rss_2.0Acta Materialia Transylvanica FeedSciendo RSS Feed for Acta Materialia Transylvanica Materialia Transylvanica 's Cover Method of Flow Modifier Polymers for Chemical Enhanced Oil Recovery<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00High Heat Input Welding of NSSC 2120 Type Lean Duplex Steel<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Investigation of the Application of Coagulants in Case of Domestic Greywater Fraction<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Reinforced Matrix Syntactic Foams Filled with Ceramic Hollow Spheres<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Estimation of Dislocation Distribution at Mid Thickness for 1050 Al<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Development of a Novel Hybrid Manufacturing Technology For Continuous Fiber-Reinforced Thermo-Plastic Composites<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Simulation of CuE Copper Alloy in a Closed-Die Multi-Axial Forging Tool<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Laser Cutting of Brass Sheet<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Investigation of the Effect of Over-Etching During Color Etching<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Analysis of Thermogravimetric and Dynamic Mechanical Properties of PLA/PBS Blends Doped With Zinc Oxide Nanoparticles<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLE2022-07-20T00:00:00.000+00:00Manufacturing, Heat Treatment and Investigation of Foam-Filled Tubes<abstract> <title style='display:none'>Abstract</title> <p>Composite metal foams are hybrid structures with the main advantages of high specific strength and mechanical energy absorption associated with low density. In the course of our research, we successfully manufactured functional metal foams of EN AC-44200 matrix filled with lightweight expanded clay aggregate particles (LECAPs) in EN AW-6060 alloy tubes with a diameter of 50 mm and a wall thickness of 5 mm. Manufacturing was performed by low-pressure infiltration directly into the aluminium tube. Six different types of samples were examined: metal matrix syntactic foam, in-situ metal foam, ex-situ metal foam, and their heat-treated pairs. In the compression tests, the heat treatment provided a visible improvement in the results of the ex-situ metal foams.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Examination of Glass-Fibre Reinforced Composite Dental Fillings<abstract> <title style='display:none'>Abstract</title> <p>In dentistry, the use of dental fillings is a routine procedure. The use of fillings is a cheap, simple and low-harm dental operation, however, the filling of deep cavities is a difficult task. During this research, three types of fillings were tested: composite fillings bonded directly to the cavity walls, fillings bonded to the cavity walls with a semi-direct method, and composite fillings bonded to the cavity lined with polyethylene fibres. In the course of our examinations, the gaps between the wall of the dental cavity and the dental filling were observed using scanning electron microscopy. The results of these measurements can be used to determine the quality of each type of filling procedure.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Design of an Experimental Injection Moulding Tool for Testing Microstructured Cavity Surfaces<abstract> <title style='display:none'>Abstract</title> <p>This research is based on the impact assessment of the active element of injection moulding tools. The quality of the tool surface has a significant effect on the filling and cooling efficiency. Our goal is to create a uniform structure on the cavity’s surface that results in a high degree of orientation during the injection moulding process. A special experimental tool is needed for the research. Our design was based on the results of previous experimental research and preliminary criteria. The design was based on the size and position tolerances of the A side of the tool. As the previous study has shown, there are three main points to consider when designing an experimental moulding tool. These are the applied manufacturing technology, Design for Assembly, and the expansion of the measurement possibilities by using different sensors. The small beam size of the femtosecond laser also allows the machining of microscopic-sized details, a technology used to structure the cavity surface. The success of this was analyzed by microscopic examination.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Manufacture of a Home-Made Spot Welding Machine from Household Electronic Waste<abstract> <title style='display:none'>Abstract</title> <p>Nowadays, spot-welding technologies are being used on a very wide range of applications. Spot-welded joints can be found in many pieces of equipment, such as toasters, computers, telephone batteries, or even in various pre-manufactured car elements. Given the prevalence of the technology, there may be a legitimate need for a machine that can be used at home for simple spot-welding operations. Such a device could be produced more cost-effectively than those currently available on the market, while using household electronic waste. These could be produced for hobby purposes, thus creating an opportunity to recycle certain types of household electronic waste, thereby improving sustainability in an engineering approach.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Design and Implementation of a Vacuum Forming Machine<abstract> <title style='display:none'>Abstract</title> <p>The purpose of this work is to present the design of a laboratory scale vacuum forming machine, which can be used for the processing of thermoplastic sheets. The designed machine can process an A4 format plastic sheet. An important consideration in the design process was to follow a cost-effective approach. The vacuum forming instrument is made for educational purposes in the framework of a final project for the Polymer Technology Laboratory of the Department of Mechanical Engineering of the Sapientia EMTE University in Târgu Mureș. The structure and the operation of the machine is similar to that found in the industry. However, the cost of production is significantly lower. The main components of the machine include the frame, heater, vacuum pump and the clamping device.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Producing a Dissimilar Joint of Copper to Austenitic Stainless Steel by Ultrasonic Welding<abstract> <title style='display:none'>Abstract</title> <p>There are several possibilities for establishing a cohesion joint between dissimilar metals. In the case of thin sheets, the ultrasonic welding process is suitable. This process can establish a cohesion joint rapidly, with a low heat input between the thin sheets. The authors have tried to determine the optimal ultrasonic welding parameters for copper and austenite stainless steel joining by using an experimental method of joining. Suitable results were obtained by welding tests due dissimilarities in the chemical, physical and mechanical properties of the copper and stainless steel. A standard size sheet thickness and test sample was used for the welding by different parameters. The parameters were refined based on the theoretical and practical knowledge during the experiments. The experimental welding was made by a Branson L20 type welder machine. The joint made by the different parameters was inspected by shearing-tensile tests (maximal force level).</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Development of Pneumatic Deformability Test of Polylactic Acid Films<abstract> <title style='display:none'>Abstract</title> <p>The aim of the present study is to develop a test method suitable for modelling thermoforming processes and which provides an index that accurately characterises the thermoformability of a film or sheet at a given temperature and pressure. For this purpose, the elevated temperature pneumatic deformability test was considered to be the most suitable. During the test, the film is blown until it tears, which takes only a few seconds. We recorded blowing during the test, and used the images to determine the ascent (k) of the specimens and approach the estimated surface of the deformed specimens with a sphere.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Development of a Clamping Device for Tensile Testing of Intracranial Flow Diverter Stents<abstract> <title style='display:none'>Abstract</title> <p>The main danger of a brain aneurysm (a sack-like bulge on the vessel wall) is that in the event of a rupture a severe hemorrhage can occur which may cause death. However, if doctors have tools at their disposal, such as numerical models and simulations for analyzing patient-specific blood vessels, they could use them to decide if a particular treatment is necessary and if so, when. For such models, the different mechanical characteristics of the flow control devices are the input data. Several of these mechanical properties of the devices, such as modulus of elasticity and tensile strength, are determined by tensile testing. In the course of our research, we have developed a clamping device suitable for uniaxial tensile testing of flow diverter stents.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Characteristics of the Levels of Mechanisation in Arc Welding<abstract> <title style='display:none'>Abstract</title> <p>Improvement of quality, reduction of the subjective possibilities of faults may be facilitated with the help of the technically rational and economically justifiable mechanisation of productive serial production as well as the use of the wide range of hardware and software IT possibilities. Mechanisation is usually understood as the mechanisation of technological operations that may otherwise be performed by manual operations (human movements and effort). Mechanisation is therefore the substitution, in whole or in part, of manual labour with the help of specialised equipment and the mechanical operation of the various movements. The present article examines the particular features of mechanisation in the field of outstandingly high significance in industrial applications, i.e. arc welding, assisting the forms of training applied in the specialty area.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00Development of Graphite- and Graphene Reinforced Styrene-Butadiene Rubber<abstract> <title style='display:none'>Abstract</title> <p>The environmental impact of rubber waste can be reduced by extending the lifetime of rubber products. It can be achieved by developing graphene/rubber nanocomposites with good abrasion resistance. In this paper, we investigated how rubber mixing technologies influence the mechanical properties of rubber. We added various amounts (0, 1, 5 and 10 phr) of graphite and graphene to rubber mixtures using a two-roll mill, an internal mixer, a single- and a twin-screw extruder. We performed tensile, tear strength and Shore A hardness tests on the vulcanisates and analysed their fracture surfaces with a scanning electron microscope. Our results show that graphene had a better reinforcing effect than graphite. Rubber mixing via extrusion may contribute to more severe polymer degradation, though their reproducibility is better than that achieved on a two-roll mill or in an internal mixer.</p> </abstract>ARTICLE2021-10-28T00:00:00.000+00:00en-us-1