Electrodeposition of Composite Chromium Coatings from Cr(III) SulfateOxalate Solution Suspensions Containing Al₂O₃, SiC, Nb₂N, and Ta₂N Particles

N. A. Polyakov, Yu. M. Polukarov, and V. N. Kudryavtsev*

Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia

* Mendeleev University of Chemical Technology of Russia, Miusskaya pl. 9, A-47, Moscow, 125047 Russia

e-maol: grottopna@ mail.ru

Received November 1, 2008

Abstract — The effect of concentration and nature of particles (dielectric Al₂O₃, broadband semiconducive SiC, and conductive Nb₂N and Ta₂N) on the adhesion of particles to the surface of coatings and the composition of electrochemical composite coatings deposited from Cr(III) sulfate–oxalate solution suspensions of various concentrations is studied. Adding particles of any nature to the solution does not affect the character of the formation of an Xray amorphous chromium matrix and the content of hydrogen in the coating. The mechanisms of inclusion of Al₂O₃, SiC, Nb₂N + Ta₂N particles in chromium layers are different. In the former case (Al₂O₃ and SiC), the inclusion of particles is determined by kinetic factors (in the absence of current, there is no adhesion of particles), while, in the latter case, the particles demonstrate a strong adhesion in the absence of current. Accordingly, the distribution of SiC and Al₂O₃ particles depends on the depth by contrast to Nb₂N and Ta₂N particles, whose concentrations close to the substrate do not noticeably differ from those in the bulk and surface layers of the coating. An increase in the temperature of solution promotes the codeposition of chromium and these particles.

Electrochemical Properties of -Fe + Fe₃C Nanocrystalline Composites in Acidic Environments

A. V. Syugaev^a, S. F. Lomaeva^a, and S. M. Reshetnikov^b

^a Physical-Technical Institute, Ural Branch, Russian Academy of Sciences, ul. Kirova 132, Izhevsk, Udmurtia, 426000 Russia

e-maol: uds@pti. udm. ru

^b Udmurt State University, ul. Universitetskaya 1, Izhevsk, Udmurtia, 426034 Russia

e-maol: chi@ani. udm. ru

Received January 28, 2008

Abstract — Regularities of the physicochemical behavior of -Fe + Fe₃C nanocomposites in a concentration range of ementite from 9 to 92 wt % in sulfate and chloride solutions are studied. Nanocrystalline state (~40 nm) is found to ntensify the active dissolution of -Fe + Fe₃C alloys and not noticeably affect the hydrogen evolution in acidic envionments. With an increase in the cementite content or when it forms a reticular structure, the catalytic activity of -e + Fe₃C nanocrystalline composites with respect to the hydrogen evolution increases. Cementite manifests a higher verpotential of dissolution in both sulfate and chloride solutions.

Adsorption of Formaldehyde from Gaseous Phase by Thermally Activated Nanoporous Celite¹

N. A. Khodosova^a, L. I. Belchinskaya^a, G. A. Petukhova^a,b, and O. V. Voishcheva^a

^aVoronezh State Academy of Forestry Engineering, 8 Timiryazeva ul., Voronezh,

394084 Russia

^bFrumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,

31 Leninskii pr., Moscow, 117071 Russia

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Received February 25, 2009

Abstract — An investigation of the adsorption of gaseous formaldehyde in mixtures with aqueous vapor from atmosphere using natural celite klinoptilotit is reported. Samples from different mining sites were characterized by structural and elemental analyses; the adsorption efficiency was studied by means of spectroscopy and derivatography methods of analysis. The strong dependence of preliminary thermal treatment on sorbent capacity was detected.

Activation of Thermal Processes in Mixtures of Some Vanadium Compounds with LiOH as a Result of Plastic Deformation under High Pressure

V. A. Zhorin^a, M. R. Kiselev^b, T. P. Puryaeva^b, and S. E. Smirnov^c

^a Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, Russia

^b Frumkin Institute of Physical Chemistry, Russian Academy of Sciences, Moscow, Russia

^c Moscow Power Institute, Moscow, Russia

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Received December 19, 2008

Abstract — V₂O₅, V₂O₃, HVO₃, and mixtures of these compounds with 15% LiOH were subjected to plastic deforation at a pressure of 2 GPa and room temperature on high-pressure testing machines of the type of Bridgman anvils. he investigation of the samples was performed using differential scanning calorimetry, thermogravimetry, and X-ray iffraction analysis. The presence of LiOH in the mixtures decreased the thermal stability of vanadium compounds. uring plastic deformation the LiV₃O₈ phase was formed in mixtures, the amount of which increased with heating the amples to 200C. It is assumed that the ions that form by treatment under pressure can affect the structure formation rocesses in mix samples.

High-Temperature Oxidation of Low-Alloyed Steel under Glass Coatings¹

K. Yu. Frolenkov, L. Yu. Frolenkova, and I. F. Shadrin

Orel State Technical University, Naugorskoe sh. 29, Orel, 302020 Russia

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Received April 5, 2008

Abstract — Some peculiarities of the time and temperature dependences of the high-temperature oxidation of a low-alloyed low-carbon steel covered with a glass coating are studied. The dependences characterizing the oxidation of steel without coating and that covered with it are found to have a similar character. Based on the data obtained, it is supposed that, at low temperatures, the prevailing mechanism involves the penetration of oxygen toward the metal surface through macro- and micropores of the coating, while, at high temperatures, the oxidation, which seems to be related to the electrochemical corrosion of the surface under a glass melt, becomes predominant.

Electrochemical Synthesis of Polypyrrole on Aluminium in Different Anions and Corrosion Protection of Aluminium¹

S. Zor^a, F. Kandemirli^a, E. Yakar^a, and T. Arslan^b

^aKocaeli University Science & Art Faculty, Chemistry Department, 41380 Kocaeli, Turkey

^bEskisehir Osmangazi University, Science&Art Faculty, Chemistry Department, 26480, Eskisehir,

Turkey

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Received August 26, 2008

Abstract — In this study, polypyrrole was deposited on the aluminium in different anions (C N Cr DBS^–). The contribution of anions to formation of polypyrrole film was investigated by using cyclic voltammetry (CV) technique. The effect of polypyrrole film on the corrosion of aluminium was searched in 0.1 M HCI solution by using potentiostatic method. For this purpose, polarization curves were obtained, corrosion current density (icorr), corrosion potential (Ecorr), polarization resistance (Rp) were determined from the polarization curves. Moreover, the percent efficiency of coating was calculated. The complexes of pyrrole pentamers and different anions (C N Cr DBS^–) were studied using ab initio quantum chemical at the Hartree-Fock (HF) levels with STO-3G, 3-21G, 6-31G(d,p) [13] basis sets and HOMO-LUMO energy gap is calculated by B3LYP method with 3-21G* and 6-31G(d,p) basis sets. The polypyrrole film obtained in Cr anion is determined to be the most effective in prevention to pitting corrosion of aluminium as experimental and theoretical.

Electrodeposition and Mechanical Properties of NiWB Composites from Tartrate Bath¹

M. G. Hosseini^a, M. Abdolmaleki^b, and S. A. Seyed Sadjadi^b

^aElectrochemistry Research Laboratory, Department of Physical Chemistry, Chemistry Faculty, University of Tabriz, Iran

^bDepartment of Chemistry, IUST University, Tehran, Iran

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Received October 29, 2007

Abstract — Electrodeposition of Ni–W–B alloys from plating baths containing tartrate in the absence of ammonia is studied. Detailed studies on the effects of bath temperature, pH, cathode current density and plating time have led to optimum operational conditions for obtaining satisfactory alloy deposits. The operational conditions for deposition the alloy with high hardness are; current density 30 mA cm^–2, pH 6.0 and bath temperature of 60C. The results have shown that the adherence of Ni–W–B is better than the Ni and Chromium on Cu substrate. It adheres to Cu substrates better than electrodeposited Ni and chromium. The morphology of the depos-
its was studied by SEM and the analysis of composition performed by EDX and inductively coupled plasma (ICP). The as-deposited alloy contained 21.66 wt % W and the highest cathode current efficiency for deposition of the alloy was about 38%. The deposit obtained under these conditions had an amorphous character with a hardness of about 800 HV, which is comparable to the hardness of chromium, occurred at a heat treatment temperature of 400C. When heat treated up to this temperature, the initial metastable structure decomposed into fine particles of Ni₄W in a nickel solid solution.

Residual Protective Effect of O-Oxyazomethine Derivatives against Iron Corrosion in 1 M HSO Solution

V. P. Grigor’ev, S. P. Shpan’ko, V. V. Boginskaya, and E. V. Plekhanova

Southern Federal University, ul. Zorge 7, Rostov-on-Don, 344090 Russia

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Received October 30, 2008

Relation between Kinetic Regularities of the Inhibition of Aluminum Corrosion with Metal Salts and the Formation of Contact Deposits on the Aluminum Surface in Chloride Electrolytes

O. I. Barteneva^a and V. V. Bartenev^b

^a Institute of Physical and Organic Chemistry, pr. Stachki 194/3, Rostov-on-Don, 344104 Russia

^b Southern Federal University, ul. Zorge 7, Rostov-on-Don, 344090 Russia

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Received April 9, 2008

Abstract — Under contact-exchange conditions at high metal depolarization, the regularities of the inhibition of aluminum corrosion in hydrochloric electrolytes containing tin and cadmium chlorides or their equimolar mixture are studied. For the inhibiting composition, the mutual effect of the components is estimated taking into account the actual component contents in the contact deposit, which was determined with the use of atomic absorption spectroscopy.

The Effect of Alcohol on the Passivation of Al Alloys in 1 N H₂SO₄ Solution

A. Büyüksa

Afyon Kocatepe University Science and Art Faculty, Afyonkarahisar, TURKEY

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Received December 24, 2007