International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Thin coatings of zirconia oxide (ZrO2) and samarium oxide (Sm2O3) on glass have been prepared by using sol-gel method and dip coating technique. Materials were characterized in detail by X-ray diffraction. The luminescent properties at room temperature were also investigated. Excitation and emission spectra of ZrO2 coating consists of broad bands with maximums at 318 and 365 nm respectively.
The photoluminescence measurements of samarium coating suggest that can be efficiently excited with 700 nm and consist of emission bands centered at 567, 603, 639 and 707 nm, consistent with characteristic Sm3+ transitions. The CIE (Commission Internationale de L’Eclairage) chromatic coordinates, color purity and color correlated temperature were determined.

Obtained experimental self-cleaning coatings (based on compositions with the participation of Eu2O3), applied by the solgel method on glass slides. This study attempts to improve the overall efficiency of a photovoltaic solar panel by using a ZrO2-based coating, with Y2O3 and addition of Eu2O3. The optical characterization and phase composition of the obtained experimental samples were investigated using UV-VIS-NIR, XRD and XRF methods. The coatings are nanocrystalline according to XRD and XRF analyzes and show transmittance close to that of pure glass when tested with a UV–VIS–NIR spectrophotometer The experimental results represent a prerequisite for the development of a series of additional compositions and a detailed technological regime for obtaining various modifications of resistant, long-lasting self-cleaning coatings, potentially applicable to photovoltaic panels.

Obtained experimental self-cleaning coatings (based on compositions with the participation of Eu2O3), applied by the sol-gel method on glass slides. The luminescence of the obtained thin layers of different ratios of the compositions were investigated. A strong emission from the 5D0 level of Eu3+ ions was registered under near UV (392 nm) excitation using the 7F0 → 5L6 transition. The values of the integrated fluorescence intensity ratio R (5D0→7F2)/(5D0→7F1) was calculated to give information about the degree of asymmetry in the vicinity around the active ions, suggesting a location of Eu3+ in non-centrosymmetric sites. The highest Eu3+ luminescence is observed in sample with 3 layers coating. The experimental results represent a prerequisite for the development of a series of additional compositions and a detailed technological regime for obtaining various modifications of resistant, long-lasting self-cleaning coatings, potentially applicable to photovoltaic panels.

Chromium coatings were obtained from spent (waste) chromium electrolyte with the addition of nanosized aluminum oxide. The recovery of the waste chromium electrolyte is carried out by the activation of the chromium ions using the addition of Al2O3 nanoparticles. Electrochemically thin chromium films were deposited directly on S235 steel. The recovered chromium electrolyte has a concentration of nanoparticles of Al2O3 up to 10 g/l, which particles act as intensifiers of the electrochemical process. Analysis was performed with a “Polyvar Met” metallographic microscope and a Bruker D8 Advance powder X-ray diffractometer (XRD). The microstructure of the layer and the matrix were examined and the main phases were determined. SEM-EDS analysis of the chromium layer and the steel matrix was performed. The thickness of the obtained chrome coating with aluminum oxide nanoparticles was determined, which varies between 5 – 10μm.

Experimental vitreous samples with the presence of self-cleaning coatings applied by the sol-gel method were selected, which were tested in a real environment under cyclic atmospheric conditions in different TPPs / TPP-Sofia and TPP-Republika, Pernik/. The resulting thin films were studied by UV-NIS – VIR spectroscopy, AFM, contact angle, etc. The experimental samples are potentially applicable in the operation of photovoltaic panels with increased efficiency and sustainability in the conditions of an industrial environment and under the influence of various meteorological factors.

A summary study of the development of solar energy and the main factors determining the productivity of photovoltaic systems has been carried out. The predominant surface contaminants of solar panels, reducing the efficiency of photovoltaic installations, and the existing different design types of cleaning systems for their effective removal are examined. The main trends in the development of singlelayer and multi-layer hydrophobic and other oxide coatings with diverse performance indicators suitable for solar panels are traced. In laboratory conditions, experimental self-cleaning coatings (based on compositions with the participation of Y2O3 and ZrO2) deposited by the sol-gel method on vitreous samples were obtained. The structure and morphology of the prepared thin films and the technological conditions for the deposition of nanoscale layers with different functional characteristics were investigated. The experimental results represent a prerequisite for the development of a series of additional compositions and a detailed technological regime for obtaining various modifications of resistant, long-lasting self-cleaning coatings, potentially applicable to photovoltaic panels.

One-component CeO2 coatings and bi-component CeO2/ZrO2 multilayer coatings were obtained by a sol gel process. The phase composition, surface morphology and roughness of the samples were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Atomic force microscopy (AFM) and X-ray scanning electron microscopy (XPS). The corrosion resistance and protective ability were characterized by using salty solution of 3.5% NaCl at 25 C. The multilayer configuration of CeO2 and ZrO2 ensure enhanced protection of the steel in comparison to the single CeO2 coatings and uncoated steel. The surface morphology and anticorrosion properties depend significantly on the treatment temperature of both CeO2 underlayer and ZrO2 top layer. At lower treatment temperatures, they are relatively dense and smooth. The corrosion resistance of the multilayers slows down, when ZrO2 coatings were heated above 500oC. This probably is due to the more pronounced crystallization of cubic zirconium dioxide, resulting in deeper boundaries between the individual grains. The protective properties of a CeO2/ZrO2 multilayers could be attributed to the low crystallized structure with very fine crystallites.

Thin films deposited on glass substrates by sol-gel containing ZrO2 show photocatalytic activity, which are compared with TiO2 – which is used as a standard photocatalytic material applied in photovoltaics. By modifying ZrO2, coatings on glass surfaces were obtained, which are characterized by high properties, which are a prerequisite for use in photovoltaics. The coatings are dense and nanocrystal line according to SEM and XRD studies and optically transparent according to UV-VIS-NIR spectra

They have been conducted on ellipsometry and contact angles. The contact angles of a surface coating on glasses applied in photovoltaics were measured. This study used a DSA 100-Expert (Krüss GmbH, Germany) to measure contact angles on glass substrates. Contact angles were measured using the DSA 100-Expert tilt table accessory to identify both advancing and receding contact angles. A drop of deionized water is deposited on the glass substrate and then the table is tilted at a constant rate of 5 degrees per minute, to a tilt angle of 90 degrees.

In this paper, we present the results of atomic force microscopy (AFM) characterizing the surface morphology of nanostructured coatings on photovoltaic glass obtained by the sol-gel method. Two organic titanium precursors were used to prepare the TiO2 deposition solution: Titanium isopropoxide (TTIP) and titanium tetrabutoxide – Ti (OC4H9). The hydrolyzing agent is distilled water and the stabilizer is nitric acid /HNO3/and acetylacetone (AcAc). Many samples were obtained at different ratios of the components involved, rate of application of the solution on the glass substrate, and different curing and holding temperatures. The samples were characterized by AFM analysis.

A general overview of a number of thermal insulation materials and products made on the basis of inorganic binders (mainly Portland cement) is presented. The technological methods of production, the main operational indicators and the application in construction of various heat-insulating and structural-heat-insulating lightweight concretes are examined. The structure of various cellular concretes (foam concretes and aerated concretes), composite materials and lightweight aggregate concrete was analyzed. The role of the origin, technological processing, characteristics and composition of different types of light additive materials for the formation of the final operational properties of the products has been traced.

The aim of this paper is to review the cleaning of solar photovoltaic (PV) systems and applied coatings that eliminates costly automated cleaning systems by using nano-sized TiO2 combined with various organic binders.