Journal of

Corrosion and Anticorrosion Protection

Volume II, Issue 3, 2007

Content

Liviu ANCĂŞ , Alexandru KACSO, Radu OPREAN
A mitigation device of stray currents in underground high pressure pipes

Abstract: A mitigation device of the AC currents induced by the high tension electric lines in the underground pipelines was tested on a high pressure underground pipeline. The measurements have estimated the characteristics of this device that can be used on every buried metallic pipeline. The study has established the device operation at different frequencies that may be induced to the buried pipelines.

Vasile BAŞLIU , Gina Genoveva NĂSTASE
Discussion on the corrosion behaviour of the tin-coated brass plates

Abstract: Corrosion-protection of brass plates by tin coating is extremely fit for the shipbuilding industry. Samples of tin-coated brass plates (by hot immersion at 280^oC with different exposure times) have been tested to sea water corrosion. Cycles of 10 days have been established measuring the variation of mass and establishing the gravimetric indices. Corrosion behavior has been assessed vs. uncoated brass plates.

V. BRÂNZOI , Alina PRUNĂ, Florina BRÂNZOI, Luisa PILAN
The influence of some surfactants on hydrogen evolution at pure zinc electrode in alkaline and neutral media

Abstract: The inhibition action of some surfactants on pure zinc in 3.5% NaCl and 0.1M KOH solutions was studied by potentiostatic and potentiodynamic methods. The used surfactants were natrium dodecylsulphate (SDS) and natrium dodecylbenzosulphonate (SDBS). Kinetic corrosion parameters obtained from anodic and cathode polarisation curves showed an inhibition action of these surfactants especially by increasing the hydrogen evolution overvoltage that leads to an overall corrosion rate decrease. The cathode inhibition action of the surfactants can be attributed to the adsorption (chemisorptions) of the organic compounds at the electrode surface resulting in a thin layer of a few molecular diameters thickness. This layer blocks the active sites at the electrode surface and therefore hinders the corrosion process and hydrogen evolution. Considering all the results, we came to the conclusion that these surfactants can be used as better alternatives to mercury in alkaline batteries and zinc corrosion inhibitors in different media.

Ioan MĂRGINEAN , Mihai TÂRCOLEA, Constantin BRATU, Vasile MIREA, Alexandru STĂNESCU, Bogdan FLOREA
The boronizing process with active powders – a corrosion protective method for casting Fe-C alloys without alloyed elements

Abstract: The classical approach, for immunising ferrous alloys to corrosive action of the atmosphere, assumes superficial enrichment with hardening elements (C, B, N, Cr). This implies complex technologies, limited to step-by-step operations, where the main step is the superficial thermo-chemical treatment. A new technology, with higher performance, is presented here. This technology eliminates the subsequent thermo-chemical treatment (post casting) by controlling the superficial layer composition directly through casting. The main advantages consist in a better adherence of the superficial layer, reduced working costs and increased reliability.

Liana MUREŞAN, Ionel Cătălin POPESCU, Caius BULEA, Horaţiu VERMEŞAN
Studies concerning electrochemical corrosion of composites layers obtained by electrodeposition of zinc with TiO₂ nanoparticles

Abstract: The aim of this work is to investigate the corrosion behavior of some composite zinc coatings obtained by electrolytic co-deposition of zinc with TiO₂ nanoparticles, on steel substrate (OL 37 / Zn-TiO₂). A comparative study of OL 37 / Zn-TiO₂ unpassivated samples and „blue”- or „yellow” passivated samples (with Cr³⁺ and Cr⁶⁺, respectively) was performed. In the presence of TiO₂, simultaneously with the positive shift of the corrosion potential, a decrease of the corrosion current density was observed, reflecting the beneficial effect of TiO₂ on the corrosion resistance of zinc coatings. In the investigated range of TiO₂ concentrations, the corrosion rate of composite Zn- TiO₂ coatings decreases with the increase of TiO2 concentration in the electrolytic bath.

Toderiţa NEMEŞ, Valentin PETRESCU, Cristian DEAC , Valeriu DEAC, Marius BIBU
Considerations with regard to the cathodic protection of metallic buried pipelines

Abstract: The paper presents some results of the experimental researches regarding the improvement of the anticorrosive protection of pipelines made of metallic materials and buried in the soil. The solution chosen was a cathodic protection with external power source. The researches targeted the selection, design and placing of the anode taps. The experimental results allow the recommending of efficient solutions applicable to the protection of pipelines for water and natural gases.

Tamara RADU, Anişoara CIOCAN, Lucica BALINT
Kinetic and microstructural aspects on the corrosion of Zn-Fe alloy coatings

Abstract: Industrially zinc-coated plates have been heat treated to convert the Zn coating into a Zn- Fe alloy one having different iron contents. The Zn coated samples obtained and the specimens have been exposed to corrosion attack by the potential-static method. In order to assess the corrosion resistance the anode polarization curves were plotted and the Tafel slope was determined. After the electrochemical test, macro and microscopic analyses were carried out to establish the type of corrosion occurred.
All data were statistically treated with Medcalc program devoted to biomedical applications.

A. PĂTRU , I. BIBICU, M. PREDA, B. TUTUNARU, M. FLOROIU
The study of the corrosion inhibition of carbon steel in ammoniacal media by using Mössbauer spectrometry

Abstract: The effects of ethylenethio-urea (ETU) and N-ciclohexylbenzothiazol sulphen amide (NCBSA) on the corrosion of carbon steel in diluted ammoniacal solution containing dissolved 10–3M NH₃ were evidenced by using electrochemical measurements and Mössbauer spectrometry. The presence of ETU and NCBSA in the corrosive medium, in a concentration of 200 ppm, decreases the corrosion current. Mössbauer spectrometry shows the presence of a superficial film on the surface of the corroded carbon steel in solution of 10–3 M NH₃ containing 200 ppm inhibitors.

Elena Maria PICĂ, Ossi HOROVITZ , Gavril BÂLC, Nicolae JUMATE
Determination of corrosion resistance of steel with protective paint

Abstract: Corrosion behavior in 3% NaCl solution of OL37 steel samples was investigated. This steel has been used in manufacturing metal structures for furniture, particularly tables and chairs for beer drinking, the so called beer set. The gravimetric method was used in determining corrosion rate versus time. In parallel the samples were also examined by optical microscopy for the study of corrosion behavior.

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