ISSN 2305-6894

2017, Vol. 6, Issue 2 (pp. 91–208)

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Protective properties of PEO coatings modified by corrosion inhibitors on aluminum alloys

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1 A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, Moscow, 119071 Russian Federation
2 Institute of Chemistry, Far-Eastern Branch of the Russian Academy of Sciences, pr. 100-letiya Vladivostoka 159, Vladivostok, 690022 Russian Federation

Abstract: The protective properties of PEO coatings on aluminum alloys belonging to various alloying systems (Al–Mg, Al–Mg–Cu–Zn, Al–Mn) in chloride media were studied. Coatings with varoius thickness (8–40 µm) was obtained by oxidation of flat samples in borate, silicate and borate–phosphate–tungstate electrolytes. It was shown that coatings on aluminum alloys doped with manganese or magnesium (3003 and 5083) have a slightly higher resistance to pitting corrosion in chloride environments compared to copper-based alloys 2024 and 7075. According to polarization studies and corrosion tests, filling of the coatings studied with IFKHAN-25 and IFKHAN-39 corrosion inhibitors increases by more than an order the time of protection of the specimens made of various types of aluminum alloys. It was observed that chemical sorption of corrosion inhibitors is the determining factor in increasing the protective ability of PEO coatings in the entire range of thicknesses. Hydrophobization of coatings filled with corrosion inhibitors increases their corrosion resistance in chloride environments to an even greater extent.

Int. J. Corros. Scale Inhib., , 2, 91–111 PDF (2 198 K)
doi: 10.17675/2305-6894-2017-6-2-1

Use of Azadirachta indica (AZI) as green corrosion inhibitor against mild steel in acidic medium: anti-corrosive efficacy and adsorptive behaviour

Green Chemistry and Sustainability Research Group, Department of Chemistry, JECRC University, Jaipur-303905, India

Abstract: The corrosion inhibition of mild steel in 1 N HCl, H2SO4 and HNO3 solution in the presence of AZI at a temperature of 304 & 313 K was studied using weight loss techniques. The Neem (AZI) works as an inhibitor in the acid surroundings. The results showed that the inhibition efficiency was increased by increasing the inhibitor concentration and reached the maximum at 1000 ppm (72 hr) in 1 N HCl and H2SO4 and in HNO3 solution. The AZI was found to follow Langmuir adsorption isotherm at all the concentrations in different acidic mediums studied. The phenomenon of physical adsorption obtained and the process is spontaneous.

Int. J. Corros. Scale Inhib., , 2, 112–131 PDF (2 262 K)
doi: 10.17675/2305-6894-2017-6-2-2

Influence of some tablets on corrosion resistance of orthodontic wire made of SS 316L alloy in artificial saliva

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1 SKV Higher Secondary School, Kandampalayam-637201, India
2 Corrosion Research Centre, Department of Chemistry, St Antony’s College of Arts and Sciences for Women, Dindigul-624005
3 PG and Research Department of Chemistry, GTN Arts College, Dindigul-624005, Tamil Nadu, India

Abstract: Corrosion resistance of orthodontic wire made of SS 316L alloy in artificial saliva in the absence and presence of five tablets namely, Limcee-500mg, Shelcal-500mg, Ferikind, Cefixime-200mg, Biogenetic (Aluminium Hydroxide And Magnesium Trisilicate), has been evaluated by polarisation study and AC impedence spectra. It is observed that in the presence of the tablets Ferikind and Biogenetic (Aluminium Hydroxide and Magnesium Trisilicate) the corrosion resistance of SS 316L alloy increases. On the other hand in the presence of the tablets Limcee- 500mg, Shelcal-500mg and Cefixime-200mg the corrosion resistance of SS 316L alloy decreases. Hence it is recommended that people implanted with orthodontic wires made of SS 316L alloy need not hesitate to take the tablets Ferikind and Biogenetic (Aluminium Hydroxide and Magnesium Trisilicate) orally. People having implanted with orthodontic wire made of SS 316L should avoid taking tablets Limcee-500mg, Shelcal-500mg and Cefixime-200mg. The increase in corrosion resistance or decrease in corrosion resistance of SS 316L alloy in the presence of these tablets in artificial saliva is due to the ingredients present in tablets.

Int. J. Corros. Scale Inhib., , 2, 132–141 PDF (1 344 K)
doi: 10.17675/2305-6894-2017-6-2-3

Inhibition of copper local depassivation in alkaline media with oxygen-containing anions

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1 MESC Air Force Military Air Academy named after N.E. Zhukovsky and Yu.A. Gagarin, ul. Staryh bolshevikov 54a, Voronezh, 394000 Russian Federation
2 Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russian Federation

Abstract: Using complex physical and chemical methods, a comparative estimation of the capability of benzotriazole (BTAH) to act as an inhibitor of copper local activation (LA) was carried out in alkaline–nitrate and alkaline–sulphate solutions in a temperature range of 20–60°C. It was shown that in both systems studied, BTAH hinders copper LA according to an adsorption–polymerization mechanism. Furthermore, the effect is the stronger, the higher the temperature of the working solution is.

Int. J. Corros. Scale Inhib., , 2, 142–150 PDF (1 534 K)
doi: 10.17675/2305-6894-2017-6-2-4

Effect of temperature on the crack growth in pipe steel X70 in a weakly acidic electrolyte

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1 A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, Moscow, 119071 Russian Federation
2 Gubkin Russian State University of Oil and Gas, Leninsky pr. 65, Moscow, 119991 Russian Federation

Abstract: The temperature dependences of crack growth in static tests of X70 pipe steel in citrate buffer (pH 5.5) and in the same solution containing 1 mM sulfide were studied. The activation energies of corrosion crack growth were determined. It was shown that addition of IFKhAN-29-3 organic corrosion inhibitor hindered the crack growth and the protective effect increased with an increase in temperature.

Int. J. Corros. Scale Inhib., , 2, 151–161 PDF (1 203 K)
doi: 10.17675/2305-6894-2017-6-2-5

Iron oxide dispersants for industrial water systems: types, performance, and selection criteria

  • Z. Amjad
Department of Chemistry, Division of Mathematics and Sciences, Walsh University, N. Canton, Ohio 44270, USA

Abstract: Dispersion of solid particles separating out from fluids is very important for fouling due to deposition of unwanted materials. Dispersion and stabilization of suspended matter i.e., clay, silt, corrosion products, precipitating salts, etc., is often overcome by incorporating a dispersant in the water treatment formulation. In this paper a variety of non-polymeric, natural polyelectrolytes, synthetic, and hybrid polymers were evaluated for their efficacy as iron oxide (Fe2O3, hematite) dispersants for industrial water systems. Results reveal that performance of dispersants strongly depends on dispersant dosage, dispersing time, dispersant architecture, and the impurities present in water. Among the non-polymeric additives evaluated phosphonates perform better than polyphosphates. Surfactants (anionic, non-ionic) tested are ineffective iron oxide dispersants. Performance data on natural polyelectrolytes show that lignosulfonate exhibits better performance compared to humic, fulvic, and tannic acids. Based on the performance of synthetic polymers the order of effectiveness is: terpolymer > copolymer > homopolymer. Results on the impact of impurities (i.e., trivalent metal ions, biocides, hardness ions, etc.) suggest that these impurities show negative influence on the polymers performance. Discussion on dispersion mechanism and dispersant selection criteria is also presented.

Int. J. Corros. Scale Inhib., , 2, 162–179 PDF (1 371 K)
doi: 10.17675/2305-6894-2017-6-2-6

High-temperature inhibitors of stainless steel corrosion in hydrochloric acid solutions

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1 K.E. Tsiolkovsky Kaluga state university, Stepana Razina str. 26, Kaluga, 248023 Russian Federation
2 A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, Moscow, 119071 Russian Federation

Abstract: The corrosion of chromium-nickel steel 08Kh18N10T in 2 M HCl has been studied in a broad temperature range, t = 0–160°C. Under these conditions, the metal corrosion is enhanced with an increase in temperature to reach 5.0 kg/(m2·h) at 160°C. It has been shown that the IFKhAN-92 inhibitor (a substituted triazole) and its formulation with urotropine in a molar ratio of 1:4 protect this steel in 2 M HCl at temperatures up to 120°C, inclusive. The three-component mixture of IFKhAN-92, KI and urotropine (1:1:4) is more promising in this respect, as it efficiently inhibits corrosion at temperatures up to 160°C and allows the protective effect to be maintained for at least 8 h. This formulation also reliably protects low-carbon steel 20 in 2 M HCl at temperatures up to 160°C, inclusive.

Int. J. Corros. Scale Inhib., , 2, 180–195 PDF (1 502 K)
doi: 10.17675/2305-6894-2017-6-2-7

Polyoxyethylene stearate of molecular weight 6000 as corrosion inhibitor for mild steel in 2.0 M sulphuric acid

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1 Faculty of Science, Department of Chemistry, Al-Azhar University,11884, Cairo, Egypt
2 Chemistry Departments, Faculty of Science, Hail University, Hail 1560, Saudi Arabi
3 Faculty of Applied Science, Umm Al-Qura University, 3712, Makkah Al Mukaramha, Saudi Arabi
4 Chemistry Department, Faculty of Science, Benha University, 13518, Banha, Egypt
5 Faculty of Science, Department of Chemistry, Ain Shams University, 11566, Cairo, Egypt
6 Egyptian Petroleum Research Institute, Nasr City, 11727, Cairo, Egypt
7 Environmental institute Ain Shams University, Abassya , 1156, Cairo, Egypt

Abstract: Polyoxyethylene stearate of molecular weight 6000 (P6000) as nonionic polymeric surfactant was prepared by the esterification reaction between citric acid with polyethylene glycol (Mwt. 6000) in the presence of para toluene sulfuric acid, PTSA as a catalyst. The chemical structure of the prepared polymeric surfactant was recognized by FT-IR spectra. The inhibition of P6000 on mild steel surface in 2.0 M H2SO4 solution was investigated using different techniques such as open circuit potential, potentiodynamic polarization and weight loss. The inhibition efficiency of the used polymeric surfactant increases with increasing its concentration, but decreases with rising temperature. The potentiodynamic polarization proved that P6000 acted as a mixed inhibitor controlling both cathodic and anodic reactions. The inhibition process is the result of the adsorption of P6000 on the mild steel surface through the formation of barrier film which separates the mild steel from the corrosive medium. The adsorption of P6000 on steel surface follows Langmuir’s isotherm.

Int. J. Corros. Scale Inhib., , 2, 196–208 PDF (1 507 K)
doi: 10.17675/2305-6894-2017-6-2-8

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