Characterization of rust phases formed on low carbon steel exposed to natural marine environment of Chennai harbour – South India

The corrosion behaviour of low carbon steel exposed to marine atmospheric, splash and immersion zones has been systematically studied by exposing steel specimens for a period of 12 months at the boat basin corrosion station of Chennai harbour, Chennai, Tamil Nadu, South India. The literature on similar work has been thoroughly reviewed which led to the initiation of this study for the first time at this harbour. The corrosion product (rust) on the specimens at 1, 2, 3 and 12 months was obtained and characterized by Fourier transform infrared spectroscopy (FT‐IR) and X‐ray diffraction (XRD) analysis. Acaganeite was the rust phase identified in the splash zone as revealed by the FT‐IR and XRD analysis. The other dominant phases were lepidocrocite, goethite and ferroxyhite. Small amounts of magnetite were also found to be present. The transformation of phases was observed in this investigation and discussed. A remarkable difference in the FT‐IR and XRD patterns of the corrosion products at the splash and immersion zones were noticed and the corresponding phases formed were reported in this paper. The rate of corrosion in all the three zones was compared.     

Corrosion resistance of environment‐friendly sealing layer for Zn‐coated sintered NdFeB magnet

In this paper, a protective sealed Zn coating (SZC) was prepared on sintered NdFeB magnet by the combination of electrodeposition and sol–gel method. The unsealed Zn coating (UZC) was also studied for a comparison. The surface morphology of UZC and the cross‐section morphology of SZC were investigated using scanning election microscope (SEM). The microstructure of Zn coating and structure of sealing layer were studied by X‐ray diffraction (XRD) and Fourier transform infrared (FT‐IR) spectrum, respectively. The corrosion characteristics of SZC and UZC in neutral 3.5 wt% NaCl solution were evaluated using electrochemical measurements including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test, indicating that the anticorrosive properties of SZC coated specimens increased 20 times compared with that of UZC coated specimens. In order to further investigate the anticorrosive properties of SZC, a long‐term immersion test was carried out in neutral 3.5 wt% NaCl solution using EIS. The results of long‐term corrosion test showed that the SZC could provide long‐term protection in neutral 3.5 wt% NaCl solution for NdFeB magnet.     

Polyamine compound as a volatile corrosion inhibitor for atmospheric corrosion of mild steel*

Bis‐piperidiniummethyl‐urea (BPMU) was developed as a volatile corrosion inhibitor (VCI) for mild steel. Its vapor corrosion inhibition property was evaluated by volatile inhibiting sieve test (VIS). Electrochemical measurements were conducted in simulated atmospheric corrosion water. Electrochemical impedance spectroscopy of a volatile corrosion inhibitor monitor cell (VCIM) was applied to study the effect of BPMU on the corrosion inhibition of mild steel under a thin electrolyte layer. The results show that BPMU has good protection effect for steel. It suppressed the anodic reaction of the steel electrode in a manner of promoted passivation. Fourier transform infrared (FT‐IR) spectroscopy was used to characterize the adsorption of BPMU on the steel surface.     

Use of atmospheric pressure plasma technology for durable hydrophilicity enhancement of polymeric substrates

Parallel plates dielectric barrier discharge (DBD) at atmospheric pressure has been investigated to modify and functionalize the surface of different polymer substrates, e.g. polyolefins, poly(ethylene terephtalate), polyamide, in order to enhance their hydrophilic properties. Surface properties have been altered to meet the requirements of specific applications by introducing the appropriate functionalities through the use of either acetic acid or ethyl acetate. The coatings have been characterized through wettability measurements, labeling coupled with X-Ray photoelectron spectroscopy, and IR spectroscopy.     

Novel zinc‐rich epoxy paint coatings with hydrated alumina and carbon nanotubes supported polypyrrole for corrosion protection of low carbon steel: Part II: Corrosion prevention behavior of the hybrid paint coatings

Utilization of various types of multi‐walled carbon nanotubes (MWCNTs) in zinc‐rich paints (ZRPs) is presented addressing percolation and porosity related phenomena of traditional ZRPs. Hybrid paint coatings were formulated with 3.21 wt% polypyrrole (PPy) deposited alumina‐MWCNT inhibitor particles (PDAMIPs) and 70 wt% zinc contents. Corrosion protection behavior of the hybrid coatings was investigated by electrochemical impedance spectroscopy (EIS), glow‐discharge optical emission spectroscopy (GD OES), X‐ray photoelectron spectroscopy (XPS), and FT‐Raman spectroscopy. Immersion and salt‐spray chamber tests gave evidence of improved galvanic protection and barrier nature of the hybrid coatings over the conventional ZRPs, whereas inhibited zinc corrosion and ignorable steel corrosion took place besides lower degradation of the binder. Zinc‐rich hybrid paints with either high relative amount of polyelectrolyte‐modified or low proportion of functionalized MWCNTs afforded enhanced corrosion prevention. This result is partly attributed to the nanotube volume fractions around the threshold of infinite cluster formation contributing to electrical percolation and galvanic action of the hybrids. Experimental results are discussed in a broader context on the basis of structure related findings of the PDAMIPs (described in Part I) and in the light of recent literature data. From the newly developed inhibitor particles, some of them are respected as worthy additives for application in hybrid coatings featuring high performance corrosion prevention functionality.     

The use of infrared thermography in the corrosion science area

The use of infrared (IR) cameras has in recent years gained interest as a non‐destructive testing (NDT) technique in a number of different research fields. All objects with a temperature above absolute zero emits IR radiation, and the amount of radiation increases with temperature. Infrared thermography is a non‐contact technique with high speed which allows inspection of large areas in a relatively short time. In the present work different aspects of IR thermography are described and discussed. Further, corrosion panels with defects, i.e. blisters and filiform corrosion, have been investigated with pulsed thermography. The area of the blisters and filaments, measured with pulsed thermography, have been evaluated, the result obtained have been compared with results from surface profile measurements of the same area. The differences between the results and the limitations of the pulsed thermography are discussed.     

Generation of nanocrystalline NiO particles by solution combustion method and its Zn?NiO composite coating for corrosion protection

The nanocrystalline nickel oxide (NiO) particles have been successfully prepared by a simple, fast, economical, and eco‐friendly solution‐combustion method using Ni(NO₃)₂ · 6H₂O (oxidizer) and sugar (dextrose as fuel). The as‐prepared compound was calcined for an hour at different temperatures. The synthesized NiO was characterized by XRD, TGA, SEM/EDX, TEM, XPS, FT‐IR, and UV–Vis spectral methods. The crystallite sizes of the NiO particles were measured. Rietveld refinement of X‐ray data matches the cubic structure with space group of Fm3m (No. 225). The thermal behavior of as‐prepared compound was examined. Scanning electron micrographs show uniform cubic like morphology of NiO and its chemical composition was measured. The TEM results reveal that the particle sizes were in the order of 70–80 nm. The red shift was noticed in UV–Vis absorption spectra. As an application part the Zn? NiO composite coating was prepared by electrodeposition method and its corrosion behavior was analyzed by Tafel, impedance and anodic polarization in aggressive medium.     

Urban and marine corrosion: Comparative behaviour between field and laboratory conditions

A detailed study of the corrosion phenomena of carbon steel has been investigated in this work by means of the comparison of field and laboratory tests. Two areas of the metropolitan area of Barcelona (Spain) were selected to carry out the field tests, whereas two different solutions of sodium chloride and sodium hydrogen sulfite were used to simulate the field conditions by means of cyclic laboratory tests. The corrosion rate has been evaluated from the weight loss of the specimens and the morphology surface has been visualized by optical and scanning electron microscopy. Corrosion products and contaminants have been analyzed by X‐ray diffraction and energy‐dispersive X‐ray spectroscopy, respectively. The penetration results can be adjusted to the Passano equation and the corrosivity degree can be assigned in accordance with ISO standards. A correlation between field and laboratory tests has been found, by comparing the specimens with the same degree of corrosion, showing the validity of the accelerated laboratory tests in order to simulate the field conditions.     

温度对油酸钠在一水硬铝石矿物表面吸附的影响

采用红外光谱和光电子能谱检测,研究了不同温度条件下油酸钠在一水硬铝石矿物表面吸附,并分析了温度影响油酸钠捕收一水硬铝石能力的根本原因.结果表明:在一定温度范围内(10～45℃),油酸钠对一水硬铝石的捕收能力随温度的升高而提高;在常温或相对低温条件下,油酸钠在一水硬铝石表面没有呈现明显的化学吸附形式,只有在较高药剂浓度和较高温度下,油酸钠在一水硬铝石表面才发生明显的化学吸附.温度影响油酸钠捕收能力的主要原因,可能是温度的不同导致了油酸钠在溶液中的各组份分布率的差异,从而影响油酸钠的捕收能力.     

Strychnos nux‐vomica an eco‐friendly corrosion inhibitor for mild steel in 1 M sulfuric acid medium

The inhibition efficiency of the extract of Strychnos nux‐vomica for the corrosion of mild steel in 1 M sulfuric acid was investigated using weight loss test (carried out at 303–323 K), electrochemical measurement, and scanning electron microscope (SEM). The results of weight loss studies indicated that the inhibition efficiency increased with inhibitor concentration and the temperature of the system (following Temkin adsorption isotherm). Electrochemical studies proved that the inhibitor acts through mixed mode of inhibition and the inhibitor molecules adsorb on the metal–solution interface. SEM studies supported the adsorption of the inhibitor over the metal surface. The possible active ingredient responsible for the anticorrosion effect is identified as brucine which is isolated and screened for the anticorrosion effect using electrochemical studies and quantum chemical studies. The possible mode of corrosion inhibition of brucine is also derived using FT‐IR studies.     

聚有机硅包覆高分子薄膜在红外分析中的应用

使用气体溶胶以及离心旋转两种方法将吸附剂包覆于红外透明薄膜的表面,在光谱分析中起到预富集水相中有机污染物的作用.考察了包括聚四氟乙烯(PTFE),ParafilmTM,聚乙烯(PE),聚丙烯(ProleneTM),聚酯(MylarTM)在内的红外透光薄膜作为红外分析中的载体对有机物进行分析表征的能力.光谱分析数据证明,这些薄膜具有被用作吸附剂的载体的潜力,它们可以使水相中的有机污染物可以沉积在薄膜包覆层.通过气体溶胶以及离心旋转两种方式,聚有机硅被成功地涂在高分子薄膜的表面,对水相中的苯含量可以进行μL/L级别的检测.     

Syntheses, characteristics, and fluorescence properties of complexes of europium with benzoic acid and its derivatives

The binary complexes of europium with benzoic acid and its derivatives (phthalic acid, m-phthalic acid,o-aminobenzoic acid, salicylic acid, and sulfosalicylic acid) were synthesized and their compositions were identified by elemental analyses. UV and IR of the complexes have been investigated. The UV spectra indicated that the complexes‘ ultraviolet absorption were mainly the ligands‘ absorption. The IR spectra showed that the IR spectra of complexes are different from those of free ligands. The fluorescence properties of them were investigated by using luminescence spectroscopy, the results showed that only three complexes appear as better luminescence, they were Eu-benzoic acid,Eu-m-phthalic acid and Eu-phthalic acid, while the others exhibited the ligands‘ wideband emission.     

Corrosion behavior of AZ91D magnesium alloy in sodium sulfate solution

The corrosion behavior of as‐cast AZ91D magnesium alloy in 0.1M sodium sulfate solution at the corrosion potential (E_corr) was investigated by using electrochemical impedance spectroscopy (EIS), environmental scanning electron microscopy (ESEM), energy dispersive X‐ray spectroscopy (EDS) and X‐ray diffraction (XRD). The results showed that the corrosion of AZ91D started at both the primary α‐Mg and the eutectic α‐Mg. The surface first was covered by a film (MgO, Mg(OH)₂) which became thicker with time. Due to the dissolution of the eutectic α‐Mg, the concentration of aluminum increased, MgAl₂(SO₄)₄ · 2H₂O precipitated at the primary α‐Mg and progressively spread to the eutectic α‐Mg areas. The surface film changed from two‐layer to three‐layer structure with the increase of immersion time.     

The formation of structure and phase composition and magnetic properties of Fe(Fe<Subscript>3</Subscript>C,Fe<Subscript>5</Subscript>SiC)-SiO<Subscript>2</Subscript> nanocomposites upon mechanical alloying

Structural and phase transformations that occur in Fe(Fe₃C, Fe₃SiC)-SiO₂ (amorphous quartz) systems during mechanical alloying in an Ar atmosphere and in air have been studied by X-ray diffraction, Mössbauer spectroscopy, IR spectroscopy, electron microscopy, and magnetometry. It has been shown that the mechanoactivation treatment leads to the formation of isolated particles 2–20 nm in size with a complex phase composition (Fe, FeSi alloy, oxides, silicates, and carbides), which depends on the milling atmosphere. It has been found out that the magnetic properties of such systems strongly depend on the oxygen and carbon compounds existing in the system, which cannot be detected by X-ray diffraction, but their presence is testified by the data of Mössbauer spectroscopy.     

Strength of spot‐welded steel sheets in corrosive environment

The load bearing capacity (LBC), often referred to as strength, of spot‐welded joints on as‐received and pre‐strained sheets of an interstitial free (IF) steel has been examined under 3.5% sodium chloride solution using tensile‐shear (TS) specimens. These tests have been carried out under three different test conditions: (i) after immersing the samples in the solution for various duration of time, (ii) at various slow strain rates by keeping the samples in solution, and (iii) at slow strain rate under in situ hydrogen charging. Analyses of the results infer that (i) increased duration of immersion of the samples in aggressive environment decreases their LBC but increases their extension corresponding to the maximum load (EML), (ii) slow strain rate tests in the solution indicate marginal decrease of LBC and EML of the spot‐welds, (iii) the LBC and EML of the spot‐welds of pre‐strained sheets decrease considerably with cathodic hydrogen charging while EML of the spot‐welded joints on the as‐received sheets is found to improve, and finally, (iv) the detrimental effect of corrosive environment increases with increased pre‐strain of the investigated sheets. These observations have been discussed together with post‐failure examinations of the broken fractured surfaces, which have assisted in understanding their failure mechanism.     

Joint Adsorption of Oleic and Phenylanthranilic Acids at Passive Iron

Adsorption of sodium oleate and its formulation with sodium phenylanthranilate from a borate buffer (pH 7.36) at passive iron was studied by ellipsometry and IR spectroscopy. The adsorption isotherm of sodium oleate was classified and its adsorption constants were determined. It was shown that the isotherm of a mixture of sodium oleate with sodium phenylanthranilate is shifted to lower concentrations, which is characteristic of a higher adsorption energy. The concurrent adsorption of these compounds is not induced since neither component enhances the adsorption of the other. IR spectroscopic data showed that, adsorbing at the oxidized iron surface, sodium oleate causes the formation of new compounds.     

Growth mechanisms,morphology, and electroactivity of PEDOT layers produced by electrochemical routes in aqueous medium

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in sodium poly(styrene-4-sulfonate) (NaPSS) polyelectrolyte aqueous solution was studied in order to establish a direct relationship between the synthesis conditions and the growth mechanisms of the polymeric film. The final morphology, the polymer structure and the electroactivity of the produced PEDOT:PSS layers have also been investigated in order to achieve a comprehensive understanding of the physico-chemical properties of the material.At this aim the current–time transients referred to the growth best conditions have been fitted using a mathematical equation that considers two contributions corresponding to 3D progressive nucleation under diffusion control and to 3D instantaneous nucleation controlled by charge transfers. The atomic force microscopy study performed on the polymeric films at various stages of electrodeposition supported the proposed growth model. The structural feature and the electrochemical performance of the PEDOT:PSS systems have been studied by Raman spectroscopy and cyclic voltammetry. These studies showed that the adopted experimental conditions allow one to grow PEDOT:PSS films in their oxidized state and characterized by high-capacitive properties.     

Electropolymerisation and properties of conducting polymers derived from aminobenzenesulphonic acids and from mixtures with aniline

The electrochemical polymerisation of 2- and 4-aminobenzenesulphonic acids (orthanilic acid and sulphanilic acid) in sulphuric acid solution and co-polymerisation of mixtures of aniline and acid monomers, have been systematically investigated. The polymers formed have been characterised voltammetrically. Further evidence concerning the polymer structure and chemical composition has been obtained by IR spectroscopy and scanning electron microscopy (SEM).     

樟叶提取物作为新型环境友好抑制剂在白钨矿与方解石浮选分离中的应用（英文）

采用简单的物理方法,直接榨取樟叶汁液作为白钨矿和方解石分离的抑制剂。通过接触角测量、傅里叶转换红外光谱测试和原子力显微镜研究樟叶提取物中活性成分及其抑制机理。浮选试验表明,樟叶提取物对方解石有较强的抑制作用,对白钨矿的抑制作用较小。原子力显微镜检测证实方解石表面吸附有樟叶提取物的有效成分。红外光谱结果表明,吸附在方解石表面的组分含有大量的羟基,这些羟基使方解石疏水。Zeta电位和红外光谱结果表明,樟树叶提取物在方解石表面的吸附量远大于在白钨矿表面的吸附量。樟叶提取物在白钨矿和方解石浮选分离中具有潜在的应用价值。     

Ca2SiO4和NaFeO2的反应和铝酸盐熟料配方的优化

用X射线衍射(XRD)和红外吸收光谱(IRS)研究了Ca_2SiO_4—NaFeO_2系的反应产物,证明其中含CaFe_2O_4和Na_4Ca_8(SiO_4)_5。热力学计算表明Ca_2SiO_4-NaFeO_2不是互易系的稳定对Na_4Ca_8(SiO_4)_5和铝酸钠溶液作用生成Ca_3[Al(OH)_6]_2(或其固溶体),使熟料Al_2O_3溶出率降低。用模式识别方法从工业生产技术记录中总结出熟料配方优化数学模型,并给出理论解释。