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Öğe The analysis of high school students' perceptions towards environment concept(Academic Journals, 2010) Kaya, Hueseyin; Coskun, Muecahit; Aydin, FatihThis research was carried out to put forward high school students' metaphors towards environment concept. The study group of the research consisted of 136 students that attend Prof. Dr. Mumtaz Turhan Social Sciences High School in Istanbul Turkey in the second term of 2009/2010 academic year. The data of the research were gathered by completing Environment is like. because. statement. The analysis and interpretation of the data were done using the phenomenological science design and content analysis technique of qualitative research method. According to the findings of the research, high school students produced 60 valid metaphors towards environment concept. The metaphors mentioned were classified into seven conceptual categories (environment as the expression of pollution, beauty, life, space, importance, reflection and variation) in terms of their common features. The research results indicate that students produced more metaphors that emphasize the importance of environment followed by the metaphors that express reflection, space and beauty. In the suggestions section, it was emphasized that teachers should teach the concepts via metaphors and such applications should be carried out to different student groups, teachers, teacher candidates and parents.Öğe The Depiction of Africa in Turkish Geography Textbooks of Turkey During the Period of Transition from Empire to Republic(Kamla-Raj Enterprises, 2015) Sagdic, Mustafa; Aydin, FatihThe aim of this study is to present Africa's perception in the establishment years of Turkish republic through geography textbooks. Geography textbooks written for secondary education institutions were examined by means of a document analysis, which is one of the techniques for qualitative research designs. Collected data was examined through descriptive statistical techniques. As a result, the findings were interpreted by considering the relevant literature, and some suggestions related with stakeholders were presented. Being acknowledged by the opinions that the perception of Africa was based on during the foundation of the Republic of Turkey will contribute to both, revising textbooks and to geography education.Öğe Determination of Knowledge Level of High School Students on Global Warming Subject(Mehmet Tekerek, 2014) Aydin, FatihThe purpose of this study is to determine the high school students' level of knowledge about global warming and their misconceptions. 592 students have joined to the researching in high schools in central province of Karabuk. Survey of the model is applied in this research; the data collection tool as Yalcin (2010) developed by the global warming Information Questionnaire was applied. Besides data analysis, descriptive statistics, t-test and one-way analysis of variance (ANOVA) were used. According to the results of research, despite the high school students' above average levels of information about global warming, there are some issues that have emerged in the missing information. Attending high school students about global warming levels does not show significant gender variable, while the most mind-boggling; class-level and significant difference has been found according to school type variable.Öğe The Effect of Boron Nitride on Tribological Behavior of Mg Matrix Composite at Room and Elevated Temperatures(Asme, 2020) Aydin, Fatih; Turan, M. EmreThe goal of the study is to examine the dry sliding wear behavior of pure Mg and Mg/nanoboron nitride (BN) composite at elevated temperatures. The wear behavior of the samples was evaluated under loads of 5, 10, and 20 N, at sliding speed of 80, 130, and 180 mm s(-1) and at temperatures of 25, 100, and 175 degrees C. The examination of worn surface, counterface, and wear debris was performed. The results showed that nano-BN particles lead to substantial enhancement of wear resistance for both room and elevated temperatures. Mg/0.25 BN has lower coefficient of friction values due to the presence of BN which act as solid lubricant. The wear mechanisms are thermal softening, melting, oxidation, abrasion, and delamination.Öğe The effect of Kar-Demir on Karabuk city population(Elsevier Science Bv, 2011) Aydin, FatihKarabuk city has been a street with a population of 13 houses in 1937 as a village affiliated to Safranbolu. It has grown rapidly after the establishment of Kar-demir and population reached over 100 000 theirby changing into a modern city of middle scale. The population increase is directly related to the employment capacities at Kar-demir, because iron and steel industry form the economical base with no comparison to other sectors. The purpose of this study was to put forward the effects of Kar-demir over the demographic developments of Karabuk City. The data was collected from TUIK and several other institutions and evaluated through descriptive research method. The results showed that this city has always taken immigrants since 1937 when Kar-demir was established followed by big developments. Karabuk was declared as a county in 1953 and as a province in 1995. An examination of the population change in the city center reveals that in 1940 it was 6825, went up to 84137 in 1980 and 105159 in 2007. Demographic developments show a stabilisation in the population because of the same levels in 1990 and 2007. The reason behind this seems to be the crisis which took place in mid 1990's and the decisions about first closing up and then privatization of Kar-demir. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of The 2nd International Geography Symposium-Mediterranean EnvironmentÖğe Effect of solid waste materials on properties of magnesium matrix composites-A systematic review(Keai Publishing Ltd, 2022) Aydin, FatihThe need for light and high specific strength materials in many fields such as automotive and aerospace is increasing day by day. Magnesium (Mg)-based materials have become attractive for many industries thanks to their high specific strength, good vibration damping ability, and recyclability. However, Mg's low strength and wear resistance are important barriers limiting its industrial use. Researchers are developing Mg matrix composites using various reinforcements and expanding the use of Mg-based materials. The conventional reinforcements are Al2O3, SiC, B4C, TiB2, CNT, and GNPs for the production of Mg matrix composites. Researchers have been trying to reduce the cost of Mg matrix composites in recent years by using cheaper and environmentally friendly reinforcements. These reinforcements are solid wastes such as eggshell, fly ash, red mud, and waste glass, and their use in composite systems is becoming more common day by day. This review focuses on the Mg matrix composites reinforced with solid waste particles and the changes in wear, mechanical, corrosion, and thermal properties with the addition of these reinforcements.(c) 2022 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )Öğe The Effect of TiB2 Content on Wear and Mechanical Behavior of AZ91 Magnesium Matrix Composites Produced by Powder Metallurgy(Springer, 2019) Aydin, Fatih; Sun, Yavuz; Turan, M. EmreIn this research, AZ91 magnesium matrix composites reinforced with three weight fractions (10, 20, and 30 wt.%) of TiB2 particulates were fabricated by powder metallurgy using hot pressing technique. The microstructure, density, hardness, wear, and mechanical properties of the specimens were investigated. Microstructure studies showed that fairly uniform distribution of reinforcements was achieved, but partial agglomeration could be clearly seen at 30 wt.% TiB2. X-ray studies exhibited that phases of Mg, Mg17Al12, and TiB2 were found. As compared to AZ91, the hardness and wear resistance considerably increased with increasing reinforcement content. The presence of TiB2 particles improved 0.2% compressive yield strength and ultimate compressive strength (UCS); however, UCS decreased above 20 wt.% TiB2. Wear mechanisms are oxidative and abrasive.Öğe Effects of carbonaceous reinforcements on microstructure and corrosion properties of magnesium matrix composites(Elsevier Science Sa, 2018) Turan, Muhammet Emre; Sun, Yavuz; Aydin, Fatih; Zengin, Huseyin; Turen, Yunus; Ahlatci, HayrettinIn this study carbonaceous (C-based) reinforced AZ91 matrix composites were fabricated with the same weight fraction of 0.50 wt.% via semi powder metallurgy. The hot pressing test machine was used under high purity argon atmosphere. Multi-wall carbon nanotube (MWCNT), Graphene Nanoplatelets (GNPs) and Fullerene (C60) were used as reinforcements. Microstructure, hardness and corrosion performances of fabricated composites were investigated. Results show that hardness of AZ91 alloy was improved with the addition of carbonaceous reinforcements. AZ91/C60 composite exhibited highest hardness performance. However, corrosion performance of AZ91 was affected negatively by the addition of reinforcements. MWCNT exhibited highest corrosion rate among the fabricated samples.Öğe Estimation of wear performance of AZ91 alloy under dry sliding conditions using machine learning methods(Elsevier, 2021) Aydin, Fatih; Durgut, RafetThe wear behavior of AZ91 alloy was investigated by considering different parameters, such as load (10-50 N), sliding speed (160-220 mm/s) and sliding distance (250-1000 m). It was found that wear volume loss increased as load increased for all sliding distances and some sliding speeds. For sliding speed of 220 mm/s and sliding distance of 1000 m, the wear volume losses under loads of 10, 20, 30, 40 and 50 N were calculated to be 15.0, 19.0, 24.3, 33.9 and 37.4 mm(3), respectively. Worn surfaces show that abrasion and oxidation were present at a load of 10 N, which changes into delamination at a load of 50 N. ANOVA results show that the contributions of load, sliding distance and sliding speed were 12.99%, 83.04% and 3.97%, respectively. The artificial neural networks (ANN), support vector regressor (SVR) and random forest (RF) methods were applied for the prediction of wear volume loss of AZ91 alloy. The correlation coefficient (R-2) values of SVR, RF and ANN for the test were 0.9245, 0.9800 and 0.9845, respectively. Thus, the ANN model has promising results for the prediction of wear performance of AZ91 alloy.Öğe Evaluation of Social Sciences High school Students' Sensitivity towards Environment(Marmara Univ, 2011) Aydin, Fatih; Kaya, HuseyinThis research was carried out to determine social sciences high school students' views towards the adequacy of environment education and environment sensitivity behaviours in their institutions. The researh group of the study is 196 students at Prof. Dr. Mumtaz Turhan Social Sciences High School at the second half term in 2010-2011 academic year. Survey model was used in the study and the researh data was gathered with Environment Sensitivity Survey tool. In data analysis, besides descriptive statistics, t-test and one way analysis of variance (ANOVA) was used. In the research it was concluded that social science high school students are sensitive at medium level. A majority of the students stated that they do not take sufficient education on air pollution, water pollution, soil pollution and ecological balance in their educational institutions. Social sciences high school students' views towards environment sensitivity behaviours did not show significant difference according to gender, class levels, parents' education level, parents' vocations and family income level variants.Öğe Evolution of Microstructure, Residual Stress, and Tensile Properties of Mg-Zn-Y-La-Zr Magnesium Alloy Processed by Extrusion(Chinese Acad Sciences, Inst Metal Research, 2019) Zengin, Huseyin; Turen, Yunus; Turan, Muhammet Emre; Aydin, FatihThe microstructure, texture, residual stress, and tensile properties of Mg-6Zn-2Y-1La-0.5Zr (wt%) magnesium alloy were investigated before and after extrusion process, which performed at 300 degrees C and 400 degrees C. The microstructural characterizations indicated that the as-cast alloy was comprised of alpha-Mg, Mg-Zn, Mg-Zn-La, and Mg-Zn-Y phases. During homogenization at 400 degrees C for 24 h, most of the secondary phases exhibited partial dissolution. Extrusion process led to a remarkable grain refinement due to dynamic recrystallization (DRX). The degree of DRX and the DRXed grain size increased with increasing extrusion temperature. The homogenized alloy did not show a preferential crystallographic orientation, whereas the extruded alloys showed strong basal texture. The extrusion process led to a significant improvement on the compressive residual stress and mechanical properties. The alloy extruded at 300 degrees C exhibited the highest basal texture intensity, the compressive residual stress and hardness, and yield and tensile strengths among the studied alloys.Öğe Examining the Skills of Geography Teachers' Technological Pedagogical Content Knowledge(Karabuk Univ, 2017) Dogru, Esengul; Aydin, FatihThe main purpose of this research was to determine the competencies of technological pedagogical content knowledge (TPCK) of geography teachers and to examine whether these competencies differed significantly according to various variables. The study included a total of a total of 42 geography teachers employed in Karabuk city centre and its districts in 20015-2015 education year. The data of the study was gathered though Technological Pedagogical Content Knowledge (TPCK) developed by Pamuk, Ergun, Cakir, Yilmaz ve Ayas (2012). Frequency and percentage values along with Kolmogorov-Smirnov (K-S) test, Mann Whitney U test and Kruskal Wallis H test were used to analyse the data of the current study. The results of the study revealed that the technological pedagogical content knowledge of geography teachers was not enough. Results also demonstrated the level of geography teachers' technological pedagogical content knowledge did not differ significantly according to their skills and knowledge at using technology, seniority, education level and gender. Content Knowledge is one of the subscales of TPCK that geography teachers had the highest level of knowledge. Furthermore, the level of technological content knowledge of geography teachers was higher than that of technological pedagogical knowledge. The results of the study were discussed in line with the related literature and some suggestions were made.Öğe Geography Teacher Candidates' Views about Classroom Management Strategies(Marmara Univ, 2011) Aydin, FatihThe main aim of this study is to determine geography teacher candidates' views regarding classroom management strategies. Within 2009-2010 Academic Year, Spring Term, 161 geography teacher candidates at University of Gazi, Educational Faculty, Geography Education Department joined the study as the research group. The data of the research were gathered item survey developed by Cakmak, Kayabasi and Ercan (2008). In the analysis of the research data t-test and one way variant analysis (ANOVA) were used along with descriptive statistics. According to the results gained in the research it was observed that geography teacher candidates' participate in the class management strategies in general. The most important class management strategies observed by the geography teacher trainees were determined as: taking the students' attention, providing motivation and sustaining attention. In addition, the results showed that there was significant relationship between geography teacher candidates' opinions on classroom management strategies both the gender variable and class level variable.Öğe Gifted students' attitudes towards environment: A case study from Turkey(Academic Journals, 2011) Aydin, Fatih; Coskun, Mucahit; Kaya, Huseyin; Erdonmez, IlkerThe purpose of this research is to examine the attitudes of primary students that study at gifted students' school (BiLSEM). A total of 156 primary school students participated in the research in Ankara BiLSEM schools in 2010-2011 academic year. As data gathering tool Environment Attitude Scale developed by Atasoy (2005) was used in the study in the form of survey model. In data analysis phase, frequency, percentage, arithmetic mean, t test and one way variance analysis (ANOVA) were used. According to the results of the study, gifted students have positive attitudes towards environment. Another result indicated that gifted students' attitudes towards environment showed significant differences according to gender and class level variants.Öğe Improved elevated temperature mechanical properties of graphene-reinforced pure aluminium matrix composites(Taylor & Francis Ltd, 2020) Turan, Muhammet Emre; Aydin, FatihIn this study, graphene nanoplatelets (0.25 and 0.5 wt-%) reinforced aluminium matrix composites were synthesised. Microstructures of composites were investigated by X-ray diffraction, scanning electron microscope and transmission electron microscope. Hardness was measured according to the Vickers test method. Tensile tests were performed at both room (25 degrees C) and elevated temperatures (150 degrees C and 250 degrees C). Results showed that hardness was improved with direct addition of graphene. Microstructure of composites was free of macro defects. Yield and tensile strength behaviours of pure aluminium were increased with the addition of graphene especially at room temperature. Graphene-reinforced samples have higher compressive residual stress. From the outer surface to inner surface, transition from compressive to tensile residual stress was observed for samples.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 Influence of graphene particles on the wear and corrosion performance of MAO produced AZ31 alloy(Taylor & Francis Inc, 2021) Erdil, Meral; Aydin, FatihIn this study, graphene was incorporated into a micro-arc oxidation coating to improve the wear and corrosion resistance of AZ31 alloy. For this purpose, the different concentration of graphene particles was used as 0 g/l, 0.5, 1, and 2 g/l. The wear tests were performed under loads of 2, 4, and 8 N. The composition and morphology of the coatings were investigated by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The coating thickness increased with increasing graphene concentration. To evaluate the corrosion performance of the coatings, potentiodynamic polarization, and electrochemical impedance spectroscopy tests were performed after immersed samples for 0.5, 16, and 32 h. The wear test results show that wear rates significantly decreases with increasing graphene concentration. Corrosion tests showed that polarization resistance increased and corrosion current density decreased for the coatings with the graphene addition compared to substrate material.Öğe The influence of low-cost eggshell on the wear and electrochemical corrosion behaviour of novel pure Mg matrix composites(Elsevier Science Sa, 2022) Demirdal, Suleyman; Aydin, FatihThe need for materials with low density and high specific strength has significantly increased. The most important requirement is to use low-cost waste materials as reinforcement in the production of low-density metal matrix composites. For this purpose, pure magnesium (Mg) matrix composites were manufactured with different content of eggshell (ES) particles (2.5, 5 and 10 wt %) using the powder metallurgy route. The density, hardness, wear, and electrochemical corrosion behaviour of the samples were investigated in this study. The scanning electron microscope was used to reveal the wear and corrosion mechanisms. The results showed that Mg/10 wt% ES composite exhibited the best wear performance. However, the addition of ES particles adversely affected the corrosion properties. At the end of this study, the potential use of waste ES as reinforcement in the Mg matrix composite industry was reported.Öğe Influence of multi-wall carbon nanotube content on dry and corrosive wear performances of pure magnesium(Sage Publications Ltd, 2018) Turan, Muhammet E.; Sun, Yavuz; Aydin, Fatih; Akgul, YasinThe present study aims to investigate the effect of Multi-Wall Carbon Nanotube on dry sliding and corrosive wear performance of pure magnesium. Multi-wall carbon nanotube reinforced composites with different weight fractions (0.25wt.% and 0.5wt.%) were fabricated by semi powder metallurgy. Hardness test was performed for all samples. To evaluate wear performance of the samples, three different loads (10 N, 20 N, and 40 N) were applied at the room temperature in both dry and 3.5wt.% NaCl corrosive environments. Worn surfaces and microstructures of the samples were characterized using Scanning Electron Microscope. Results show that carbon nanotubes embedded in the matrix without any macro-defects. The hardness of pure magnesium was improved with the addition of multi-wall carbon nanotube considerably. 0.5wt.% multi-wall carbon nanotube reinforced composite exhibited best wear performance both in dry and corrosive conditions.Öğe Influence of TiC content on mechanical, wear and corrosion properties of hot-pressed AZ91/TiC composites(Sage Publications Ltd, 2020) Aydin, Fatih; Sun, Yavuz; Turan, M. EmreThis study aims to investigate the mechanical, wear and corrosion performances of TiC reinforced AZ91 matrix composites. AZ91 alloy and AZ91/TiC composites with different weight fractions of 10, 20 and 30 (wt%) were fabricated by powder metallurgy incorporating hot pressing. Microstructure characterization shows that partial agglomeration of particles is present especially in AZ91/30 wt% TiC composite. The addition of TiC led to significant improvement in hardness and wear resistance. Observed wear mechanism is abrasive. As compared with AZ91, compressive yield strength and ultimate compressive strength of the composites were also significantly improved. On the other hand, corrosion rate increased with the addition of TiC particles by virtue of presence of the galvanic reactions.
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