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.

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.

Wire and arc additive manufacturing is a rapidly developing technology for the production of metal parts used in various industries such us space, automotive, shipbuilding, etc. Today, it is a potential alternative to traditional manufacturing processes due to its shorter lead time, low material losses and cost-effectiveness. In recent decades, this technology has been used to produce components from various materials. This overview examines the methods of realization, the specifics of the technological process, the process parameters and their influence on the formation of the layers and typical.

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 solution was synthesized in a system ZrO2-CeO2 by sol-gel synthesis and deposited by the immersion method. The pretreated Nb substrate was treated with sulfuric acid and absolute alcohol solutions. Layering was in three stages. The sample was heat treated at 500°C. The obtained results are characterized by XRD, XPS, CEM analyzes.

Electrochemical coatings of chromium modified with nanodiamond particles applied directly on niobium-aluminum alloy were obtained. Nanodiamond particles produced by detonation synthesis were used. Chromium coatings were deposited on a monolithic composite with a complex structure based on niobium and aluminum alloys, called later matrix for short. Standard chromium electrolyte and electrolyte with nanodiamond particles concentration of 10 g/l were used. Analyzes were performed by Scanning Electron Microscope system of Bruker Inc. and the Polyvar Met metallographic microscope. The microhardness was measured using a PolyvarMet 4000 microhardness tester. The obtained results of the microhardness were 788 kg/mm2 in the chromium layer and 168 kg/mm2 and 692 kg/mm2 in the matrix. The microstructural and SEM-EDS analysis showed the presence of two intermetallides Nb2Al and Nb3Al in the monolithic composite of niobium aluminum matrix. The average thickness of the chromium coatings modified with nanodiamond particles is 55 μm.