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Microstructure,mechanical properties,and corrosion resistance of an explosively welded Mg-Al composite

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Journal of Magnesium and Alloys 2022年第4期10卷 1086-1095页

作者： Mustafa Acarer Bilge Demir burak dikici Emin Salur Department of Metallurgical and Materials Engineering Technology FacultySelcuk UniversityKonya 42075Turkey Department of Mechanical Engineering Karabuk UniversityKarabuk 78100Turkey Department of Metallurgical and Materials Engineering Atatürk UniversityErzurum 25240Turkey

In this study,an attempt was made to manufacture an AZ31–Al5005 laminated composite by explosive welding.A mixture of ammonium nitrate(90%),fuel oil(5%),and TNT(5%)was used as the explosive.The detonation velocity of the explosive material was approximately 3100 m•s^(−1).The microstructure and mechanical and corrosion properties of the joint were comparatively investigated.Microstructural characterisation of the joint was conducted by optical microscopy(OM),scanning electron microscopy with energy-dispersive spectroscopy(SEM-EDS),high-resolution transmission electron microscopy(HR-TEM),and X-ray diffraction(XRD).The mechanical properties were determined using micro-Vickers hardness,tensile,and Charpy impact tests.In addition,electrochemical tests were conducted on the AZ31–Al5005 laminated composite and the individual components to determine their corrosion resistance.The corrosion behaviours of the structures were determined in a 3.5%NaCl solution at room temperature using potentiodynamic scanning(PDS).The metallurgical structure and mechanical properties of the joints were within the acceptable limits.

关键词： corrosion welded Microstructure

Self-assembly of coumarin molecules on plasma electrolyzed layer for optimizing the electrochemical performance of AZ31 Mg alloy

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Journal of Magnesium and Alloys 2023年第5期11卷 1618-1628页

作者： Mosab Kaseem burak dikici Ali Dafali Arash Fattah-alhosseini Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Department of Metallurgical and Materials Engineering Ataturk UniversityErzurum 25240Turkey Faculty of Sciences Oujda Department of ChemistryMohamed the First UniversityOujdaMorocco Department of Materials Engineering Bu-Ali Sina UniversityHamedan 65178-38695Iran

A novel inorganic-organic layer with outstanding corrosion resistance in a 3.5wt.% NaCl solution was fabricated by taking advantage of the unique interactions between coumarin (COM) molecules and the porous layer formed on Mg alloy. To achieve this aim, the AZ31 Mg alloy coated via microarc oxidation (MAO) coating was placed in an ethanolic solution of COM for 6 and 12 h at 25 ℃. By reducing the surface area exposed to the corrosive species, the donor-acceptor complexes produced by the particular interactions between the COM and MAO surface would successfully prevent the corrosion of Mg alloy substrate. The MAO layer would provide the ideal sites for the charge-transfer-induced physical and chemical locking, leading to uneven organic layer nucleation and crystal growth with a thatch-like structure. To evaluate the formation mechanism of such hybrid composites and highlight the key bonding modes between the COM and MAO, theoretical simulations were conducted.

关键词： Mg alloy Hybrid coating Coumarin Porous layer Corrosion DFT

A novel dual-functional layer exhibiting exceptional protection and photocatalytic activity by organic functionalization of plasma electrolyzed layer

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Journal of Magnesium and Alloys 2023年第4期11卷 1247-1263页

作者： Mosab Kaseem Tehseen Zehra burak dikici Ali Dafali Arash Fattah-alhosseini Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Department of Metallurgical and Materials Engineering Ataturk UniversityErzurum 25240Turkey Department of Chemistry Faculty of Sciences OujdaMohamed the First UniversityOujdaMorocco Department of Materials Engineering Bu-Ali Sina UniversityHamedan 65178-38695Iran

The formation of inorganic-organic hybrids(IOH)on the metallic substrates would play a decisive role in improving their structural and functional features.In this work,the growth of organic coating(OC)consisting of coumarin-3-carboxylic acid(3-CCA)and albumin(ALB)on the inorganic layer(IC),produced by plasma electrolysis of AZ31 Mg alloy,led to enabling organically synergistic reactions on the porous inorganic surface,forming a flake-like structure sealing the structural defects of IC.Synergistic actions between OC and IC endow the flake-like structures with chemical protection and photocatalytic performance.Upon contact with a corrosive solution,the IOH layer possesses stable morphologies that delay the corrosive degradation of the whole structure.The electrochemical stability of the sample produced by immersion IC in the organic solution for 10 h(IOH2 sample)was superior to the other samples as it had the lowest corrosion current density(1.69×10^(−10)A·cm^(−2))and the highest top layer resistance(1.2×10^(7)Ω·cm^(2)).Moreover,the IOH layer can photodegrade the organic pollutants in model wastewater,where the highest photocatalytic efficiency of 99.47%was found in the IOH2 sample.Furthermore,computational calculations were performed to assess the relative activity of different parts of the ALB and 3-CCA structures,which provide helpful information into the formation mechanism of the IOH materials.

关键词： Functional layer PE Albumin Coumarin Porous layer Corrosion Photocatalyst

Improving the electrochemical stability of AZ31 Mg alloy in a 3.5wt.%NaCl solution via the surface functionalization of plasma electrolytic oxidation coating

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Journal of Magnesium and Alloys 2022年第5期10卷 1311-1325页

作者： Mosab Kaseem Tehseen Zehra burak dikici Ali Dafali Hae Woong Yang Young Gun Ko Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Department of Metallurgical and Materials Engineering Ataturk UniversityErzurum 25240Turkey Faculty of Sciences Oujda Department of ChemistryMohamed the First UniversityOujdaMorocco Pohang Institute of Metal Industry Advancement Pohang 37666Republic of Korea Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea

The unique interactions between hexadecanoic acid(HA)and albumin(ALB)molecules on the surface of the porous layer of AZ31 Mg alloy were exploited to fabricate a novel hybrid composite film with excellent electrochemical stability in a 3.5 wt.%Na Cl solution.Herein,the inorganic layer(IL)obtained by plasma electrolytic oxidation of AZ31 Mg alloy in an alkaline-phosphate-WO_(3)electrolyte was soaked in an organic solution composed of ALB and HA for 10 and 24 h at 60℃.Although albumin and HA may coexist on the same surface of IL,the higher reactivity of ALB molecules would prevent the formation of a thick layer of HA.The donor-acceptor complexes formed due to the unique interactions between ALB and/or HA and IL surface would reduce the area exposed to the corrosive species which in turn would efficiently protect the substrate from corrosion.The porous structure of the IL would provide preferable sites for the physical and chemical locking triggered by charge-transfer phenomena,leading to the inhomogeneous nucleation and crystal growth of a flowery flakes-like organic layer.DFT calculations were performed to reveal the primary bonding modes between the ALB,HA,and IL and to assess the mechanistic insights into the formation of such novel hybrid composites.

关键词： Hybrid composite Coordination bond Albumin Fatty acid Porous layer Corrosion Theoretical approach

羟基磷灰石与氧化锆体积比对钛基复合支架力学性能和腐蚀性能的影响

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Transactions of Nonferrous Metals Society of China 2022年第3期32卷 882-894页

作者： Mehmet TOPUZ burak dikici Mehmet GAVGALI Yasemin YILMAZER Department of Mechanical Engineering Van YüzüncüYıl UniversityVan 65080Turkey Department of Metallurgical and Materials Engineering Atatürk UniversityErzurum 25240Turkey Department of Mechanical Engineering Necmettin Erbakan UniversityKonya 42090Turkey Department of Molecular Biology and Genetics İstanbul Sabahattin Zaim Universityİstanbul 34303Turkey

通过环保、低成本的混合法制备氧化锆(ZrO2)和羟基磷灰石(HA)增强钛基支架材料,该材料具有较低的弹性模量(E)、足够的物理、电化学和生物学性能。研究羟基磷灰石和氧化锆体积分数的变化对支架力学性能、腐蚀性能和抗菌性能的影响。采用... 详细信息

通过环保、低成本的混合法制备氧化锆(ZrO2)和羟基磷灰石(HA)增强钛基支架材料,该材料具有较低的弹性模量(E)、足够的物理、电化学和生物学性能。研究羟基磷灰石和氧化锆体积分数的变化对支架力学性能、腐蚀性能和抗菌性能的影响。采用扫描电子显微镜结合电子色散光谱和X射线衍射对支架进行表征,通过压缩试验检测材料的力学性能及其详细的断裂机制,用电化学法测试样品在37℃模拟体液中的体外腐蚀敏感性,通过比较大肠杆菌和金黄色葡萄球菌的抑菌面积进行抑菌试验。结果表明,随着HA:ZrO_(2)体积分数比例的增加,支架的力学强度降低,当其比例为6:4时,复合支架的E最低(6.61GPa)。纯钛、HA:ZrO_(2)体积分数比例为3:2和6:4的支架材料,其腐蚀电流密度(J_(corr))分别为21、337和504μA/cm^(2)。体积分数比例为6:4的支架对金黄色葡萄球菌的抑菌能力优于其他支架。

关键词：钛生物复合材料羟基磷灰石氧化锆支架力学性能体外腐蚀

COVID-19 frequency and clinical course in children with asthma

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World Journal of Virology 2023年第5期12卷 272-285页

作者： Muhammet Cihat Ozata Ummugulsum dikici Oner Ozdemir Medical Faculty Sakarya UniversityAdapazari 54100SakaryaTurkiye Department of Pediatric Allergy and Immunology Sakarya UniversityAdapazarı54100SakaryaTürkiye

BACKGROUND The epidemic of severe acute respiratory syndrome coronavirus 2 infection,known as the coronavirus disease 2019(COVID-19),has caused a global health concern.Since its emergence,numerous studies have focused on various clinical manifestations and outcomes in different populations.However,studies are ongoing as the consequences and impact of COVID-19 in children with chronic diseases such as asthma are controversial.AIM To fill this research gap by retrospectively evaluating the course,laboratory,and clinical findings of COVID-19 among 414 asthmatic children followed up from the pediatric allergy outpatient clinic and known to have had COVID-19.METHODS The data of 5510 patients over the age of 5 diagnosed with asthma in our hospital's data were retrospectively scanned with specific parameters using protocol numbers from the hospital filing system.The data included retrospective evaluation of pulmonary function test results before and after COVID-19,routine hematological and biochemical parameters,sensitization states(total IgE,specific IgE,and skin prick test results),and radiological(computed tomography)findings.To inquire about the course and symptoms of COVID-19,asthma patients or their parents were then called and evaluated with a questionnaire.RESULTS As a result of retrospectively scanning the data of 5510 asthma patients over the age of 5,it was determined that 414(7.5%)patients had COVID-19.The mean age of 414 patients was 17.18±4.08(min:6;max:28)years.Two hundred and three of our 414 patients are male,and 211 are female.When their vaccination status was questioned,21.5% were vaccinated.When the symptoms of our 290 patients were questioned,it was stated that 59.0% had fever symptoms.The rate of using regular prophylactic asthma medications was 19%.The rate of using salbutamol in asthma was found to be 22%.The rate of patients using methylprednisolone was 1%.Emergency service admission was 17.2%,and hospitalization was found to be 4.8%.Leukopenia(<4000)was found in 14.1%of patients,and 8.08% of ou

关键词： COVID-19 SARS-CoV-2,Children Asthma Exacerbation Allergy

Comparisons of Structured Surface Floors for Pool Boiling Enhancement at Low Heat Fluxes: Hands-On Learning Setup for Heat Transfer Classroom

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World Journal of Engineering and Technology 2023年第2期11卷 303-318页

作者： Birce dikici Basim Q. A. Al-Sukaini Department of Mechanical Engineering Embry-Riddle Aeronautical University (ERAU) Daytona Beach FL USA Rumaila Operating Organization (ROO) HQ Basra Oil Company (BOC) Rumaila Basra Iraq

Various enhanced surfaces have been proposed over the years to improve boiling heat transfer. This paper introduces an experimental setup designed for boiling demonstration in the graduate-level Heat Transfer course. The pool boiling performance of water under atmospheric pressure of 1.025 bar is investigated by using several structured surfaces at heat fluxes of 28 and 35 kW/m2. Surfaces with holes, rectangular grooves, and mushroom fins are manufactured by an NC-controlled vertical milling machine. The heat flux versus excess temperature graph is plotted by using thermocouple measurements of water and base temperatures of the boiling vessel. The separation, rise, and growth of individual vapor bubbles from the surface during boiling were recorded with a digital camera. The results for the plain surface are compared to the Rohsenow correlation. The enhancement of heat transfer coefficient (h) ranged between 15% - 44.5% for all structured surfaces. The highest heat transfer coefficient enhancement is observed between 41% - 56.5% for holed surface-3 (405 holes) compared to the plain surface. The excess temperature dropped around 29% - 34% for holed surface-3 (405 holes) compared to the plain surface. The heat transfer coefficient increases as the spacing between channels or holes decreases. While the bubbles on holed and mushroomed surfaces were spherical, the bubbles on the flat and grooved surfaces were observed as formless. The suggested economical test design could be appropriate to keep students focused and participating in the classroom.

关键词： Boiling Pool Boiling Heat Transfer Coefficient Enhancement Techniques Engineering Education

Effect of Si on austenite stabilization,martensite morphology,and magnetic properties in Fe-26%Ni-x%Si alloys

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 192-196页

作者： H.Gungunes E.Yasar M.dikici Science and Arts Faculty Department of Physics Hitit University Science and Arts Faculty Department of Physics Kirikkale University

The effect of Si on the austenite stabilization, martensite morphology, and magnetic properties in Fe-26%Ni-x%Si （x=3.5, 5, and 6） alloys have been studied by means of transmission electron microscopy （TEM） and M？ssbauer spectroscopy techniques. TEM observations reveal that the martensite morphology is closely dependent on the Si content. The volume fraction changes of martensite and austenite phases, the hyperfine magnetic field, and isomer shift values have been determined by Mssbauer spectroscopy. The M？ssbauer study reveals that the hyperfine magnetic field, the isomer shift values and the volume fraction of martensite decrease with increasing Si content.

关键词： ferrous alloys martensite morphology magnetic properties transmission electron microscopy （TEM） m6ssbauer spectroscopy

Effects of aging on the microstructure of a Cu-Al-Ni-Mn shape memory alloy

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International Journal of Minerals,Metallurgy and Materials 2011年第4期18卷 430-436页

作者： U.Sari T.Kirindi F.Ozcan M.dikici Department of Elementary Education Elementary Science EducationKirikkale UniversityKirikkale 71450Turkey Department of Computer Education and Instructional Technology Kirikkale UniversityKirikkale 71450Turkey Institute of Sciences Kirikkale UniversityKirikkale 71450Turkey Department of Physics Kirikkale UniversityKirikkale 71450Turkey

The influence of aging on the microstructure and mechanical properties of Cu-11.6wt%Al-3.9wt%Ni-2.5wt%Mn shape memory alloy（SMA） was studied by means of scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray diffractometer,and differential scanning calorimeter（DSC）.Experimental results show that bainite,γ2,and α phase precipitates occur with the aging effect in the alloy.After aging at 300°C,the bainitic precipitates appear at the early stages of aging,while the precipitates of γ2 phase are observed for a longer aging time.When the aging temperature increases,the bainite gradually evolves into γ2 phase and equilibrium α phase（bcc） precipitates from the remaining parent phase.Thus,the bainite,γ2,and α phases appear,while the martensite phase disappears progressively in the alloy.The bainitic precipitates decrease the reverse transformation temperature while the γ2 phase precipitates increase these temperatures with a decrease of solute content in the retained parent phase.On the other hand,these precipitations cause an increasing in hardness of the alloy.

关键词： copper alloys shape memory effect martensitic transformations aging precipitates