Solid State Phenomena Vol. 326

Abstract: The influence of hydrophilic electrochemically exfoliated graphite (EEG) and hydrophobic reduced EEG (rEEG) on the electrical conductivity, dielectric properties, and high-frequency dielectric losses of epoxy-based composites with montmorillonite was described. It was confirmed, that the addition of EEG changes the low-temperature conduction mechanism. The electrical conductivity in composite with EEG and montmorillonite was described by correlated barrier hopping model, whereas for composites with montmorillonite and rEEG two models were used: non-overlapping small polaron tunneling and correlated barrier hopping. The addition of EEG drastically changes the activation energy of charge carriers motions from 2.68 to 0.83 eV, whereas the addition of rEEG only to 2.43 eV. Also composite with EEG was characterized by highest high-frequency dielectric losses.

Abstract: Polymer nanocomposites with unique optical properties are currently one of the materials most desired by the industry. An effective method of producing this type of materials is the method of electrospinning from a solution or melted polymers, which allows to obtain a nanocomposite in the form of a mat composed of nanofibers. This paper describes the process of producing nanofibers from polyacrylonitrile (PAN) and composite thin nanofiber mats from PAN with the addition of graphene oxide (GO) particles using the electrospinning method. In addition, the aim of the work was to investigate the influence of process parameters and filler on the morphology and optical properties of the nanomaterial. By changing the configuration of the distance between the nozzle and the collector (10 and 20 cm) and keeping the remaining parameters of the electrospinning process constant, two PAN polymer samples and two PAN/GO composite samples were manufactured. The analysis of the chemical composition and morphology of the obtained materials was performed using X-ray microanalysis (EDX) and scanning electron microscopy (SEM), respectively. In order to examine the chemical structure of the polymer and composite nanofibers, Fourier-Transform Infrared Spectroscopy (FTIR) was used. The analysis of the optical properties and the energy band gap of the prepared nanofibers was determined by spectral analysis using a UV–Vis spectrophotometer. The research showed a significant influence of the filler on the morphology.

Abstract: In this study, selectively laser melted AlSi10Mg alloy was subjected to ECAP processing for the first time. Mechanical properties of the ECAP processed samples were compared based on hardness measurement, compression and wear tests. The results showed exceptional synergy of high yield strength ~382 MPa and strain to failure of ~48% of the SLM ECAP processed sample. This sample also offered approximately ~71% higher wear resistance, than an unprocessed one. The proposed novel route expands the opportunities of both technologies to produce materials with exceptional properties.

Abstract: The application of stereolithography, gives the possibilities to manufacture components with complex shape, during one continuous process based on the prepared virtual model in CAD system. The paper presents the results of experimental tests for samples printed using Low Force Stereolithography (LFS)TM technique, using Rigid 4000 Resin, Formlabs company. The experimental studies used unconventional post-processing, which consists in extending the exposure to UV lamps, without the application of heating. In the next step, optimized post processing parameters were used to manufacture components with different types and degrees of filling - linear and hexagonal. In the experiment, the samples were testes to a tensile strength test and a three-point bending test. The goal of the experiment was to select optimal parameters for post-processing and element design to reduce the component weight.

Abstract: In order to meet the expectations of the global industry in areas such as: energy, heating, aviation, automotive, railway, chemical, petrochemical, oil, gas, river and marine sectors, where material wear processes may occur due to the flow of water gas and steam or their mixtures with various degree of saturation at different pressures, the authors of this article have conducted research on the resistance to cavitation wear of a low-friction composite anti-wear PVD coating in the form of chromium nitride and tungsten carbide (CrN+WC/C) deposited by a physical method on the surface of structural elements in the form of cavitation generators operating in extreme conditions of cavitation wear. Structural elements were examined made of steel with the ferritic-perlitic structure of the P265GH grade and with the austenitic chromium-nickel structure of the X2CrNi18-9 (304L) grade with a protective composite low-friction coating applied onto their surfaces by the Physical Vapour Deposition (PVD) technique, intended for operation in the cavitation wear environment. In order to obtain the results, the investigations of mass loss and roughness profile changes were conducted and the analysis of structural-metallographic morphology changes on the surfaces of structural elements was performed using a scanning electron microscope at voltages accelerating from 5 to 20kV using secondary electrons detection. The results of cavitation wear on the surface of structural elements were obtained using a digital microscope operating in 4K technology with a progressive scanning system.

Abstract: The paper contains the results of surface modification on the properties of the pure titanium Grade II, obtained by the SLM procedure. In the paper, the analysis of the results of physicochemical properties, such as pitting corrosion test and contact angle measurements and Surface Free Energy calculated were performed. Additionally, the microscopic observation with microchemical analysis, surface topography analysis using Atomic Force Microscopy, surface roughness measurements and wear test were performed too. The studies were carried out on three groups of samples in an initial state (1) (after mechanical treatment - mechanical grinding and polishing) and after surface modification by PVD method using CrN layer (2) and TiN layer (3). Based on the obtained results it can be concluded that the samples with TiN layer were characterized by the optimum properties.

Abstract: Photoelectrodes are key components of the dye-sensitized solar cells (DSSCs), and as such improving their properties, may lead to an overall improvement of the entire cell.This paper aims to fabricate and compare the properties of various photoanodes (resulting in DSSCs) to determine how the overall efficiency of the cell is affected by various additives mixed into the TiO₂ paste deposited on fluorine-doped tin oxide (FTO) covered glass, thus changing the photoanode composition. The TiO₂ paste has been previously mixed with various materials such as ZnO, SiO₂, Pd, and carbon nanotubes (CNTs). Basing on the prepared photoanodes, DSSCs have been prepared and analyzed by UV-Vis spectroscopy and atomic force microscopy. Moreover, were tested on a SS I-V CT-02 laboratory stand equipped with a Photo Emission Tech SS150AAA solar radiation simulator and Keithley 2401 low-voltage multimeter. The test results allowed for a determination of their properties and comparison. The highest efficiency has been obtained for the DSSCs based on photoanodes with TiO2 (1.58%) and TiO₂/ZnO (1.52%).

Abstract: Aim of the work was obtaining of the composite in form of n-layer polymer film and investigation of the structure. Manufacturing of the film combine the advantages of individual layers in one production process to achieve multilayer composite. In the experiment LDPE was used as main material. Processing of material was done using blow molding process and final product was obtained if the form of thin film. Conventional blown film line contains one extruder, die head, cooling ring and calibration basket, collapsing frame and winding rolls. To develop structure unique blow film line has been used. Two another extruder were joined to existing one transferring material simultaneously to the die head where 3 materials were joined together to combine 3-layered film. This process gives possibility to design final product and control the structure in many various combinations.

Abstract: In the first stage of the experiment, the effect of Al10Sr modification and Al5TiB grain refiner and interaction of both additions on the microstructure of AlMg5Si2Mn alloy and Mg₂Si phase morphology was investigated. Then the influence of Al10Sr and Al5TiB addition on nucleation temperatures of various intermetallic phases formed in AlMg5Si2Mn alloy also have been interpreted by the formation of distinct peaks in the first derivative cooling curve and microstructural observations. It was found that modification has a meaningful influence on the microstructure of the investigated alloy as well as the crystallization process