Anodic dissolution of titanium in NaCl-containing ethylene glycol

Anodic dissolution behavior of titanium in NaCl-containing ethylene glycol has been examined to obtain electropolished titanium surface. During anodic polarization in 1 mol dm^?3 NaCl ethylene glycol solution at 293 K, the titanium electrode covered with oxide dissolves with gas evolution at potentials higher than 10 V (Ag/AgCl) while it is in passive state at potentials lower than 5 V. However, after removal of the oxide layer by pre-polarization at gas-evolving potentials, no gas evolution is observed, and the titanium electrode shows a limiting dissolution current as tetravalent species at potentials higher than 5 V, producing a smooth surface. The polarization of the rotating disk titanium electrode reveals that the kinetics of the mass transfer reaction for electropolishing of titanium is controlled by titanium species dissolved into the solution, not by chloride ions or water containing in the solution. Repetition of dynamic polarization gives a well-electropolished surface.     

Anodic dissolution of titanium in chloride-containing ethylene glycol solution

Anodic dissolution behavior of titanium in chloride-containing ethylene glycol was examined using a rotating disk electrode. A potential-independent dissolution current flowed depending on the rotation speed, species and concentration of chloride salts. In solutions with lower concentrations of chloride, a potential-independent current was controlled not only by the mass transfer process but also by the charge transfer, and the kinetic-controlling current depends on solution conductivity. In concentrated chloride solutions, the current was controlled only by mass transfer process and decreased with increase in chloride concentration. A smaller current also flowed in a solution with a high concentration of titanium species. These results indicated that the diffusion-controlling species are titanium species, not chloride ions. Electrochemical impedance spectroscopy revealed that a titanium chloride salt layer, which maintains titanium species at a high concentration, accumulates a low charge (0.1 μF cm⁻²) and becomes thicker with increase in applied potential, is formed between the titanium substrate and diffusion layer during the mass transfer-controlling dissolution.     

Individual ionic activities and mass transfer in anodic chlorate formation

The individual activity of hypochlorite ion in concentrated neutral salt (NaCl-NaClO₃) solutions has been estimated kinetically by measurement of the Faradaic efficiency in a chlorate producing system comprised of a cell and external reactor, with provision for brine re-circulation. By use of this activity in the diffusion relationships developed by Ibl and Landolt [1–3], reasonable agreement has been achieved between the experimental chlorate yield and the yield expected based on the combined hydrolytic and diffusional flux of active chlorine. In this way it has been shown as expected from basic theory that the gradient of chemical potential rather than the concentration difference represents the driving force of diffusion. A formal activity coefficient for active chlorine species is suggested as being a useful term when considering the chlorate cell system.     

Anodic coloring of titanium and its alloy for jewels production

Anodized titanium with its interference colors, its appearances and its light, is undoubtedly of great appeal to the field of architecture and to all ramifications of design, to visual communication and to the world of fashion. On its surface, it is possible to create a visionary world of colors, perfectly controlled by the imposition of determined anodizing parameters and surface conditions. This article presents one of the applications of anodized titanium, which most earns general interest nowadays in the designers' world, that is, the production of colored titanium jewels. Since titanium is considered a seminoble metal, its use is mainly directed to small series production: therefore, a good know‐how giving high reliability of the anodic coloring process is required. The chosen procedure will be described, together with a full characterization of the obtained interference colors. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012     

隔膜法电解过程中减少氯酸盐产生量的方法

综合分析了隔膜法电解生产烧碱过程中氯酸盐的产生原因及其危害,重点提出了减少和产生氯酸盐的具体措施.     

Pressure drop through platinized titanium porous electrodes for cerium‐based redox flow batteries

The pressure drop, , across a redox flow battery is linked to pumping costs and energy efficiency, making fluid properties of the electrolyte important in scale‐up operations. The at diverse platinized titanium electrodes in Ce‐based redox flow batteries is reported as a function of mean linear electrolyte velocity measured in a rectangular channel flow cell. Darcy's friction factor and permeability vs. Reynolds number are calculated. Average permeability values are: 7.10 × 10^?4 cm² for Pt/Ti mesh, 4.45 × 10^?4 cm² for Pt/Ti plate + turbulence promoters, 1.67 × 10^?5 cm² for Pt/Ti micromesh, and 1.31 × 10^?6 cm² for Pt/Ti felt. The electrochemical volumetric mass transport coefficient, , is provided as a function of . In the flow‐by configuration, Pt/Ti felt combines high values with a relatively high , followed by Pt/Ti micromesh. Pt/Ti mesh and Pt/Ti plate gave a lower but poorer electrochemical performance. Implications for cell design are discussed. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1135–1146, 2018     

Platinum-iridium catalyzed titanium anode. I. Properties and use in chlorate electrolysis

The use of dimensionally stable titanium anodes activated with Pt, Ir or ruthenium oxide for electrolytic chlorate production has been investigated. Simultaneous measurements were made of the amount of noble metal at the surface and of electrode activity, as functions of time of electrolysis at constant current and temperature. After more than 400 days of operation, an electrode with 7 g m^–2 of surface of noble metals exhibits good polarization characteristics as well as freedom from corrosion of the coating.     

Anodic formation of polypyrrole/tungsten trioxide composites

The anodic codeposition of WO₃ and polypyrrole at constant current densities was studied. The powdery solid was dispersed in the electrolyte (0.1m pyrrole, 0.1m LiClO₄) under strong convection at c _L = 0.01–30 g dm⁻³. Water or wet acetonitrile were employed as solvents. Various modes of convection were developed. The resulting WO₃ Concentrations in the PPy/WO₃ composites were up to c _C = 53 wt%. c _C was found to increase with increasing convection intensity and with decreasing current density. Quantitative evaluation leads to a relationship c _C = K log c _E/c _E.0, where K is a constant,and c _E.0 is a threshold concentration. This equation was derived from a model assuming a Temkin type adsorption of the impinging particles and their field enhanced final incorporation into the polypyrrole matrix K is proportional to j ⁻¹. The new model complements the older theory of Guglielmi originally developed for systems with metal matrices, and it also holds for these very well known composites. The homogeneous distribution of WO₃ in PPy is demonstrated by the linear increase of the WO₃ mass with the thickness of the composite in combination with SEM techniques.     

Phase formation in titanium glazes

Phase formation in titanium-containing systems is examined. The results of studies of phase formation under crystallization are reported for the SiO₂−TiO₂−CaO−Al₂O₃−B₂O₃−Na₂O system. The principal phases in the compositions studied were found to be sphere, anorthite, and rutile. Translated from Steklo i Keramika, No. 1, pp. 17–20, January, 1997.     

氯酸盐分解工艺讨论

介绍了2种氯酸盐分解工艺.给出新的氯碱盐分解工艺.优化后HAZOP分析记录显示装置运行稳定可靠.     

Anodic aqueous electrophoretic deposition of titanium dioxide using carboxylic acids as dispersing agents

The dispersion of anatase phase TiO₂ powder in aqueous suspensions was investigated by zeta-potential and agglomerate size analysis. The iso-electric point (IEP) of anatase was determined to be at pH 2.8 using monoprotic acids for pH adjustment. In comparison, it was found that the use of carboxylic acids, citric and oxalic, caused a decrease in zeta-potential through the adsorption of negatively charged groups to the particle surfaces. The use of these reagents was shown to enable effective anodic electrophoretic deposition (EPD) of TiO₂ onto graphite substrates at low pH levels with a decreased level of bubble damage in comparison with anodic EPD from basic suspensions. The results obtained demonstrate that the IEP of TiO₂ varies with the type of reagent used for pH adjustment. The low pH level of the IEP and the ability to decrease the zeta-potential through the use of carboxylic acids suggest that the anodic EPD of anatase is more readily facilitated than cathodic EPD.     

离子膜法烧碱生产中氯酸盐的产生原因及解决措施

分析了离子膜法烧碱生产中产生氯酸钠的原因、危害,给出降低系统氯酸盐含量的办法。以实例说明了真空脱氯方式下氯酸盐的分解工艺。     

氯酸盐对隔膜电解的影响

前言氯碱工业生产中 ,电流效率是衡量企业经济效益的标准之一 ,氯酸盐含量高是氯碱隔膜电解生产经常遇到的问题。电解液中氯酸盐含量居高不下 ,电流效率下降 ,不仅影响企业经济效益、产品质量 ,增大设备维修费用 ,而且威胁生产安全。近来我公司固碱产品含盐量高 ,质量下降 ,一级品率极低。针对上述情况 ,我们通过查阅资料和咨询有关技术专家 ,认为氯酸盐含量高是问题所在。1　氯酸盐的生成氯酸盐是电解副反应的产物。阳极液中的氯气与水反应生成次氯酸。当阴极室中大量OH- 反渗到阳极室时 ,就会与HClO在隔膜近侧反应生成NaClO ,NaClO进…     

钛白生产中酸解用酸换热器的阳极保护

研究了316L 不锈钢在91%硫酸中的阳极过程,确定了保护参数,提出了 RS4阴极材料。实验和工业运行结果表明,采用阳极保护大大地降低了不锈钢在80和96℃浓硫酸中的腐蚀速率,阳极保护参数稳定,保护效果良好。     

Amorphous carbonated apatite formation on diamond-like carbon containing titanium oxide

Thin films of diamond-like carbon (DLC) containing titanium oxide (DLC-TiO_x, x ≤ 2) were synthesized using a pulsed DC metal–organic plasma activated chemical vapor deposition (MOCVD) technique. X-ray photoelectron spectroscopy (XPS) results confirmed the presence of TiO₂ on the surface of the films. The compressive stress, elastic modulus and hardness of the films decreased with increasing Ti content. The water contact angle reduced from 62° for DLC to 45° for DLC-TiO_x films containing 13.3 at.% of Ti. The biomimetic growth of amorphous carbonated apatite on the DLC-TiO_x in simulated body fluid (SBF) was found and dependent on the Ti content of the film. UV light exposure prior to immersion in SBF increased the growth rate of apatite formation significantly as a result of increased hydrophilicity of the surface.     

Anodic formation of low-aspect-ratio porous alumina films for metal-oxide sensor application

Thin nanoporous anodic alumina films, of low aspect ratio (1:1), with two distinctive pore sizes and morphologies were prepared by two-step constant-current anodising of aluminium layers on SiO₂/Si substrates in 0.4 mol dm⁻³ tartaric (TA) and malonic acid (MA) electrolytes and then modified by open-circuit dissolution. The anodic films were employed as a support material for sputtering-deposition of thin WO₃ layers in view of exploiting their gas sensing properties. The films and deposits were characterized by scanning electron microscopy, X-ray diffraction and electric resistance measurements at fixed temperatures in the range of 100-300 °C upon NH₃ and CO gas exposures. Test sensors prepared from the annealed and stabilized alumina-supported WO₃ active layers were insensitive to CO but showed considerably enhanced responses to NH₃ at 300 °C, the sensitivity depending upon the anodic film nature, the pore size and the surface morphology. The increased sensor sensitivity is due to the substantially enlarged film surface area of the TA-supported WO₃ films and the nanostructured, camomile-like morphology of the MA-supported WO₃ films. Sensing mechanisms in the alumina-supported WO₃ active layers are discussed.     

氯酸盐分解槽结构改造

探讨离子膜法烧碱装置中使用的氯酸盐分解槽分解效果不佳问题,对氯酸盐分解槽进行了结构改造,同时调整相关工艺参数等,使氯酸盐分解效果达到预期要求。     

大有发展前景的氯酸钠工业

详细分析了国内外氯酸钠的产需现状，二氧化氯的广泛应用，为氯酸钠带来了广阔的市场空间，氯碱企业生产氯酸钠，可大大提高企业的经济效益。