scholarly journals Photocatalytic activity of oxide systems based on doped d-elements of titanium alloys

2021 ◽  
pp. 97-102
Author(s):  
Mykola Sakhnenko ◽  
Iryna Stepanova ◽  
Svitlana Zyubanova ◽  
Anatoly Djenyuk ◽  
Sergey Indykov
Keyword(s):  
Photocatalytic Activity ◽  
Surface Morphology ◽  
Metal Oxide ◽  
Decomposition Reaction ◽  
Titanium Monoxide ◽  
Tio2 Films ◽  
Oxide Systems ◽  
Plasma Electrolyte ◽  
Plasma Electrolyte Oxidation ◽  
Electrolyte Oxidation

CO-, W-, MO- and Zn-containing hetero-oxide nanostructured coatings on titanium and its alloys formed by plasma-electrolyte oxidation in galvanostatic mode from alkaline electrolytes were investigated. The morphology of the surface of the formed coatings was studied by scanning microscopy on the Zeiss Evo 40XVP microscope. The phase composition of the obtained coatings was determined on the X-ray diffractometer Drone-2. Photocatalytic activity of ZnO-WO3/TiO2 films, ZnO-MOO3/TIO2, ZnO-Co3O4/TiO2, CoO-WO3/TiO2 tested in a model reaction of decomposition of an aqueous solution of azobye with a concentration of 12,2·10-5 mol/L (MО) at UV irradiation. It is shown that with plasma-electrolyte oxidation of titanium and its alloys in alkaline diphosphate electrolytes in the mode of «drop-down power» forming heterostructural composites with micro-globular surface morphology. The possibility of controlling the phase and elemental composition of oxide layers, as well as the topography of the surface by changing the composition of the electrolyte and the content of individual components, as well as the modes of formation is confirmed. Heteroxide coatings formed in PEO modes differ in composition and surface morphology, but all exhibit photocatalytic properties of varying degrees of activity. The study of the photocatalytic activity of the obtained coatings in the azo dye decomposition reaction by means of UV testing allowed to rank the heteroxide systems according to the specified parameter. Thus, the degree of decomposition of MF on ZnO-WO3/TiO2 films in 50 minutes was 23 %. Metal oxide systems ZnO-Co3O4/TiO2 had similar characteristics of the degree of decomposition – 21 %. The incorporation of CoO and WO3 oxides into the coating composition reduced the catalytic activity of the system to 19 %. The unstable mode of formation of ZnO-MoO3/TiO2 oxides and the low speed of the process have affected the quality of the catalytic coating activity, reduced the degree of decomposition of MO to values of titanium monoxide Ti/TiO2 without dopants. Comparison of quantitative characteristics of the properties of the obtained coatings allowed to determine the effects of dopants, incorporated into metal oxide systems, on their photocatalytic activity.

scholarly journals APPLICATION OF PLASMA-ELECTROLYTE COATINGS ON TITANIUM WITH REFRACTORY METALS FOR DETOXIFICATION OF ENVIRONMENTS FROM POLLUTING SUBSTANCES

2021 ◽  
pp. 96-102
Author(s):  
Mykola Sakhnenko ◽  
Serhii Indykov ◽  
Hanna Karakurkchi
Keyword(s):  
Photocatalytic Activity ◽  
Low Cost ◽  
Autonomous Systems ◽  
Quantitative Composition ◽  
High Catalytic Activity ◽  
Catalytic Layer ◽  
Oxide Systems ◽  
Metal Compounds ◽  
Anthropogenic Pollutants ◽  
Plasma Electrolyte

Based on the review of the peculiarities of the photocatalytic processes, the peculiarities of the catalytic action of oxide systems based on titanium dioxide are determined. It is shown that TiO2 is one of the most chemically and thermally stable and non-toxic inorganic oxides of semiconductors, whose photocatalytic activity is manifested by irradiation with ultraviolet part of the spectrum (λ 320–400 nm) and allows the oxidation of a significant amount of toxic agents to water and carbon dioxide. The essence of the photocatalytic process of oxidation of toxicants under the action of UV radiation on the TiO2 surface is considered. The proposed technology of photocatalytic detoxification of contaminants is economically available, environmentally friendly and allows its widespread use, in particular for autonomous systems, including dual purpose. It is established that the main requirements for materials for photocatalysis are their chemical and biological inertness, photocatalytic stability and activity, low cost. It is shown that the most rational technological form of the photocatalyst is the application (synthesis) of the catalytic layer on structured metal substrates, in particular titanium alloys. It is proved that these catalytic oxide systems can be effectively formed by the method of plasma-electrolyte oxidation in aqueous electrolytes with the addition of dopant metal compounds that increase the photocatalytic activity of the obtained heterooxide systems. It is proposed to use tungsten oxides of variable valence as the target additive. The kinetic regularities of the process of plasma-electrolytic oxidation of titanium VT1-0 in a diphosphate-borate electrolyte with the addition of tungstates have been studied. It is shown that in an electrolyte of this type at a current density of 1.0 A/dm2 in the galvanostatic mode for 30 min a uniform coating of TiO2·WxOy with a tubular torus-like structure and tungsten content of 2.5–7.5 wt.% is formed. The predicted quantitative composition of the heteroxide layer in combination with the surface morphology creates the preconditions for high catalytic activity of the synthesized coating for detoxification of media from anthropogenic pollutants.

The competitive mechanism of plasma electrolyte oxidation for the formation of magnesium oxide bioceramic coatings

2018 ◽  
Vol 5 (7) ◽  
pp. 15677-15685 ◽  
Author(s):  
Arezoo Ghanbari ◽  
Aidin Bordbar Khiabani ◽  
Ali Zamanian ◽  
Benyamin Yarmand ◽  
Masoud Mozafari
Keyword(s):  
Magnesium Oxide ◽  
Plasma Electrolyte ◽  
Competitive Mechanism ◽  
Plasma Electrolyte Oxidation ◽  
Bioceramic Coatings ◽  
Electrolyte Oxidation

Effect of nano-hydroxyapatite and dutycycle on the structure and corrosion performance of plasma electrolyte oxidation coatings in simulated body fluid on Ti–6Al–4 V

2018 ◽  
Vol 232 (23) ◽  
pp. 4229-4236 ◽  
Author(s):  
B Barooghi ◽  
M Sheikhi ◽  
A Amiri
Keyword(s):  
Corrosion Resistance ◽  
Simulated Body Fluid ◽  
Duty Cycle ◽  
Body Fluid ◽  
Oxide Coatings ◽  
High Concentration ◽  
Plasma Electrolyte ◽  
Plasma Electrolyte Oxidation ◽  
Electrolyte Oxidation

The formation of titanium oxide coatings on Ti–6Al–4 V substrates by plasma electrolyte oxidation and the corrosion behavior of coatings in simulated body fluid were investigated. The effect of the addition of nano-hydroxyapatite particles to electrolyte and duty cycle of plasma electrolyte oxidation on the coating thickness and its surface morphology was studied. Phase structure and morphology of coated parts were studied using X-ray diffraction patterns and scanning electron microscopy. Wear and corrosion resistance were compared in coated and uncoated samples. Biocompatibility of coating was investigated using in vitro immersion in simulated body fluid. It was found that the plasma electrolyte oxidation forms dense and compact oxide coatings with slightly porous outer layers. Formation of apatite phase on the surface of coated samples was examined after immersion in simulated body fluid for two weeks. The corrosion resistance of plasma electrolyte oxidation coatings formed in electrolyte with high concentration of nano-hydroxyapatite and high duty cycle (60%) is better than the corrosion resistance of plasma electrolyte oxidation coatings formed in other electrolytes. Energy-dispersive spectroscopy results indicate the formation of a complete and preservative coating on Ti base materials.

Synergistic influence of inorganic oxides (ZrO2 and SiO2) with N2H4 to protect composite coatings obtained via plasma electrolyte oxidation on Mg alloy

2017 ◽  
Vol 19 (3) ◽  
pp. 2372-2382 ◽  
Author(s):  
Wail Al Zoubi ◽  
Muhammad Prisla Kamil ◽  
Young Gun Ko
Keyword(s):  
Composite Coatings ◽  
Mg Alloy ◽  
Inorganic Oxides ◽  
Plasma Electrolyte ◽  
Coating Layers ◽  
Plasma Electrolyte Oxidation ◽  
Functionalized Coatings ◽  
Electrolyte Oxidation

The addition of nanoparticles to the coating layers provided an electrochemical pathway to generate functionalized coatings.

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