.     

Melt-spun Al<Subscript>70−<Emphasis Type="Italic">X</Emphasis></Subscript>Si<Subscript>30</Subscript>Mn<Subscript><Emphasis Type="Italic">X</Emphasis></Subscript> (<Emphasis Type="Italic">X</Emphasis>=0, 3, 5, 7, 10) anode in lithium-ion batteries

Al_70−X Si₃₀Mn _X (X=0, 3, 5, 7, 10, mol%) ribbons were prepared by melt spinning. A supersaturated solid solution of Si and Mn in fcc Al and some microstructures consisting of nano grains were obtained. Some alloys with nano-sized grains exhibited high discharge capacities and favorable cycle properties. The capacity of more than 400 mAh/g could be obtained in melt-spun Al₆₇Si₃₀Mn₃ alloy after 20 cycles and more than 300 mAh/g after 40 cycles. Li/Si and Li/Al compounds in the anodes of pure Al and pure Si were not detected in Al-Si-Mn alloys inserted by Li. It is considered that the formation of the supersaturated solid solution and refinement of microstructures have prevented the alloys from the forming the compounds with superfluous Li. As a result, the electrochemical properties have been improved. Supported by the National Natural Science Foundation of China (Grant No. 50371066)     

Influences of melt spinning on electrochemical hydrogen storage performance of nanocrystalline and amorphous Mg2Ni-type alloys

In order to improve the electrochemical hydrogen storage performance of the Mg₂Ni-type electrode alloys, Mg in the alloy was partially substituted by La, and the nanocrystalline and amorphous Mg₂Ni-type Mg_20−x La _x Ni₁₀ (x=0, 2) alloys were synthesized by melt-spinning technique. The microstructures of the as-spun alloys were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical hydrogen storage properties of the experimental alloys were tested. The results show that no amorphous phase is detected in the as-spun Mg₂₀Ni₁₀ alloy, but the as-spun Mg₁₈La₂Ni₁₀ alloy holds a major amorphous phase. As La content increases from 0 to 2, the maximum discharge capacity of the as-spun (20 m/s) alloys rises from 96.5 to 387.1 mA·h/g, and the capacity retaining rate (S ₂₀) at the 20th cycle grows from 31.3% to 71.7%. Melt-spinning engenders an impactful effect on the electrochemical hydrogen storage performances of the alloys. With the increase in the spinning rate from 0 to 30 m/s, the maximum discharge capacity increases from 30.3 to 135.5 mA·h/g for the Mg₂₀Ni₁₀ alloy, and from 197.2 to 406.5 mA·h/g for the Mg₁₈La₂Ni₁₀ alloy. The capacity retaining rate (S ₂₀) of the Mg₂₀Ni₁₀ alloy at the 20th cycle slightly falls from 36.7% to 27.1%, but it markedly mounts up from 37.3% to 78.3% for the Mg₁₈La₂Ni₁₀ alloy.