Sirota V.V.

Candidate of phys.-mat. Sciences (Ph.D.), Belgorod State Technological University named after V.G. Shukhov

Effect of substrates on the photocatalytic activity of the composite coating fabricated by detonation sprayed Ti powders

https://doi.org/10.58224/2618-7183-2025-8-5-3
Аннотация
Composite coatings based on titanium oxides were successfully deposited on fine-grained concrete and porcelain tile substrates using a robotic complex for detonation spraying. The study focused on the influence of substrate roughness and composition on the microstructure, phase composition, and photocatalytic properties of the coatings. Dense, uniform coatings with a bimodal lamellar microstructure and thicknesses ranging from 20–30 µm on concrete to 250–300 µm on porcelain tiles were obtained without cracks or significant porosity. It was observed that the phase composition of the coatings, which included a mixture of titanium, anatase, rutile, TiO, and Ti₂O₃ phases, remained unaffected by variations in the substrate composition. Regardless of the substrate material used, all coatings exhibited similar phase constituents. However, the surface roughness of the substrates played a crucial role in determining the microstructure and photocatalytic performance. The rougher concrete surface promoted a higher anatase content, resulting in enhanced photocatalytic activity compared to coatings on smoother porcelain tiles. Coating thickness and porosity did not significantly affect photocatalytic efficiency. Additionally, the kinetic constants of the obtained coatings exceeded those of commercial sol-gel coatings and aligned with values typical for thermally sprayed coatings. The obtained results indicate that composite titanium oxide coatings demonstrate high potential for industrial applications where effective breakdown of organic pollutants on diverse surfaces is required.
PDF

The effect of the introduction of B4C on the adhesive and cohesive properties of self-fluxing coatings

https://doi.org/10.58224/2618-7183-2024-7-6-5
Аннотация
Wear and tear of technical equipment elements is a serious problem that negatively affects the productivity of production processes. The work analyzed the strength of cohesive and adhesive bonds of wear-resistant coatings obtained by detonation gas-dynamic spraying method based on a self-fluxing alloy, depending on the introduction of B4C particles into the composite composition. The chemical composition of the cohesive bonds of the resulting coatings and the effect of boron-containing elements on their strength were analyzed. The method of transverse scratching of transverse sections of thick coatings is a qualitative assessment of adhesive and cohesive properties and helps to determine the mechanisms of their destruction. The purpose of the work is to study the effect of the introduction of B4C particles on the adhesive and cohesive properties of coatings obtained by detonation gas-dynamic spraying based on self-fluxing NiCrBSi alloy. Methods for studying coating samples obtained by detonation gas-thermal method: scanning electron microscopy, energy dispersive analysis, optical metallographic microscopy, scratch testing. Previously, wear-resistant coatings based on self-fluxing NiCrBSi-B4C alloy have proven their effectiveness as protective coatings for centrifugal beet cutter knives. This study substantiates the feasibility of obtaining a composite based on such coatings with the introduction of boron carbide to improve its strength characteristics.
PDF

Effect of powder morphology on the structure and properties of Al2O3 based coatings obtained by detonation spraying

https://doi.org/10.58224/2618-7183-2024-7-5-7
Аннотация
Aluminum oxide (Al2O3) remains a crucial material in the field of engineering ceramics, particularly in industrial applications. Notably, its transitional phases, in addition to the α-phase, demonstrate good properties. In this article the structure and properties of coatings obtained by detonation spraying from aluminum oxide powder with different production methods (fragmentation and spherical particle shape) and crystalline modification (α-Al2O3 and γ-Al2O3) but with similar average particle size were studied. The goal of the study was to investigate the influence of the morphology and phase composition of the powder on such properties of the coatings as microstructure, porosity, roughness and hardness. The results of the study showed that agglomerated spherical powder leads to low porosity of the coatings, while crushed fragmentation particles provide dense layers. In addition, the coating obtained using fragmentation powder showed higher hardness, and the surface had twice the roughness, compared to the coating applied using spheroidal powder. These results confirm the effect of the morphology of the original powder on the final properties and efficiency of the coatings. The study showed that the detonation spraying method allows for the efficient application of coatings from two types of Al2O3 powders with different morphology (spherical and fragmentation) and phase composition (γ-Al2O3 and α-Al2O3) but with similar particle sizes.
PDF