Effect of Cerium on Gas Evolution Behavior of Pb-Ca-Sn Alloy

The effect of Ce on the behavior of gas evolution on Pb-Ca-Sn alloy in 4.5 mol·L^-1 H2SO4 was investigated using cyclic voltammetry （CV）, cathodic polarization curves and AC impedance （EIS）. Cyclic voltammetry experiments show that the current of oxygen evolution on Pb-Ca-Sn-Ce electrode is lower than that of Pb-Ca-Sn electrode in the same anodic voltage. Moreover, the oxygen evolution potential on the former electrode is greater than that on the latter, and this means that Ce can increase the potential of oxygen evolution on Pb-Ca-Sn alloy. The AC impedance experiments show that Ce can also enhance the resistance of hydrogen evolution on Pb-Ca-Sn electrode, i.e., Ce can inhibit the hydrogen evolution on Pb-Ca-Sn electrode. The reason why Ce decreases the volume of hydrogen evolution on Pb-Ca-Sn alloy is that Ce increases the resistance of absorbing step of hydrogen evolution reaction. All the experimental results indicate that Pb-Ca-Sn-Ce alloy can rapidly decrease the oxygen and hydrogen evolution on Pb-Ca-Sn-Ce alloy. It is concluded that Pb-Ca-Sn-Ce alloy can promote the maintenance-free property of lead acid battery, and can serve as the candidate of the grid material for maintenance-free lead acid battery.

Pb-Ca合金板栅电池早期容量衰减的原因

Pb-Ca合金在阀控式铅酸(VRLA)电池中应用广泛。针对Pb-Ca合金浇铸板栅电池的早期容量衰减问题进行研究。用同批次Pb-Ca合金极板,制作不同加酸化成工艺的电池,进行循环测试。充电电流小的电池发生了早期容量衰减,而大电流充电的电池循环性能正常。对发生早期容量衰减的电池进行分析,发现板栅腐蚀界面生成的硫酸铅晶体阻挡层是导致电池发生早期容量衰减的主要原因。提高电池的充电效率,如添加电解液添加剂、化成前对电池反充、增大充电电流等,可以使硫酸铅得以转化,能较好地避免电池发生早期容量衰减。

PREPARATION OF Pb-Ca-Na MASTER ALLOY USING MOLTEN CHLORIDE SALT ELECTROLYSIS

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Anodic Layer of Pb-Ca-Sn-Ce Alloy for Maintenance-Free Lead/Acid Batteries

The anodic films of novel Pb-Ca-Sn-Ce alloy, traditional Pb-Ca-Sn and Pb-Sb alloys formed in sulfuric solution at anodic +0.9 V potential corrosion for 6 h were investigated by means of XPS, XRD methods and AC impedance measurement. The results show that the growth of Pb(Ⅱ) oxide on the new Pb-Ca-Sn-Ce alloy surface is inhibited. The AC impedance measurement shows that resistance of the corrosion layer of novel Pb-Ca-Sn-Ce alloy decreases. It is found that the novel Pb-Ca-Sn-Ce alloy can encourage the development of PbO2 in the scale, and enhance the conductivity of the anodic scale. Hence the deep recycling properties of the battery can be expected better.

Effect of melt convection on primary dendrite arm spacing in directionally solidified Pb-26%Bi hypo-peritectic alloys

Primary dendrite arm spacing（PDAS） of α phase in directionally solidified Pb-26%Bi（mass fraction） hypo-peritectic alloys was measured by considering the effect of melt convection in cylindrical samples with different diameters.The experimental results show the measured PDAS increases with increasing diameter of the sample.At the growth velocity of 5 μm/s,its value changes from 161.5 μm for the sample with 1.8 mm in diameter to 240.4 μm for the sample with 7 mm in diameter.The strong melt convection in large diameter samples causes a high bulk alloy composition and a high concentration gradient in peritectic β phase,resulting in a larger PDAS.Simultaneously,the high concentration gradient could effectively promote the peritectic transformation,enhancing the dissolution of the thin α dendrite.

Effect of Al_2Ca intermetallic compound addition on grain refinement of AZ31 magnesium alloy

The Al2Ca intermetallic compound was prepared by melting process in a vacuum induction furnace. And the A12Ca compound was added in as-cast AZ31 alloys for grain refinement. The effect of its additional levels on grain refinement of as-cast AZ31 alloy was investigated and the mechanism of the grain refinement was discussed. The results reveal that the addition of 1.1% Al2Ca （mass fraction） decreases the average grain size of as-cast AZ31 alloy from 354 to 198 μm. And the thermal stability of the grains refined by Al2Ca is superior. The grain refining mechanism is attributed to the combined effects of solute and heterogeneous nucleation from the Al2Ca.

冷轧变形Pb-Ca-Sn-Al合金在回复和再结晶过程中的晶界特征分布

采用电子背散射衍射(EBSD)技术研究了冷轧变形Pb-0．1％Ca-1．5％Sn-0．026％Al合金在回复和再结晶过程中的晶界特征分布(GBCD)．结果表明:在回复过程中,合金内形成了比例接近50％的平直∑3晶界,这类晶界不处在由一般大角度晶界构成的晶界网络上,不能使合金的GBCD得到优化;相反,在再结晶过程中,除了生成比例超过50％的∑3晶界外, 还出现了较多的∑9和∑27等低∑重位点阵晶界(CSL),并且这些晶界和相当多的弯曲的∑3晶界均处在由一般大角度晶界构成的晶界网络上,可以使合金的GBCD得到优化．进一步的分析指出:回复过程中所形成的平直的∑3晶界是共格孪晶界, 它们能量很低,很难迁移;在再结晶过程中,除了生成不可迁移的共格的∑3孪晶界外,还可形成大量可迁移的弯曲的非共格∑3 晶界,这类晶界的迁移和彼此会合可形成∑9和∑27等∑3n(n为正的整数)晶界,这是合金GBCD得到优化的根源．

Effects of minor Ca on as-cast microstructures and mechanical properties of Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys

The effects of the addition of 0.6%Ca（mass fraction） on the as-cast microstructure and mechanical properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc magnesium alloys were investigated and compared by optical microscopy and scanning electron microscopy,differential scanning calorimetry analysis,and tensile and creep tests.The results indicate that the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can refine the grains of the two alloys.At the same time,the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can effectively improve the tensile properties of the two alloys.In addition,the addition of 0.6%Ca can also improve the creep properties of the Mg-3Ce-1.2Mn-0.9Sc alloy but is not beneficial to the creep properties of the Mg-4Y-1.2Mn-0.9Sc alloy.The different effects of minor Ca on the creep properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys are possibly related to the difference in the solid solubilities of Ce and Y in Mg.

Simulation of formation and evolution of nano-clusters during rapid solidification of liquid Ca_(70)Mg_(30) alloy

A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM） was adopted to describe microstructure evolutions of nano-clusters during solidification. Results indicate that amorphous structure is mainly formed with three bond-types of 1551, 1541 and 1431 at the cooling rate of 5~1011 K/S, and glass transition temperature Tg is about 530 K; the icosahedron cluster of （12 0 12 0） plays a key role in formation of amorphous structure, and smaller Mg atoms are much more probable to be central atoms of icosahedron clusters; and nano-clusters are mainly formed by combining medium-size clusters. Interestingly, it was also found that formation and evolution processes of the nano-cluster display a three-stage feature which is analogous to crystallization process of amorphous alloy.

Pb-Ca-Bi合金的电化学行为研究

利用线性电位扫描、恒电位阶跃、交流阻抗等方法分别研究了Pb Ca Bi合金被阳极或阴极极化后,表面上析氧、析氢以及合金腐蚀行为。结果表明:与Pb Ca合金相比,Pb Ca Bi合金可增加氧的析出,但抑制氢的析出,同时铋的加入,使Pb Ca耐蚀性提高,且不同含量的铋对合金腐蚀有不同的影响。

Microstructure of Mg-8Zn-4Al-1Ca aged alloy

The microstructure of Mg-8Zn-4Al-1Ca aged alloy was investigated by TEM and HRTEM. The results show that the hardening produced in the Mg-8Zn-4Al-1Ca alloy is considerably higher than that in the Mg-8Zn-4A1 alloy. A dense dispersion of disc-like Ca2Mg6Zn3 precipitates are formed in Mg-8Zn-4Al-1Ca alloy aged at 160 ℃ for 16 h. In addition, the lattice distortions, honeycomb-looking Moir＆#233; fringes, edge dislocations and dislocation loop also exist in the microstructure. The precipitates of alloy aged at 160 ℃ for 48 h are coarse disc-like and fine dispersed grainy. When the alloy is subjected to aging at 160 ℃ for 227 h, the microstructure consists of numerous MgZn2 precipitates and Ca2Mg6Zn3 precipitates. All the analyses show that Ca is a particularly effective trace addition in improving the age-hardening and postponing the formation of MgZn2 precipitates in Mg-8Zn-4Al alloy aged at 160 ℃.

锌电积用Pb-Ag-Sb-Ca四元合金阳极的电化学性能研究

实验通过恒电流极化(24 h)、阳极极化曲线等技术在酸性硫酸锌溶液中测试了Pb-0.3%Ag-0.6%Sb-0.06%Ca四元合金阳极的电化学性能,并分析了其析氧动力学参数.结果表明:相对于传统的Pb-0.3%Ag-0.06%Ca阳极,Pb-0.3%Ag-0.6%Sb-0.06%Ca四元合金阳极析氧过电位低27 mV(500 A/m2);电极表观交换电流密度增高将近一倍.元素Sb明显的提高了Pb-0.3%Ag-0.06%Ca阳极的电催化活性,有利于析氧反应的发生和槽电压的降低,节约电能消耗,是很好的锌电积阳极改性剂,具有较好的工业应用前景.

锡含量对Pb-Ca-Sn-Al合金性能的影响

采用恒电位阳极极化、线性扫描阴极极化、交流伏安、恒流阳极腐蚀和金相显微观察等方法,研究锡(Sn)在铅钙合金(Pb-Ca-x%Sn-Al)中的作用和锡含量对铅钙合金性能的影响。锡的加入可以细化铅钙合金晶粒。随着锡含量从0.1%增加到2.0%,铅钙合金在1.2 V下腐蚀电流下降55%,腐蚀膜的形成量减少49%,0.5 A/cm^2下恒流阳极腐蚀3 d,失重减少75%;腐蚀膜转化阻抗下降到4.1Ω/cm2;在相同的阴极或阳极极化电位下,析氢或析氧反应速度减小。

锡含量对电积铜用Pb-Ca-Sn合金阳极电化学性能的影响

交叉轧制的合金材料各向异性明显减小,性能较好,目前将其用作电积铜阳极并对其耐蚀性能进行研究的报道较少。采用恒电流极化曲线、循环伏安曲线、交流阻抗曲线、X射线衍射、扫描电镜等测试手段研究了不同Sn含量交叉轧制8次的Pb-Ca-Sn合金的性能。结果表明:随着Sn含量的增加,合金的耐腐蚀性和导电性逐渐增加,析氧过电位逐渐降低,其中Pb-Ca-(1.20%)Sn合金的综合性能最好。

蓄电池板栅Pb-Ca-Sn-Al合金组织与性能的研究

采用连铸连轧工艺成功制备了Pb-Ca-Sn-Al合金的蓄电池板栅,通过光学显微观察、力学性能实验、腐蚀实验和电导率实验对不同浇铸温度、轧制温度、冷却方式及轧制变形量的蓄电池板栅Pb-Ca-Sn-Al合金的金相组织及其性能进行研究。结果表明:采用480℃浇注温度、93℃轧制温度、水喷淋冷却方式生产的Pb-Ca-Sn-Al合金厚板带的力学与导电等综合性能最优,通过五道变形量为20%的轧制后,Pb-Ca-Sn-Al合金板带的抗拉强度σb与屈服强度σp0.2分别提高了40.3%和61.5%,抗腐蚀性能是轧制一道的1.69倍。

Pb-0.3%Ag-0.06%Ca三元合金阳极在锌电积过程中的电化学行为—循环伏安曲线研究

Pb-0.3%Ag-0.06%Ca三元轧制合金阳极在酸性硫酸锌溶液中进行了360 h(15 d)的恒电流极化.通过循环伏安技术研究分析了恒电流极化过程中合金阳极的电化学行为的变化.通过X射线衍射技术分析了合金阳极在恒电流极化过程中形成的氧化膜物相.结果表明:合金阳极的阳极氧化膜形成和稳定需要一个过程.在这个过程中,电化学行为和氧化膜物相呈现明显的变化.随着恒电流极化时间的延长,阳极峰(Pb→PbSO4)的强度在前两天的电解中显著升高,其后保持在稳定状态(0.25 mA/cm2),同时向正方逐渐移动.然而阳极峰(PbSO4→β-PbO2,PbO→α-PbO2)却显著地向负方向移动.阴极峰(β-PbO2和α-PbO2→PbSO4)和(PbO和PbSO4→Pb)呈现一个逐渐增加的趋势,同时逐渐的向负方向移动.而且合金阳极氧化膜的腐蚀物相主要为PbSO4、α-PbO2、β-PbO2、PbS2O3和Pb.随着电解时间的延长,PbSO4峰逐渐变弱,α-PbO2峰逐渐增强.PbSO4择优取向为(021)、(121)和(212)晶面.α-PbO2的择优取向为(111)晶面.

极化时间对Pb-Ca-1.2%Sn合金阳极的影响

采用阳极极化曲线、塔菲尔曲线、循环伏安曲线、交流阻抗曲线和腐蚀性能的测试研究了不同极化时间对交叉轧制八次的Pb-Ca-1.2%Sn合金阳极的性能影响。实验结果表明,随着极化时间的增加,合金阳极的耐腐蚀性和导电性逐渐增加,而析氧电位逐渐降低。其中,以极化时间为12天的Pb-Ca-1.2%Sn合金阳极的性能最佳。

Pb-Ag-Sb-Ca合金在锌电沉积过程中阳极性能的研究

实验在72h恒电流电解过程中,通过暂稳态极化曲线测试方法,在酸性硫酸锌溶液中研究了Pb-0.3%Ag-0.6%Sb-0.06%Ca四元合金阳极的电化学性能,并分析了析氧动力学参数。结果表明,在电解过程中,阳极析氧过电位和析氧动力学参数发生很大的变化,这是因为阳极氧化层存在一个形成与稳定的过程。随着电解时间的延长,阳极材料的析氧过电位呈现不断降低的趋势,电极表面交换电流密度呈现逐渐升高的趋势。

铋对铅酸蓄电池用Pb-Ca-Sn合金性能的影响

实验采用塔菲尔曲线、动电位线性扫描、交流伏安等电化学方法研究了不同铋含量的铅钙锡铝板栅合金的电化学性能,并用显微硬度计测试硬度。结果表明,添加适量的铋,可以提高合金的耐腐蚀性,抑制Pb(Ⅱ)的生长,减小阳极膜的阻抗,提高电池的深充/放电性能,提高合金板栅的显微硬度。但过多的铋反而恶化Pb-Ca合金的电化学性能和机械性能。

冷轧变形Pb-Ca基合金在退火过程中的晶界特征分布

采用电子背散射衍射(EBSD)技术研究了冷轧变形Pb-0.1%Ca-1.5%Sn-0.026%A l合金在退火过程中的晶界特征分布(GBCD)。结果表明:经10%冷轧变形后在220℃退火72小时,合金内形成了比例超过60%的平直的∑3共格孪晶界,这类晶界不处在由一般大角度晶界构成的晶界网络上,不能使合金的GBCD得到优化;相反,经30%冷轧变形后在270℃退火7分钟,除了生成比例超过65%的∑3晶界外,还出现了较多的∑9和∑27等低∑重位点阵晶界(CSL),并且这些晶界和相当多的弯曲的∑3晶界均处在由一般大角度晶界构成的晶界网络上,可以使合金的GBCD得到优化。