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Öğe Corrosion and Wear Behaviour of Boronized high Carbon and Chromium Cast Steel(Iron Steel Inst Japan Keidanren Kaikan, 2013) Ahlatci, Hayrettin; Yargul, Gorkem; Cug, Harun; Cevik, Engin; Yasin, Suleyman; Sun, YavuzThe purpose of this study was to examine the effect of boronising heat treatment on the corrosion behaviour (in two different corrosive media) and wear properties (on two different counter sliding discs) of the DIN 1.4777 quality cast steel containing 1.7% C, 30% Cr and 1.1% Si. The steel supplied as cast was exposed to homogenisation heat treatment at 1150 degrees C for 3,5 hours and then to boronising heat treatment at 900 degrees C for 8 hours using the powder of Ekabor 2. An optical light microscope, SEM and XRD analyses were used to conduct microstructural characterisation of the steel investigated. Electrochemical potentio-dynamic polarisation measurements were taken to evaluate corrosion behaviours of the examined steels. Wear tests were conducted in a pin-on-disc type wear device by using a load between 10 N and 60 N. While the corrosion resistance of the boronising heat treated steel deteriorated by the pitting damage mechanism within corrosive media, uniform corrosion damage enhanced the corrosion resistance of the examined boronised steel. Oxidative adhesion, cracking of oxide and/or boride layer, and severe plastic deformation mechanisms were dominant during the wear tests. Severe plastic deformation and cracking of the oxide and/or boride layer caused wear mechanism to transform from mild to severe.Öğe Dry Sliding Wear Behavior of (GNPs + TiB2)-Reinforced AZ91 Magnesium Matrix Hybrid Composites Produced by Pressure Infiltration Casting Method(Springer Int Publ Ag, 2021) Cevik, Engin; Gundogan, MuratIn this study, TiB2- and graphene-reinforced Mg matrix (AZ91) composites were produced by the pressure infiltration method. The production process was carried out at 750 degrees C and 8 bar pressure in the SF6 gas atmosphere. The hardness, compression, and wear behaviors of the composite materials were examined. In addition, SEM examinations were conducted to understand the wear mechanisms of produced samples. The porosity ratio increased with the increasing graphene ratio. At the end of the measurements, the highest compressive strength was measured as 415 MPa and 140.6 HB in composite containing 0.25 vol% graphene compared to pure matrix and composite containing only TiB2. The highest abrasion resistance was achieved with the addition of 0.25 vol% graphene.Öğe Evaluation of thermal conductivity of GNPs-doped B4C/Al-Si composites in terms of interface interaction and electron mobility(Elsevier Science Sa, 2019) Polat, Safa; Sun, Yavuz; Cevik, Engin; Colijn, HendrikThe examination of the interactions between graphene and other components commonly used in thermal applications is an important approach for the development of materials with high thermal conductivity. For this purpose, graphene-doped boron carbide reinforced Al Si matrix composites were produced using semi-powder and pressure infiltration methods together. These composites were then characterized by SEM, TEM and XRD analysis. Thermal conductivity coefficients of these composites were determined experimentally by Laser Flash method. In order to examine the effect of phonon transfer on the experimental data, the interacting components were simulated, and the interfacial thermal conductivity was calculated with the acoustic mismatch model. Then, theoretical thermal conductivity of composites was calculated by Hasselman-Johnson model and Maxwell's approach. The electrical conductivity of the composites was measured by four-point probe method for electron mobility. As a result, experimental results were found to be slightly lower than the theoretical ones. This was affected by several different factors but the most important one is thought to be related to porosity.Öğe Improvement of coke strength after reaction value (CSR) by spraying boron solutions on metallurgical coke(Pamukkale Univ, 2024) Esin, Fatih; Acur, Onur; Isci, Berkman; Canturk, Caner; Besun, Cansu; Cevik, EnginIn the Coke Plant of KARDEMIR, coking coal is charged to the furnaces, the hot coke is obtained after 18-21 hours of coking is discharged to the quenching wagon via the guide car with the help of the pusher machine. The hot coke is quenched by water spraying in the quenching towers and is poured into the coke ramp. The metallurgical coke is sized in the Coke Crushing and Screening Plant and sent to the blast furnaces. In the blast furnace process, the use of metallurgical coke with high CSR values obtained from high quality coking coals is preferred. In the blast furnace process, it is preferred to use metallurgical coke with CSR values in the range of 60-70% obtained from high quality coking coals. However, the reserves of high quality coal beds are decreasing day by day. In this study, it is aimed to increase the CSR value of metallurgical coke by spraying various concentrations of boron solutions in order to obtain the same efficiency from low quality coals. In this way, low quality coals in the coal blend in metallurgical coke production will be used at higher rates and raw material costs will be reduced. Solutions prepared with three different boron products and various concentrations were applied to the hot coke obtained at 1050 +/- 50 degrees C in coke ovens, and its effects on the alteration of coke strength after reaction (CSR) values were investigated. When the coke reactivity test results of the applications were examined, it was observed that there was a 20-48% improvement in the CSR value of the coke samples with boron solution compared to the coke samples quenched by spraying water. A 46.29% increase in CSR value and a 34.92% decrease in CRI value of the hot coke sample, which was quenched with 7 g/l concentration Disodium Octaborate Tetrahydrate solution giving the optimum value, was determined.Öğe Influence of GNPs and B4C reinforcements on mechanical, thermal and wear properties of magnesium matrix composite produced by powder metallurgy(Sage Publications Ltd, 2021) Sun, Yavuz; Cevik, Engin; Turen, Yunus; Ahlatci, Hayrettin; Turan, Muhammet Emre; Aydin, Fatih; Zengin, HuseyinIn this study, graphene nanoplatelets (GNPs) and boron carbide (B4C) nano reinforcements were incorporated to the pure magnesium (Mg). Powder metallurgy route was used to fabricate composite samples. Microstructures of specimens were examined and tensile, hardness, wear tests were performed to determine the mechanical and tribological performance of produced samples. The results indicate that the hardness was increased especially with the addition of 2% B4C and 0.5% GNPs reinforcements. A general trend was observed for the enhancements of yield and tensile strengths when nano reinforcements were added to the pure magnesium. The composite samples showed better wear resistance than the unreinforced sample. However, thermal conductivity began to decrease with the addition of B4C reinforcements. It is also observed that the porosity level was also higher for the composite samples.Öğe Investigation of wear and corrosion behavior of graphene nanoplatelet-coated B4C reinforced Al-Si matrix semi-ceramic hybrid composites(Sage Publications Ltd, 2019) Polat, Safa; Sun, Yavuz; Cevik, Engin; Colijn, Hendrik; Turan, M. EmreThe present study aims to produce graphene nanoplatelet-coated B4C ceramic particle using semi-powder method and to investigate the effect of graphene nanoplatelets on wear and corrosion performance of Al-Si-based metal matrix hybrid composites. For this purpose, first graphene nanoplatelets at different ratios (0.25, 0.5, and 1 vol.%) were coated to the surfaces of B4C particles and then the Al-Si alloy was infiltrated into the reinforcements by gas pressure infiltration method. The characterization of graphene nanoplatelet-coated B4C powders and its composites was carried out by X-ray diffraction, differential scanning calorimetry, scanning electron microscope, and transmission electron microscope analysis. Tribological properties were investigated by reciprocating ball-on-flat method under three different loads (10-20-40 N) in a dry environment. The corrosion resistance was carried out with Tafel polarization method in 3.5% NaCl solution. Characterization results show that graphene coated on the B4C surface was successfully achieved by semi-powder method. After infiltration process, a new phase formation was not observed, but porosity increased with the increase of graphene content. When the boron carbide surface was coated with 0.5vol.% graphene, it was determined that the specific wear resistance increased by 55% and the corrosion resistance decreased by 12%.Öğe An investigation on dry sliding wear behaviour of pressure infiltrated AA1050-XMg/B4C composites(Walter De Gruyter Gmbh, 2018) Cevik, Engin; Sun, Yavuz; Turen, Yunus; Ahlatci, HayrettinIn this study, the effect of Mg alloying addition (1-4 wt.%) on dry sliding wear behaviour of AA1050 matrix composites was investigated. Composites were produced by the pressure infiltration technique at 800 degrees C and had a B4C particle volume fraction of 60%. Reinforcement particles were uniformly distributed in the aluminium matrix. Compared with the AA1050 matrix, the weight loss of the composites decreased with increasing Mg content. The wear rate of the composites increased when the applied load and sliding distance were increased. The results show that when the applied load reaches critical values (30 N), the weight loss increases significantly.Öğe MECHANICAL AND WEAR PROPERTIES OF HIGH RATE NIAL PARTICLE-REINFORCED AL COMPOSITES PRODUCED BY PRESSURE INFILTRATION METHOD(Springer Int Publ Ag, 2021) Demirtas, Huseyin; Yildiz, Ramazan; Cevik, EnginIn this study, Al matrix composites reinforced by the high amount of NiAl (40%) were produced by the pressure infiltration method. Commercially AA1050 (99.59 %) was used as matrix material and NiAl (at. 1:1) particles were used as reinforcement. Also, a small amount of Mo (wt. 2%) was added into NiAl for a better matrix-particle interface and to increase the mechanical properties. The proportion of particles was kept constant, and their sizes were changed from 45 to 125 mu m. The microstructures were examined by SEM, and formed phases were determined by EDS and XRD analysis. Mechanical properties and wear behavior were determined by compression, hardness, and abrasion tests. As a result of these tests, it was determined that composites were produced successfully. It was determined that compressive strength increased with decreasing particle size. And also, small particle size composites showed higher wear resistance.Öğe Microstructure and synergistic reinforcing activity of GNPs-B4C dual-micro and nano supplements in Al-Si matrix composites(Elsevier Science Sa, 2019) Polat, Safa; Sun, Yavuz; Cevik, Engin; Colijn, HendrikThe aim of this study is to investigate the mechanical effect of graphene nanoparticles and boron carbide microparticles together on Al-17Si alloy. For this purpose, graphene nanoparticles were firstly attached to boron carbide surfaces by semi-powder method. The Al-17Si alloy was then infiltrated into these particles. Systematic characterization of produced composites, microstructure investigations, strengthening mechanisms were investigated respectively. The composites were systematically characterized by XRD, DSC, SEM and TEM. Their mechanical strength was determined experimentally by compression test. In addition, the contribution of these reinforcements to strength by using some models has been calculated theoretically and the results have been associated with the microstructure. According to these results, the yield strength of pure matrix was increased from 185 MPa to 547 MPa by increasing 195% with the reinforcement of 0.5 vol% GNPs thorn B4C at most. This result is also the case where the theoretical and experimental are the most compatible. In this case, it is thought that load transfer mechanism and dislocations make the most positive contribution while porosity makes the most negative effect. (C) 2019 Elsevier B.V. All rights reserved.Öğe Reference material development process for tensile test method(Pamukkale Univ, 2022) Incesu, Alper; Ercan, Betul; Cevik, Engin; Akgul, YasinReference materials (RMs) are one of the basic materials used by the laboratories to prove the reliability of their test results. In this research, preliminary studies have been carried out to develop RM to use in tensile tests according to ISO 6892-1. For this purpose, bone shape flat specimens were prepared from EN 10130:2006 quality 1 mm thick sheet steel related to the given standard. Homogeneity tests and inter-laboratory comparison tests were performed for calculation of measurement uncertainty and value assignment of proposed RM. Results were compared with commercial certified reference materials (CRMs). It was found that relative uncertainty values of the proposed RM were coherent with commercial CRMs. Therefore, these produced RM can be used in quality control studies for laboratories, also by the production route proposed in this study, every laboratory can be produced RM related to their needs.Öğe Wear Behavior of TiB2/GNPs and B4C/GNPs Reinforced AA6061 Matrix Composites(Asme, 2021) Polat, Safa; Sun, Yavuz; Cevik, EnginIn this study, it was aimed to investigate the effects of reinforcements used for improving the thermal properties of AA6061 alloy on wear resistance. For this purpose, AA6061 matrix composites were produced by pressure infiltration method using ceramic microparticles (TiB2 and B4C) and graphene nanoparticles (GNPs). The produced composites were first characterized by porosity measurement, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis. Then, the wear behavior was examined under three different loads (20-40-60 N) with the reciprocating ball on the flat method in a dry environment. Specific wear-rates were calculated according to the Archard principle by measuring the depth and width of the traces after tests with a profilometer. Wearing mechanisms were determined with the help of optical and microstructure images. According to the obtained results, it was found that B4C + GNPs reinforced samples were more resistant to abrasion at low loads, but TiB2 + GNPs reinforced samples were higher at higher loads.
