Browsing by Publisher "CSIC Consejo Superior de Investigaciones Cientificas"
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Item The mechanical and tribological characteristic of Aluminium-Titanium dioxide composites(CSIC Consejo Superior de Investigaciones Cientificas, 2018) Gezici L.U.; Gül B.; Çavdar U.The purpose of this work was to investigate the mechanical and tribological effects of Titanium dioxide (TiO2) reinforcement in Aluminium (Al). Aluminium composites consist of 99.8% pure aluminium reinforced with five different partions of TiO2. Aluminium powders were mixed with TiO2 by ball milling for 30 minutes in a planetary mixer. The powder mixture was compacted by the cold pressing technique at 250 MPa. Two different methods used for sintering. The green compact was sintered at 600 °C for 300 seconds in open atmosphere with an Ulta-High Frequency Induction System (UHFIS) and with furnace at 600 °C for 1800 seconds. The mechanical and microstructural properties of examples were compared for different amount of reinforcement. We have observed a maximum hardness for 5 wt.% TiO2 reinforced composites. © 2018 CSIC.Item An investigation into the wear behavior of aged Alumix321/SiC composites fabricated by hot pressing(CSIC Consejo Superior de Investigaciones Cientificas, 2019) Durmuş H.; Gül C.; Çömez N.; Yurddaşkal M.Aerospace or automobile industries need materials that have a combination of several features such as lightness, high strength, corrosion and wear resistance. With ceramic particulates reinforcement, the properties of aluminum alloys can be greatly improved. The aim of this study is to investigate the effect of precipitation age hardening and the mass percentage of SiC particles on hardness and wear resistance of the 6061 aluminum matrix composites produced by hot pressing. Composites were solution treated at 530 °C for 1.5 h and then artificially aged at 160 °C for 18 h. The ball-on-disc wear test was carried out under 2N load using an alumina ball as the counterpart. The density of the composites was calculated according to Archimedes principle. Porosity tended to increase with increasing SiC reinforcement. Hardness and wear resistance of composites were improved by SiC particles and aging. Maximum hardness and minimum wear loss was obtained heat treated sample that contains 20 wt.% SiC reinforcement. © 2019 CSIC. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License.Item Analysis of artificial aging with induction and energy costs of 6082 Al and 7075 Al materials(CSIC Consejo Superior de Investigaciones Cientificas, 2019) Taştan M.; Gökozan H.; Çavdar P.S.; Soy G.; Çavdar U.In the study, 6082 Al and 7075 Al samples were subjected to a solution taking place at 580 °C for 1 min using ultrahigh frequency induction heating system (UHFIHS) and water was supplied at the end of the process. Artificially aging was then carried out at 190 °C for 2, 4, 6 and 8 min. In both applications, heating was carried out using an induction system with a frequency of 900 kHz and a power of 2.8 kW. For these aluminum series and shapes, induction heating and heat treatment costs in different shapes are calculated. In addition, the hardness values obtained from artificially aged 6082 Al and 7075 Al samples at 190 °C for 10 h were compared with conventional methods after 5 h at 540 °C for 5 h. As a result, the hardness values of 6082 Al samples, which were obtained in 10 h by conventional methods, were obtained by artificial aging for only 8 min using induction system. © 2019 CSIC.Item Microstructural properties and tribological behaviours of ultra-high frequency induction rapid sintered Al-WC composites; [Propiedades microestructurales y comportamiento tribológico de composites Al-WC sinterizados mediante inducción rápida a ultra alta frecuencia](CSIC Consejo Superior de Investigaciones Cientificas, 2020) Çavdar U.; Gezici L.U.; Gül B.; Ayvaz M.In this study, sinterability of 1, 3, 5, 9 and 15 wt.% WC reinforced aluminum matrix composite samples by induction fast and conventional sintering methods was investigated. For this purpose, firstly, it was pressed by unaxial cold pressing method under 200 MPa pressure. Some of these raw samples were sintered by ultra-high frequency induction fast sintering method at 600 °C temperature for 300 sec., while the other part of the samples were sintered by 600 °C for 1800 sec. The density and hardness values of sintered composite samples were measured and microstructural properties, abrasion and friction behaviours were investigated. In this study, it was seen that increased WC reinforcement ratio and abrasion resistance and friction coefficient increased together. In addition, this study showed that ultra-high frequency sintering is as successful as traditional method in Al-WC composite production. Copyright: © 2020 CSIC.Item Surface characterization of EPD coating on AZ91 Mg alloy produced by powder metallurgy(CSIC Consejo Superior de Investigaciones Cientificas, 2020) Aydin I.; Bahçepinar A.I.; Gül C.Intense implants which are used widely in biomedical applications such as Ti and its alloys and 316 L stainless steel can harm the surrounding tissues, hence may also cause infection. In order to eliminate this risk, it is necessary to produce new generation implant materials that are lighter than their existing biomaterials for use in biomedical applications and whose mechanical properties and structure are close to bone. In this study AZ91 Mg alloy implant material is created by using powder metallurgy method. In addition, in order to improve the bio-compatibility and bio-activity, the generated implant material was also coated with hydroxyapatite (HA) which is known as a ceramic based biomaterial. In this study, AZ91 Mg alloy is created by using powder metal-lurgy method. HA coating was applied to the alloy surface using the electrophoretic deposition method. The surface properties and corrosion resistance of the coatings made were examined. The applied voltage values in the coating process were determined as 100, 150, 200 and 250 V, the time parameter was stabilized as 2 minutes. HA, ethanol, polyvinyl alcohol (PVA), N, N-Dimethylformamide chemicals were used to prepare the coating solution. At the end of the study, microstructures of the coatings were examined by using scanning electron microscopy (SEM) and elemental analyzes (EDS) of the coating surfaces were performed. The X-ray diffrac-tion method (XRD) was used to determine the phases of the coatings and its concentration. Coating thickness and surface roughness values were also determined. Corrosion behavior of coated samples was determined by potentiodynamic electrochemical potential corrosion test in artificial body fluid. © 2020 CSIC.Item Wear behavior and corrosion properties of Age-hardened AA2010 aluminum alloy(CSIC Consejo Superior de Investigaciones Cientificas, 2021) Çömez N.This study aims to investigate the wear and corrosion resistance after heat treatment of AA2010 alloy. AA2010 alloy was solutionized at 500 °C for 1 h, and then quenched in water at room temperature. Solu-tion treatment was followed by aging treatment at 160 °C for 16, 18, and 22 h. Peak hardness was achieved at 18 h. Ball-on-disc wear test caused cold deformation and hence increased the hardness of the worn surface lo-cally. The corrosion rate of heat treated AA2010 alloy was determined according to Tafel extrapolation meth-od. Corrosion test was carried out in 3.5 wt.% NaCl solution at room temperature. The minimum corrosion rate was obtained in 18 h aged AA2010 alloy. For moderate wear resistance and good corrosion resistance, 18 h aging is recommended for AA2010 alloy. Both the intergranular and pitting corrosion mechanisms were observed on the corroded surface of the AA2010 alloy. © 2021 CSIC Consejo Superior de Investigaciones Cientificas. All rights reserved.Item The effect of welding on reliability of mechanical properties of AISI 1020 and AISI 6150 steel materials(CSIC Consejo Superior de Investigaciones Cientificas, 2021) Civi C.; Iren E.Welding is one of the most important manufacturing and repair method of today s technology. Though it is known that it can reduced the mechanical properties of materials, it is a necessity in many areas and in some cases, it is preferred because of the efficient and fast manufacturing. The widespread use of welding has raised the problem of reliability of welded structure. It is important to carry on reliability analysis especially on critical welded constructions or some critical materials. In this study, two steel material (AISI 1020 and AISI 6150) which different weldability levels were selected. Gas metal arc welding (GMAW), Gas Tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) were chosen as widespread industrial welding techniques. Welded and non-welded mechanical properties of these materials were examined taking into consideration the reliability, and effect of welding and welding methods were investigated. Reliability analyzes revealed that non-predictable mechanical properties and microstructures are main characteristic of welding process especially in some materials or methods. © 2021 CSIC Consejo Superior de Investigaciones Cientificas. All rights reserved.Item Investigation of metallurgical properties of Al-Si-Mg casting alloys with integrated computational materials engineering for wheel production; [Investigación de las propiedades metalúrgicas de las aleaciones coladas Al-Si-Mg para la producción de llantas utilizando ingeniería de materiales computacional integrada](CSIC Consejo Superior de Investigaciones Cientificas, 2023) Yağcı T.; Cöcen Ü.; Çulha O.; Armakan E.In this study, integrated computational materials engineering, which is one of the new generation approaches in materials science, was used in the production of aluminum alloy wheels by low pressure die casting method. In casting alloys, the efficiency of grain refinement provided by master alloys added to the melt decreases with increasing silicon content of the alloy. In this context, as-cast properties of silicon reduced (Si: 5.0 wt.%) alloys with different Mg ratios (Mg: 3.0, 5.0, 7.0 wt.%) are discussed using integrated computational materials engineering approaches. It has been evaluated whether the examined alloys can be an alternative to the AlSi7Mg0.3 alloy, which is currently used traditionally in the production of aluminum-based wheels, with their microstructural and mechanical properties. The study consists of three stages which are computer-aided production, pilot production, testing and characterization studies. In computer-aided production, original sub-eutectic compositions were determined in types and amounts of alloying elements, alloy designs were realized and a database was created with a computational materials engineering software. Then, low pressure die casting analysis were performed in a virtual environment by transferring these data directly to the casting simulation software. Thus, the microstructural and mechanical properties of the wheel were obtained computationally on the basis of the varying alloy composition. In the second stage, the virtually designed alloy compositions were prepared and sample wheels were manufactured by the low pressure die casting method on an industrial scale. In the testing and characterization phase, spectral analyses, macro and microstructural examinations, hardness measurements and tensile tests were carried out. As a result of this study, it was determined that the studied alloys could be used in the production of wheels by the low pressure die casting method considering the metallurgical properties expected from the wheel. In addition, it is thought that the mathematical design of the material with integrated computational materials engineering approaches before casting simulations will play an active role in the competitiveness and sustainability of the aluminum industry in technological conditions. © 2023 CSIC.Item Failure analysis of copper pipes used in the heat exchangers in fan coil units(CSIC Consejo Superior de Investigaciones Cientificas, 2023) Sargın F.; Kanbur K.; Türkmen İ.Heat exchangers (HE) consist of copper and steel pipes and are used for heating and cooling the ambient air. One of the main problems seen in HE is the leakage on copper pipes. In this study, failed and properly working copper pipe samples used for different durations were examined in detail. The microstructural analyses were performed using optical microscopy (OM) and scanning electron microscopy (SEM) to detect corrosion occurrences on copper pipe surfaces. In addition, corrosion products of the samples were defined by X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Fourier-Transform Infrared Spectroscopy (FTIR) analyses. The formation of interconnected tunnels in cross section of the failed copper pipe sample that were in microscopic dimensions and corrosion products were observed. Consequently, all the analyses result that were obtained from the samples pointed out a corrosion mechanism known as ant-nest corrosion. It was concluded that the main reason of corrosion was related to ethylene glycol type additives which were used in HE along with mains water. © 2023 CSIC.