Surface morphology and crystal orientation of electrodeposited tin from acid stannous sulphate solutions containing various additives

The changes in surface morphology and crystal orientation of electrodeposited tin from acid stannous sulphate solutions containing 1 mm N,N-bis(tetraoxyethylene)octadecylamine (TOGA) and various concentration (0.2–2 mm) of benzalacetone (BA) have been studied as functions of electrolysis time or BA concentration by electrochemical methods, scanning electron microscopy and X-ray diffractometry. The inhibitory effect on the reduction of the tin (II) ion became stronger with increasing concentration of BA. In the presence of both TOOA and BA, when electrolyses were carried out at the more negative potentials than the reduction potential of BA, the reduction product of BA induced reticular crystals (network structure) of tin over the whole surface. This structure appeared in the early stage of electrolysis and exhibited an intense (200) diffraction peak. On the other hand, the crystal grain size and the surface roughness of electrodeposited tin became smaller with increasing concentration of BA from 0.2 to 2 mm. Further, fine-grained and smooth electrodeposits of tin were obtained from acid stannous sulphate solutions containing TOOA and high concentration of BA due to the synergistic effect of these adsorbed species.     

Synergistic effects of benzalacetone and benzophenone on the electrocrystallization of tin from acid stannous sulphate solutions

The synergistic effects of two kinds of aromatic ketones (benzalacetone (BA), benzophenone(BP)) and N,N-bis(polyoxyethylene)octadecylamines (POOA) on the surface morphology and the crystal orientation of electrodeposited tin from acid stannous sulphate solutions have been studied by electrochemical methods, scanning electron microscopy and X-ray diffractometry. BA itself had no effect on the reduction of tin (II) ions, but the reduction product of BA had a strong inhibitory effect on the reduction of tin (II) ions. However, the inhibitory effect of BP was stronger than that of the reduction product of BP. POOA induced a uniform deposition of tin over the whole surface, but the crystal grain size and the surface roughness of electrodeposited tin were relatively large. On the other hand, fine-grained and smooth electrodeposited tin, which had a preferred orientation with the (10 0) plane parallel to the surface, were obtained from acid stannous sulphate solutions containing POOA, BA and BP due to the synergistic effects of the three kinds of adsorbed species. It was found that BA has a levelling action and BP has a grain refinement action.     

利用模糊神经网络模型优化化学镀锡液的成分

选取化学镀锡液中四种主要成分——硫酸亚锡、次磷酸钠、浓硫酸和硫脲作为影响因素,将它们设置不同的取值进行组合实验,以化学镀锡层的表面粗糙度为评价指标。根据实验得到的样本数据,建立了模糊神经网络模型。以化学镀锡层的表面粗糙度最低为寻优目标,根据模型的输出结果确定了硫酸亚锡、次磷酸钠、浓硫酸和硫脲的最佳配比,实现了对化学镀锡液成分的优化。     

Stannous chloride—an effective reducing agent for the removal of selenium(IV) from acidic solution

BACKGROUND: Selenium removal from aqueous solutions can be a significant industrial problem, particularly in the metallurgical industry. In order to evaluate new reducing agents for this application, the reduction of selenious acid (H₂SeO₃) species with stannous ions (Sn²⁺) from weakly acidic sulfate solutions containing 300 mg L^?1 of selenium at 23 °C was studied. RESULTS: At initial pH values < 1.3 and molar ratio ≥ 2, less than 0.5 µg L^?1 of selenium(IV) remained in solution after reduction. The reductive precipitation reaction started as soon as the stannous ions were added to the selenium‐bearing solution and was completed in less than 5 min. The reaction products, characterized using X‐ray diffraction, electron microscopy, particle and surface area measurements, X‐ray photoelectron spectroscopy and chemical analysis, were composed of approximately equal amounts of tin selenide and tin dioxide. In addition to tin selenide a minor amount of selenium(IV) was found to be removed via adsorption on the tin dioxide formed in situ. Tests with a complex industrial solution also resulted in full and stable selenium precipitation. CONCLUSION: Stannous ions were found to be very effective in removing selenious ions from synthetic and industrial solutions, producing very stable precipitates. Copyright © 2012 Society of Chemical Industry     

BH-411光亮硫酸镀锡工艺及实践

介绍了BH-411光亮硫酸镀锡的工艺配方、工艺流程和镀液的维护与管理,讨论了镀液中的硫酸、硫酸亚锡和添加剂的作用。中试实验结果表明：使用BH-411光亮硫酸镀锡工艺,所得镀层结晶细致、光亮,与基材的结合力良好,可焊性能好,抗变色性强该工艺可以在生产中推广使用。     

Additive-effects during plating in acid tin methanesulfonate electrolytes

The effects of organic additives on the electrochemical and morphological deposit changes from acid tin methanesulfonate solutions are presented. In the absence of additives, tin deposition is diffusion-controlled with concomitant hydrogen gas evolution and the tin deposits are rough. Addition of polyethylene glycol suppresses hydrogen gas evolution yet has little effect on the mechanism of stannous reduction and the deposit structures. Polypropylene glycol enhances stannous reduction and produces a slightly smoother tin coating. The addition of phenolphthalein to solutions already containing the glycol additives results in a kinetically-controlled tin reduction process and a smooth matte tin deposit.     

甲基磺酸亚锡与硫酸亚锡镀哑光锡的比较

从实验验证、成本分析两个方面对甲基磺酸亚锡和硫酸亚锡为主盐的镀哑光锡电解液在镀液性能和镀层性能进行比较,验证了甲基磺酸亚锡镀哑光锡在镀层和镀液方面的性能优势,在成本上,对甲基磺酸亚锡镀哑光锡和硫酸亚锡镀哑光锡做对比分析,发现二者成本接近,综合研究结论认为:甲基磺酸亚锡为主盐镀哑光锡在未来几年内,有取代硫酸亚锡的趋势。     

Formation of nanocrystalline Zinc on ITO and Silicon substrates by electrochemical deposition

Zn was deposited by means of cyclic voltammetry (CV) and square wave pulsating overpotential (OP) methods on ITO (indium tin oxide) and n-doped silicon (n-Si) substrates from an acetate-based electrolyte at two different temperatures in the absence of additives. The surface morphology of the Zn deposits was studied by scanning electron microscopy (SEM). The preferred orientation and the average size of the Zn electrodeposited particles on n-Si substrates were obtained by X-ray diffraction and the microhardness of the deposits was measured by standard means. The results show that the grain size of the electrodeposits increases as the temperature rises, and on the other hand that the PO method yields smaller grains and higher hardness values compared with those obtained by CV, irrespective of the temperature. Furthermore, in PO conditions a preferential (101) orientation is obtained for the growth of the Zn electrodeposits, but for long deposition times the growth direction is that [100] corresponding to the basal plane (002).     

多功能硫酸盐镀锡添加剂的研制

硫酸盐光度锡工艺具有电流次效率高、沉积速度快、成本低及废水易处理等优点,在电镀生产中已广泛应用。为进一步提高镀锡层的性能,研制出一种多功能硫酸盐镀锡添加剂。通过赫尔槽试验优选出最佳镀液配方和工艺条件,并对镀液、镀层性能进行了测试。结果表明：采用自制的多功能添加剂能明显提高镀液的稳定性,所得镀层光亮、致密、均匀,无锡须,结合力强,可焊性和抗氧化性好。     

Effects of saccharin and aliphatic alcohols on the electrocrystallization of nickel

The effects of saccharin and three kinds of aliphatic alcohols (n-propyl alcohol, allyl alcohol, propargyl alcohol) on the surface morphology and crystal orientation of electrodeposited nickel from a Watts bath (1 M NiSO₄ + 0.21 M NiCl₂ + 0.51 M H₃ BO₃ have been studied by means of electrochemical methods, scanning electron microscopy, energy-dispersive X-ray analysis and measurements of X-ray diffraction patterns. Saccharin and three kinds of aliphatic alcohols were adsorbed on the electrode and inhibited the reduction of nickel ion. The inhibitory effect on the reduction of nickel ion increased in the order n-propyl alcohol, allyl alcohol and propargyl alcohol. Large granular electrodeposits were obtained from the Watts bath in the absence of organic additives. When saccharin was added, fine-grained crystals were observed and the surface roughness was relatively small. When aliphatic alcohols were added, the size of surface morphological features became smaller in the order n-propyl alcohol, allyl alcohol and propargyl alcohol. Fine-grained, compact and smooth nickel electrodeposits, which had a preferred orientation with a (111) plane parallel to the surface, were obtained from the Watts bath containing both saccharin and propargyl alcohol.     

Corrosion Inhibition and Adsorption Behavior of Sodium Lauryl Ether Sulfate on L80 Carbon Steel in Acetic Acid Solution and Its Synergism with Ethanol

The application of sodium lauryl ether sulfate (SLES) as an anionic surfactant and its synergistic combination with ethanol for inhibition of corrosion of L80 carbon steel in acetic acid solutions were investigated by means of potentiodynamic polarization measurements, scanning electron microscopy (SEM), X‐ray diffraction (XRD), and energy‐dispersive X‐ray (EDX) investigations. The inhibition efficiency increases with an increase in concentration of SLES. The adsorption of SLES on the surface of L80 carbon steel obeys the Freundlich isotherm. SLES acts predominately as an anodic inhibitor. XRD, EDX, and SEM examinations of the electrode surface confirmed the adsorption of SLES on the electrode surface. The addition of ethanol with SLES significantly enhances the inhibition effectiveness and generates a strong synergistic effect.     

Leaching behaviour of tin with oxygen in recycled phenolsulfonic acid tin plating solutions

The dissolution characteristics of metallic tin with oxygen in recycled phenolsulfonic acid (PSA) tin plating bath to compensate tin consumed during the previous plating operation were investigated using electrochemical methods and leaching experiments at 30 °C. Electrochemical polarization data indicate that the diffusion of dissolved oxygen is the rate determining step and this is confirmed by leaching experiments. The sludge formed due to further oxidation of stannous ions during leaching in PSA tin plating solutions contains approximately 40 wt % Sn.     

Codeposition of copper and tin from acid sulphate solutions containing polyether sintanol DS-10 and benzaldehyde

Cu(II) and Sn(II) reduction in acid sulphate solutions containing polyether laprol DS-10 and benzaldehyde (BA) was studied by means of impedance, voltammetric, XPS and XRD techniques. Both additives demonstrate weak surface activity on copper substrate in Cu(II) solutions in the absence of halide impurities. In contrast, their effect is overwhelmingly higher in the Sn|Sn(II) system. The additives induce a significant increase in Sn-electrode impedance and simultaneous strong inhibition of Sn(II) reduction over a wide range of cathodic polarizations. The effects of sintanol and BA in mixed Cu(II) and Sn(II) solutions demonstrate a kind of synergism. Underpotential deposition of tin on foreign (copper) substrate is observed at potentials more positive than the equilibrium potential of the Sn|Sn²⁺ system. Incorporation of tin into the Cu crystalline lattice results in the formation of multiphase material containing pure copper, α-CuSn phase, and intermediate hexagonal hcp phase. Formation of the pure tin phase occurs at more negative potentials and results in a strong inhibitive adsorption that manifests itself in the development of a deep voltammetric minimum. The tin content in the coatings depends on BA concentration and, particularly, on the electrode potential.     

Effect of Pyridine and its Derivatives on the Electrodeposition of Nickel from Aqueous Sulfate solutions Part I: Current Efficiency, Surface Morphology and Crystal Orientation

The effects of pyridine and its derivatives on current efficiency, surface morphology and crystallographic orientations of electrodeposited nickel from acidic sulfate solutions were investigated. The results indicated that the presence of pyridine and picolines had no significant effect on current efficiency. The deposits obtained were smoother, more compact and uniform with picolines than with pyridine. A significant change in surface morphology of the electrodeposits was observed and picolines were found to be better additives than pyridine, 4-picoline being the best. X-ray diffraction revealed that the (200) plane was the most preferred plane and was not affected by the presence of any of these additives in the electrolyte.     

Nucleation and growth of tin on low carbon steel

The nucleation and growth of tin from stannous sulfate and sulfuric acid with an organic additive of gelatin was studied on low carbon steel. Investigations were conducted by linear sweep voltammetry and current step methods. The agitation effect on the morphology of tin deposits was also studied. From the results, a mechanism of tin deposition on a steel substrate is suggested. Initially, 3D tin crystallites are formed preferentially on step edges, and this is followed by fast covering of neighboring sites with much smaller and densely packed crystallites of about 150-180 nm in size. Without gelatin, the coverage was poor and tri-modal structures were dominating. It is discovered that the synergy between hydrogen co-evolution and gelatin contributes to fast and complete coverage of the steel substrate and the bi-modal grain size distribution is observed. The diffusion coefficient of tin ion was determined according to the Sand equation.     

氰化镀铜锡合金工艺改进

采用正交试验研究了氰化镀铜锡合金工艺中各因素水平的与镀液,镀层性能的关系,优选出一种最佳工艺配方。该工艺成本低,槽液稳定,镀层质量好。     

Glycolate adsorption at gold and platinum electrodes: A theoretical and in situ spectroelectrochemical study

The adsorption of glycolate anions at sputtered gold thin-film electrodes was studied in perchloric acid solutions by cyclic voltammetry experiments combined with in situ Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Reflection Absorption Spectroscopy under attenuated total reflection conditions (ATR-SEIRAS). Theoretical harmonic vibrational frequencies and band intensities obtained from B3LYP/LANL2DZ,6-31+G(d) calculations for glycolate species adsorbed on Au clusters with (1 1 1) orientation were used to interpret the experimental spectra. Vibrational data confirm the bidentate bonding of glycolate anions through the oxygen atoms of the carboxylate group, in a bridge configuration with the OCO plane perpendicular to the metal surface. The DFT calculations show no significant effect of the total charge of the metal cluster-adsorbate adduct on the vibrational frequencies of adsorbed glycolate species. The infrared experimental study is extended to platinum films electrochemically deposited onto sputtered gold thin-film electrodes showing the potential-dependent formation of adsorbed CO upon dissociative adsorption of glycolate anions. As in the case of gold, the reversible adsorption of glycolate anions takes place in a bidentate configuration as predicted by DFT calculations for glycolate adsorbed on Pt(1 1 1) clusters. At low glycolic acid concentration, the in situ ATR-SEIRA spectra evidence the formation of adsorbed oxalate as reaction intermediate.     

Modulation of magnetic and structural properties of cobalt thin films by means of electrodeposition

Cobalt electrodeposits were prepared from an electrolytic bath containing cobalt perchlorate. The effect of different species, organic (thiourea and sodium gluconate) and inorganic (boric acid), on the crystallographic structure, morphology, magnetic properties and electrochemical behaviour of cobalt electrodeposits was investigated. Amorphous cobalt, hcp cobalt and a non-usual primitive cubic cobalt phase were observed depending on the bath composition. Depending on the structure, different morphologies and magnetic properties were found. Coercivity values of the cobalt coatings ranged from around 15 Oe for amorphous, nodular deposits to 380 Oe for cobalt coatings showing acicular morphology and hcp structure with a (002) preferred orientation. Knowledge of the influence of the species on the properties of cobalt makes it possible to obtain tailored cobalt films.     

Effects of antimony(III) on zinc electrodeposition from acidic sulfate electrolyte containing [BMIM]HSO<Subscript>4</Subscript>

The effect of antimony(III) on the cathodic current efficiency (CE), power consumption (PC), deposit morphology, and polarization behavior during electrodeposition of zinc from acidic sulfate solutions containing 1-butyl-3-methylimidazolium hydrogen sulfate-[BMIM]HSO₄ was investigated. The results indicated that the addition of Sb(III) alone decreased the CE, increased the PC, and deteriorated the quality of the zinc electrodeposits. However, the combined addition of Sb(III) and [BMIM]HSO₄ was found to be beneficial for zinc deposition and improved the surface morphology of the zinc electrodeposits. Maximum CE and minimum PC were obtained at the combined addition of 0.02 mg dm⁻³ Sb(III) and 5 mg dm⁻³ [BMIM]HSO₄. Depolarization of the cathode was noted in the presence of Sb(III) alone in the electrolyte whereas this effect was partly counteracted by the addition of [BMIM]HSO₄. Cathodic polarization curves were traced and analyzed to determine the electrokinetic parameters such as Tafel slope, transfer coefficient, and exchange current density so as to elucidate the nature of the electrode reactions. The data obtained from X-ray diffractogram revealed that the presence of Sb(III) did not change the structure of the electrodeposited zinc but affected the crystallographic orientation of the crystal planes.     

Adsorption of benzoic acid and phenol from aqueous solution by activated carbons—effect of surface acidity

Effect of surface acidic groups of activated carbons on their adsorption characteristics for substrates from aqueous solutions were studied. Six kinds of carbons obtained commercially and their heat-treated products were used. Pore-size distribution, BET surface area and surface acidity were measured. Adsorption isotherms for benzoic acid and phenol from aqueous solutions (single or double components) were obtained. Substitution adsorption, i.e. substrate adsorbed preliminarily is substituted by another substrate, was also carried out. It was found that adsorption of benzoic acid is scarcely affected by surface acidity of carbons and the amount adsorbed is almost entirely controlled by the specific surface area of carbons. On the contrary, adsorption of phenol is retarded considerably by the acidity of carbons. In the case of solution of double components, benzoic acid is adsorbed predominatedly. The phenol adsorbed preliminarily is easily substituted by benzoic acid, but the substitution of benzoic acid by phenol scarcely proceeds.