Corrosion monitoring of nickel-containing steels in marine atmospheric environment

Corrosion monitoring of nickel-containing steels has been performed in a natural atmospheric environment using AC impedance technique. A pair of identical comb-shape steel electrodes embedded in epoxy resin was used as a probe electrode for the corrosion monitoring. Three different probes of ordinary carbon steel, 2.5%Ni- and 5%Ni-containing steels were exposed to a natural marine atmosphere for the period of 14 months. The instantaneous corrosion rate of the steels was monitored by continuous measurements of the polarization resistance, and time of wetness of the steel surface was determined from high frequency impedance. The measurement was automatically carried out with an AC corrosion monitor placed at the exposure site, and data transmission between the exposure site and laboratory was performed through cellular phones.     

The fabrication and properties of aesthetic FRP wires for use in orthodontics

Transparent or translucent fibre-reinforced polymeric wires have been produced in an attempt to reproduce the mechanical properties of the metallic wires in current use in orthodontics. Two methods were employed: mould polymerization, and hot-drawing. Both methods produced wires of 0.5 mm diameter. Two polymers were investigated, poly(methyl methacrylate) and epoxy resin, and these were filled with either long silane-coated alumina fibres or fibres made from CPSA glass. Whilst mould-polymerized wires showed a linear increase in Young's modulus with fibre content, they did not obey the rule of mixtures. However, the hot-drawn wires did, and they also demonstrated the rigidity, strength and good elastic recovery needed for use in orthodontics.     

Effect of tetracosahexaenoic acid on the content and release of histamine, and eicosanoid production in MC/9 mouse mast cell

6,9,12,15,18,21-Tetracosahexaenoic acid (24∶6n−3) was isolated from a brittle star, Ophiura sarsi Lütken, at>95% purity to evaluate its physiological functions. The effects of 24∶6n−3 on the production of leukotriene (LT)-related compounds such as LTB₄, LTC₄ and 5-hydroxyeicosatetraenoic acid, and the accumulation and release of histamine in an MC/9 mouse mast cell line were studied. We found that 24∶6n−3 could inhibit the antigen-stimulated production of LT-related compounds as well as other n−3 polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (20∶5n−3) and docosahexaenoic acid (22∶6n−3), which are major n−3 PUFA in fish oils; 24∶6n−3 was also shown to reduce the histamine content in MC/9 cells at 25 μM (27% reduction from the control), and the effect was diminished with increase of the fatty acid concentration (up to 100 μM). These two n−3 PUFA, 20∶5n−3 and 22∶6n−3, also reduced the histamine content (16 and 20% reduction at 25 μM, respectively), whereas arachidonic acid (20∶4n−6) increased it (18% increase at 25 μM). Spontaneous- and antigen-induced release of histamine was not influenced with these PUFA (at 25 μM). Ionophore-stimulated release of histamine was suppressed by the PUFA (13,9,15, and 11% reduction with 20∶4n−6, 20∶5n−3, 22∶6n−3, and 24∶6n−3, respectively). The patterns of the effects of 24∶6n−3 on the synthesis of eicosanoids and histamine content were more similar to those of 22∶6n−3 than 20∶5n−3. From these results, 24∶6n−3 can be expected to have anti-inflammatory activity and antiallergic activities similar to those of 22∶6n−3.     

Dissolution amounts of nickel, chromium and iron from SUS 304, 316 and 444 stainless steels in sodium chloride solutions

The release of nickel and chromium from stainless steels by sweat, is often responsible for allergic contact dermatitis. The amounts of metal released from stainless steels were in trace amounts, because corrosion resistance was excellent. However, measurement of dissolution amounts is difficult, and if these amounts are not known, the improvement and development of stainless steels with excellent resistance to NaCl solution is difficult. In this work, trace dissolution amounts from the main components of stainless steels which can cause an allergy were investigated. SUS 304, 316 and 444 stainless steels were used in this test. The test solutions used were 0.9 (isotonic sodium chloride solution), 1, 3, 5 and 10 wt% NaCl solutions. Nickel,chromium and iron ions in the test solutions were rapidly determined by stripping voltammetry. The detection limits of Ni(II), Cr(VI) and Fe(III) ions in 1 wt% NaCl solution were 1.0, 0.1 and 0.5 ng cm^-3, respectively, with standard deviations of five tests at 5 ng cm^-3 Ni(II), Cr(VI) and Fe(III) ions, of 6.4%, 1.8% and 2.2%, respectively. Generally, the amounts of the metals dissolved increased in direct proportion to the immersion, in the range 30–60 days for nickel, 30–90 days for chromium and 30–120 days for iron. The dissolution amounts of nickel from SUS 304 and 316 stainless steels increased rapidly over 60 days, while that of chromium increased rapidly over 90 days, in isotonic sodium chloride solution. The ratio of the three dissolved metal ions was not consistent with the composition of the specimens. The ratio of dissolved nickel in SUS 304 and 316 stainless steels was larger than that in the specimen, and dissolved preferentially. The dissolution ratio of chromium and iron in SUS 444 stainless steel approximately agreed with the composition of the specimen. This revised version was published online in November 2006 with corrections to the Cover Date.     

Effect of Cl ion implantation on electrical properties of CuInSe2 thin films

The effects of Cl ion implantation on the properties of CuInSe₂ epitaxial thin films have been investigated. Using five kinds of accelerating energies, the doped layer with a constant profile of Cl concentration along the depth direction was fabricated. From the results of reflection of high-energy electron diffraction, the damages due to implantation were removed by annealing at 400°C in N₂. The conductivity type in all implanted films was n-type, and the carrier concentration was increased with increasing Cl concentration in the thin films. Consequently, it is considered that Cl acts as a donor in CuInSe₂.     

Hydrogen entry behaviour of newly developed Al–Mg–Si coating produced by physical vapour deposition

A ternary Al–Mg–Si alloy was prepared by co-evaporation technique and tested with respect to hydrogen entry behaviour as an alternative to conventional zinc coating on steel. Hydrogen entry behaviour evaluated using Devanathan cell showed a smaller hydrogen entry for this new coating than conventional zinc coating. Compared to an unscratched surface, hydrogen entry increased by more than 100 times in the scratched surface, but it was lower than that for the zinc coating with a scratched surface owing to the moderate galvanic corrosion potential of the new coating. This new coating is proposed especially for high-strength steel application.     

氧化时间对纯钛表面微弧氧化膜结构特性的影响

采用微弧氧化技术在纯钛表面制备了含钙磷的多孔复合氧化膜,用扫描电子显微镜、X射线衍射仪、电子探针分析等手段分析了处理时间对氧化膜形貌、厚度、成分、结构的影响。结果表明：随处理时间的延长,膜厚逐渐增大,微孔数量增多、孔径增大、分布趋匀;表面沉积的钙磷盐逐渐减少并消失,膜中钙磷摩尔比趋于稳定;膜中金红石相TiO2增多、锐钛...     

厌氧消化技术在日本有机废水和废弃物处理中的应用

日本污泥厌氧消化始于1932年,目前污泥厌氧消化工程已超过300个,消化池总容积达210×10<'4>m<'3>.目前,全日本共有300多座升流式厌氧污泥床反应器(upflow anaerobic sludgebed,UASB)和膨胀颗粒污泥床(expanded granular sludge bed,EGSB)处理厂,主要用于包括啤酒废水、软饮料废水、酿酒废水、食品加工废水和化工废水在内的高浓度有机工业废水的处理.总结了厌氧消化技术在日本有机废水和有机废弃物处理中的应用状况,以及运行参数.此外,对日本厌氧消化技术在厌氧膜生物反应器、产氢产甲烷两段发酵和沼气生物脱硫等方面的新进展也进行了介绍.