Myroslav Holovchuk

The kinetics of platinum nanoparticles formation by galvanic replacement of H2[PtCl6] on the silicon surface in an aprotic solvent was investigated using the methods of spectrophotometry and scanning electron microscopy. For a quantitative description of the scheme of formation of platinum nanoparticles the principles of “lump” modeling were proposed. It was shown that the minimally sufficient kinetic scheme of the process, which satisfactorily agrees with the experimental data, includes 4 intermediates and 4 pseudo-elementary stages. Numerical values of the effective rate constants of the pseudo-elementary reactions of the formation of platinum nanoparticles were calculated using mathematical modeling methods.

Nanosized MgMn2O4 spinel particles were synthesized by co-precipitation in an ultrasonic field. It was found that the Bragg peaks on the diffractogram of the synthesized product were in good agreement with the reference model of MgMn2O4 spinel with a tetragonal structure. According to the Debye–Scherrer equation, the average size of the MgMn2O4 crystallite was calculated, which was ~24 nm. Nanosized spinel particles were tested as sodium percarbonate activators during the oxidative degradation of the xanthene dye rhodamine B (advanced oxidation – ultrasound/MgMn2O4/Na2CO3×1.5 H2O2). It was estab­lished that at the sodium percarbonate concentration of 5 mM, the catalyst content in the reaction medium of 1 g/l, and the treatment time of 3600 s, the degradation degree of rhodamine B was 98%, and the rate constant was – 4.1×10–3 s–1.

The effect of complex zeolite-phosphate anti-corrosion pigment obtained by mechanoche­mical modification of synthetic zeolite with calcium cations followed by liquid-phase de­position of zinc-phosphate phase on the protective properties of epoxy coating on aluminum alloy was investigated. The methods of electrochemical impedance spectroscopy, optical 3D profilometry, and tests in a humidity and heat chamber established that the addition of such pigment to an epoxy coating provides a significant increase in its anti-corrosion properties. As a result, the metal charge transfer resistance increases and the amount of corrosion products in the sites of defects in the paint layer decreases.

The modification of the contact and outer surfaces of strip amorphous alloys Fe78.5Ni1.0Mo0.5Si6.0B14.0 and Fe73.1Cu1.0Nb3.0Si15.5B7.4 with 1% solutions of oligoperoxides based on vinyl acetate, 2-tert-butylperoxy-2-methyl-5-hexen-3-ine (VEP), maleic anhydride and n-vinyl pyrrolido­ne, VEP and 2-phosphonooxy ethyl 2-methacrylate in isopropyl alcohol was investigated by the methods of voltammetry, impedance spectroscopy, scanning electron and atomic force microscopy. The formation of denser coatings on the surface of the Fe78.5Ni1.0Mo0.5Si6.0B14.0 strip and the smoothing of its topography due to the local adsorption of macromolecules of oligoperoxides were established.

High efficiency of corrosion inhibition of aluminum alloy in a 0.1% NaCl solution by the composition of guar gum and potassium sorbate was established. The formation of an organic adsorption film was found on the surface of the metal samples. The degree of metal protection against corrosion by this inhibitory composition is more than 90%. The results of the research can be used for the development of eco-friendly “green” corrosion inhibitors of aluminum alloys from renewable plant materials.