Materials and Technology https://mater-tehnol.si/index.php/MatTech <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> en-US mit@imt.si (Roman Celin) mit@imt.si (Roman Celin) Thu, 30 Sep 2021 16:37:05 +0200 OJS 3.1.2.4 http://blogs.law.harvard.edu/tech/rss 60 HIGH ENTROPY ALLOWS A BETTER AFFINITY BETWEEN METAL IONS AND ACTIVATED CARBON FIBRES https://mater-tehnol.si/index.php/MatTech/article/view/275 <p>Recent numerical approaches to extracting metal species using carbonaceous materials have de facto stimulated an interest in the field of microextraction, but theoretical observations inspired by randomness changes have been elusive. In this contribution, we present the degree of randomness using Cu (II) and Pb (II). Here, activated carbon fibres were employed as the skeleton adsorbent, providing scientific insights via the aqueous phase. Coupled isotherms of Langmuir and Freundlich were represented to unravel the aforementioned thermodynamics. Findings revealed that the Langmuir isotherm best described the equilibrium state and the trend was in accordance with the energy computation. The maximum microextraction performance was 84.75 mg/g and 102.04 mg/g for Cu (II) and Pb (II), respectively. Under all circumstances, there was a high randomness change as the microextraction performance increased.</p> Sang Sun Choi, Soon Hong Lee, Kyung Jae Yun, Young Min Jin, Joon Hyuk Lee Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/275 Thu, 30 Sep 2021 00:00:00 +0200 MANUFACTURING THINNED FRICTION-STIR WELDED 1050 ALUMINUM BY POST ROLLING: MICROSTRUCTURE AND MECHANICAL PROPERTIES https://mater-tehnol.si/index.php/MatTech/article/view/276 <p>One of the friction-stir welding (FSW) limitations is joining thin sheets in sheet-metal manufacturing. To solve this limitation, thicker sheets can be welded with FSW and then rolled to a thinner thickness. This can improve the mechanical properties and save the weld zone soundly. In this work, 3-mm aluminum sheets were joined with FSW. The microstructure and mechanical properties of the samples were assessed at various rotational speeds (w) and travel speeds (<em>v</em>). Then, the welded samples were cold worked (CW) by rolling them at different percentages so that the samples were 2 mm and 1 mm thick. The effects of welding and post rolling on the mechanical properties and a failure analysis were deliberated. It was shown that welding reduces the transverse ultimate tensile strength (UTS) of FSWed samples by up to 29 % compared to the UTS of the base metal (BM), while rolling FSWed samples increased the UTS of the cold-worked FSWed samples by up to 94.7 % in comparison to the UTS of FSWed samples. Also, during the tensile test of the specimens FSWed at a lower travel speed, a fracture occurred at the stir zone (SZ)/thermo-mechanically affected zone (TMAZ) interface, on the advancing part; however, at a higher travel speed, it occurred at the interface of the heat-affected zone (HAZ) and TMAZ, on the retreating part. Moreover, during the tensile test of the cold-worked FSWed samples, the failure took place at the HAZ and the interface of the SZ and TMAZ, respectively. The UTS was risen by increasing the cold work. The UTS of a specimen FSWed at 50 mm/min and 1200 min<sup>–1</sup> went up from 76 MPa to 124 MPa due to 33-% cold work and to 148 MPa due to 66-% cold work; meanwhile, the fracture occurred at the SZ/TMAZ interface or TMAZ of most of the post-rolled FSWed samples.</p> Sina Zinatlou Ajabshir, Mohsen Kazeminezhad, Amir Hossein Kokabi Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/276 Thu, 30 Sep 2021 00:00:00 +0200 CHARACTERIZATION OF CHEMICALS FROM PROSOPIS JULIFLORA (PJ) – A POTENTIAL ENHANCER FOR LIGHTWEIGHT POLYMER APPLICATIONS https://mater-tehnol.si/index.php/MatTech/article/view/158 <p>The latest research is about ProsopisJuliflora’s mining and characterization officers. The fibres were cut, chemically treated using sodium and hydrochloric acid (alkali) solutions. Chemically modified and non-modified fibres have been analysed for their thermal, chemical, crystalline, electrical, morphological and tensile characteristics. The findings showed that a cellulose content was increased by 59.8 % with a reduction of amorphous content and humidity by chemical treatment with alkali. However, due to its acid-plus attacks whose values were lower than untreated, the treatment for hydrochloric acid reduced cellulosis material. There were four hundred and seventeen nm of crystalline fibre of alkaline therapy, less than one 68.01 nm. Thus the ProsopisJuliflora can be suggested for lightweight polymer applications as a possible reinforcement.</p> D. Narayana Moorthy, L. Jayakumar, K. Muthukumaran Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/158 Thu, 30 Sep 2021 00:00:00 +0200 TAILORING SURFACE MORPHOLOGY AND TOPOGRAPHY OF SHOT-PEENED Ti6Al4V VIA GRIT BLASTING https://mater-tehnol.si/index.php/MatTech/article/view/32 <p>The present study aims to reveal the effectiveness of grit blasting when modifying the surface properties of a Ti6Al4V alloy deteriorated due to shot peening. Ti6Al4V samples shot-peened under different parameters were grit-blasted (at impingement angles of 30° and 90°, blasting pressures of 1.5 bar and 3 bar). Grit blasting proved to be an effective way of tailoring the surface topography as the surface roughness of shot-peened samples (approx. 10 µm) declined to approx. 2 µm. The surface modifications mainly occurred via micro-ploughing and micro-cutting wear mechanisms, indicating that grit blasting at 30° was more favourable than at 90° for modifying the deteriorated surface properties after shot peening. Shot-peened samples behaved similarly to mirror-polished unpeened samples during grit blasting, showing that the modified surface and subsurface properties obtained via shot peening have an insignificant effect on grit blasting of the alloy. A quantitative analysis of the area covering the embedded particles on the surface of the alloy due to grit blasting showed that the area almost doubled when the alloy was grit blasted at 90° compared to 30°, highlighting an excessive amount of embedding, which would be critical when surface decontamination is important.</p> Yasemin Yıldıran Avcu, Okan Yetik, Mert Guney, Tamer Sınmazçelik, Egemen Avcu Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/32 Thu, 30 Sep 2021 00:00:00 +0200 SINTERING BEHAVIOUR OF MAGNESIUM OXIDE OBTAINED FROM SEAWATER DOPED WITH NANO-TiO2 https://mater-tehnol.si/index.php/MatTech/article/view/277 <p>In order to improve the properties of sintered MgO (80 % precipitation) obtained from seawater, an investigation was carried out with (0, 1, 2) <em>w</em>/% of nano-TiO<sub>2</sub> and micro-TiO<sub>2</sub> additions during sintering at a temperature of 1500 °C (1 h and 2 h). The effects of the TiO<sub>2</sub> addition on its microstructural properties, density, porosity and chemical composition after sintering were observed. The SEM/EDS analysis confirmed the formation of a homogeneous microstructure composed mainly of periclase grains and well-distributed secondary phases. CaTiO<sub>3</sub> and MgTiO<sub>4</sub> are predominantly located at the inter- and intra-periclase grain boundary surfaces during cooling. The microstructure of the MgO samples with the addition of nano-TiO<sub>2</sub> become more compact, having a positive impact on the porosity and density of the samples. The addition of 1<em> w</em>/% of nTiO<sub>2</sub> represents the optimal amount for the improvement of the properties of the MgO samples (80 % precipitation) obtained from seawater.</p> Jelena Jakić, Miroslav Labor, Vanja Martinac, Martina Perić Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/277 Thu, 30 Sep 2021 00:00:00 +0200 NEXAFS – SODOBNA TEHNIKA ZA ŠTUDIJ MOLEKULSKIH ORBITAL V TANKIH PLASTEH https://mater-tehnol.si/index.php/MatTech/article/view/142 <p>In the present paper I present <em>Near Edge X-ray Absorption Fine Structure, NEXAFS</em> – the experimental technique nowdays being widely used in characterization of unoccupied electronic levels around Fermi level and chemical state of elements in homogeneous or heterogeneous thin layers. First I explain the excitation and relaxation mechanism of core level electrons based on brief quantum-mechanical theoretical background. I continue with basics of molecular orbital theory and corresponding transition selection rules for various combinations of molecular orbitals and polarization direction of X-rays. The usage of experimental technique is demonstrated in the case study of thin PTCDA film on Ge(001) surface, where the energy alignment of unoccupied molecular electronic states around Fermy level is determined, as well as the spatial orientation of PTCDA molecules with respect to substrate.</p> Gregor Bavdek Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/142 Thu, 30 Sep 2021 00:00:00 +0200 STUDY OF THE SUITABILITY OF VARIOUS TYPES OF CASTING MATERIALS FOR THE MANUFACTURE OF A SHIP ENGINE https://mater-tehnol.si/index.php/MatTech/article/view/278 <p>The objective of this work was to study the suitability of three types of cast iron for the manufacture of a ship engine: EN-GJS-500-7U for the manufacture of the engine block, EN-GJS-400-15U for the cylinder head and EN-GJL-200 for the liner. Tensile tests were carried out to obtain the ultimate tensile strength (UTS) of each material. The results for the UTS were: 460&nbsp;MPa for EN-GJS-500-7U, 390 MPa for EN-GJS-400-15U and 170 MPa for EN-GJL-200. Likewise, Brinell-hardness measurements were carried out and the elements present in the materials were determined with spectrometry. Finally, the size of graphite particles in each sample was determined.</p> Juan José Galán, Nuria Varela-Fernández, Manuel Ángel Graña-López, Almudena Filgueira-Vizoso, Ana García-Diez Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/278 Thu, 30 Sep 2021 00:00:00 +0200 MECHANICAL TESTING OF LAMINATED COMPOSITE MATERIALS FOR PROSTHETIC SOCKETS https://mater-tehnol.si/index.php/MatTech/article/view/279 <p>The mechanical properties of the composite materials for prosthetic sockets are a key determinant of the quality and usability of prostheses. Our aim was to compare the existing materials used in production at our institution with some modified, potentially improved materials. We conducted an industrial experiment. The existing material (A) was compared with three newly produced materials that introduced changes in the lamination process: B1, where an infusion spiral tube was added; B2, where the resin was degassed; and B3, where a mesh and peel ply were used. The specimens underwent laboratory strength testing. The strength measurements were statistically analysed using one-way analysis of covariance (ANCOVA) that was adjusted for specimen thickness because of the observed negative correlation of thickness with strength. Material A had the highest bending strength, on average, but there were no statistically significant differences in the bending strength between the materials after adjusting for the specimen thickness (<em>p </em>= 0.941). Materials B1 and B2 exhibited statistically significantly lower tensile strengths than material A (<em>p </em>&lt; 0.001). Material B3 had the lowest average tensile strength, but it could not be statistically distinguished from the others, because of the significantly larger average specimen thickness. The compressive strength was tested only for materials B1, B2 and B3; their averages did not differ statistically significantly (<em>p </em>= 0.291). Laboratory strength testing provided important insights into the differences between the various laminated composite prosthetics materials. We did not reach our initial goal to produce a better material, but we will continue our research and development in this field with a more systematic, technological approach.</p> Matic Bombek, Uroš Vesenjak, Marko Pisek, Gaj Vidmar, Sašo Knez, Sergej Medved Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/279 Thu, 30 Sep 2021 00:00:00 +0200 SOLVOTHERMAL SYNTHESIS AND CHARACTERIZATION OF POROUS Co MICROSPHERES https://mater-tehnol.si/index.php/MatTech/article/view/160 <p>Porous cobalt (Co) microspheres were successfully synthesized via a facile surfactant-free solvothermal route. These microspheres have an average diameter of about 2 µm, assembled by many primary Co nanosheets. A possible formation mechanism of porous Co microspheres is discussed. The magnetic hysteresis loop shows a ferromagnetic feature of porous Co microspheres and the saturation magnetization (<em>M</em><sub>s</sub>) and coercivity (<em>H</em><sub>c</sub>) are 115.3 J/T·kg and 6.883 kA/m, respectively.</p> Mingdong Zhong, Jianguo Huang, Jiasheng Yuan, Sheng Rong, Ping Ou, Xin Chen, Bei Zhang, Qiaoling Ke, Zhiyun Zhu Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/160 Thu, 30 Sep 2021 00:00:00 +0200 PREPARATION OF ATO NANOPOWDERS WITH Co-PRECIPITATION AND THEIR LASER-REFLECTION PROPERTIES https://mater-tehnol.si/index.php/MatTech/article/view/280 <p>Antimony tin oxide (ATO) nanoparticles were prepared using co-precipitation with tin chloride and antimony chloride as the main raw materials. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and ultraviolet-visible spectrophotometry were used to characterize the crystal structure, morphology and laser reflectivity. The effects of the pH value, co-precipitation reaction temperature, calcination temperature and calcination time on the laser reflectivity of ATO nanoparticles were studied. The results show that, compared with the undoped SnO<sub>2</sub> powder, the reflectivity of a Sb-doped ATO powder at a laser wavelength of 1.06 µm is significantly reduced, and with an increase in the Sb doping, the reflectivity of the ATO powder at 1.06 µm first decreases and then increases. When the Sb/Sn molar ratio is 2/10, the reflectivity decreases to the lowest point, which is caused by the high concentration of Sb<sup>5+</sup>. ATO powders (Sb/Sn = 2/10) prepared at a titration-end-point pH of 2, co-precipitation temperature of 70 °C, calcination temperature of 800 °C and calcination time of 6 h have the lowest laser reflectivity at the laser wavelength of 1.06 µm, which is less than 0.02 %.</p> Jing Zhang Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/280 Thu, 30 Sep 2021 00:00:00 +0200 EVALUATION OF A HYBRID BIOCOMPOSITE OF HA/HDPE REINFORCED WITH MULTI-WALLED CARBON NANOTUBES (MWCNTs) AS A BONE-SUBSTITUTE MATERIAL https://mater-tehnol.si/index.php/MatTech/article/view/162 <p>In this investigation, multi-wall carbon nanotubes (MWCNT) with various percentages (0.6%, 1%, 1.4%, 2%) were combined into&nbsp;&nbsp; ​and High-density polyethylene HDPE (60) wt. % and hydroxyapatite (40) wt. % to form biocomposite using hot-press techniques. The surface topography by AFM images illustrates differences in the roughness of the sample's surface with different adding percentages of MWCNT. The DSC technique exhibits the effect of adding MWCNT in different percentages with the degree of crystallinity, which its effect on mechanical properties for samples. The in vitro bioactivity was investigated by immersion the samples in Ringer's solution as simulated body fluid (SBF) at (0, 3, 6, 9, 12) days (after immersing). The FE-SEM and EDx image explained the apatite layers formation on the sample's surface after 3 days immersed in Ringer solution. Based on XRD Technique, after immersion days in the Ringer solution, the crystallographic structure of hydroxyapatite is formed, forming the monetite.&nbsp; ​The enhancement of bioactivity has been shown during the incorporation of MWCNT into HA/HDPE composite. These results exhibited excellent indications of biocompatibility properties with the possibility of making promising biomaterials for making bone substitute applications.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;</p> Ali A. Al- Allaq, Jenan S. Kashan , Mohamed T. El-Wakad , Ahmed M. Soliman Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/162 Thu, 30 Sep 2021 00:00:00 +0200 STUDY ON ALTERNATE IMMERSION CORROSION BEHAVIOR AND MECHANISM OF SDCM DIE STEEL FOR HOT STAMPING https://mater-tehnol.si/index.php/MatTech/article/view/192 <p>In this paper, the alternate immersion corrosion test of Cr-Mo-V series SDCM steel for hot stamping was carried out, and different stresses were loaded with self-made fixture. The results shown that regardless of hardness and stress, the corrosion mode of the material is&nbsp;<a href="https://cn.bing.com/dict/search?q=uniform&amp;FORM=BDVSP6&amp;mkt=zh-cn">uniform</a>&nbsp;corrosion. Stress could significantly increase the corrosion rate, with lower hardness and higher corrosion rate. Because of the existence of Corrosion Removal Layer (CRL), the maximum corrosion pit depth would be reduced. The maximum corrosion pit depth and Corrosion Pit density (CPD, ρv) were used to describe the degree of corrosion damage. From low to high hardness, the CPD ρv and corrosion resistance increased gradually. With the increased of tempering temperature, the hardness decreased, and the percentage of carbide area in the field of view increased from 16.36% to 24.32%. The irregular spherical carbide M23(C, N)6 rich in Cr coarsens and consumes Cr element in the material, which lead to the decrease of corrosion resistance. Through the polarization curve of the dynamic potential, we known that the current density was increased with the hardness decreased, from 28.53 μA/mm2 to 40.93 μA/mm2.</p> Jiang Bin, Zuo Pengpeng, Wu Xiaochun Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/192 Thu, 30 Sep 2021 00:00:00 +0200 EFFECT OF TOOL PIN PROFILES OVER SQUARE WAVE TOOL PATH PATTERN ON FRICTION STIR WELDING OF AA6061-CU DISSIMILAR ALLOYS https://mater-tehnol.si/index.php/MatTech/article/view/202 <p>In this present work friction stir welding of Al6061-annealed pure copper dissimilar metals with square wave pattern tool pin movementwas investigated.&nbsp; The aim of this experiment is to identify the significance square wave tool movement on friction stir welding process along with three different tool pin profiles. Different tool pin profiles of square, round and hexaspiral shapes were selected and their significant outcomes were unveiled. Friction stir welding process parameters of 1500 and 2000rpm &amp; tool pin movement step size of 1.0mm and 2.0mm &amp; weaving rate of 100mm/min and 150mm/min were selected. The advantages of tool movement pattern and tool pin profile shape wereexamined by mechanical testing, microstructure analysis. The mechanical results were showed that process parameter of 1500 rpm, 1.0mm step size, weldingrate of 150mm/min and square tool pin profile combination gives better mechanical properties. Micro structural results unveiled achievement of better grain refinement and uniform dispersion of micro constituents by implementation of square wave tool pin movement pattern along with square tool pin profile.The EDAX report confirms that the weld nugget contains both aluminum and copper as equal percentage, which indicates fine mixing of two parent metals.</p> Loganathan Prabhu, Satish Shanmugam, Thiagarajan Chandrasekaran Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/202 Thu, 30 Sep 2021 00:00:00 +0200 TREATING WASTE SLUDGE FROM WATER-PURIFICATION PLANTS WITH THE GEOPOLYMERIZATION METHOD https://mater-tehnol.si/index.php/MatTech/article/view/281 <p>Treatment of the sludge from water-purification plants is becoming more and more urgent due to the inability to increase its storage area. To avoid CO<sub>2</sub> emissions, the use of non-Portland cement binders is recommended. The application of geopolymerization of waste sludge (WS) from water-purification plants is a novel solution. Curing conditions including high temperature, pressure or microwaves enhance the formation of geopolymer bonds. This paper presents the results of a research on the treatment of the WS of the Thu Duc water-purification plant (Vietnam) with the geopolymerization method. Solid phases were prepared by mixing the WS and fly ash (FA). The FA proportions of the solid phases were (10, 40, 70) <em>w</em>/%. The alkali-activated solution (AAS) was a mixture of a 40 <em>w</em>/% NaOH 6M solution and 60 <em>w</em>/% water glass (WG: Na<sub>2</sub>O.nSiO<sub>2</sub> with n&nbsp;=&nbsp;1.75&nbsp;and volumetric density r&nbsp; = 1.40 kg/L). The geopolymer materials were mixtures containing an 80 <em>w</em>/% solid phase and a 20 <em>w</em>/% liquid phase of the AAS. Geopolymer samples were formed in a cylindrical steel mold with a diameter of 10 mm at a high pressure. The samples were cured in a 112 W microwave oven for 30 s or in a dryer at 110 °C for 24 h. The compressive strength and volumetric density of both sample groups were determined and compared to each other. The formation of geopolymer bonds was investigated using XRD, FTIR and SEM.</p> Do Quang Minh, Thai Tien Dat, Nguyen Hoc Thang, Kieu Do Trung Kien, Pham Trung Kien, Huynh Ngoc Minh, Nguyen Vu Uyen Nhi Copyright (c) https://mater-tehnol.si/index.php/MatTech/article/view/281 Thu, 30 Sep 2021 00:00:00 +0200 THE INFLUENCE OF CHEMICAL COMPOSITION AND HEAT TREATMENT ON THE MECHANICAL PROPERTIES AND WORKABILITY OF THE ALUMINIUM ALLOY EN AW 5454 https://mater-tehnol.si/index.php/MatTech/article/view/155 <p>The influence of chemical composition and heat treatment on the mechanical properties and formability of the selected commercial aluminium alloy EN AW 5454 was investigated. The main properties of alloy 5454 from the AA 5xxx series are very good corrosion resistant and has good formability. From the cast slab a 50 mm thick slice was taken in the width cross section in the slab centre. One half of the slice was homogenised for 10 hours at a temperature of 530 °C. The cast and homogenised samples were investigated using light and scanning electron microscopy. For the study of the influence of the heat treatment, samples in the as-cast state were annealed in the laboratory furnace at a temperature of 530 °C for 4, 6, 8, 10 and 12 hours. To study the influence of chemical composition, four different samples were prepared: the first without additions, the second with an addition of 1 wt% Mn, the third with 3 wt% Mg and the fourth with an addition of both elements, Mn and Mg. The XRF analyses confirmed the desired chemical composition of all four produced alloys. Half of each alloy’s sample was homogenised at the same temperature and time as the base alloy in the as-cast state. The hot deformation behaviour of the different alloys was investigated using cylindrical hot compression tests performed on a Gleeble 1500D thermo-mechanical simulator. By comparing flow curves a high influence of the thermo-mechanical parameters on the alloy formability can be seen. The alloy has good workability and with the addition of Mn and Mg, the stress values are higher than those of the base alloy.</p> <p>&nbsp;</p> Alenka Šalej Lah, Maja Vončina, Irena Paulin, Jožef Medved, Peter Fajfar, Darja Volšak Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/155 Thu, 30 Sep 2021 00:00:00 +0200 WARM DEFORMATION BEHAVIOR OF A 65MN SPRING STEEL https://mater-tehnol.si/index.php/MatTech/article/view/193 <p>The warm deformation behavior of 65Mn spring steel has been carried out by a thermomechanical simulator. The deformation temperatures are in the range of 550 ~ 700℃ and strain rates are in the range of 0.001 ~ 1 s<sup>-1</sup>. The deformation activation energy is calculated to be 486.829 KJ•mol<sup>-1</sup>. The strain compensated Arrhenius-type constitutive model was established. The relationship materials constants and strain were fitted with an 8th order polynomial.&nbsp; It was found that the strain has a significant influence on the instability map. At the strain is 0.3, the optimum flow zone may take place with the deformation temperatures higher than 626 ℃ and strain rate in the range of 0.001 ~ 1 s<sup>-1</sup>.</p> Peng-fei Zhang, De-cheng Wang, Peng Cheng, Chen-xi Shao, Jun-ying Zhou, Ji-hua Huang Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/193 Thu, 30 Sep 2021 00:00:00 +0200 A SULPHIDE CAPACITY PREDICTION MODEL OF BLAST FURNACE SLAG https://mater-tehnol.si/index.php/MatTech/article/view/157 <p>A sulphide capacity prediction model of CaO-SiO<sub>2</sub>-MgO-Al<sub>2</sub>O<sub>3</sub> slags has been developed based on the ion and molecule coexistence theory(IMCT). Sulphide capacity(<em>C</em>s) of slag for blast furnace (BF) with high Al<sub>2</sub>O<sub>3 </sub>in the CaO-SiO<sub>2</sub>-MgO-Al<sub>2</sub>O<sub>3</sub> system at 1773K were measured by applying slag-metal equilibrium method. The feasibility of the developed IMCT model is verified by the sulphide capacity measured in the experiment. Effects of <em>R</em>(<em>w</em>(CaO)/<em>w</em>(SiO<sub>2</sub>)), <em>w</em>(MgO)/<em>w</em>(Al<sub>2</sub>O<sub>3</sub>) and <em>w</em>(Al<sub>2</sub>O<sub>3</sub>) on sulphide capacity were discussed. There is a good linear relationship between the experimental value and the predicted value. Therefore, the theoretical model of ion and molecule coexistence can be used to calculate the sulphide capacity of CaO-SiO<sub>2</sub>-MgO-Al<sub>2</sub>O<sub>3 </sub>quaternary slag system. When <em>w</em>(Al<sub>2</sub>O<sub>3</sub>)=20% and <em>w</em>(MgO)/<em>w</em>(Al<sub>2</sub>O<sub>3</sub>)=0.5, the sulphide capacity of slag increased with the increase of <em>R</em>. When <em>w</em>(Al<sub>2</sub>O<sub>3</sub>)=20% and <em>R</em>=1.30, the sulphide capacity of slag increased with the increase of <em>w</em>(MgO)/<em>w</em>(Al<sub>2</sub>O<sub>3</sub>). When <em>R</em>=1.30 and <em>w</em>(MgO)/<em>w</em>(Al<sub>2</sub>O<sub>3</sub>)=0.4, the sulphide capacity of slag decreased with the increase of <em>w</em>(Al<sub>2</sub>O<sub>3</sub>).</p> Yongchun Guo, Shen Fengman, Haiyan Zheng, Shuo Wang, Xin Jiang, Qiangjian Gao Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/157 Thu, 30 Sep 2021 00:00:00 +0200 HIGH-TEMPERATURE OXIDATION BEHAVIOR OF AN N5 NANOCRYSTALLINE COATING DEPOSITED BY ESD ON A NI-BASED SINGLE-CRYSTAL SUPERALLOY https://mater-tehnol.si/index.php/MatTech/article/view/171 <p>An N5 nanocrystalline coating was prepared on a Ni-based single-crystal superalloy by electrospark deposition. The morphologies, chemical composition, and phase constitution of the coating were analyzed by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD), respectively. The high-temperature oxidation resistance of the substrate and coating at 1100℃ was tested in a static isothermal oxidation experiment. The results show that the electrospark deposition coating with columnar crystal structure is composed of nanocrystalline; there is no elemental interdiffusion between the substrate and the coating, which effectively avoids decreasing the mechanical properties of the substrate alloy due to the interdiffusion. Migration and aggregation of a reactive element, Ta, in the nanocrystalline coating substantially improves oxide film adhesion</p> Rongyan Wang, Quan Liu, Meng Wang, Xudong Lu, Cean Guo, Jian Zhang Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/171 Thu, 30 Sep 2021 00:00:00 +0200 EXPERIMENTAL STUDY ON THE DYNAMIC SHEAR MODULUS AND DAMPING RATIO OF SATURATED SAND UNDER CYCLIC LOADING https://mater-tehnol.si/index.php/MatTech/article/view/230 <p>Initial shear stress is inevitable in actual engineering slopes, subgrades and foundations, and soils exhibit different dynamic characteristics under the influence of initial shear stress. Using a dynamic triaxial test system, this study explores the dynamic shear modulus and damping ratio of saturated sand from Wenchuan, investigates the effects of the initial shear stress and vibration frequencies on the dynamic shear modulus and damping ratio of saturated sand and proposes a normalised dynamic shear modulus formula that considers the initial shear stress and vibration frequency. Results show a threshold dynamic shear strain of the saturated sand. When the dynamic shear strain is below this threshold, the dynamic shear modulus significantly increases with the initial shear stress and vibration frequency. Otherwise, the influence of the initial shear stress and vibration frequency gradually decreases and eventually stabilises. The initial shear stress significantly affects the normalised dynamic shear modulus/strain curves where a larger initial shear stress corresponds to a higher curve. Meanwhile, the vibration frequency only exerts a slight influence. The curves under different frequencies are generally within the same band and fall near the Seed upper envelope. The initial shear stress also has a significant influence on the damping ratio where a larger initial shear stress corresponds to a smaller damping ratio. On the basis of the experimental results, a normalised dynamic shear modulus/shear strain formula that considers the influence of the initial shear stress and vibration frequency is established. Fitting results indicate that this formula shows good agreement with the test data.</p> Jian Zhang, Jiuting Cao, Sijie Huang, Baocun Shi Copyright (c) 2021 Materials and Technology https://mater-tehnol.si/index.php/MatTech/article/view/230 Thu, 30 Sep 2021 00:00:00 +0200