Vol 54, No 1 (2018)

Three Gemini cationic surfactants named N¹,N¹,N³,N³-tetramethyl-N¹,N³-bis(3-octanamidopropyl) propane-1,3-diaminium bromide (C8-S3-C8), N¹,N¹,N³,N³-tetramethyl-N¹,N³-bis(3-dodecanamidopropyl) propane-1,3-diaminium bromide (C12-S3-C12) and N¹,N¹,N³,N³-tetramethyl-N¹,N³-bis(3-hexadecanamidopropyl) propane-1,3-diaminium bromide (C16-S3-C16) were evaluated as corrosion inhibitors for mild steel in 1.0 M HCl. The corrosion rate of mild steel in 1.0 M HCl at three different temperatures 25, 45 and 60oC was investigated gravimetrically. The corrosion rate of mild steel was confirmed electrically at 25oC. The corrosion inhibition efficiency directly proportionally with the hydrophobic chain length of inhibitors. The inhibition efficiency exhibit a positive trend with raising the solution temperatures. The potentiostatic polarization study revealed that the tested gemini cationic surfactants act as mixed type inhibitors with predominant control of cathodic reaction. The Villamil isotherm provide the best describing of the adsorption process on the selected steel in 1.0 M HCl. The adsorption of the tested inhibitors on the steel surface is a mixture of chemical and physical adsorption.

The inhibiting effect of three compounds of pyrazolo[3,4-d] pyrimidnone derivatives toward the corrosion of carbon steel in 1.0M HCl solution was investigated using galvanostatic and potentiodynamic anodic polarization techniques. The rise of the concentration of the inhibitors and decreasing the temperature led to the greater of inhibition efficiency. The inhibiting action of these compounds was explicated on the footing of its adsorption on the carbon steel surface. The adsorption operation of these compounds was obeyed Langmuir isotherm. There is only one anodic peak during the anodic cyclic voltammogram This peak was elucidated due to the active dissolution of Fe as Fe²⁺. The percentage inhibition efficiency was computed from the values of peak current density.There is a good convention between the values of the percentage inhibition efficiency gained from the diverse techniques.These compounds inhibit the pitting corrosion of carbon steel by shifiting the pitting corrosion potential to more noble direction. The effect of elevation of temperature on the rate of corrosion in devoid of and containing these compounds was studied and some activated thermodynamic parameters were computed.

In this study, nanocrystalline Co-(1–2)wt %P coatings were obtained by pulsed elec[trodeposition method on 1.6959 steel substrate. Coating operation carried out with current density of 150 mA/cm² on the basis of the preliminary studies and tests, coating was accomplished in 5 different pulsed current. XRD studies and EDX analysis results showed that the coatings all had the same phosphorous-cobalt composition with Co-1.5% P. XRD studies demonstrated the amorphous structure in all coatings. Heat treatment on the coatings showed that annealing the coatings at 400°C for 1 hour causes development of crystal nanostructure coatings and increases the hardness. XRD studies on nanocrystal coatings prove that the least size of the Nano grains belongs to coatings with higher off times. Heat stability of the coatings was proved with the help of DTA experiments on coatings up to 650°C.

From solutions of organic precursors, nanosized films of titanium dioxide with photoelectrochemical activity in the visible region are obtained. A possibility of photoelectrochemical oxidation of a number of organic compounds under illumination with monochromatic light at a wavelength of 464 nm is demonstrated, which may be due to a decrease in the n-TiO₂ band-gap energy to 2.7 eV.

In the present study the possibility of the commercially available acryl and diatomite earth (DE) mineral as a composite coating for corrosion protection of Mg alloys has been evaluated. The acrylic coating is used as a top coating in a wide field of applications like automotive, aerospace, medicine and electronics where it shows beneficial properties. Diatomite-dispersed acrylic paint was applied over the substrate by conventional spray technique with an air pressure of 3 kg cm⁻². Firstly the acryl was mixed with hardener and then the DE was added to the mixture. Four types of coating with 0, 2, 4, 8 g/L DE have been prepared. The results show that adding up to 4 g/L of the DE improved the corrosion resistance and produced a coating with acceptable surface roughness.

The synthesis of organosilicon derivative monomers and polymers characterized with sorption properties has been performed. The synthesized organosilicon polymers have been investigated as sorbents for heavy (Hg(II)) and noble (Ag(I), Au(III), Rh(II), Pd(II), and Pt(IV)) metals. The coefficients of the interphase metal distribution have been estimated.

Relaxation behavior of a styrene–acryl latex polymer with a vitrification temperature of ≤5°С is analyzed using the method of dynamic mechanic-relaxation spectroscopy and atomic-force microscopy for its further use in frost-resistant compositions as a polymer binder. The change in the intensity of maximum of dissipative losses of α-relaxation and the μ-process is found in polymer films in the negative temperature range as dependent on the duration and number of their preliminary freezing–thawing cycles at–30°С, which indicates a change in the polymer-relaxation structure confirmed by the values of Young’s modulus and modulus defect.

The effect of detonation-synthesis nanodiamonds (extracted from detonation products by thermal treatment in air in the presence of boric anhydride) on the characteristics of chemical composite nickel–phosphorous coatings has been investigated. It has been established that the introduction of nanodiamonds results in formation of a finer structure of the obtained coatings, reduction in the size of the coherent-scattering region, and an increase in the size of the crystal-lattice parameter. The coatings’ microhardness increased by 30% on average. Application of nanodiamonds with a surface modified with nickel compounds has yielded an additional increment of the microhardness of composite coatings by 33%.

This work presents an original approach to obtaining highly sensitive ultrathin film sensors that allows molecular design of surface–active modular molecules by completing a signal anthraquinone block with hydrophobic radicals and polar receptor groups, with their number and size provided in accordance with the sensor type. An important advantage of the suggested approach is that it not only allows the functioning of sensors in the aqueous medium, but also their manufacturing (supramolecular assembly). The key regularity of ligands of the suggested series is selectivity with respect to mercury and copper cations. Application of amphipilic ligands in film liquid (Langmuir monolayers) and solid–state (Langmuir–Blodgett films) sensors allowed developing optical sensors for mercury and copper cations with the detection limit, as dependent on the sensor type, varying from several to hundredths of ppm.

Ultrathin LbL films based on protamine sulfate and pectins, including silver nanoparticles, have been obtained. Using the methods of quartz crystal microbalance and atomic force microscopy, the characteristics of the formed films are studied. It is shown that films based on pectin–Ag nanocomposites are elastic with a surface roughness of ≤3 nm, water content of <10 wt %, and bilayer thickness of ~5 nm.