Электрохимический синтез композиционных покрытий Ni/TiO2 из низкотемпературного эвтектического растворителя и электрокаталитические свойства осадков

Kinetics of electrodeposition of composite Ni/TiO2 coatings was studied using the electrolyte based on a deep eutectic solvent (DES) containing choline chloride, ethylene glycol, water additive, and nickel chloride. Degussa P 25 nanopowder was used as a dispersed phase in the electrolyte (1–10 g dm3). The developed electrolyte allows depositing composite coatings with the content of titanium dioxide reaching ~ 10 wt.%. The electrolytic deposition of the composite was shown to obey Guglielmi's kinetic model. The main parameters of co-deposition of TiO2 particles into a nickel matrix were determined in the framework of this kinetic model. The co-deposition of titanium dioxide was found to inhibit the reaction of the nickel ions discharge. Electrocatalytic properties of the prepared composite Ni/TiO2 coatings were evaluated with respect to the hydrogen evolution reaction in an aqueous alkaline solution. A noticeable improvement in the electrocatalytic activity was observed when titanium dioxide particles were introduced into an electrodeposited nickel matrix.

The Effect of Heat Treatment on the Microstructure and Phase Composition of Plasma Sprayed Al2O3 and Al2O3-TiO2 Coatings for Applications in Biomass Firing Plants

This study presents the thermal and chemical resistance of plasma-sprayed Al2O3 and Al2O3 doped with 13 wt.% of TiO2 coatings and their suitability for the fire grate of straw pellet furnaces. Coatings were deposited on steel substrates using direct current atmospheric pressure plasma spraying. The surface structure, elemental, and phase composition of formed coatings were analyzed before and after the thermal treatment, imitating natural application conditions. For the experiment, the annealing temperature was 500 °C for twenty-five cycles (80 min each). It was found that the steel substrate oxidized after five thermal cycles, and the formation of iron oxides was observed. The elemental composition of the Al2O3 and Al2O3-13 wt.% TiO2 coatings remained unchanged even after 25 cycles of heat treatment. The X-ray diffraction (XRD) results revealed that the alpha-Al2O3 to gamma-Al2O3 phase ratio in the Al2O3-TiO2 coating was reduced by only 8.7% after 25 cycles.