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Correlations of Structural, Dielectric, magnetic and magnetoelectric Properties of Ca1-xSrx(Fe0.5Ta0.5)O3multiferroic Ceramics

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materials Sciences and Applications 2017年第1期8卷 64-84页

作者： m.K.H.Bhuiyan m.a.gafur m.N.I.Khan A.A.momin A.K.m.Akther Hossain Department of Physics Bangladesh University of Engineering&TechnologyDhakaBangladesh Pilot Plant&Process Development Centre DhakaBangladesh materials Science Division Atomic Energy CentreDhakaBangladesh

Conventional solid state reaction technique was used to synthesize Ca1-xSrx(Fe0.5Ta0.5)O3 multiferroic ceramics (where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5). Powder of ingredients was mixed thoroughly in stoichiometric amount and calcined at 1150°C for 5 h. Disk and toroid shaped samples prepared from each composition were sintered at 1450°C for 5 h. The XRD analysis confirms that all compositions are single phase cubic perovskite structure. The theoretical and bulk density increases with increase of Sr content, which may be attributed to the fact that the atomic weight and density of Sr are larger than those of Ca. The average grain size increased with increasing Sr content up to x = 0.2, and then decreased with further increase of Sr content. Frequency dependent dielectric constant shows usual dielectric dispersion at lower frequencies due to maxwell-Wagner type interfacial polarization. The higher values of real and imaginary part of impedance at lower frequencies are also due to the fact that all kinds of polarization mechanism are present and increase with Sr content indicating the enhancement property of the composition. The continuous dispersion on increasing frequency contributes to the conduction phenomena. Two semicircles correspond to the grain boundary and grain resistance separately. The complex modulus analysis reveals the polaron hopping and negligibly small contribution of electrode effect. The continuous dispersion on increasing frequency may be contributed to the conduction phenomena. The ac conductivity, σac, was derived from the dielectric measurement and it increases with increase of frequency for all the compositions and can also be explained on the basis of polaron hopping mechanism. At higher frequencies conductive grains are more active, and thereby increases of hopping of charge carrier contribute to rise in conductivity. The real part of initial permeability increased with increasing Sr content up to x = 0.2, and then decreased further incr

关键词： Perovskite Impedance Spectroscopy Initial Permeability Saturation magnetization magnetoelectric Voltage Coefficient

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Extraction and characterization of alumina nanopowders from aluminum dross by acid dissolution process

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International Journal of minerals,metallurgy and materials 2015年第4期22卷 429-436页

作者： Saifur Rahman Sarker Zahangir Alam Rakibul Qadir m.a.gafur mohammad moniruzzaman Department of Applied Chemistry and Chemical Engineering University of Dhaka Pilot Plant & Project Development Centre (PP& PDC) Bangladesh Council of Scientific and Industrial Research (BCSIR) BCSIR Laboratories Dhaka

A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai and manikgang, near the capital city, Dhaka. Alu- minum dross samples were found to approximately contain 75wt% A1203 and 12wt% SIO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extrac- tion of alumina were studied to optimize the dissolution process. First, AI（OH）3 was produced in the form of a gel. Calcination of the AI（OH）3 gel at 1000℃, 1200℃, and 1400℃ for 2 h produced O-AlcOa, （t~＋O）-A1203, and u-alumina powder, respectively. Thermal charac- terization of the AI（OH）3 gel was performed by thermogravimetric/differential thermal analysis （TG/DTA） and differential scanning calo- rimetry （DSC）. The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence （XRF） spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials.

关键词： aluminum dross alumina nanoparticles acid dissolution calcination X-ray fluorescence analysis

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Development and Characterization of Aluminium-Based metal matrix Composites

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materials Sciences and Applications 2023年第1期14卷 1-19页

作者： m. A. gafur Al Fahad Ahmed Raisul Abrar Surya Sabrin Soshi Pilot Plant & Process Development Centre Bangladesh Council of Scientific & Industrial Research (BCSIR) Dhaka Bangladesh Department of Naval Architecture and marine Engineering Military Institute of Science and Technology Dhaka Bangladesh Department of mPE AUST Dhaka Bangladesh

Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemical-corrosion etc.) were measured and compared with base metals/alloys. The properties were significantly varied. The highest density was obtained for pure aluminium with 5% Al2O3 whereas the lowest was obtained for AA-4032 alloy. The highest hardness was obtained for AA-4032 with 5% Al2O3 whereas the lowest was obtained for pure Al with 5% Al2O3. The highest strength was obtained for AA-6061 with 5% coarse SiC whereas the lowest was obtained for pure Al. The highest impact strength was obtained for AA-4032 with 5% Al2O3 whereas the lowest was obtained for AA-6061. The corrosion resistance of all composites was lower than that of the base materials.

关键词： Al AA-6061 AA-4032 SiC Al2O3 Stir-Casting metal matrix Composite mmC Nanocomposites

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Soil chronosequence and biosequence on old lake sediments of the Burdur Lake in Turkey

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Pedosphere 2021年第6期31卷 882-891页

作者： gafur GOZUKARA Yakun ZHANG Alfred EHARTEmINK Sevda ALTUNBAS mustafa SARI Department of Soil Science and Plant Nutrition Eskisehir Osmangazi UniversityEskisehir 26160(Turkey) Department of Soil Science FD Hole Soils Lab1525 Observatory DriveUniversity of Wisconsin-MadisonMadison 53706(USA) Department of Soil Science and Plant Nutrition Akdeniz UniversityAntalya 07059(Turkey)

The Burdur Lake is located in the southwest of Turkey,and its area has decreased by 40% from 211 km^(2) in 1975 to 126 km^(2) in *** this study,we investigated how the soil has changed in the lacustrine *** soil profiles were sampled from the former lakebed(chronosequence profiles:P1,2007;P2,1994;and P3,1975),and three soil profiles under different land use types(biosequence profiles:P4,native forest vegetation;P5,agriculture;and P6,lakebed)were *** chronosequence and biosequence soil profiles represented various distances from the Burdur Lake and showed different stages of lacustrine *** electrical conductivity(EC;18.1 to 0.4 dS m^(-1)),exchangeable Na^(+)(34.7 to 1.4 cmol kg^(-1))and K^(+)(0.61 to 0.56 cmol kg^(-1)),and water-soluble Cl^(-)(70.3 to 2.1 cmol L^(-1))and SO_(4)^(2-)(275.9 to 25.0 cmol L^(-1))decreased with increasing distance from the Burdur Lake,whereas the A horizon thickness(10 to 48 cm),structure formation(0 to 48 cm),gleization-oxidation depth(0 to 79 cm),and montmorillonite and organic matter(Om;25.9 to 46.0 g kg^(-1))contents increased in the chronosequence soil *** formation of P3 in the chronosequence and P5 in the biosequence soil profiles increased due to longer exposure to pedogenic processes(time,land use,vegetation,etc.).Changes in EC,exchangeable cation(Na^(+) and K^(+))and water-soluble anion(Cl^(-) and SO_(4)^(2-))concentrations of the salt-enriched horizon,Om,gleization-oxidation depth,A horizon thickness,and structure formation of the chronosequence and biosequence soil profiles(especially the topsoil horizon)were highly related to the distance from the Burdur Lake,time,and land use.

关键词： biosequence soil profile chronosequence soil profile lacustrine material lakebed soil formation

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Characterization of Isotactic Polypropylene/Talc Composites Prepared by Extrusion Cum Compression molding Technique

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materials Sciences and Applications 2015年第11期6卷 925-934页

作者： Rahima Nasrin m. A. gafur A. H. Bhuiyan Department of Physics University of Barisal Barisal Bangladesh Pilot Plant & Process Development Centre Bangladesh Council of Scientific & Industrial Research (BCSIR) Dhaka Bangladesh Department of Physics Bangladesh University of Engineering and Technology (BUET) Dhaka Bangladesh

Extrusion-Compression molded isotactic polypropylene (iPP) composites containing 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% of talc filler were studied by scanning electron microscopy (SEm), simultaneous thermal analysis (STA) and physical testing. The scanning electron microscope (SEm) micrographs of neat iPP and composites with 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% talc content show that neat PP, 10 wt%, 20 wt%, and 30wt% talc composites surface is smooth in comparison to 40 wt% and 50 wt% talc composites. It is also observed that talc is dispersed uniformly in the matrix and this uniform dispersion is not decreased even with talc content as high as 30 wt% talc. The composites of 40 wt% and 50 wt% talc contain more crack, agglomerates or larger particles. Bulk density of the composites decreases with the increase of talc content. With the increase of percentage of talc and period of immersion, the water absorption (WA) increases. Thermal analyses indicate a considerable increase of thermal stability of the composites with filler addition.

关键词： Isotactic Polypropylene Water Absorption Thermal Behavior Talcs

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matrix-material Fabrication Technique and Thermogravimetric Analysis of Banana Fiber Reinforced Polypropylene Composites

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Journal of Building material Science 2023年第2期5卷 15-24页

作者： Nazrul Islam m.a.gafur Department of Basic Sciences Primeasia UniversityDhaka1213Bangladesh Pilot Plant and Process Development Centre(PP&PDC) Bangladesh Council of Scientific and Industrial Research(BCSIR)Dhaka1205Bangladesh

From the environmental consideration,it would be very interesting to use natural fibers such as banana,jute or coir as reinforcement materials instead of artificial fibers or any kind of synthetic *** fibers have many advantages over synthetic *** banana fiber composites(PPBC)are prepared using untreated and alkali-treated banana fibers at 10-25%by weight of the fiber *** thermal properties of polypropylene natural fiber composites are very important for technological *** measurements show that the incorporation of banana fiber into PP enhances the thermal stability of composites containing treated fibers,in comparison with untreated fibers.A composite of biodegradable polypropylene(PP)reinforced with short banana natural fibers was prepared by melt blending followed by a hot press molding *** thermal properties of matrix materials were studied using thermogravimetric analyzers TGA *** is observed that the introduction of short banana fibers slightly improved the thermo oxidative stability of PP-banana *** and chemical changes occurred through dehydration,phase transition,molecular orientation,crystallinity disruption,oxidation and decomposition,and incorporation of several functional *** investigations of the thermal behavior of polymers in gas,vacuum or inert atmosphere give the knowledge of how change takes place in *** understand such changes thermogravimetric analysis(TGA)and thermal analysis(TG)were *** is observed reinforcement of short banana fiber leads to little improvement in the thermooxidative stability of *** to the enhancement of thermo-mechanical properties,such composites may be used as building materials namely roof materials,selling materials and many other engineering applications.

关键词： Polypropylene banana composites(PPBC) Natural fiber Oxidative stability Thermogravimetric analysis(TGA) Decomposition

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Study of the Physical and mechanical Properties of Coconut Spathe Fiber Reinforced Obsolete Polymer Composites

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materials Sciences and Applications 2021年第5期12卷 223-238页

作者： Rabeya Akter Budrun Neher m. A. gafur Rakib Hossain Farid Ahmed Department of Physics Jahangirnagar University Dhaka Bangladesh Pilot Plant and Process Development Centre Bangladesh Council of Scientific and Industrial Research Dhaka Bangladesh Department of Physics Bangabandhu Sheikh Mujibur Rahman Science & Technology University Gopalganj Bangladesh

Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion resistance. This study was carried out with composites prepared by hot press molding method using coconut spathe fiber as reinforcing material and HDPE (from HDPE can as obsolete polymer) as polymer matrix. Composites were made at 150°C under 60 kN load by taking diverse weight percentage (wt.%) of fiber from 0 to 20 of its total weight. In this research investigation, different properties of the composites such as bulk density, water absorption, tensile and flexural properties, impact strength and hardness test properties were carried out. The fiber content enhancement increases the bulk density in all composites. The rate of water absorption improves with the improvement of fiber addition with respect to HDPE in all composites. But the water absorption was not increased uniformly with the increase of fiber addition in composites. In all cases, composites absorbed water very rapidly up to 80 hrs and then water absorption is in saturated condition. The mechanical properties like tensile strength (TS), flexural strength (FS), impact strength (IS) and hardness were observed to be comparatively more enhanced for 5% composite, while further increasing of fiber addition, all mechanical properties changes irregularly. The irregular nature of change might be caused due to the over loading of fiber in polymer matrix.

关键词： Coconut Spathe Fiber Obsolete Polymer matrix Tensile Strength Impact Strength

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Fabrication and Characterization on Physico-mechanical and Structural Properties of Sawdust Reinforced Acrylonitrile Butadiene Styrene (ABS) Composites

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materials Sciences and Applications 2020年第9期11卷 644-658页

作者： Budrun Neher Nabila Tasnim Nova Rakib Hossain m. A. gafur Farid Ahmed Department of Physics Jahangirnagar University Dhaka Bangladesh Department of Physics Bangabandhu Sheikh Mujibur Rahman Science & Technology University Gopalganj Bangladesh PP and PDC Bangladesh Council of Scientific and Industrial Research Dhaka Bangladesh

The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180°C temperature and 50 KN load. Sawdust was collected from local saw mill of Savar, Dhaka, Bangladesh and ABS polymer was collected from local market of Dhaka, Bangladesh. In this study, different properties of composites like physical (bulk density and water absorption), mechanical (tensile properties and hardness) and structural (Fourier Transform Infrared Spectroscopy) properties were studied. The bulk density of composites was not altered consistently and it gave greater value for 5% and 20% composites. The water absorption enhanced for all composites with the accumulation of fiber content and soaking time. The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions. maximum (%) of elongation was found for 5% composite, and then it gradually decreased;however, elastic modulus increased with the increased of fiber content in composites. Fourier Transform Infrared (FTIR) spectroscopy study was done for structural characterization. It was found that there was a new bond (C≡C) stretching formed for 20% composite;moreover, C-H rocking for 0% composite was broken for all other composites after the addition of sawdust in ABS polymer matrix.

关键词： Sawdust-ABS Composite Hot Press molding machine Tensile Strength Leeb’s Rebound Hardness FTIR Spectroscopy

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Structural and Dielectric Properties of (Bi₂O₃Fe₂O₃)_0.4(Nb₂O₅)_0.6 for Different Sintering Temperature

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materials Sciences and Applications 2016年第8期7卷 421-429页

作者： Sadia Tasnim mowri m. A. gafur Quazi Delwar Hossain Aninda Nafis Ahmed muhammad Shahriar Bashar Electrical and Electronic Engineering Department Chittagong University of Engineering and Technology Chittagong Bangladesh Pilot Plant & Process Development Centre Bangladesh Council of Scientific and Industrial Research Dhaka Bangladesh Institute of Fuel Research & Development Bangladesh Council of Scientific and Industrial Research Dhaka Bangladesh

In this research work, (Bi2O3Fe2O3)0.4(Nb2O5)0.6 was made by the solid state reaction method. Samples were sintered at four different temperatures (850°C, 925°C, 1000°C and 1150°C) to study the effect of sintering temperature on the various properties of the samples. X-ray diffraction analysis confirmed that single phase Bi1.721δ0.089Fe1.056Nb1.134O7 was found when sintering temperature increased. At the same time, larger grain size was found when sintering temperature increased. From variation of dielectric loss with respect to frequency, a small peak was found when sample was sintered at higher temperature (1150°C). Dielectric constant of the sample decreases with the increase of frequency for all the samples. With the variation of temperature, DC resistivity of the samples showed that resistivity decreases with the increase of measuring temperature which indicates semiconducting nature.

关键词： XRD Niobium SEm Dielectric Constant Dielectric Loss Loss Tangent Bismuth Ferrite Resistivity

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Thermal and Electrical Properties of Sn-Zn-Bi Ternary Soldering Alloys

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materials Sciences and Applications 2015年第11期6卷 1008-1013页

作者： m. A. Wadud m. A. gafur m. R. Qadir m. O. Rahman Department of Physics Jahangirnagar University Savar Bangladesh PP&PDC BCSIR Dhaka Bangladesh

Sn-Zn based solder is a possible replacement of Pb solder because of its better mechanical properties. The alloys need to be studied and explored to get a usable solder alloy having better properties. In this work, eutectic Sn-9Zn and three Tin-Zinc-Bismuth ternary alloys were prepared and investigated their thermal and electrical properties. Thermo-mechanical Analysis and Differential Thermal Analysis were used to investigate thermal properties. microstructural study is carried out with Scanning Electron microscope. The alloys have single melting point. The co-efficient of thermal expansion and co-efficient of thermal contraction varies with alloy composition and temperature range. Electrical conductivity changes with Bi addition.

关键词： Lead Free Solder Alloy Eutectic Alloy DTA TmA Conductivity

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