Journal of

Corrosion and Anticorrosion Protection

Volume II, Issue 2, 2007

Content

Lucica BALINT , Dumitru DIMA, Simion BALINT, Elena DRUGESCU, Corina RADU
Obtaining and characterization of niobium - cobalt composite layers on steel support

Abstract: This paper presents the researches of niobium – cobalt composite layers, obtained by electrolytic method and their characterization depending on the electrochemical parameters. Samples obtained were subject of thermo treatment with the purpose of adherence and toughness improvement by diffusion. Some macro and microscopic analyses, micro-hardness measurements, appreciatory tests for corrosion resistance and for the corrosion mechanism were made.

Silvia BURCĂ, George VERMEŞAN , Caius BULEA, Maria STANCA, Andrada MĂICĂNEANU, Horea BEDELEAN
Preliminary studies regarding electroplating wastewaters treatment in order to remove iron and zinc ions

Abstract: Electroplating wastewaters contain heavy metal ions in high concentrations. These types of wastewaters are toxic for the environment and, in consequence, before discharge or reuse in other technological processes, they have to be treated in order to remove iron and zinc ions until a maximum allowable concentration for the specific type of water is reached. This paper proposes an ionic exchange method to remove iron and zinc ions from electroplating wastewaters using a natural zeolite, in static regime. Experiments were performed on a zeolitic volcanic tuff from Pâglişa area, Cluj County. Iron and zinc ions determination in solutions was done by using a spectrophotometric method. The results showed that the ionic exchange process took place with good results for all wastewater samples with the best results for neutralized and filtered samples (100% removal efficiency). We used electroplating wastewaters from SC BETAK SA Bistriţa.

Cristian CĂLIN , Eleonora Maria RUS, I. BÂLDEA
Aspects concerning low carbon steels corrosion in different aggressive media

Abstract: Electrochemical methods have been used to obtain details on the corrosion behaviour of the following carbon steels: OLT 35, OL 37, OL 44, OL 60 in different electrolytic environments (neutral aqueous solutions, salty, swamp and normal soils). Corrosion parameters of electrochemical reactions at the steel/environment interface as: corrosion potential (Ecor) and current density (icor), were determined using steady state polarization curves method and compared with corrosion rates values obtained by gravimetric measurements. OLT 35 carbon steel was found as the most corroded as compared to the other studied steels.

Neluţă IBRIŞ, Paula PRIOTEASA, Teodor VIŞAN
Corrosion study of dental alloys in artificial saliva. The influence of fluoride ions

Abstract: The paper presents the corrosion resistance behaviour of certain dental alloys (wiron, minicrom, niadur, wirobond, AuAgPd) in Fusayama-Meyer artificial saliva without/with fluoride ions, at human body temperature (37°C). From the evolution of open-circuit potential and polarization curves, as well as by processing Nyquist and Bode impedance plots, it was concluded that the biocompatibility of dental alloys depends mainly on the forming of the passivating film. The electrochemical impedance results have shown that the highest electrical resistance of oxide passivating film was recorded for alloys with the largest Cr content (niadur -with 27%Cr, wirobond -26%Cr.

Simona VARVARA, Ioana IGNAT, Alin CADAN, Liana Maria MUREŞAN
Influence of 2 mercapto-5-r-acetilamino-1, 3, 4-thiadiazole on bronze corrosion in aqueous electrolytes

Abstract: The present paper focuses on the investigation of the efficiency of a non-toxic thiadiazole derivative, 2 mercapto-5-R-acetylamino-1, 3, 4-thiadiazole, as bronze corrosion inhibitor in aqueous electrolytes (sodium sulphate and sodium hydrogen carbonate) using electrochemical polarization methods (Tafel extrapolation and polarization resistance method) and electrochemical impedance spectroscopy measurements. The calculated corrosion parameters suggest that the thiadiazole derivative reduces the rate of bronze corrosion, its inhibiting action being attributed mainly to the blockage of the bronze surface by a protective film consisting of a polymeric Cu(I)-inhibitor complex in which the inhibitor acts as a bidentate ligand through the aminic nitrogen atom and the closed ring nitrogen.

Gina UNGUREANU , Julia MIRZA ROSCA, Neculai AELENEI, D. MARECI
Electrochemical corrosion of some Ni-Cr based biomaterials

Abstract: Ni-Cr based alloys are the most frequently used alloys in dentistry. Corrosion resistance in artificial saliva of two alloys with different structures (V and WironNT) was studied by using electrochemical techniques: potentiodynamic polarization and electrochemical impedance spectroscopy. The main parameters of the corrosion process were determined. The corrosion currents are small, nA/cm2 range, indicating a big corrosion resistance. By maintaining these alloys in artificial saliva, an increase of the corrosion resistance is determined due to increase of the passive film stabilization, but does not influence the type of corrosion. It was found that the surface of WironNT alloy it is general degraded but the surface of the V alloy is pitting attacked. Among that V alloy has a wide passivation range thus the passive film is stabilized in real operating conditions.

V. HOTEA , E. POP, Gh. IEPURE, I. JUHASZ, S. BRÂNZEI
The study of the 6063 aluminium alloy behaviour under corrosion in alkaline environment

Abstract: The effect of the addition of some metallic cations such as Li+ and Mg+ on the corrosion of the 6036 aluminium alloy in a 3% NaCl solution has been studied through electrochemical methods. The results obtained show that the most vibrant inhibitor of the aluminium alloy is represented by the Li+ cations. Their concentration growth may lead to an increased difference between pitting potential and corrosion potential. The maximum efficiency reaches 85% and corresponds to a 5x10-3 M concentration. In the presence of Li cations, the increased temperature produces a decrease of the inhibitive effect, but improves the resistance to corrosion by pores forming.
All data were statistically treated with Medcalc program devoted to biomedical applications.

Eduard COMAN, George VERMEŞAN
Aspects regarding the process of corrosion and anticorrosive protection in natural gas transportation industry

Abstract: In this item, is made a presentation of the activity area of the natural gas transportation industry and the main factors which influences the corrosion processes and the anticorrosive protection activities.

George VERMEŞAN, Ernest GRUNWALD, Claudiu BUMBUC, Horaţiu VERMEŞAN , Caius BULEA
The characterization of electro-chemical co-depositions of zinc-nickel layers

Abstract: Nowadays the Zn-Ni coatings research, as an alternative of replacing cadmium depositions, has a special attention by the researchers and customers. In the paper the Zn-Ni electrochemical co-depositions methods are analyzed, giving a distinct attention to corrosion and wear behaviour. By analyzing bibliographical materials, results that there are lot of an elucidate aspects, for substituting cadmium depositions whit Zn-Ni alloys depositions.

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