Effects of graphene content in alkaline silicate electrolyte on AA1060 pure aluminum micro-arc oxidation coating

Ceramic coatings were obtained by micro-arc oxidation (MAO) on the surface of AA1060 pure aluminum in alkaline silicate electrolyte with the addition of graphene. The effects of graphene contents in the range of 0–.30 g/L in the electrolyte on surface morphology, corrosion resistance, and wear resistance of the ceramic coatings were investigated. The outer surface structure, outer surface element content, coating cross-section structure, coating cross-section element content, coating/substrate interface structure, and coating phase were characterized by scanning electron microscope and X-ray diffraction. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion behavior of MAO samples in a 3.5-wt% NaCl solution. In addition, the resistance to sliding and abrasive wear of the oxide coating were studied experimentally. The results show that the alkaline silicate electrolyte with the addition of graphene has a significant effect on the characteristics of MAO coating. The performance of micro-arc oxide coatings is best when the graphene content in the electrolyte is .15 g/L, the average thickness of the film is 7.24 μm, the average pore size is 6.07 μm, the impedance value is approximately 4.01 × 106 Ω, and its friction coefficient is .55.     

高性能碱性无氰光亮镀锌的使用和维护

以SF-529碱性无氰光亮镀锌为例,介绍了碱性无氰光亮镀锌的工艺条件以及镀液各组分的作用和使用方法,对镀液维护和常见故障的处理方法进行了讨论,为SF-529碱性无氰光亮镀锌工艺应用提供参考。     

Chemical and morphological analyses of zinc powders for alkaline batteries

Zinc powders containing Bi, In and either Mg or Al were analyzed to determine chemical and morphological differences. Morphology and chemistry may influence the reactivity of Zn powders in the basic environment found inside alkaline batteries. Increased reactivity leads to increased Zn corrosion, increased hydrogen gas evolution, and possibly leakage of the battery electrolyte. The surface chemistry of the powders was examined using Auger electron spectroscopy, X-ray photoelectron spectroscopy, and atomic absorption spectroscopy to check for surface ZnO. Powder chemistry was measured using an electron probe micro analyzer equipped with an energy dispersive X-ray analyzer. Inert gas fusion determined the bulk oxygen content. Morphology studies included powder sieving for size determination, examining loose powders with a scanning electron microscope (SEM), and determining surface areas via Brunauer, Emmet, and Teller (BET) analyses. SEM images showed differences in powder shapes and surface conditions between passed and failed powders. Powders exhibiting smooth surfaces and regular shapes were more likely to pass gas testing. However, pass/fail gas test results could not be correlated to powder chemistry, powder size, or surface area. Powder roughness and irregularity may indicate an increase in the number of active sites such as peaks and barbs versus particles with smooth surfaces.     

BH-铝合金浸锌液中锌的化学分析

在浸锌液的日常维护中,掌握浸锌液中锌的含量非常重要。采用络合滴定法测定浸锌液申的锌。选用络合能力很强的w=5％的NaCN溶液络合浸锌液中全部的金属离子,待全部金属离子完全络合后选用w=4％的释放剂甲醛释放锌离子,然后采用紫脲酸铵作为指示剂,用EDTA滴定。该法简单、方便．方便工厂对浸锌液的维护。     

铝上一次浸锌工艺的研究

研制出一种新型的不含氰化物,氟化物以及有毒重金属离子的HG铝合金浸锌液。研究了浸渍温度,时间,搅拌和铝合金材料对镀层结合力的影响。该浸锌液的工作温度为0－40度,较佳温度范围为20－30度,当温度低于20度时,浸锌时间应在30S以上;当温度高于30℃时,浸锌时间应小于30S。在静止,机械或超声搅拌的情况下均能获得结合力优异的镀镍层,可用于硬铝、锻铝、铸铝及粉末冶金铝件的镀镍前处理。此外,热震试验能提高镀层与基体的结合力,因此,不能用于评价铝上镀镍的结合力。     

pH梯度萃取-碱性氧化铝柱层析分离长春花中的文多灵和长春质碱

利用生物碱在不同pH值下存在形式不同的性质,采用pH梯度萃取法将长春花总生物碱分为单吲哚生物碱部分（含有文多灵和长春质碱）和双吲哚生物碱部分（含有长春碱）,然后采用碱性氧化铝柱层析对单吲哚生物碱部分进行分离。pH梯度萃取后得到的单吲哚生物碱部分中文多灵和长春质碱的含量分别为18.12%和11.44%,收率分别为80.86% 和88.91%;经碱性氧化铝柱层析分离后,得到文多灵和长春质碱含量分别为85.56%和76.73%,收率分别为85.23%和86.34%;重结晶后文多灵和长春质碱纯度分别达到95.22%和98.46%,收率分别为92.15%和98.24%。此方法适合文多灵和长春质碱的工业化大规模生产。     

Dual role of activated carbon as fuel and template for solution combustion synthesis of porous zinc oxide powders

In this work, nanosized zinc oxide (ZnO) powders were fabricated by urea–nitrate solution combustion synthesis using activated carbon as a structure-directing template and secondary fuel at different fuel–oxidant ratios. The as-synthesized powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption–desorption measurements, UV–Vis diffuse reflectance spectroscopy, and photoluminescence. The effect of fuel amount on photocatalytic activity of ZnO powders was evaluated by the degradation of an azo dye Orange G. It was observed that combustion synthesis with activated carbon as a secondary fuel had a profound effect on reducing crystallite size and enhancement of specific surface area. The crystallite size of the as-synthesized powders varied from 46 to 26 nm. The ZnO powder prepared at a fuel–oxidant ratio of 1.8 possessed the small crystallite size and high specific surface area of 69 m²/g. It correspondingly resulted in the highest dye removal percentage of 99% with a rate constant of 0.027 min⁻¹. The improvement in dye degradation can be due to the synergistic interaction and interplay of enhanced surface area and catalytic ability of the photocatalyst. This study provides a simple single-step synthesis methodology to produce metal oxide nanopowders with tunable surface properties for high potential applications in catalysis, optoelectronics, and gas sensors.     

铬酸钠碱性液除钒工艺研究

采用无钙焙烧或湿法冶金工艺制备的铬酸钠碱性液,铬酸钠溶液中钒杂质已成为必须去除的杂质之一。研究探讨了羟氧化铬在铬酸钠含钒溶液中的除钒效果,考察了温度、羟氧化铬加入量、反应时间、溶液p H值等因素对除钒效果的影响。结果表明:每升铬酸钠溶液[ρ(V2O5)=0.600 g/L]需使用羟氧化铬40 g,在除钒温度60℃、时间30~120 min、p H值9~12的条件下,除钒效果较好。     

Effect of an organic additive on the electrocrystallization of cadmium in alkaline solution

The electrocrystallization of Cd(OH)₂ in KOH solution was studied on a solid cadmium electrode using the potential step method. An organic additive, polyvinyl alcohol (PVA), sometimes considered for use as an additive in nickel-cadmium batteries, was found to inhibit the nucleation process. A two-dimensional instantaneous nucleation and growth was found to take place in the absence of the expander, whereas deviation occurred when PVA was present. The general effect of adding PVA was to loweri _m and increaset _m.     

Effect of an organic additive on the impedance of cadmium in alkaline solution

The a.c. impedance of a planar cadmium electrode in KOH solution was measured over the active and passive region using a potentiostatic technique. Different concentrations of polyvinyl alcohol (PVA) were subsequently introduced into the alkaline solution and the impedance remeasured. It was found that the addition of PVA markedly increased the double layer capacity of the electrode and decreased electrolyte resistance,R _sol. The impedance spectra in the presence of PVA were analysed in terms of an equivalent circuit involving the series combination of two double layer capacitances and a resistance proportional to the conductivity of the electrolyte.     

烟气SO2与氧化锌在水溶液中的反应研究

以氧化锌为吸收剂的烟气脱硫工艺能实现硫、锌资源的回收利用,特别适合于铅锌冶炼行业的烟气净化。试验研究了氧化锌与SO2在水溶液中的反应过程。通过固、液相中亚硫酸盐含量,锌离子浓度以及溶液pH值等对反应过程进行了表征,考察了SO2浓度、温度对反应的影响。试验结果表明,SO2在水溶液中首先是与氧化锌反应生成固体亚硫酸锌,然后固体亚硫酸锌溶解进入液相。当SO2水溶液w(SO2)1%以上时,25～35℃的反应温度对于提高SO2吸收率有利,进一步的表观反应活化能分析表明,氧化锌和SO2水溶液的反应活性与Ca(OH)2和SO2水溶液的反应活性相似。     

Effect of aluminum annealing on the galvanoluminescence properties of anodic oxide films formed in organic electrolytes

The galvanoluminescence (GL) properties of anodic oxide films formed in organic electrolytes were investigated at different aluminum annealing temperatures. The results of the spectral measurements showed two different types of GL sources: carboxylate ions incorporated in oxide films during the anodization and the molecules AlH, AlO, Al₂, AlH₂, also formed during anodization process and already recognized in the case of inorganic electrolytes. The latter was related to gamma alumina crystalline regions formed by annealing of the aluminum samples at temperatures above 500 °C.     

Cyclic voltammetric study of zinc and zinc oxide electrodes in 5.3 M KOH

The behaviour of zinc and zinc oxide in 5.3 M KOH in the presence of alkaline earth oxides, SnO, Ni(OH)₂ and Co(OH)₂ was examined by cyclic voltammetry. The influence of the alkaline earth oxides was compared with additives of established effects (Bi₂O₃, LiOH, Na₂CO₃ and CdO). The alkaline earth oxide each exhibits a distinct behaviour towards zincate. Whereas, a single process of interaction with zincate was shown by CaO; two modes of reaction were obtained with SrO and BaO. Solid solution formation was noticed with BeO and MgO. The other additives forming solid solution with ZnO were CdO, SnO. The ionic sizes of Ni(OH)₂ and Co(OH)₂ allow solid solution formation with Zn(OH)₂. Both Bi₂O₃ and Na₂CO₃ enter into complexation with zincate. LiOH forms two distinct zincates, of which one is an oxo zincate leaching the `hydroxyl' functionality. Cyclic voltammetry revealed the deposition of the oxide/hydroxide additives as metal prior to the onset of zinc deposition and the potential range for this additive metal deposition is almost the same for different additives (SnO, CdO, Ni(OH)₂). The beneficial action of these additives to zinc alkaline cells is associated with a substrate effect. The implication of this electrocatalytic deposition of metals on a zinc oxide electrode is also discussed.     

由粗氧化锌制备纳米活性氧化锌的研究

采用碳酸氢铵法由粗氧化锌制备纳米活性氧化锌。研究了用碳酸氢铵法由粗氧化锌制备活性氧化锌的热力学、中间体碱式碳酸锌的主要组成和碱式碳酸锌热分解的温度对形貌的影响;考察了中间体碱式碳酸锌的热分解温度和时间对纳米活性氧化锌的纯度、白度、比表面积和表观密度的影响。碱式碳酸锌焙解生成纳米活性氧化锌适宜的温度和时间分别为600℃和1h时,产品中氧化锌的质量分数为97.6%,粒度<100nm,比表面积50m2/g,表观密度0.21g/cm3。     

Effect of time of application on the effectiveness of zinc sulphate and zinc oxide as sources of zinc for wheat

Field experiments with wheat were conducted for two years on flood plain alluvial soils to study the effectiveness of soil application of zinc sulphate and zinc oxide at 0, 15, 45, 60, 75 and 90 days after sowing. Yield and zinc uptake of wheat increased significantly with the application of zinc. Delaying the application of both zinc sulphate and zinc oxide up to 45 days of sowing did not adversly affect the zinc nutrition of wheat. However, delaying the application for 75 or 90 days after sowing eliminated the response. Zinc sulphate, when applied within 60 days of sowing performed better than zinc oxide. In a laboratory study, zinc sulphate maintained a higher level of zinc in the soil solution than zinc oxide at least over a 3-week period.     

NaF添加剂对铝合金等离子电解氧化陶瓷膜形成的影响

研究了Na2SiO3-KOH电解溶液中添加NaF对铝合金等离子电解氧化陶瓷膜形成的影响。研究表明：电解溶液中加入NaF可加速氧化物陶瓷膜的形成,提高其硬度。NaF的最佳加入量为0．5～0．75g／L。     

聚硅酸铝锌絮凝剂的制备及其絮凝性能研究

研究了聚硅酸铝锌絮凝剂适宜制备条件和提高絮凝性能的适宜条件。以硅酸钠、氯化铝、氯化锌为原料,制备聚硅酸铝锌絮凝剂,处理含磷废水。结果表明,硅酸钠浓度0.5mol/L,活化p H为4,活化时间60min,n(Al)/n(Si)为2,n(Zn)/n(Si)为3,水样p H为12,静沉时间10min时,含磷废水处理效果较好,除磷率可达98.6%。     

Corrosion electrochemical behavior of epoxy anticorrosive paints based on zinc molybdenum phosphate and zinc oxide

Electrochemical impedance spectroscopy (EIS) was applied as a principal tool to describe the efficiency of anticorrosive epoxy paints (primers) based on zinc molybdenum phosphate (ZMP) pigment. Steel-coated samples were exposed to a 0.5 M NaCl solution. During the study the corrosion potential (E_oc) and R_p values also were monitored every 24 h. It is discussed the incorporation of micronized ZnO (1 μm) pigment to the base mixture and its positive, reinforcement effect on the protective properties of ZMP primer. The explanation is related to the izoelectric point (IEP) of ZnO particles (pH < 9), which determines their positive surface charge and electrostatic attraction with the molybdate anion. In this case the charge of the formed double layer capacitor is very high. Moreover, the mentioned attraction inhibits and saves ZnO particles from their rapid dissolution to hydroxide.     

Effects of stannous ions on the electrochemical performance of the alkaline zinc electrode

The effect of stannous ions as an electrolyte additive on the electrodeposition characteristics of Zn was investigated by chronoamperometry, the potential-step method and cyclic voltammetry. The chronoamperometry measurements showed that the addition of stannous ions inhibited the dendritic growth of Zn deposits. SEM observation also revealed that the Zn deposit was in the form of compact cylinders with rounded tops that consist of many small crystallites, rather than the classical dendrites with side branches. The inhibition effect of Sn²⁺ on the very initial electrocrystallization of Zn was not a substrate effect. The 0.17 V difference in reduction potential between Zn and Sn resulted in the codeposition of Sn and Zn. An interruption effect was proposed to illuminate the inhibition effect of Sn²⁺ on the formation of Zn dendrites. Furthermore, Sn²⁺ additive was found to suppress the corrosion reaction of Zn by 87% in the Sn²⁺-containing zincate electrolyte, comparing to that in the blank zincate electrolyte.     

碳铵法制备纳米氧化锌的研究

一种纳米氧化锌的制备方法，其过程包括：以硫酸锌和碳酸铵(或碳酸氢铵和氨水)为原料中和制备碱式碳酸锌，碱式碳酸锌经水洗除掉硫酸根后，再醇洗、干燥、煅烧，制备了纳米氧化锌。经表观密度、比表面积、孔容积和透射电镜(TEM)的测定，确定了研制的物料为纳米氧化锌，粒子峰值为10～20nm。