LOW TEMPERATURE ALUMINUM FLOATING ELECTROLYSIS IN HEAVY ELECTROLYTE Na_3AlF_6-AlF_3-BaC1_2-NaCl BATH SYSTEM

Multiple regression equations of liquidus temperature, electrical conductivity and bath density of the Na_3AlF_6-AlF_3-BaC1_2-NaCl system were obtained from experiments by using orthogonal regression method. The experiments were carried out in 100A cell with low melting point electrolyte, the influences of cathodic current density, electrolytic temperature, density differences of bath and liquid aluminum on current efficiency (CE) were studied; when the electrolyte cryolite ratio was 2.5, w(BaC1_2) and w(NaCl) were 48% and 10%, respectively, CE reached 90% and specific energy consumption was 10.97k Wb/kg/kg. Because of the fact that aluminum metal obtained floated on the surface of molten electrolyte, this electrolysis method was then defined as low temperature aluminum floating electrolysis. The results showed that the new low temperature aluminum electrolysis process in the Na_3AlF_6-AlF_3-BaC1_2-NaCl bath system was practical and promising.

Preparation of Mg-Li alloys by electrolysis in molten salt at low temperature

A new technology for preparation of low cost Mg-Li alloys was studied. The alloys were prepared by electrolysis in molten LiCl-KCl （weight ratio is 1：1） electrolyte with Mg rod severing as the consumed cathode. Main factors that affect current efficiency were investigated, and optimal electrolysis parameters were obtained. Mg-Li alloys with low lithium Content （about 25%） were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving. The new technology for the oreoaration of Mg-Li alloy by electrolysis in molten salt was laroved to be feasible.

A two-dimensional air streamer discharge model based on the improved Helmholtz equation at low temperature and sub-atmospheric pressure

In this paper,an efficient boundary condition is applied to solve the photoionization rate,and a two-dimensional numerical simulation is carried out for the development and propagation of an air streamer at low temperature and sub-atmospheric pressure.The results show that the new boundary condition improves the calculation accuracy,but the influence of photoionization on the streamer discharge process is not obvious.The discharge current in the development of streamer discharge is defined,and the corresponding expression of the positive and negative streamer discharge current is given.The influence of the electric field exceeding the threshold value on the discharge process is preliminarily introduced.In the process of discharge,only the propagation velocity of the streamer is obviously higher than that of normal temperature and pressure,and the trend of the other parameters is basically the same as that described in the previous paper.The above results give us a deeper understanding of the discharge characteristics under low temperature and sub-atmospheric pressure,which has certain significance for the development of aviation and high voltage engineering.

Nickel electrodeposition from novel citrate bath

A new type of electroplating bath suitable for nickel electrodeposition was developed. Trisodium citrate was used as a complexing agent and a buffer in the bath. The buffering capacity between trisodium citrate and boric acid were compared. The effects were investigated under different conditions of bath composition, current density, pH and temperature on the potentiodynamic cathodic polarization curves, cathodic current efficiency and throwing index, as well as the electrical conductivity of these baths. The optimum conditions for producing sound and satisfactory nickel deposits were: NiSO4·6H2O 350 g/L, NiCl2·6H2O 45 g/L and Na3C6H5O7 30 g/L at pH=4 and 55 ℃. The surface morphology of the as-plated Ni deposit was examined by SEM. The results reveal that the nickel deposition obtained from the optimum conditions are composed of compact, non-porous fine grains covering the entire surface. X-ray analysis shows that nickel deposits obtained from the citrate bath have a fine crystal structure compared with deposits from the Watts bath.

Transport enhancement and efficiency optimization in two heat reservoir ratchets

We study a Brownian motor moving in a sawtooth potential in the presence of an external driving force and two heat reservoirs.Based on the corresponding Fokker-Planck equation,the analytical expressions of the current and efficiency in the quasi-steady-state limit are obtained.The effects of temperature difference and the amplitude of the external driving force on the current and efficiency are discussed,respectively.The following is our findings.（i） The current increases with both δ and A.In other words,δ and A enhance the transport of the Brownian motor.（ii） The competition between the temperature difference and the amplitude of the external driving force can lead to efficiency optimization.The efficiency is a peaked function of temperature,i.e.,δ 0 and a lower amplitude value of the external driving force is necessary for efficiency optimization.（iii） The efficiency increases with δ,and decreases with A.δ and A play opposite roles with respect to the efficiency,which indicates that δ enhances the efficiency of energy transformation while A weakens it.

酸性一价铜电镀铜的工艺及能效分析

针对电镀铜过程电力成本高的问题,通过极化曲线、赫尔槽试验、槽压变化以及扫描电镜等手段,分析了酸性一价铜电镀铜的电极过程及能效。通过对阴极的分析表明:优先发生亚铜离子的还原,阴极电流效率高于92%,且随阴极电流密度的增大而提高;当阴极电流密度不高于4.0 A·dm^(-2)时,镀铜层表面状态和微观形貌较为优异。通过对紫铜阳极的分析表明:优先发生铜的氧化,阳极电流效率高于94%,且随阳极电流密度的增大而提高;阳极会发生钝化,导致槽压急剧升高;当采用大阳极小阴极进行电镀时,既可以克服槽压升高的问题又可以保证阴阳极电流效率的匹配。

电镀温度对钢板镀铬效果的影响研究

传统二步法电镀铬工艺要求镀液温度一般较高,需要控制在50℃-60℃,高温电镀带来许多不利影响。针对这一问题,本文研究了不同温度对二步法电镀铬效果的影响,开发了精准控温六价铬电镀技术,将温度控制在45℃~48℃,研究结果表明温度越低电流效率越高,即在镀铬层同样厚度的情况下,所需消耗的电镀电流减少,实现节能降耗,降低电镀成本,同时提高生产效率,减少镀铬污水排放。

NaCl和LiF对低温铝电解电流效率的影响

低温铝电解是铝电解工艺的重要研究方向,熔盐体系的组成对电解温度和电流效率影响较大.为了获得较优的低温熔盐体系组成,在NaF-AlF_(3)-CaF_(2)-Al_(2)O_(3)熔盐体系中添加NaCl和LiF,在840~880℃下电解4 h,分别分析添加剂和Al_(2)O_(3)的质量分数对电流效率的影响.结果表明:添加10%(质量分数,下同)NaCl时电流效率为72.5%,与传统NaF-AlF_(3)-CaF_(2)-Al_(2)O_(3)熔盐体系电解4 h的电流效率相比提高了16.4%;添加2.5%NaCl-7.5%LiF,5%NaCl-5%LiF,7.5%NaCl-2.5%LiF时电流效率约为68%;添加10%LiF时电流效率为57.8%;当Al_(2)O_(3)质量分数为2%时,NaF-AlF_(3)-5%CaF_(2)-10%NaCl-5%LiF熔盐体系电解2 h的电流效率为48.1%,与Al_(2)O_(3)质量分数为3%时的电流效率相比提高了5.2%.

电解槽分槽控温的研究与应用

介绍槽温对槽电压、离子膜电流效率和安全运行的影响。给出电解槽槽温的控制原理及工艺流程。提出分槽控温的运行方式。分槽控温投用后,工艺电消耗总量降低5032.23kW·h/d,经济效益达601551.2元/a。

前端进水温度对CuZn合金微观形貌和阻垢性能影响

本文通过精确控制实验条件,基于EDTA滴定法精确测定不同温度下水中Ca^(2+)浓度,分析了温度对CuZn合金阻垢效率的影响规律。随着温度的升高,合金的阻垢效率呈现明显下降趋势。本文为开发适用于不同温度条件的高效阻垢技术和材料提供了重要理论依据和实验支持,具有显著的理论意义和应用前景。

抽酸电流对铅酸蓄电池性能的影响

采用不同的抽酸电流,验证其对阀控式铅酸蓄电池性能的影响。实验证明,抽酸电流对阀控式铅酸蓄电池的热失控敏感性、密封反应效率、酸饱和度、循环寿命、高温加速浮充寿命有较大的影响。

温度和电流对白光LED发光效率的影响

对大功率白光LED发光效率进行了研究,得出温度和电流对LED发光效率的影响:随着温度的升高,势阱中辐射复合几率降低,从而降低了发光效率;电流的升高,使更多的非平衡载流子穿过势垒,降低了发光效率。LED工作时,过高的工作温度或者过大的工作电流都会产生明显的光衰:如果LED工作温度超过芯片的承载温度,这将会使LED的发光效率快速降低,产生明显的光衰,并且对LED造成永久性破坏;如果LED的工作电流超过芯片的饱和电流,也会使LED发光效率快速降低,产生明显的光衰。并且LED所能承载的温度与饱和电流有一定关系,散热良好的装置可以使LED工作温度相对降低些,饱和电流也可以更大,LED也就可以在相对较大的电流下工作。

电镀锡工艺条件对锡镀层孔隙率的影响

为了提高镀锡板产品质量,降低生产成本,研究了电镀锡溶液组成、电流密度、温度等电镀工艺条件对镀锡板孔隙率的影响。结果表明:镀锡液各成分对镀锡板孔隙率的影响次序是EN>PSA>ENSA>Sn2+;最优配方是5 g/L ENSA,5 g/L EN,16 g/L PSA,22 g/L Sn2+;随着电流密度从0.5 A/dm2增加到3.0 A/dm2,电沉积的锡晶粒度逐渐细化,孔隙率逐渐降低,至3.0 A/dm2时,锡晶粒度最小,孔隙率也最小;随着镀液温度的升高,镀锡板铁溶出值(PHG)值先减小,后增大,在40℃附近出现了最小值。

直流电沉积Ni-W-P镀层研究

采用直流电沉积法,在低碳钢表面成功沉积Ni-W-P镀层。应用X射线荧光(XRF)、扫描电子显微镜(SEM)、俄歇电子能谱(AES)、X射线衍射(XRD)仪等方法,研究电流密度、镀液pH值和镀液温度对Ni-W-P镀层成分、表面形貌和结构的影响。结果表明,电流密度和镀液pH值的变化对Ni-W-P镀层成分的影响很大,而电流密度、镀液pH值和温度对镀层厚度的影响较小。电流效率随着电流密度和镀液温度的增大分别降低和升高,而随着镀液pH值的变化,在pH=7.0时有极大值。镀液pH值对Ni-W-P镀层结构有较大影响,在pH=8.0时,镀层呈现明显的Ni(111)峰,此时镀层硬度达到极大值7130MPa。在此基础上,对Ni-W-P镀层的电沉积机制做了进一步探讨。

大流量三叶罗茨风机的全绝热效率及温度特性分析

介绍了大流量三叶罗茨风机的容积效率、机械效率、理想罗茨的绝热效率和全绝热效率ηad,对风机的无逆流冷却和有逆流冷却的两种温度变化情况进行了比较分析.结合生产实例说明,罗茨风机容积效率随径距比的变化,罗茨风机理想罗茨的绝热效率、全绝热效率ηad随风机的压力ε比增加呈现的下降趋势,排气温度随压力比ε增加呈现的上升趋势规律.大流量三叶罗茨风机采用逆流冷却极大地降低排气温度、减小回流冲击噪声.

温度和电流密度对亚硫酸盐电镀金的影响

采用亚硫酸盐体系镀液在紫铜表面电镀金。研究了镀液温度和电流密度对电镀金层晶相结构和纳米硬度的影响。结果表明,随着镀液温度升高,金层由(220)面择优生长转变为(111)面择优生长,纳米硬度变化不大。随着电流密度增大,金层由(111)面择优生长转变为(220)面择优生长,纳米硬度减小。电镀金层的晶粒尺寸受镀液温度和电流密度的影响不大,维持在30 nm左右。较佳的镀液温度和电流密度分别为55℃和3 mA/cm^(2),该条件下所得金层呈镜面光亮,结晶细致,纳米硬度约2.6 GPa,远高于冶炼纯金。

酸性低温脉冲化学镀镍磷合金的性能

介绍了低温脉冲化学镀镍的研究工作。结果表明：由于电脉冲的催化作用，使得酸性化学镀镍的施镀温度降低至５０℃时，仍具有１１μｍ／ｈ的沉积速度，镀层磷含量达１０．４８ｗｔ％，结构组织仍为非晶态。其镀层的性能与８０℃施镀的化学镀镀层性能相当。

油田深井用材新型铝合金牺牲阳极的防腐蚀性能

为了提高油田深井用材铝合金牺牲阳极保护TP110Nc-3Cr套管的性能,研制了一种新型的耐温铝合金牺牲阳极材料,用于对管外壁进行有效防护。采用电化学技术对铝合金牺牲阳极材料进行了极化曲线、电流效率和耐温性测试。结果表明:90℃时,极化较平缓,无钝化现象,电流效率大于80%,对套管材料具有较好的保护作用。

温度对光伏电池转换特性影响的理论及实验研究

根据光伏电池的转换特性,详细分析温度对光伏电池开路电压、短路电流、填充因子及转换效率的影响。并设计测试平台,对多晶硅光伏电池实际输出转换效率的温度特性进行了实验研究。结果表明,硅光伏电池输出开路电压随温度升高的减少率约为-2.3mV/K,理想填充因子随温度升高的减少率约为-4.5×10-4/K,短路电流随温度增加而增大,其随温度升高的增加率约为1.21mA/K。总体而言,光伏电池转换效率随温度增加而减少。同时,实验结果也证明多晶硅光伏电池实际输出效率随其温度升高的减少约为-0.22%/K,实验结果与理论分析基本一致。研究结果为光伏系统的优化设计提供了理论及实验基础。

Cr^(3+)镀液的双向脉冲电沉积特性

采用双向脉冲电沉积法从Cr^(3+)镀液中电沉积出铬镀层,并利用扫描电子显微镜(SEM)研究脉冲参数对铬镀层的微观形貌影响的规律,分析脉冲波形参数与Cr^(3+)镀液阴极电流效率之间的相关性,就双向脉冲电沉积与直流电沉积过程中所得铬镀层的微观形貌、Cr^(3+)镀液的阴极电流效率进行分析、比较。结果表明:平均电流密度、逆向脉冲系数、脉冲频率、以及占空比均对铬镀层的微观形貌及电流效率有较大影响;采用双向脉冲电沉积法制备出的铬镀层具有表面平整、结晶细致、粗糙度良好的特点,且具有较高的阴极电流效率。