https://mater-tehnol.si/index.php/MatTech/issue/feed Materials and Technology 2024-04-09T10:24:52+02:00 Miro Pečar mit@imt.si Open Journal Systems <div class="article"> <div class="article"> <p>The journal Materiali in tehnologije / Materials and Technology is a scientific journal, devoted to original scientific papers concerned with the areas of fundamental and applied science and technology. Topics of particular interest include metallic materials, inorganic materials, polymers, vacuum techniques, nanomaterials and lately biomaterials.<br>© MATERIALI IN TEHNOLOGIJE<br><br><strong>Published by:</strong><br>Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana, Slovenia</p> <p><br><strong>Associated publishers:</strong><br>IMPOL Slovenska Bistrica, Slovenia • METAL Ravne, Slovenia • TALUM Kidričevo, Slovenia<br><br>Materiali in tehnologije / Materials and Technology journal is financially supported by Slovenian Research Agency (ARRS).</p> </div> </div> https://mater-tehnol.si/index.php/MatTech/article/view/960 EFFECT OF OUTPUT VOLTAGE ON AN AZ91D MAGNESIUM ALLOY ROLLED USING AN ELECTRIC PULSE TREATMENT 2024-04-05T06:58:42+02:00 Jing Feng 1402766945@qq.com Yuezhang Zhou zyzhowlong@foxmail.com Dehua Liu 321510446@qq.com Yong Zhang drzhangy@ustb.edu.cn Guihong Geng gengguihong@nmu.edu.cn <p>Magnesium alloys have poor deformation properties at room temperature, and the application of an electric pulse current during deformation can improve the plastic-forming ability. In this study, the electric pulse rolling of AZ91D magnesium alloy specimens has been examined by changing the pulse output voltage. The results demonstrate that the best surface quality and lowest content (8.4 %) of the β-Mg<sub>17</sub>Al<sub>12</sub> phase are achieved at an output voltage of 300 V. EBSD tests have revealed the lowest weave strength on {0002} and {100} at a pulse output voltage of 300 V, as well as the greatest enhancement of twinning. The maximum tensile strength was 165 MPa at an output voltage of 300 V, with a maximum elongation of 4.1 % at an output voltage of 200 V.</p> 2024-04-02T13:14:32+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1054 STUDYING THE STRENGTH OF DISSIMILAR JOINTS OF AISI 430 AND 301 STAINLESS STEEL WELDED AT DIFFERENT WELDING PARAMETERS 2024-04-05T06:58:42+02:00 Sedat Aras arassdt@gmail.com Rukiye Ertan arassdt@gmail.com <p>Investigating the best welding parameters for resistance spot welding joints between AISI 430 and AISI 301 stainless steels was the primary focus of this study. This research involved welding samples of these stainless steel types using various welding parameters. Ferritic stainless steel (AISI 430) and austenitic stainless steel (AISI 301) were subjected to resistance spot welding, and different welding conditions were applied to produce a range of samples. The study specifically analyzed the influence of the welding current (2.5, 3.1 and 3.7) kA and welding time (40, 70 and 100) ms on the joining capability of these stainless steels. To determine the best welding parameters, microhardness measurements and tensile-shear tests were performed on the welded materials. The results indicated that increasing the welding current and welding time led to an increase in the tensile load. The maximum tensile-shear load 2036 N was observed at 3.7 kA and 100 ms. However, after a salt spray test (48 and 96) h, a serious decrease in the tensile load from 2036 N to 750 was observed at the high current 3.7 kA and time (70 and 100) ms. At 3.1 kA and 70 ms before and after the salt test, its value remained relatively constant, and the corrosion resistance of the weld joint was at the best level. The microhardness of the heat-affected zone increased, reaching its maximum point (for 3.1 kA and 70 ms: 347.3 HV and for 3.1 kA 100 ms: 369 HV) in the fusion zone. Moreover, the increase in the welding time and current was associated with an increase in the nugget size. The maximum nugget size was 3.61 mm at 3.7 kA and 100 ms.</p> 2024-04-02T13:21:46+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1055 EFFECT OF A MAGNETIC FIELD ON THE MICROSTRUCTURE AND PROPERTIES OF RESISTANCE SPOT WELDED JOINTS OF 444 FERRITIC STAINLESS STEEL/6082 ALUMINUM ALLOY 2024-04-05T06:58:43+02:00 Xiaoou Zhu clzxo@lnut.edu.cn Zhanqi Liu clzxo@lnut.edu.cn Qi Zhou clzxo@lnut.edu.cn Jie Chen clzxo@lnut.edu.cn Shouhong Li clzxo@lnut.edu.cn <p>To improve the welding quality of resistance spot welding joints of steel/aluminum lightweight structures, the steady magnetic field-assisted resistance spot welding method was used to weld 444 ferritic stainless steel and 6082 aluminum alloy, both with a thickness of 1 mm. Under the same welding parameters, the effect of a magnetic field on the microstructure and mechanical properties of the joint was analyzed. It was found that the Lorentz force generated by the addition of a magnetic field promoted the circumferential movement of the molten metal in the nugget zone, increased the size of the Fe/Al contact interface in the joint along the horizontal direction, and made an effective use of the heat generated during resistance spot welding. Although the intermetallic compounds in the intermediate transition layer of the two welded materials were mainly composed of (Fe, Cr, Si)Al<sub>2 </sub>and (Fe, Cr, Si)Al<sub>3</sub>, relatively low contents of (Fe, Cr, Si)Al<sub>2 </sub>and (Fe, Cr, Si)Al<sub>3 </sub>were found and a there was a significant decrease in the thickness of the intermetallic compound layer when the magnetic field was applied. Compared with the welded joint devoid of a magnetic field, the tensile strength and ductility of the joint were effectively improved, and the dimples in the fracture surface became relatively deep and numerous. In essence, resistance spot welding joints of steel/aluminum obtain better comprehensive mechanical properties when a magnetic field is applied.</p> 2024-04-02T13:28:26+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/869 MICROSTRUCTURE CHARACTERISTICS OF Cr3C2-NiCr COATINGS DEPOSITED WITH THE HIGH-VELOCITY OXY-FUEL THERMAL-SPRAY TECHNIQUE 2024-04-05T06:58:43+02:00 Jason Lauzuardy jasonlauzuardy@gmail.com Eddy Agus Basuki basuki@mining.itb.ac.id Erie Martides erie001@brin.go.id Selly Septianissa selly.septianissa@yahoo.co.id Budi Prawara budi006@brin.go.id Dedi dediamada1@gmail.com Endro Junianto endrojuni56@gmail.com Edy Riyanto edy.riyanto@brin.go.id <p>With the goals of protecting boiler tubes from hostile surroundings, increasing thermal efficiency, and minimizing time losses from damage, thermal-spray coating methods for high-temperature operations were created. Ceramic-metal composite materials (e.g., Cr<sub>3</sub>C<sub>2</sub>-NiCr) are well known for protecting components from erosion decay in a high-temperature environment. In this investigation, the high-velocity oxy-fuel (HVOF) thermal-spray technique was employed to successfully deposit several variations of feedstocks containing Cr<sub>3</sub>C<sub>2</sub>-NiCr and NiCr powders onto a medium-carbon steel substrate, with and without filtering through a 400-mesh screen. Utilizing X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the microstructure features of the deposited coatings were assessed. The experiment results demonstrate that the crystallite and grain sizes of the deposited coatings can be increased by reducing the powder size through a sifting process using a 400-mesh sieve. This procedure also resulted in a coating with a higher density and lower porosity. Furthermore, new compounds including Cr<sub>2</sub>O<sub>3</sub> and MnCr<sub>2</sub>O<sub>4</sub> were formed in the coating layers as indicated by the XRD spectra. These phenomena are in good agreement with the EDS mapping of Cr and O, which reveals highly similar distributions. Manganese was originally a part of the substrate composition. Manganese could diffuse rapidly across the Cr<sub>2</sub>O<sub>3</sub> layer and form the MnCr<sub>2</sub>O<sub>4</sub> compound, indicating the manganese diffusion from the substrate into the Cr<sub>3</sub>C<sub>2</sub>-NiCr coating. The formation of MnCr<sub>2</sub>O<sub>4</sub> can be attributed to the prior emergence of the Cr<sub>2</sub>O<sub>3</sub> compound.</p> 2024-04-02T13:35:44+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1037 A NOVEL HYBRID DECISION-MAKING MODEL: FUZZY AHP-TOPSIS APPROACH FOR PRIORITISING COPPER SMELTING PROCESSES 2024-04-05T06:58:44+02:00 Ivica Nikolić inikolic@tfbor.bg.ac.rs Anđelka Stojanović inikolic@tfbor.bg.ac.rs Milijana Mitrović inikolic@tfbor.bg.ac.rs <p>The construction of a copper smelting facility and its undisturbed and profitable business undoubtedly contribute to the development of each country’s economy. These facilities employ many workers and produce a large amount of copper, reducing imports and dependence on this important raw material, thereby improving the economic situation in a given country. More than a hundred copper smelters operate worldwide, many of which use different types of copper extraction processes. Strict legislation relating to ecology and environmental protection as well as stakeholder involvement in selecting and constructing copper smelting facilities limit the maximisation of short-term economic objectives. The prioritisation of technological processes for the extraction of copper must consider the impacts of often mutually opposing economic, technical and environmental objectives. No research from the available literature analyses the economic, technical and environmental parameters systematically. Studies have mainly dealt with exploring individual influences of factors through the use of one selection method. This paper presents the development of a novel hybrid AHP-TOPSIS model in fuzzy environments that will provide both informative decisions and optimum results of decision making.</p> 2024-04-02T13:40:36+02:00 Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/989 GENETIC ALGORITHM-BASED OPTIMIZATION OF THE LASER-BEAM PATH IN ADDITIVE MANUFACTURING 2024-04-05T06:58:45+02:00 Primož Potočnik primoz.potocnik@fs.uni-lj.si Andrej Jeromen andrej.jeromen@fs.uni-lj.si Edvard Govekar edvard.govekar@fs.uni-lj.si <p>This study presents a methodology of genetic-algorithm-based optimization of the laser-beam path for improving laser-based additive manufacturing (AM). A simple thermal model was developed to simulate the effects of laser-induced heat input on the temperature distribution within the substrate during the fabrication of one layer. The optimization approach aims to find solutions with more homogeneous temperature properties that minimize the thermal gradient on the substrate caused by laser-based AM. The laser beam, i.e., the tool-path planning, is formulated as the search for the optimal sequence of cell depositions that minimize the fitness function, which is composed of two components, i.e., the thermal fitness and process fitness. The thermal fitness is expressed as the average thermal gradient, and the process fitness regulates the suitability of the proposed tool path for the implementation of the AM process. Various tool-path generators are proposed to initialize the initial population of tool-path solutions. Genetic-algorithm-based tool-path optimization is proposed, where custom initialization, crossover and mutation operators are developed for application in laser-based AM. Simulation studies demonstrate the effectiveness of the genetic-algorithm-based optimization in finding solutions that minimize the fitness function and therefore provide both thermally and, for the AM process implementation, more suitable laser-beam-path solutions.</p> 2024-04-02T13:47:31+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/794 EFFECT OF CYCLIC NaCl SOLUTION IMMERSION CURING ON THE MECHANICAL PROPERTIES OF PLAIN CONCRETE 2024-04-05T06:58:45+02:00 Wei He shoujun_wu@163.com Shoujun Wu shoujun_wu@163.com Bo Zhang shoujun_wu@163.com Yiming Luo shoujun_wu@163.com Yanyu Liu shoujun_wu@163.com Guo Fu shoujun_wu@163.com <p>The effects of cyclic curing (CC) alternating between NaCl solution immersion and drying for 28 d on the microstructure, phase composition and mechanical properties of ordinary concrete are studied in comparison with those cured by standard curing using municipal water. Compared to standard curing, CC enhances the compressive strength, flexural strength and static compressive elastic modulus of concrete by (5.71, 11.14 and 8.06) %, respectively. Ca(OH)<sub>2</sub> is significantly reduced, while C-S-H is increased, and a minor amount of 3Ca(OH)<sub>2</sub>·CaCl<sub>2</sub>·12H<sub>2</sub>O is formed. Hydration products become finer, more uniform and denser. The use of CC is proposed as it improves the strength.</p> 2024-04-03T06:50:32+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/914 EFFICIENT WASTEWATER TREATMENT THROUGH INTEGRATED WATER HYACINTH SYSTEMS: ADVANCES AND APPLICATIONS IN CONCRETE 2024-04-05T06:58:46+02:00 Ananthakumar Ayyadurai ananthakumariei@gmail.com M. M. Saravanan ananthakumariei@gmail.com M. Devi ananthakumariei@gmail.com <p>This research focuses on enhancing water quality for concrete construction by utilizing treated wastewater from wetlands. The study employs a dual-stage treatment process involving charcoal and aggregate layers for primary treatment, followed by water hyacinths for secondary treatment. Investigating water hyacinths’ ability to absorb nutrients and contaminants from wastewater is a unique aspect of the study, offering a potential solution for soil and water remediation. Water hyacinths, especially stems and leaves, act as natural filters, effectively indicating heavy-metal pollution in tropical regions. The primary goal is heavy-metal removal from wastewater, allowing treated-water use in concrete production at varying proportions (20 %, 40 %, 60 %, 80 %, and 100 %). Silica fume at 15 % concentration is incorporated to enhance the concrete’s durability. Concrete specimens undergo thorough preparation and mechanical property evaluations, compared to conventional M20-grade concrete. The results reveal improvements in mechanical properties, particularly with 80 % treated wastewater in the mix. The dual-stage treatment process removes heavy metals, and the inclusion of silica fume enhances the concrete’s durability and resistance.</p> 2024-04-03T06:59:05+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1038 EFFECT OF HIGH-INTENSITY ULTRASONIC TREATMENT ON REFINEMENT OF Al-5Cu ALLOY INGOTS 2024-04-05T06:58:46+02:00 Zheng Jia jz140@syu.edu.cn Zhi Zhuo Wang jz140@syu.edu.cn Li Fu jz140@syu.edu.cn <p>The effect of high-intensity ultrasonic treatment combined with bottom cooling treatment on the refinement of Al-5Cu alloy ingots was studied. The results show that ultrasonic treatment combined with forced cooling at the bottom of ingots has a good refining effect, and the best refining effect can be obtained at 2000 W and after 120 s. The cross-section of an ingot exhibits almost 100 % refined equiaxed grains and no porosity. The method of combining ultrasonic treatment and forced cooling at the bottom of ingots not only influences the ingot refinement, but also decreases the porosity of the ingots with an increase in the ultrasonic duration. The ultrasonic degassing effect is due to the release of hydrogen in biofilms, which expand and grow gradually; finally, they burst on the melt surface, achieving the effect of degassing.</p> 2024-04-03T07:03:52+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1047 THREE-DIMENSIONAL MODEL OF EQUIVALENT ROLL GAP OF CVC MILL UNDER CONDITIONS OF ROLL CROSSING AND NO LOAD 2024-04-05T06:58:47+02:00 Xiaoxin Ma mxxwzgz@163.com Peisen Yuan mxxwzgz@163.com Fuyi Li mxxwzgz@163.com Jiang Ji mxxwzgz@163.com <p>Traditional roll technologies focus solely on the contour of the roll gap at the outlet under ideal conditions. However, upon roll crossing, the three-dimensional distribution of the deformation zone becomes asymmetrical, leading to an adverse impact on the rolling pressure in the deformation zone. To study the screw-down load deviation of plate mills, it is necessary to accurately calculate the equivalent three-dimensional roll gap in the deformation zone under roll-crossing conditions. In this paper a model for calculating the equivalent three-dimensional roll gap under the conditions of roll crossing and no load was established based on the method of the coordinate nonlinear transformation of the spatial rectangular coordinate system. Based on this model, the influences of roll-crossing angles and translation parameters on the symmetry of the equivalent three-dimensional roll gap were analyzed. The distribution of the three-dimensional equivalent roll gap was calculated with different roll lengths, roll radii, and the roll gap’s nominal thickness. The intuitive contour map reveals that under the same condition of crossing angle and translation parameters, the larger the roll length and roll radii and the smaller the roll gap’s nominal thickness are, the greater the influence of the roll crossing on the asymmetrical distribution of roll gap is. It put forward a quantitative calculation method for evaluating the symmetrical distribution of the roll gap, and the calculation results can provide the equivalent roll profile for the roll-deformation model.</p> 2024-04-03T08:19:23+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1033 INVESTIGATION OF MECHANICAL AND PHYSICAL PROPERTIES OF DATE PALM STEM FIBRE REINFORCED EPOXY COMPOSITES 2024-04-05T06:58:47+02:00 Mathu Kumar S. smathukumar@gmail.com Rejikumar R. smathukumar@gmail.com Mini Jose Anand smathukumar@gmail.com Mohamed Shebu M. smathukumar@gmail.com <p>The growing demand for sustainable materials, particularly date palm stem fibre (DPSF), has garnered attention in the area of engineering applications due to its advantageous traits. Its composites offer distinctive characteristics such as satisfactory mechanical properties, low density and a cost-effective production. This study examines the mechanical characteristics of epoxy (LY-556) composites reinforced with DPSF. A range of composite configurations with different compositions and fibre loadings were meticulously crafted, using a hand lay-up technique. The research meticulously examines DPSF and epoxy composites with loadings of (10, 15, 20, and 25) <em>w</em>/%, comprehensively characterizing their flexural, tensile, impact and water-absorption behaviours. Across the varied compositions, the characteristics of flexural strength, tensile strength, impact strength and water absorption are thoroughly analysed. The conclusive findings underscore optimal enhancements in the flexural, tensile and impact strengths achieved with the DPSF loading of 20 %. This empirical understanding bears significance for designing natural fibre reinforced composites with superior mechanical attributes, reaffirming DPSF’s potential as a valuable reinforcement in modern engineering applications.</p> 2024-04-03T08:26:07+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1062 EXPERIMENTAL STUDY ON MAG WELDED E350 HSLA STEEL JOINTS 2024-04-05T06:58:48+02:00 Bradeesh Moorthy S. bradeeshmoorthys@gmail.com Malayalamurthy R. bradeeshmoorthys@gmail.com Amirthagadeswaran K. S. bradeeshmoorthys@gmail.com <p>Activated flux has been used successfully to improve the penetration of Tungsten Inert-Gas (TIG) welding, which is normally a welding process with low penetration. But the same activated flux when used for Metal Active Gas (MAG) welding showed a moderate improvement in penetration. Hence only a few research articles reported on activated flux MAG welding. TIG dressing is a post-weld treatment intended to improve the fatigue life of welded joints. The use of activated flux along with TIG dressing were not yet reported. In this work, an experimental study was conducted on the metallurgical changes and their effects on fatigue life in E350 steel welded by MAG welding with activated flux coating as well as toe TIG dressing. The metallurgical changes induced by various weld conditions and the effect on the fatigue life of welded joints were discussed. Welding conditions were categorised as: as weld (AW), weld with flux coating (FW), weld with TIG dressing (AWT), and flux weld with TIG dressing (FWT). Fatigue tests at stress ranges closer to the yield stress (80 % to 90 % of yield) were studied. In comparison with AW joints, the AWT and FWT showed a fatigue-life improvement of 60 % to 80 %, and 69 % to 103 % respectively. Whereas the FW joints showed 10 % to 17 % deterioration in fatigue life. Upon investigation with electron microscopy it was found that the variation in grain sizes and phase changes induced by the usage of flux and TIG dressing, as well as the changes in weld toe radius by TIG dressing and root strengthening due to extra penetration induced by the use of flux were the reasons behind these fatigue behaviours. In this work a novel effort is made to find a way to improve the fatigue life of a welded joint with a combination of two techniques. The activated flux is used to improve the penetration, whereas TIG dressing is performed to reduce the stress concentration. This new combination of techniques has improved the fatigue life of the weld significantly, which can lead to reduced maintenance costs of welded joints and a longer life.</p> 2024-04-03T10:49:00+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1002 INFLUENCE OF SPRAY DISTANCE ON THE POROSITY OF Ni-BASED AMORPHOUS COATINGS: NUMERICAL SIMULATION AND EXPERIMENT 2024-04-05T06:58:48+02:00 Rui Wang wunianchu@163.com Deming Wang wunianchu@163.com Nianchu Wu wunianchu@163.com <p>The influence of injection distance on the porosity of Ni-based amorphous coatings (AMCs) prepared with a high-velocity air fuel (HVAF) process is discussed based on a numerical analysis and experimental methods. A computational fluid dynamics model was established to demonstrate the gas flow field and behavior of particles in flight at different spraying distances during HVAF spraying. When analyzing the changes in the particle velocity and temperature, the spraying distance is less than 30 µm. The velocity and temperature changes of small particles have a significant impact, and the optimal spray distance (350 mm) for obtaining a low porosity coating is predicted. The calculation was validated experimentally by producing a Ni-based AMC with a low porosity (1.87 %) that was manufactured using the predicted HVAF optimal spraying distance.</p> 2024-04-03T10:53:15+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1040 A SIMPLE STRUCTURED MULTIBAND TERAHERTZ METAMATERIAL ABSORBER WITH A HIGH Q FACTOR 2024-04-05T06:58:49+02:00 Deepa Nivethika S. deepanivethika.s@vit.ac.in <p>A terahertz Eight-/Nine-/Twelve-/Fourteen-/Sixteen-Band Metamaterial Absorber (MMA) for sensing applications is built and simulated. The substrate is sandwiched between the bottom ground plane and the top patch structure of this primitive MMA. The top patch is made up of two concentric circular ring resonators. This structure generates a multiple number of multi bands without utilising stacked layers, multiple resonators, or overlapping in a single unit cell by altering the radius of the top patch structure within the shorter frequency range of 0.8 THz to 1.2 THz. The polarisation and angle insensitivity properties are investigated by shifting the angle values from 0 to 90 degrees. To learn about the inside mechanism of the planned structure, the magnetic field distribution, electric field distribution and surface current distribution plots are explained. For the sixteen-band MMA, the Q-Factor and full width half maximum are also determined. This proposed MMA will be used in biosensing applications, sensors and wireless communications.</p> 2024-04-03T11:27:20+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/905 EFFICIENT PRODUCTION OF SMALL-SIZED SiO2 NANOPARTICLES AND THEIR APPLICATION IN A WATERBORNE ACRYLIC-AMINO VARNISH 2024-04-05T06:58:49+02:00 Jinping Wu minminchen@xzhmu.edu.cn Jinxiang Mao minminchen@xzhmu.edu.cn Hong Liu minminchen@xzhmu.edu.cn Xichuan Cao minminchen@xzhmu.edu.cn Minmin Chen minminchen@xzhmu.edu.cn <p>In this study, we optimized the preparation of 100–160 nm monodispersed SiO<sub>2</sub> nanoparticles and, through doping, investigated their effects on the physical properties of a water-based acrylic-amino varnish. First, using a non-fixed point feeding technique based on the half-batch sol-gel method, we enhanced the yield of small-sized monodispersed SiO<sub>2</sub> nanoparticles. To reduce the cost of production and organic-matter pollution, we assessed certain solution parameters including tetraethyl orthosilicate (TEOS), ethanol (ETOH) and ammonia in a single-reaction system. We found that the gloss, clarity, hardness, adhesion, and other physical properties of the acrylic-amino varnish were successfully enhanced through an addition of 1.2 % SiO<sub>2</sub> nanoparticles.</p> 2024-04-03T11:37:46+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1049 EXPERIMENTAL STUDY OF THE CHLORIDE-ION PERMEABILITY OF BAMBOO-FIBER-REINFORCED CONCRETE 2024-04-05T06:58:49+02:00 Yong Luo felix06102023@126.com Mustafasanie M Yussof felix06102023@126.com Yiming Jiang felix06102023@126.com Zhongwei Peng felix06102023@126.com Chaoxing Wu felix06102023@126.com Fangcheng Shi felix06102023@126.com Yuepeng Chen felix06102023@126.com <p>This study investigated the chloride-ion permeability of C30 concrete by adding bamboo fibers with different treatments (untreated, treated with calcium hydroxide solution and treated with sodium hydroxide solution) and different dosages. Three testing methods, namely the electric-flux method, AC test method and the RCM method, were used to characterize the concrete. Parameters such as electric-flux value, AC resistivity and chloride-ion diffusion coefficient were obtained. Results showed that the surface impurities of the bamboo fibers treated with calcium hydroxide solution were removed and the thermal stability of the bamboo fibers was improved, which can effectively enhance the chloride-ion permeability of concrete. Compared to untreated bamboo fibers, the improvement rate was between 14 % and 17 %. Sodium hydroxide is a strong alkaline solution, which can easily disrupt the structure of bamboo fibers and reduce the resistance of concrete to chloride-ion penetration. The best chloride-ion permeability was achieved when the bamboo fiber content reached 2 %. The electric-flux method, AC test method, and the RCM method were mutually validated with good correlation. It is recommended to choose a suitable and simple method for testing. Bamboo-fiber concrete lays a solid foundation for the future transformation of the civil-engineering industry.</p> 2024-04-03T11:48:44+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1126 EVALUATION OF THE MAGNETIC PROPERTIES OF Ag-Au-Pd-Cu DENTAL ALLOYS 2024-04-05T06:58:50+02:00 Leo Gusel leo.gusel@um.si Peter Majerič peter.majeric@um.si Mirko Glišić mirko.glisic@stomf.bg.ac.rs Aleksandra Kocijan aleksandra.kocijan@imt.si Rebeka Rudolf rebeka.rudolf@um.si <p>The paper discusses four Ag-Au-Pd-Cu dental alloys, with different chemical compositions, which are used to produce fixed dental-prosthetic structures. These dental alloys must have a low level of biological risk after being implanted in the oral cavity, which means minimal release of ions from their surface, or the absence of corrosion, and, recently, the absence of ferromagnetism has been introduced as an additional requirement. The latter requirement is particularly important when magnetic resonance (MR) is used in the medical diagnosis of a patient who has an implanted fixed dental-prosthetic structure. With this technique, the internal structure of the human body is imaged using a strong magnetic field, radio waves and computer technology. Therefore, the absence of ferromagnetic, embedded biomaterials is necessary in the part of the body where medical diagnostics are performed. Microstructural investigations of four Ag-Au-Pd-Cu dental alloys (Auropal S, Auropal SE, Midor S and Midor SE) and measurements of their magnetic properties were carried out as part of the research. The results showed that Ag-Au-Pd-Cu dental alloys have a stable microstructure, which allows them to be processed later into fixed prosthetic constructions. The measurements of the magnetic properties showed that the Ag-Au-Pd-Cu dental alloys are diamagnetic.</p> 2024-04-03T11:53:46+02:00 Copyright (c) 2024 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/1130 CORROSION BEHAVIOUR OF ADDITIVELY MANUFACTURED METALLIC MATERIALS 2024-04-09T10:24:52+02:00 Aleksandra Kocijan aleksandra.kocijan@imt.si <p>Additive manufacturing (AM) represents a technological advancement over traditional manufacturing methods, offering cost-effective production of high-quality, geometrically complex components for various applications. With its ability to rapidly manufacture metallic parts and a capability to better customise products due to the possible recycling of used powder materials, AM facilitates customized product development. On the other hand, the technology raises questions regarding microstructure, residual stresses, porosity and surface roughness. All these aspects need to be evaluated to achieve the quality of the end products. This paper reviews the corrosion behaviour of AM-produced metallic materials, examining how various factors, including porosity, microstructure, melt-pool boundaries, residual stresses, and surface roughness, influence the end-product quality.</p> 2024-04-03T11:56:37+02:00 Copyright (c) 2024 Materials and Technology