Protective properties of redox polymer film deposited on stainless steel

We propose a novel composite organic-inorganic coating in the form of a redox polymer film for protection of stainless steel against general corrosion in strong acid medium (2 M H₂SO₄). We utilize an anion exchange polymer, protonated poly(4-vinylpyridine), into which hexacyanoferrate anions have been introduced. Owing to the presence of Fe(CN)₆^3–/4– at the interface formed by the film and the steel, a sparingly soluble metal hexacyanoferrate (mostly Prussian blue, PB) is formed as an overcoating on the steels surface, presumably on the passive (metal oxide) layer. The redox polymer film on the steel seems to act as a composite three-dimensional bilayer-type coating in which hexacyanoferrate(III,II) anions (that are capable of effective charge storage) exist in the outer portions of the film, whereas the inner PB layer improves the systems overall adherence and stability. By analogy to a conducting polymer (e.g. polyaniline, polypyrrole), introduction of the redox polymer composite film leads to stabilization of the steel substrates potential within the passive range.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003)     

硅基多孔氧化铝模板非水电沉积CdS纳米线的研究

纳米材料,包括尺寸为纳米量级的超细微粒?线?薄膜?量子阱和超晶格等引起了人们广泛的重视 [1,2] ?其中 , 半导体纳米微粒和由其构成的纳米固体结构开辟了材料科学研究的新领域?硫化镉 (CdS) 作为一种重要的Ⅱ - Ⅵ族无机半导体材料 , 具有独特的光电性质 , 在光电化学电池和多相光催化反应中都有广泛应用?近年来 , 已有大量关于合成 CdS 纳米结构的文献报导 [3～12] , 所采用的方法如反胶束法?单分子膜法?自组装法以及电化学沉积法等 , 其中非水电解与模板技术相结合的制备方法引起了人们高度的重视并且被广泛的采用?自从 Baranski 等在上…     

Evaluation of epifluorescence image analysis of biofilm growth on stainless steel surfaces

Biofilm growth of Bacillus subtilis, Pseudomonas fragi, Pediococcus inopinatus and Listeria monocytogenes was studied on stainless steel surfaces at room and low temperatures to evaluate the results of traditional hygiene measures. The results were compared with those of image analysis of stainless steel surfaces in an epifluorescence microscope. Statistical analyses were carried out to determine the variations between the conventional cultivation swab method, the glycocalyx amount obtained using swabbing, and the values of the areas of the biofilm, slime and cells. As a general rule, old biofilms showed total counts at approximately the same levels as the young biofilm. The results showed that temperature affected the results for all strains except B. subtilis. The strains of Pe. inopinatus and Ps. fragi showed increased attachment at 6°C and L. monocytogenes at 25°C. The biofilm slime was more easily detached than the cells. The results indicated that the traditional swab method is not reliable for the measurement of biofilm formation on surfaces.     

The role of oxalate ions in the coverage of mild steel with polypyrrole

In this study, the coverage conditions of mild steel with polypyrrole (PPy) were investigated. It was observed that the surface was passive up to 0.6 V, to the oxidation potential of pyrrole in oxalic acid solution. The PPy coverage was obtained with 0.1 M oxalic acid + 0.2 M pyrrole. A passivity mechanism supported with current potential curves was proposed. The PPy deposition was also investigated according to pyrrole and oxalic acid concentrations by successive voltammetric scans.This article was submitted by the authors in English.From Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 175–180.Original English Text Copyright © 2005 by Asan, Kabasakaloglu, Aksu.This revised version was published online in April 2005 with corrections to the article note and article title and cover date.     

Investigation on corrosion inhibition and adsorption mechanism of azomethine derivatives at mild steel/0.5 ​M ​H2SO4 solution interface: Gravimetric,electrochemical, SEM and EDX studies

The inhibition performance of five azomethine derivatives such as: 1-(4-Methyloxy phenylimino)-1-(phenylhydrazono)-propan-2-one (SB₁), 1-(4-Methylphenylimino)-1-(phenylhydrazono) propan-2-one (SB₂), 1-(phenylimino)-1(phenylhydrazono)-propan-2-one (SB₃), 1-(4-Bromo phenylimino)-1(phenylhydrazono)-propan-2-one (SB₄) and 1-(4-Chlorophenylimino)-1(phenylhydrazono) -propan-2-on (SB₅) as corrosion inhibitors for mild steel in sulfuric acid 0.5 ?M were investigated using different methods. All experimental results demonstrate that these compounds are eficients inhibitors. The inhibition efficiencies ($IE$) increase with inhibitors concentration. At 7.5 $\times$ 10^?5 ?M, the $IE$ was 97.27%, 96.31%, 94.23%, 93.19 and 91.64% for SB₁, SB₂, SB₃, SB₄ and SB₅, respectively. The potentiodynamic polarization results indicated that all the studied inhibitors act as mixed type. The adsorption process on mild steel surface obeyed Langmuir isotherm. The associated activation parameters and thermodynamic have been calculated and discussed. The adsorbed film formed on the metal surface was characterized by SEM and EDX.     

表面电沉积Ni—La2O3复合镀层的Fe26Cr1Mo不锈钢的氧化行为研究

Ｆｅ２６Ｃｒ１Ｍｏ不锈钢在９００℃氧化时，生成的氧化层在冷却过程中大量剥落，经表面共电沉积ＮｉＬａ２Ｏ３复合镀层后，抗热循环能力明显提高。     

TG and DSC studies of filled porous copolymers

A complex approach including thermogravimetry, differential thermal analysis and differential scanning calorimetry was applied to study characteristics of non-filled and filled porous copolymers of divinylbenzene with styrene or some acrylic monomers: di(methacryloyloxymethyl)naphthalene, methacrylic ester of p,p’-dihydroxydiphenylpropane diglycidyl ether, and dimethacrylglycolethylene. High disperse silicas with the grafted methyl and silicon hydride groups in the surface layer were used as fillers. The kinetic parameters of thermal degradation for composites obtained were determined by different methods.     

Investigation of Glass-Like Sol-Gel Coatings for Corrosion Protection of Stainless Steel Against Liquid and Gaseous Attack

Glass-like sol-gel coatings have been investigated as corrosion protective coatings on stainless steel. Magnesium- and borosilicate coatings with thickness of about 100–700 nm and methyl-modified SiO2 coatings with a thickness of about 2 m were deposited on stainless steel plates by dip-coating. The coatings were densified between 400°C and 500°C in different atmospheres (N2, air) for 1 h. The corrosion protection against gaseous attack was investigated by accelerated corrosion tests, at 800°C in air for 1 h. A corrosion protection factor was calculated from the relation Fe/Fe2O3, determined by XRD on the surface of coated and uncoated samples. Methyl-modified SiO2 coatings showed a protection factor, which was 2 orders of magnitude higher than for the other coatings. Electrochemical investigations were performed on samples submerged in a NaCl solution for 200 h. The corrosion propagation, polarization resistance and impedance vector were measured. For accelerated corrosion tests, polarization intensity curves were determined for high potentials of up to 1 V. Again excellent results were obtained for the methyl-modified SiO2 coatings, which remained passive for 200 h. Results of the salt spray corrosion test, however, showed no corrosion protection by the sol-gel coatings. After 2000 h in the salt spray chamber the steel was corroded and the coatings peeled off. It is concluded that for the further development of these coatings an improved interfacial passivation will be required.     

柱前衍生-高效液相色谱法测定钢及合金中钨和钼

以tiron作为柱前衍生试剂,用含3mmol·L-1pH 3.8的HOAc-NaOAc,40mmol·L-1TBA-Br和2mmol·L-1tiron的甲醇-水溶液(53+47)作流动相,在C18柱上,于15min内实现了WO42-、MoO42-的分离测定。钨和钼的检出限分别为5.98和3.20ng·ml-1。方法快速,选择性好,用于钢及合金中高含量钨和钼的测定,结果与标准值相符。     

Preparation and Characteristics of Porous Silica Films by a Modified Base-Catalyzed Sol-Gel Process Containing PVA: II. Film Preparation

Porous SiO₂ films were successfully deposited on silicon substrates by a modified base-catalyzed Sol-Gel process (MBCP) containing polyvinyl alcohol (PVA). The process conditions, such as the gelation time, the synthesis temperature, the stabilizing agent of the precursor solution and the spin coating speed, the heat-treatment, the annealing temperature of the film on the microstructure and porosity of porous SiO₂ films were systematically investigated by SEM, XRD and ellipsometry techniques. This study provides a novel preparation technique for the porous SiO₂ film. Using this process, the resultant film can reach a thickness of 3.6 m for one layer, a porosity of 25–50%, a low thermal conductivity of 0.11 W/m·K. This film will be used as a low dielectric layer, an thermal-insulating layer and a low refractive index layer.