Abstract: This paper investigates the phenomenon of Laser-induced Periodic Surface Structures (LIPSS) on Si single crystals. As usual, by variation of parameters, the morphological and physical properties of the resulting surfaces can be tailored, with respect to their use in many applications. One application-oriented use of LIPSS is the preparation of SERS (Surface Enhanced Raman Spectroscopy) substrates, which can be used to detect extremely low concentrations of molecules. In this experimental work, a possible way of manufacturing of SERS substrates, followed by SERS enhancement testing has been shown. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: The aim of this work is to design a high-productivity, continuously operating fiber producing device utilizing the centrifugal force to yield polymeric nanofibers. The requirements for the design were 1) to provide a capillary-to-collector distance of 50–200 mm that could be adjusted automatically, 2) allow the rotational speed of the spinneret to be changed in the range of 0–25000 1/min and have continuous feeding. The equipment will form the basis of several research topics, such as the creation and study of solid dispersions of drugs, the development of pressure sensors, and the creation of porous filter membranes. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: Extreme Pressure (EP) additives are commonly used in lubricants to reduce wear and prevent seizures at high temperature and pressure. In terms of their mechanism, these build up a film on the surface with chemisorption. This film efficiently prevents metal-metal adhesion. Industrial statistics show that extreme pressure additives are mostly used in metalworking fluids, lubricating greases and engine oils.Sulfurized vegetable oils can be used as EP additives of lubricants. This type of EP additive is ashless, derived from renewable sources and have a lesser negative effect on the environment compared to those that are not derived from vegetable sources. To determine the appropriate vegetable oils to be used as the raw material of EP additives, the structure of triglycerides, cost-effectiveness and availability aspects must be considered. Results of experiments show that rapeseed oil and soybean oil best meet this criteria system. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: One of the most important components of a tube end flaring machine is the flanging tool, which is subjected to mechanical stresses such as compression, bending and abrasion. It is therefore very important to choose the optimal material and manufacturing technology for the flanging tool. Böhler tool steel grades K110 and K340 were chosen as the subject of our research. Both materials were used to produce tube flanging tools, which were subjected to hardness testing, microscopic examination and surface wear testing after simple cooling or deep cooling and triple high temperature tempering after austenitisation in a vacuum at elevated temperature. Based on the measurements, the deep cooled and triple tempered K340 steel was found to be the most favourable tool steel for the production of the tube flanging tool. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: Dental fillings are one of the most widespread minimal invasive procedures in modern restorative dentistry. Thanks to the advantages of recently developed filling materials, adhesive systems, and filling techniques, it is possible to create high strength, long-lasting dental fillings. Qualifying these structures is a complicated procedure; the most common method is the use of a microtensile bond strength test, for which specimens need to be formed and stabilised with adhesives in special jigs. During our research, three different cyanoacrylates were examined to find the ideal adhesive for bonding the metal and dentin and the metal and EverX short fibre composite, respectively. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: There is a continuous development in automotive body production to expand the use of metal foams. The use of aluminium foams in vehicles is made possible by the high strength/mass ratio, which means that mass reduction is not accompanied by a reduction in safety. Reducing mass (self-weight), on the other hand, is essential due to increasingly stringent environmental regulations. The present composition draws attention to the structural properties of metal-based foams and its testability. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: In material-processing fiber lasers, the resonator in the closed box produces the laser radiation. Even with the same resonator, the diameter of the laser beam transporting fiber optics and the properties of the optical elements in the laser focusing head decide the cross-section of the focused laser beam used for machining. If we summarize the formulas in different sources in the literature, we can predict the effect of each optical element: what will happen if we choose another focusing lens, put a beam expander in the system, set on the beam expander how many times the laser beam expands. The other important point is that if we want to repeat an experiment or start a production process based on a scientific publication, then in addition to the resonator, it would be good to know the data of the optical elements in the focusing head, which is usually incomplete in the presented articles, but we can determine them approximately using the four formulas listed in the article. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: Arc welding produces several harmful health effects on the welder. The authors aimed to determine the intensity of ultraviolet (UV) radiation as a function of distance from the welding. The research focused on the UV radiation generated during the arc welding process as it is a widely used process in industrial practice today. During the experiment, several tests were performed on the gas metal arc welding process (GMAW). This procedure is also used automated in the industry, so research can help to designate a specific safety zone in an industrial area so that there is no need to separate the welder robot with a curtain, but at the same time be able to move around them. Where the production is not fully automated yet, it highlights the problems which cause possible damage to health and helps create safer working conditions. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: Beside prosthesis loosening, wear is the mechanical factor that most significantly influences the lifetime of total knee replacements (TKRs), which can only be described by a number of interrelated parameters. The examination of the wear occurring in TKRs is mostly carried out as a combination of experiments and mathematical modeling. The experiment can provide the real magnitude of wear, while the model is intended to mathematically describe the relationship between wear and the wear-inducing parameters. On the one hand, this study focuses on the mathematical description of wear as a natural-technical phenomenon, presenting the most important analytical and numerical models, while also providing an open view on exciting questions that still await answers. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: The work focuses on the development of an artificial neural network (ANN) based model that can describe the adsorption of benzalkonium chloride from aqueous solutions onto commercially available kitchen paper. Various ANN architectures were tested in order to find the most suitable one in terms of overlapping between calculated and measured output data (coefficient of determination and mean absolute percentage error), as well as correctly interpolating outputs when using inputs form inside the experimental training range. The networks all had 4 inputs and 1 output, as well as a single hidden layer. Optimal ANN design was sought by varying both the number of neurons in the hidden layer and the type of transfer function towards it. The best find was employed in assessing the relative importance of input parameter values in the output, as well as the model’s suitability for predictions outside the training range. PubDate: Thu, 05 Jan 2023 00:00:00 GMT
Abstract: Chemically enhanced oil recovery methods can provide a solution to increase oil recovery. Of these, surfactant- polymer flooding is common. Efficient selection of polymers and surfactants is essential for a successful EOR project. Detailed selection of polymers is a lengthy task that involves a number of studies. Our goal is to create a fast polymer selection method based on which the most promising polymer can be selected. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: Duplex stainless steels offer a high strength alternative to stainless steel, while providing excellent corrosion resistance, due to their dual-phase microstructure. This microstructure can be significantly influenced during welding, thus the maximum recommended heat input is usually 2.5 kJ/mm. In this research, we inspected the high heat input (3 kJ/mm) weldability of NSSC 2120 lean duplex stainless steel, which is designed and developed specifically for this purpose. The welds were evaluated by metallographic techniques and corrosion tests. It was found the NSSC 2120 grade can be welded with high heat input without deterioration in the phase balance and microstructure. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: During our research work, we examined the removal of contaminants from synthetically produced bathing waters using different coagulants and studied the efficiency and the mechanism of coagulation-flocculation processes in detail. In our work, we performed experiments with two different types of coagulants (iron(III) chloride and polyelectrolyte) and compared their efficiencies. The zeta potential and its change were monitored as a qualifying parameter while other water quality parameters were also analyzed. In our experiments, a newly acquired flocculator device was also used to study the coagulation-flocculation processes of larger volume samples. The main goal of our research is to promote the sustainable management of drinking water quality and to study the bathing water reuse possibilities. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: Metal matrix syntactic foams are cellular materials in which the matrix is metal and within that matrix are non-metallic cells formed by filler material. These materials have low density, and besides that, they have high compressive strength and energy absorption. The main goal was to improve these properties by reinforcing the matrix with ceramic grains. During the experiment, molten A356 aluminium (7Si-0,3Mg) was infiltrated between the mixture of the filler and the reinforcement material. The specimens were produced with low-pressure infiltration. Different reinforcement materials were used: aluminium-oxide with three different grain sizes and colour designations and one type of silicon carbide. After heat-treatment, standardised compression tests were executed on the specimens. The results were compared to the results of the non-reinforced samples. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: The current study reports three different techniques to estimate the distribution of dislocation density at the mid thickness of 1050 Al alloy. It is well known that the strain distribution is inhomogeneous through the thickness of rolled materials, which affects the evolution of dislocation density during the process of deformation. In this study, the number of dislocations was calculated experimentally using indentation technique in 46.8% cold rolled 1050 Al sheet and the result was verified by two numerical methods. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: In this study, we present a novel approach for the production of continuous fiber-reinforced thermoplastic composites by combining injection molding and additive manufacturing. After exploring the design requirements, we manufactured inserts via continuous fiber-reinforced 3D printing, then we used them as reinforcement for injection-molded samples. Improper fiber placement can cause warpage as the continuous fibers prevent shrinking; however, warpage can be compensated with the insert geometry. The reinforcement resulted in an increase of about 30% in the properties tested. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: Two-way multi-axial forging was performed on a newly designed closed-die forging tool. The tool was operated on an MTS 810 material testing system. The connected computer recorded force and crosshead displacement as a function of time during operation. The sample material of the four-step forging experiment was CuE copper alloy. The plastic deformation was 0.8 per step, thus the rate of cumulative equivalent plastic strain was 3.2 by the end of the process. The speed of movement of the active tools during the whole test was 2 mm/min. Finite element simulation was performed with QForm3D software to investigate the force conditions of the process. The necessary flow curve was determined by Watts-Ford test. The force-displacement curves of the physical simulation were compared with the results of the finite element modeling. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: Laser cutting of copper-based alloy sheets is very difficult due to their high reflectivity, which can be modified with graphitization. The optimal parameters for a 2.5 mm thick brass sheet were determined by examining the laser beam parameter variations and the laser cut kerfs. The best characteristics of kerfs were obtained when the surface was graphitized, the laser frequency was 200 Hz, the applied laser speed was 1400mm/min on 2500 W power and the focal point was under the surface by 0.8 mm. The applied working gas was nitrogen. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: During color etching, the examined grain structure undergoes a continuous, cyclic color change. This phenomenon is accompanied by a continuous loss of light intensity reflected from the surface. If the etching process is not stopped in time, the surface will be over etched. As a result, the separability of the individual grains will be greatly damaged, which can lead to a significant loss of information. It was investigated how to determine the moment of over-etching for each grain. During the in-situ observation of the etching, the time at which a particle can be considered over etched was determined by measuring the luminance normalized to the initial state. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
Abstract: In the present work, PLA-PBS blends of 80/20 weight ratio were doped with zinc oxide (2.5; 5; 7.5 and 10 phr) and the flow, thermogravimetric and thermomechanical behaviour of the resulting blends were investigated. Using capillary plasstometry, thermogravimetry (TGA) and dynamic mechanical analysis (DMA), it was found that the increase in zinc oxide content resulted in an increase in the flow indices (MFI, MVR), as well as in the storage and loss modulus values, and a decrease in the thermal stability and glass transition temperature. PubDate: Wed, 20 Jul 2022 00:00:00 GMT
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