ISSN 2305-6894

2017, Vol. 6, Issue 4 (pp. 359–503)

Influence of melting and casting conditions on the structure
and properties of sacrificial anodes

      • V. Kechin1 and E. Lyublinski2
1Vladimir State University, ul. Gor’kogo, 87, Vladimir, 600000 Russian Federation
2COR/SCI, LLC, 6421 Dorset Ln., Solon, OH 44139, USA

Abstract: Broad application of aluminum, magnesium and zinc alloys used for production of cast galvanic anodes (GA) is well known in the systems for corrosion protection of metal constructions and structures in sea water, soil, etc. The main requirement of the standards for various brands of protective alloys is their chemical composition (content of alloying components and maximum permissible concentrations of major cathodic impurity elements) that defines the electrochemical properties of alloys (working potential, current output and capacity). In terms of industrial production any deviations of technological parameters for melting and casting, found in various combinations, have a negative impact on both content of the non-regulated impurity elements (dissolved hydrogen, oxide inclusions, etc.) and on the structural homogeneity of cast anodes. This explains the conflicting data about the effectiveness of individual cast anodes made from one alloy grade and even one melting. Based on theoretical and experimental research, the role of metallurgical (provision of specified chemical composition and purity of alloys) and technological (ensuring homogeneous cast structure) factors in changing the quality of cast anodes was found. To provide specified and stable protective properties of aluminum, magnesium and zinc sacrificial anodic alloys technological processes of melting and casting were developed, which take into account the physicochemical nature of alloys, as well as design, weight and dimensions of the cast anodes. Presented are the main properties of modified sacrificial anodic alloys in sea water and soil.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 359-371 (PDF 1551 K)
doi: 10.17675/2305-6894-2017-6-4-1

Mixtures of substituted pyridinium perchlorates with sulfur-containing organic compounds as inhibitors of acid corrosion of steel

      • A.G. Berezhnaya, Gh.A.H. Shayea and V.V. Chernyavina
Southern Federal University, ul. Zorge 7, Rostov-on-Don, 344090 Russian Federation

Abstract: 2,4,6-Triphenyl-N-(4´-aminophenyl) pyridinium perchlorate (PP1) and 2,4,6-triphenyl-N-(2´-bromophenyl)pyridinium perchlorate (PP2), Thiourea (TU), phenylthiourea (PhTU), diphenylthiourea (DPhTU), sodium diethyldithiocarbamate (DEDTC), 2-mercaptobenzo¬thiazole (MBT), and mixtures of pyridinium perchlorates with sulfur compounds were investigated as corrosion inhibitors of steel in a hydrochloric acid solution at temperatures of 20–80°C. The concentration ranges of substituted pyridinium perchlorates and sulfur-containing substances were 0.01–0.5 and 0.1–10 mmol/l, respectively. The coefficients of mutual influence of additives in mixtures, the degree of protection and the coverage of steel surface with inhibitors were estimated. The effect of the investigated additives and their mixtures on the partial reactions of the corrosion process was determined. The mechanism of action of individual additives was determined.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 372-383 (PDF 1450 K)
doi: 10.17675/2305-6894-2017-6-4-2

Organic corrosion inhibitors: where are we now? A review. Part IV. Passivation and the role of mono- and diphosphonates

      • Yu.I. Kuznetsov
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation

Abstract: This article continues the review of studies (2006–2016) dealing with the passivation of various metals by solutions of organic corrosion inhibitors. It provides an overview of papers on the passivating properties of mono- and diphosphonic acids and their salts. The results of corrosion and electrochemical studies, as well as studies on the composition and structural features of surface layers on metals by a variety of physicochemical methods are considered.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 384-427 (PDF 1226 K)
doi: 10.17675/2305-6894-2017-6-4-3

Corrosion inhibition and thermodynamic activation parameters of Myrtus communis extract on mild steel in sulfamic acid medium

      • A.S. Fouda,1 S.A. Abd El-Maksoud,2 M.Sh. Zoromba2 and A.R. Ibrahim1
1Department of chemistry, Faculty of Science, Mansoura University, Mansoura-35516, Egypt
2Department of chemistry, Faculty of Science, Port Said and King Abdulaziz University, Port Said, Egypt and KSA

Abstract: The effect of an aqueous extract of Myrtuis communis on the corrosion behavior of mild steel (MS) in 5% NH2SO3H solution has been investigated by the following techniques: weight loss (WL), potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation techniques (EFM). The inhibition efficiency (IE) increased with increase in inhibitor dose and increased with rise in temperature. The thermodynamic parameters of corrosion and adsorption processes were calculated and discussed. The adsorption of this extract was found to obey Langmuir adsorption isotherm. The PP tests indicated that the extract is mixed type. The results obtained from the three different techniques were in good agreement. The morphology of the surface was analyzed and discussed.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 428–448 (PDF 1226 K)
doi: 10.17675/2305-6894-2017-6-4-4

Protection of aluminium alloys from atmospheric corrosion by thin films of inhibitors

      • A.M. Semiletov
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, Moscow, 119071 Russian Federation

Abstract: Some prospects for protection of aluminum alloys by corrosion inhibitors such as carboxylates and trialkoxysilanes are considered. The efficiency of inhibition of anodic dissolution of Al alloys by these compounds in a neutral borate buffer solution containing chlorides (pH 7.4) was investigated. The protective capability of the layers obtained was estimated by an express method (drop test method) and by tests in a heat and moisture cabinet, and in a salt fog cabinet. The efficiency of treatment of Al alloys by aqueous solutions of organic inhibitors was compared with the protective ability of chromate films. It is shown that the passivation of Al alloys by the composition of oleyl sarcosinate with aminoethylaminopropyl–trimethoxysilane at a ratio of 3:1 is an efficient protection method even under salt fog conditions.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 449–462 (PDF 1057 K)
doi: 10.17675/2305-6894-2017-6-4-5

Inhibition effect of 1,1´-(pyridine-2,6-dihylbis(methylene))-bis(5-methyl-1-H-pyrazole-3-carboxylic acid) on the corrosion of mild steel in 1 M HCl. Part A: Experimental study

      • M. El Azzouzi,1 A. Aouniti,1 M. El Massaoudi,2 S. Radi,2 B. Hammouti,1 M.A. Quraishi,3 H. Bendaif4 and Y. El Ouadi1
1Laboratoire de Chimie Analytique Appliquée Matériaux et Environnement (LCA2ME), Faculté des Sciences, University Mohammed Premier, B.P. 717, 60000 Oujda, Morocco
2Laboratory of Applied Chemistry and Environment (LCAE-URAC18), COSTE, Faculty of Science, University Mohammed Premier, Oujda, Morocco
3Center for Research Excellence in Corrosion, Research Institute (King Fahd University of Petroleum & Minerals), Dhahran, Saudi Arabia
4Laboratoire de Chimie Organique Macromoléculaire et produits Naturels (URAC25), Faculté des Sciences, University Mohammed Premier, 60000 Oujda, Morocco

Abstract: The inhibitory effect of 1,1´-(pyridine-2,6-dihylbis(methylene))bis(5-methyl-1-H-pyrazole-3-carboxylic acid) (EM1) was estimated on the corrosion of mild steel in 1 M hydrochloric acid using weight loss, Electrochemical Impedance Spectroscopy (EIS) and Tafel polarization curves. Inhibition was found to increase with increasing concentration of inhibitor studied. The adsorption of inhibitor molecules on mild steel surface was found to be spontaneous and obeyed the Langmuir adsorption isotherm. Values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS are in good agreement. Polarization curves showed that EM1 behaves as mixed type inhibitor in 1 M HCl medium. The results obtained showed that EM1 could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid solution.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 463–475 (PDF 1438 K)
doi: 10.17675/2305-6894-2017-6-4-6

A computational study of two hexitol borates as corrosion inhibitors for steel

      • G. Gece1 and S. Bilgiç2
1Department of Chemistry, Bursa Technical University, Bursa, Turkey
2Department of Chemistry, Ankara University, Ankara, Turkey

Abstract: Herein we investigated computationally the inhibition characteristics of sodium sorbitol borate and sodium mannitol borate on steel corrosion in aqueous media using density functional theory (DFT). To further our understanding of the role of energetic parameters on inhibition by these compounds, quantum chemical parameters such as the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), and energy gap (ΔE) have been calculated at the B3LYP/6-311++G(d,p) basis set. The results of theoretical calculations confirm the experimental findings on the superiority of sodium sorbitol borate to protect the corrosion of steel in aqueous media compared to sodium mannitol borate.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 476–484 (PDF 1544 K)
doi: 10.17675/2305-6894-2017-6-4-7

Self-assembled monoterpenoid phenol as vapor phase atmospheric corrosion inhibitor of carbon steel

      • V. Vorobyova,1 O. Chygyrynets´,1 M. Skiba,2 І. Kurmakova3
        and O. Bondar3
1National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine. Ave Peremogy 37, Kiev, 03056 Ukraine
2Ukrainian State Chemical-Engineering University, Gagarin Ave. 8, Dnipro, 49005 Ukraine
3Chernihiv National T.G. Shevchenko Pedagogical University, 53 Hetmana Polubotka str., 14013 Chernihiv, Ukraine

Abstract: The inhibition efficiency of сarvacrol as a non toxic volatile corrosion inhibitor for the temporary protection of mild steel was investigated. Weight loss measurements were used to measure the corrosion rate in the absence and presence of these volatile inhibitor compounds. It is demonstrated that the corrosion rate of steel decreases as its concentration increases, and the process of formation of films from the vapor phase has a long-term character. Atomic force microscopy (SEM) revealed that a protective film was formed on the surface of the inhibited sample. Fourier transform infrared (FT-IR) spectroscopy was used to characterize the adsorption of carvacrol on the steel surface. The results suggest the formation of an adsorbed inhibitor film on the steel surface, leading to a decrease in corrosion rate. Persistency experiments were also performed to evaluate the residence time for inhibitors adsorbed on carbon steel. Among the inhibitors tested, inhibitor showed very good corrosion inhibition properties as well as high persistency. The results show that carvacrol, as a mixed inhibitor, had good volatility and short induction period. The adsorption capacity of carvacrol was evaluated using quantum chemical calculations.

Int. J. Corros. Scale Inhib., 2017, 6, no. 4, 485–503 (PDF 2002 K)
doi: 10.17675/2305-6894-2017-6-4-8