Papers by Keyword: Titanium Oxide

Abstract: The paper presents an optimization approach for enhancing the hardness and adhesion of Al₂O₃-40%TiO₂ coatings produced by High-Velocity Oxi-Fuel (HVOF) thermal spraying, aimed at their application in protecting components subjected to aggressive environments and severe mechanical stresses [1-4]. Through an experimental factorial program, key parameters of the HVOF process such as fuel flow rate, oxygen flow rate, spray distance, and powder feed rate were investigated to identify optimal conditions leading to improved mechanical performance of the deposited layers. Vickers hardness and tensile adhesion tests were utilized to evaluate the properties of the coatings. The results indicated that increasing the fuel and oxygen flow rates, coupled with reducing the spray distance, significantly increased the hardness of the coatings, achieving values up to 244 HV5. Moreover, optimizing these parameters maximized the coating-substrate adhesion, reaching values exceeding 30 MPa. Microstructural analysis using scanning electron microscopy (SEM) revealed that optimized HVOF parameters generated dense layers with low porosity and enhanced adhesion at the layer-substrate interface, thereby explaining the superior mechanical behaviors of the coatings. These findings demonstrate the capability of HVOF technology to produce Al₂O₃-40%TiO₂ layers with optimal mechanical properties, essential for applications requiring resistance to wear, impact, and corrosive environments [5-7].

Abstract: Preparation conditions of titanium oxide (TiO₂) powders were examined by the hydrolysis of titanium potassium oxalate (K₂TiO(C₂O₄)₂), through the homogeneous precipitation method (80oC for 24 h) and hydrothermal treatment (160 or 170oC for 1 h). According to the Rietveld analysis, almost a single phase of anatase TiO₂ could be obtained by the hydrothermal treatment at 160oC for 1 h, followed by the heating at 900oC for 10 min in air. The molar ratio of anatase to rutile TiO₂ was found to be controlled by optimizing the hydrothermal conditions in the solution and the heating conditions in air for the photocatalytic activity.

Abstract: Intumescent fire-retardant coatings based on epoxy resins, compared to traditional fire-retardant compositions, have improved performance properties – high strength, chemical and atmospheric resistance, adhesion to many materials. However, unmodified epoxy polymers are combustible and to obtain IFR based on them, flame retardants and mineral fillers are added to their composition. Intumescent systems for flame retardant coatings based on epoxy oligomers (non-halogen-containing) usually consist of ammonium or ammophos polyphosphate as an acidic agent and a wide range of fillers, both inert and gaseous, or which are an additional source of carbon. Each component of the fire-retardant intimate coating in different ways affects the processes of coke formation, which determines the requirements for their choice. Thus, the aim of this work is to conduct experimental studies of the dependence of the characteristics of the expanded coke layer on the composition of the intumescent epoxyamine composition. The results of experimental studies of the effect of ammonium polyphosphate and binary mixtures of ammonium polyphosphate (APP) with aluminum hydroxide (AH), sodium tetraborate decahydrate (STD), titanium oxide TiO₂ (TO), pentaerythritol (P), aerosil (A) and expandable graphite are presented (EG) on the multiplicity of expanding and weight loss of epoxy compositions at study temperatures of 350, 400 and 450°C. Studies have shown that the production of intumescent flame retardant coatings based on epoxy oligomers is possible provided they are filled with ammonium polyphosphate in an amount of more than 20 mass parts. The most effective in terms of expanding are additives titanium oxide and aluminum hydroxide in an amount of 20 mass parts, which allows to obtain intumescent fire-retardant coatings with a linear coefficient of expanding 30-32 and 24-27, respectively, throughout the range of temperatures. The obtained data are useful in the development of fire-retardant coatings based on epoxy oligomers.

Abstract: This article is concerned with the analysis of ordering the arrays of TiO₂ and Al₂O₃ nanotubes using the correlation-spectral methods. As the tools, the spatial Fourier spectrum and one-dimensional autocorrelation function of SEM-image have served. It was shown that the arrays of the aluminum oxide nanotubes can have a nearly ideal ordering on a small scale at the expense of two-stage anodizing. It this case, the degree of order depends also on the purity of initial aluminum and sample preparation method. The introduced characteristics can serve as the measures of the structure order-disorder sensitive to both type and degree of order as a whole and to configuration of structural elements themselves.

Abstract: TiO₂-based nanotubes are a very promising material with many applications in solar cells, biomedical devices, gas sensors, hydrogen generation, supercapacitors, and lithium batteries, among others. Nanotube thickness is a very important property since it is related to electronic and surface mechanics. In this sense, transmission electron microscopy (TEM) can be used. However, it can be difficult to acquire a good TEM image because the transversal section of the nanotubes needs to be visible. In this work, TiO₂-based nanotubes obtained via hydrothermal synthesis were studied using X-ray line profile analysis. Scherrer and Single-Line methods provided consistent results for the thickness of the nanotubes (≃ 5 nm) when compared with TEM. Additionally, Single-Line method was also applied to estimate the microstrain. The advantage of using XRD is given by the fact that it is a quick and statistically significant analysis when compared with TEM. The results show that XRD can be used as a rapid and reliable alternative for the thickness estimation of nanotubes.

Abstract: As its much lower thermal conductivity than other usual materials, Silica aerogel is a potentially efficient heat insulation material with the lowest bulk density. However, it is transparent for infrared light when used in high temperature. Herein, titanium oxide was added in the silica aerogel by in-situ blending. The dispersion property of titanium oxide particles, microstructure mechanical property, thermal conductivity, and thermal insulation were investigated. The results of this in-situ blending process indicated a potential application value in aerospace thermal protection industry.

Abstract: The paper considers the problems of creating new protective coatings based on organosilicon polymer – polymethylphenylsiloxane, modified with tetraisopropyltitanate. The mechanisms of siloxane polymer nanostructuring have been suggested. The coating surface nanostructure and the impact of material components content and nature on its properties have been studied. To research protective surface nanostructure, the method of atomic-force probe microscopy applying IntegraAura device has been used. Nanoparticles formations with 10-20 nm effective scale have been revealed. Adhesive properties of the protective coating have been studied. Glass and metal adhesion was determined applying the method of detachment from the steel discs substrate using adhesive meter PSO-MG4. The modification was stated not to cause any substantial loss of coating adhesive properties. Simultaneously modification process was accompanied with the increase of relative coating firmness.The developed compounds and corresponding coatings are aimed at protecting buildings and constructions against negative impact of natural and anthropogenic factors.

Abstract: Ti/TiO₂,Au electrodes were prepared via plasma electrolytic oxidation (PEO) of Ti plate, followed by deposition of a thin (10 nm) Au layer by electron beam evaporation (EBE). The electrodes obtained were used for potentiometric indication of different types of chemical reactions. Ti/TiO₂,Au electrodes showed an excellent performance for end point indication in the oxidation-reduction and complexometric titrations similar to the traditional Pt and in the acid-base titration similar to glass electrode.

Abstract: The control of environmental pollution has led to an intensive search for innovative and efficient technologies for wastewater treatment, especially those with toxic or non-biodegradable compounds. In this sense, this work involved the preparation of a hybrid composite of TiO₂ with amorphous carbon by partial pyrolysis method and the analysis of their photocatalytic potential using phenol red dye as a test molecule. The composite was characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The evaluation of morphology and the structural characterization of the powder confirmed the formation of the hybrid composite of TiO₂ dispersed in a carbon matrix with turbostratic structure, organized in the shape of overlapping plates. The composite presented a discoloration rate of 67% after 4 hours of irradiation. The photocatalytic reaction follows a kinetics of first order type.

Abstract: Issues with existing vanadium beneficiation stimulate the development of new technologies for wasteless production of vanadium. The present work investigates a possibility of beneficiation of vanadium and titanium oxides in a low-titanium magnetite concentrate by using selective reduction and extraction of iron. Iron was selectively reduced by coal without melting and separated from the oxide (slag) phase during further smelting operation. After the liquid-phase separation vanadium and titanium oxides were accumulated in a slag phase. The following products were produced: slag, containing vanadium and titanium oxides, and iron with relatively low carbon content. The content of vanadium and titanium in a final product has increased in comparison to the initial concentrate.