锂离子蓄电池用Cu-Sn合金负极的制备及改性

用机械合金化法经20h、50h和100h球磨制备了3种Cu-Sn合金,由合金制备的电极经300℃、500℃和700℃热处理后具有良好的电化学性能,其中经300℃热处理5h的电极具有最优的循环性能:电极循环50次后放电容量为205mAh·g-1以上,库仑效率为99.5%;电极循环100次后放电容量还有152mAh·g-1左右,库仑效率仍能维持在约99.5%,并且电极自放电率很小。     

An improved numerical method for predicting intermetallic layer thickness developed during the formation of solder joints on Cu substrates

An improved numerical method has been developed for calculating the thickness of intermetallic layers formed between Cu substrates and solders during the soldering process. The improved method takes into account intermetallic dissolution during heating and intermetallic precipitation during cooling and requires as input (1) the temperature-time profile for the soldering process, (2) the experimentally determined isothermal growth parameters for the growth of the intermetallic layer into Cu saturated molten solder, (3) the experimentally determined Nernst-Brunner parameters for the dissolution of Cu into molten solder, (4) the experimentally determined solubility of Cu in molten solder and (5) assumptions about the thickness of the boundary layer in the liquid ahead of the growing intermetallic. Calculations show that the improved method predicts intermetallic growth between Cu substrates and 96.5Sn-3.5Ag solder during reflow soldering better than a previously developed method, which did not take into account dissolution during heating and precipitation during cooling. Calculations further show that dissolution has a significant effect on growth, while precipitation does not.     

电镀铜锡合金工艺研究进展

电镀铜锡合金具有装饰性好、可焊性优良、成本低、无毒、不使人体过敏等优点,而得到广泛的应用.介绍了电镀铜锡合金工艺的研究进展和应用、电镀铜锡合金镀液配方和工艺条件.     

某铜锡多金属矿尾矿工艺矿物学研究

针对某铜锡多金属矿尾矿进行工艺矿物学研究,发现该尾矿含有钨、锡、铋等有价金属,含量分别为0.088%、0.082%和0.054%。研究结果表明虽然有价元素含量低,但均以矿物形式存在且粒度较粗,有价矿物集合体解离情况好,且与脉石矿物之间存在较大的相对密度差异。富集试验表明硫化物矿物通过淘洗可得到有效富集,因此选矿试验可利用矿物之间的密度差。通过重选实现有价矿物的预富集;针对淘洗富集产品的工艺矿物学研究结果表明:有价矿物磁黄铁矿、白钨矿、锡石、黑钨矿和自然铋的粒度相对较粗,一般为0.02~0.104mm,而且单体解离度都在80%以上,解离比较充分,有利于后续彼此之间的分离。根据尾矿中有用矿物嵌布关系、粒度分布和解离度等工艺矿物学结论,选厂采用"重选预富集-铋硫混浮-铋硫分离-钨锡重选富集-浮选分离"工艺,获得了铋精矿、钨精矿和锡精矿,提高了企业的经济效益。     

焦磷酸盐铜-锡合金镀液性能的研究

以焦磷酸铜和锡酸钠为主盐,焦磷酸盐为配位剂,加入一种自制的铜-锡合金添加剂组成焦磷酸盐镀液,通过赫尔槽实验优选出最佳镀液配方和工艺条件,并对镀液的分散能力、深镀能力、阴极电流效率和沉积速率等性能进行测试。结果表明:镀液的分散能力为98.05%,深镀能力为100%,平均电流效率为86.65%,平均沉积速率为59.2μm/h。加入添加剂后明显改善了镀液的极化性能,提高了铜离子及锡离子的析出电位,得到均匀致密、结晶细致、光亮整平的铜-锡合金镀层。     

Room temperature crystallization kinetics of amorphous Cu6Sn5 + C alloys

Thin film combinatorial sputter deposited Cu₆Sn₅ + C alloys were prepared and found to be amorphous and/or nanostructured upon removal from the sample preparation chamber. Samples having approximate compositions (Cu₆Sn₅)_1−xC_x with 0.16 < x < 0.26 have been stored at room temperature and investigated over the course of about one year using X-ray diffraction (XRD). Simple models were employed to analyze the observed changes in the XRD patterns. Relatively sharp (nanocrystalline) components having Bragg angles corresponding to hexagonal Cu₆Sn₅ grew in intensity at the expense of broader (amorphous) components as a function of time. The grain size of the nanocrystalline components was approximately time independent, but depended on the amount of carbon present. The logarithm of the recrystallization time and the activation energy for crystallization appeared to be linearly dependent on the carbon content for the composition range that has been studied, as inferred from the Avrami-Johnson-Mehl equation. XRD patterns of samples with x > 0.26 appear to be relatively unchanged after a period of storage at room temperature for one year.     

Comparative TEM investigation on the precipitation behaviors in Cu–15wt%Sn alloy

The decomposition and precipitation behaviors of a quenched Cu–15wt%Sn alloy as a function of aging temperature were investigated using transmission electron microscopy (TEM). Focused ion beam (FIB) was employed to assist TEM specimen preparation. At 300 °C, the decomposition of the supersaturated α′ phase occurred at grain boundaries, displaying a cellular morphology. The lamellae were found with ζ and α phases, rather than with the equilibrium ε and α phases. The ζ and α phases exhibit a well-defined orientation relationship (OR) as $ (1\bar{1}0)_{\alpha } //(0001)_{\zeta } ,\;[11\bar{2}]_{\alpha } //[\bar{1}2\bar{1}0]_{\zeta } $ . On the other hand, at 320 °C, only incipient lamellar structures of several micron meters were observed, which were composed of the δ and α phases. At the same time, abundant intragranular precipitation of the ε phase in the form of platelets was observed, and OR as $ (1\bar{1}1)_{\alpha } //(001)_{\varepsilon } , $ [110] _α //[100] _ε exists between ε phase and the α phase. These contrasting precipitation behaviors are discussed from the viewpoint of crystallographic coherency of these phases.     

Interfacial energy gradient at a front of an electrochemical wave appearing in CuSn-alloy oscillatory electrodeposition

In the present work, we show that a large interfacial energy gradient is produced at a front of an electrochemical wave appearing in CuSn-alloy oscillatory electrodeposition from an aqueous solution by observing the directional lateral motion of an oil droplet put on an electrode surface. During the oscillation, the surface composition of the electrodeposit changed periodically between Cu-rich and Sn-rich alloys. The transition from the Cu-rich phase to the Sn-rich phase, or vice versa, initiated at a region of the electrode and propagated to the entire surface as an electrochemical wave. Contact angle measurements of the droplet revealed that the electrochemical interfacial energy varies largely between during Cu-rich and Sn-rich alloy electrodeposition. Repetitive approaches of the electrochemical wave front to the droplet drives the directional movement of the droplet, indicating the lateral imbalance of the interfacial energy (i.e., the interfacial tension) at the front is so large that the force produced by the imbalance can transport macroscopic objects such as an oil droplet.     

Effect of electrodeposition parameters on the hydrogen permeation during Cu-Sn alloy electrodeposition

The Cu-Sn alloy coatings were synthesized on 27SiMn steel by direct current (DC), pulse current (PC) and pulse reverse current (PRC) electrodeposition techniques from pyrophosphate-based electrolyte. The hydrogen permeation behaviors during the electrodeposition by different techniques were investigated using Devanathan-Stachurski method. The results demonstrated that the hydrogen permeation amount of different electrodeposition techniques decreased in the order: DC > PC > PRC. Frequency and duty cycle have great effect on the sub-surface concentration C_o of atomic hydrogen and hydrogen permeation amount. The minimum of hydrogen permeation amount was observed at the frequency of 1000 Hz or 2500 Hz and the duty cycle of 40%. It indicates that the amount of permeated hydrogen in the steel during deposition can be reduced due to the decrease of C_o by PC and PRC methods.