Dissertations/Theses - Department of Materials & Metallurgical Engineering

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Alteration of ilmenite in the inani heavy mineral deposit
(Department of Materials and Metallurgical Engineering, BUET, 2009-06) Shamsun Nahar; Kurny, Dr. A. S. W.
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Analysis and projection of the population of Bangladesh using a multi-scale logistic model 2023
(Department of Mathematics, BUET, 2023-04-30) Sharif Ullah, Mohammad; Abdul Hakim Khan, Dr. Md.
Bangladesh isoneofthemostovercrowdedanddenselypopulatedcountriesglobally.Thus,in recent years, the population problem has been a great concern of the policymakers ofBangladesh.Forthedevelopmentandprogressofthecountry,itwouldbecrucialtoperceiveand estimate the increasing trend of the population. This research work principally focuses on theanalysis through data fitting using the nonlinear least square curve fitting method andforecastofthefuturepopulationgrowthofthecountry byconsideringmathematicalmethods. Available actual and adjusted census data (1974-2022) of Bangladesh populationapplied in the well-known autonomous logistic population growth model and fund that alldata sets of logistic (exact), deterministic (Adam-Bashforths-Multon predictor-corrector(PECE) method), Atangana-Baleanu-Caputo (ABC) fractional-order derivative approach,and logistic multi-scaling approximation fits with a good agreement. Again the existenceand uniqueness of the solution for deterministic and fractional-order and Hyers-Ulamstabilityhavebeenstudied.Generally,thegrowthrateandcarryingcapacityofthepopulationofanycountryslowlyfluctuatewithtime.Thisanalysisprovidesseveraladvantages to assessing an approximate closed-form of straightforward solutions, as mostprevious studies conducted with population models of single species employed constantgrowth rates and carrying capacity, and no fractional-order method is studied. Finally, ourprojectionadhereswithanexcellentagreementtotheestimate(2012-2061)oftheBangladesh Ministry of Planning and Bureau of Statistics (BBS). Thus, we bank on thefindingsofthisresearch workwillassistinsuccessfulpopulationforecastandplanning,development,and progression ofthe nation.
Ballistic properties enhancement of jute, kevlar and glass fiber reinforced thermoset polymer hybrid composite
(Department of Materials and Metallurgical Engineering (MME), BUET, 2024-08) Shakhawat, Hossain; Gulshan, Dr. Fahmida
In the last few years, natural fiber-reinforced composites have attracted the attention of materials scientists worldwide. These composites have low cost, are lightweight, are readily available, and are biodegradable. In addition, these composites have low density and high specific strength and are the most suitable candidates for low load-bearing applications. Researchers hybridize the composite with high tensile strength fiber, which can be used against high-velocity impact and in high load-bearing applications. This research used Kevlar, jute, and glass fiber with epoxy matrix for better performance, focusing on designing ballistic composite. This hybrid ballistic composite was used to defend high-impact energy projectiles. The ballistic composite is fabricated to reduce fragment penetration when dispersing bullets. This study aimed to see how epoxy matrix composites reinforced with natural jute fibers performed as a stand-alone target against high-energy munitions. To develop hybrid composites, jute fabrics must be laminated with Kevlar and plain glass cloth before being combined with epoxy. Press molding has been applied to fabricate the composite. In this research work, raw jute, scoured jute, bleached jute, jute composite, jute-glass composite, jute-Kevlar composite, and jute-glass-Kevlar composite were characterized by FTIR. The tensile, flexural, and impact properties of the four composites are found through the tensile, flexural, and impact tests. The high-velocity impact properties are found by conducting a ballistic test. The water absorption test was done for jute and different composites in normal, distilled, and saltwater for 24 hours. Fracture surface morphology and fraction nature were observed using a Field Emission Scanning Electron Microscope. The volume fraction's impact on the primary failure mechanism and tensile behavior was investigated to derive the ballistic parameter. The collected results were evaluated using statistical techniques. The depth of penetration induced by the bullet in a clay witness block representing a human body is used to assess ballistic performance according to international standards. The results have demonstrated that jute fiber and aramid fiber mixed hybrid composites absorb high-velocity impact, and jute fiber acts like brittle components like glass fiber, which helps to diminish the initial trauma of bullet impact.
Beneficiation of locally available sand for the manufacture of colourless glass
(Department of Materials and Metallurgical Engineering, BUET, 1998-08) Abdul Matin, Md.; Bazlur Rashid, Dr. A. K. M.
The investigation of Noapara glass sand deposit of Sylhcl di"J_rict is performed to beneficiEltc the sand for Ihc manufaclure of colourless glass. First of all the physical and mineralugical identlficatlOn of heavy' minerals present in the sand were carried out, The study includes sieve analysis, heavy mineral separation and magnetic separation. SemI-quantitative analyses of the glass sand were performed wIth the help of XRD and Petrography and the results arc reported in sequence. The classified sand is then subjected to water wash and attrition to remove clay and ferruginous coating followed by magnetic separation to eliminate magnetic minerals. The waler-washed and magnetically treated sands arc then subjected [0 vanous chemical treatments in order to reduce the iron level. Finally. a number reagent batch combinations are prepared using water-washed and magnetic treated sand for the forth flotation le<.:hmque. One of such reagent combinations reduce Fe203 and Cr203 levels in the sand to 0.032 and 0.0012 % respectively after froth flotation. This is close to the required chemical composition for Ihe manufacture of colourless glass.
Characterisation and beneficiation of Narsingdi clay
(Department of Materials and Metallurgical Engineering (MME), 2012-05) Ummul Khair Sultana; Kurny, Dr. ASW
A sample of clay was collected from Narsingdi, near Dhaka for the purpose of this study. The sample of clay was characterized by its moisture content, bulk density, organic matter content, pH, alkalinity, liquid limit, plastic limit, firing properties etc. X-ray fluorescence analysis, X-ray diffraction analysis, Thermogravimetric analysis and Differential thermal analysis were also done for the characterization of the sample. The average moisture content (%m) in the clay was 3.27 % which is rather low. Bulk density of the clay, as measured by pycnometer method, was found to be 2.28 g/cc. The organic matter content in the clay was about 6.31% and the pH of the clay was 5.16 which means that the clay is acidic in nature. The alkalinity of the clay was found about 4.5 (wt.%). The average liquid limit is 45.27, the plastic limit is 33.81 and the plasticity index is 11.46. The x-ray diffraction analysis showed that the clay contained mostly quartz and a small amount of kaolinite. X-ray fluorescence analysis showed that the clay sample contained 8.15% iron oxide, 27.49% alumina and 59.45 % of silica and minor amounts of other elements. The thermogravimetric analysis curves showed a mass loss till 500OC due to loss of moisture and organic matter. Subsequently a gain in mass was noted and the reasons for this gain in mass could not be identified. Four sets of bricks were prepared and fired at four different temperatures. The bricks fired at highest temperature (i.e., 1100OC) showed maximum bulk density (2.25 gm/cm3), lowest water absorption (4.64%) and maximum shrinkage (23.3% ). It also showed the maximum cold crushing strength which was 40.724 N/mm2. The clay was leached in oxalic acid and in hydrochloric acid. Process variables, effects of concentration of acids, time and temperature and effect of stirring speed on the rate of dissolution of iron, contained in the clay sample was investigated. Temperatures studied in this investigation were in the range of 400C to 1000C, concentrations of both acids were in the range of 0.2M to 2M and the stirring speed was in the range of 0 rpm to 1000 rpm. While finding out the kinetic models that fit the leaching reactions, the Mixed controlled process i.e., t/τ = [(1-2X/3)-(1-X)2/3 ]+b[ 1-(1-X)1/3 ] seemed to be the most appropriate one to fit the kinetic data of leaching of clay in oxalic acid and the diffusion controlled reaction model i.e., t/τ = (1-2X/3)-(1-X)2/3 seemed to be the most appropriate while leaching in hydrochloric acid.. The Arrhenius activation energy for leaching in oxalic acid was found to be 41.03 kJ/mole and for hydrochloric acid was 50.82 kJ/mole. Alumina content was found to be affected by leaching in both the acids. The x-ray diffraction analysis showed that leaching did not cause any change in phases. The beneficiated clay was again characterized by the Atterberg limit, organic matter content, cold crushing strength, thermogravimetric analysis and X-ray diffraction analysis. The average liquid limit for the clay leached in oxalic acid was 41.72 and the plastic limit was 28.37. The plasticity index was 13.35. On the other hand the liquid limit for the clay leached in hydrochloric was 40.46 and the plastic limit was 29.1. The plasticity index was 11.36. The sample leached in oxalic acid contained 4.58% of organic matter and the sample leached in hydrochloric acid contained 3.1% of organic matter. Bricks were made by using the beneficiated clay. These bricks were fired at 1100OC and then crushed. The cold crushing strength of these bricks was found 37.26 N/mm2 (i.e., clay leached in hydrochloric acid) and 40.9 N/mm2 (i.e., clay leached in oxalic acid).
Characterisation and recovery of metal values from spent lithium-ion batteries
(Department of Materials and Metallurgical Engineering, 2013-01) Al Hossaini Shuva, Mohammad; Kurny, Dr. ASW
Lithium ion batteries were characterized to identify the potential of recovering metal values from these batteries. Different component parts of spent batteries of two types (M 660 and V83) were examined. The outer casings were found to be of aluminum alloy. Aluminum , lithium , copper and cobalt consisted were 45.99 percent of the total weight of the spent batteries. The rest was electrolyte solvent, adhesive and other impurity elements. In cathode electrode, lithium and cobalt constituted 7.09 and 60.24 percent respectively. LiCoO2 was the prominent phases in cathode of the spent batteries. Graphite was presence in anode of spent lithium ion battery. The proportion of aluminum in aluminum foil current conductor was determined by Atomic Absorption Spectroscopy (AAS). In the M 660 and V 83 batteries aluminum was found to be 98.90% and 98.66 % respectively and thickness of foil was 25μm. The proportion of copper in copper foil current conductor was determined by Chemical Analysis. In the M 660 and V83 LIB copper was found to be 99.06% and 98.86 % respectively and thickness of foil was 25μm In order to determine the presence of lithium and cobalt, the active cathode with foil was leached in sulfuric acid. During leaching the process parameters were kept fixed at acid concentration = 2.5M, temperature = room temperature (due to exothermic reaction), solid-liquid ratio = 1: 30 (gm/ml), time=2-5 min, and percentage of hydrogen peroxide = 5. After completion of leaching the solution was filtered this will separate the aluminum foil. Then this leach out sample was analyzed in Flame Photometer (AFP) and UV- Spectroscopy (UVS) to determine the presence of lithium and cobalt. To analyze the lithium in AFP and cobalt in UVS we had to calibrate the machine with analytical reagent lithium carbonate and analytical reagent cobalt sulfate powder according to the standard procedure. With respect to that calibration curve the presence of lithium and cobalt of spent lithium ion battery was determined. The effect of process variables, such as concentration of sulfuric acid and hydrogen peroxide and solid/liquid ratio were studied to determine the optimum conditions for this purpose. Leaching of the cathode paste was also carried out in hydrochloric acid media in presence of hydrogen peroxide as a reducing agent. Effect of process variables, such as concentration of hydrochloric acid and hydrogen peroxide, temperature, time and solid/liquid ratio were studied to determine the optimum conditions. It was found that the dissolution of LiCoO2 increased with increasing temperature, concentration of HCl, time and solid/liquid ratio (S/L) ratio. Li and Co from LiCoO2 were leached around 89% with addition of 3.5 Vol% of H2O2 as a reducing agent. VIII Kinetic parameters were established from the time versus dissolution curve using temperature as variable and keeping the other parameters fixed. Dissolution reached up to 81% for lithium and 79% for cobalt at 800C temperature within 40 minutes. Leaching behavior for both lithium and cobalt were found to follow the chemical reaction controlled process. Activation energy of lithium and cobalt were found to be 23.83KJ/mol and 27.72 KJ/mol respectively; which again justified the appropriateness of the model. The recovery products lithium carbonate and cobalt hydroxide were got by chemical precipitation with 2M NaOH at PH value 11-12. X-ray diffraction results ensure the presence of lithium carbonate and cobalt hydroxide in recovery product.
Characterisation of Bangladesh ilmenite in the process of its upgradation into synthetic rutile
(Department of Materials and Metallurgical Engineering, BUET, 2006-03) Amirul Momin, Md.; Kurny, Dr. A. S. W.
Heavy minerals found in the beach sands of Bangladesh are one of the most important mineral deposits that have, so far, been identified in Bangladesh. Ilmenite is the most abundant mineral in these deposits and constitutes about 25 per cent of all the heavy minerals. It has been estimated that about one million tons of ilmenite can be separated from the beach sands of Bangladesh. In 1977, a pllot planl was set up at Cox's Bazar by the Bangladesh Atomic Energy Commission to separate the indlvidual heavy mmerals from these deposits. Unfortunately, however, the ilmenite produced at Cox's Bazar pilot plant contains less than 40 percent TiD, together with a large amount of iron in the form of oxides, silica, magnesium and unaeeept1ble amounts of manganese and chromium. Ilmenite containing less than 55 pereent titanium di-oxide is not considered suitable for industrial use. As a result, this valuable mmeral separated from the beach sands of Bangladesh, which is used in Ihe mnnufaeture of paints, welding electrodes, ceramics, etc. could not find any market in Bangladesh or elsewhere. In view of rapid depletion of known reserves of natural rutile (TiD,) efforts are being made throughoutlhe world to transform ilmenite into rutile through thermo-chemical treatment. As a result of these investigations, a number of eommereial processes for the produetion of rutile from ilmenite have been developed. This rutile is known as synthetic rutile. No efforts arc known 10 have been made to convert Bangladesh ilmenite to synthetic rulile. It was, therefore, considered necessary to explore the possibility of converting Bangladesh ilmenite to synthetic rutile througb thermo--chemical treatment. It is believed that the successful conversion of Bangladesh llmem1Cinto synthetic rutile will make litis valuable mineral of Bangladesh useful at home and abroad, enhance the confidence in our ability 10use cur own natural resources and also the preslige of the nation. In this dissertation mvestigations were carried out 10charactenze Bangladesh ilmenite in the process of its up-gradation into synthetic rutile. Raw sand containing the heavy minerals was collected from the back dune surfuce layers ofhcavy mineral deposits at Teknaf village area (Lengurbil deposit) from points located 2-3 Km away from the water line and 5-6 meter above mean sea leveL The area selected fur the study falls between the latitude 20'52'7" to 20'52'21"N and longitude 92'16'10" to 92"15'58"E at Teknaf. lbe heavy mineral proportions VllJ of the concentrates were determined to be 89-92% by point counting grams using both reflected and transmitted light microscopy. Among the minerals found in the Tdmafbeach sands ilmenite is the most important One It constitutes around 24% percent of heavy mineral tonnage, the other important constituent minerals of the heavy minerals being rutile and zircon. Factory grade llmenite was produced at thc Beach Sand Mineral Exploitation Centre, Cox's Baulr. The techniques of seperation are based on the difference in physical properties hke density, electrical and magnetic properties, The reduction-leach routc of up gradation of ilmenite was followed in this investigation. The sample of ilmenite was analyzed chemically by standard methods of wet chemical analysis in the as received condition, after oxidation and reduction and also after magnetic and sizc fractionation. X-ray diffraction analysis was performed to identify the phases present in the various fractious. Thermo-gravimetric analysis of the magnctic fractions was carried out to detect the presence of water in the sample. Combined water in ilmenite is an indicator of tile extent of alteration, The effect of oxidation on the extent of reduction and also on subsequent leaching of Bangladesh ilmenite has been investigated. The effects of time and temperature on the oxidation ofllmenite have been followed by chemical analysis, X-ray diffraction and optical microscopy. A few samples of ilmenite wete also observed under a scanning electron microscope. The sample of ilmenite both oxidized and as received was reduced with charcoal in the temperature range of800"C to llOO'C for treatment tlme ofup-to 5 hr, The magnctic fractions and the size fractions were also reduced under identical conditions. The extent of reduction was followed by chemical analysis and X-ray diffractlOn analysis. The reduced samples werc also observed under optical and scanning electron microscope. The reduced samples were leached in hydrochloric acid. An attempt has been made to understand the kincties and mechanisms ofleaching process. llemenite sample under invcstigallon contained 25.32% FeD, 32.53% Fe,O, and 39.96% TiO,. From the sieve analysis it was found that more than %%ofthe ilmenite belongs to the US sieve no, 100, 140 and lOO.Thesphericity of all three samples was found he in a narrow range, 0.822-0,843. However, finer size fractions were found to have a slightly hlgher sphericity than the coarser one. Magnetic fractionation showed that ahont 96% ofTeknaf ilmenite belongs to the fractions separated by a current of 0.10 - 0,30 amperes and relativc sp,gr, range of 4, 1-4.5 in comparison of synthetic rutile sp.gr. 4.7 X-ray diffraction patterns of different magnetic fractionated as received ilmenite shows the presence of pscudorutile phase and TGA report indicate the presence of bonnd water. " 1. .- Detailed investigatIon on the X-ray pattern and TGA report led to the conclusion Teknaf ilmenite is in a partially altered stale bUInol hydrated enough. Samples of ilmenite have been oxidized in the tcrnp1:rature range of 750-950'C for a period of up--to 2 he Scanning electron microscopic studies revealed tbe presence of cracks in the o:
Characterization and performance analysis of natural fibres as reinforcement in polymer composite
(Department of Materials and Metallurgical Engineering (MME), 2010-02) Biswas, Subhankar; Qumrul Ahsan, Dr.
A systematic study has been carried out in the current study to investigate the mechanical (tensile strength, Young’s modulus and strain to failure) and physical properties (SEM, FTIR and TGA) of jute, bamboo and coir (brown and white) single fibres. Subsequently, unidirectional as well as woven fabric composites were manufactured and tensile, flexure (longitudinal and transversal both directions were conducted for unidirectional [UD] composites) and impact properties of the composites were determined. Void free composite have been made by using vacuum technique in case of unidirectional composites. On the other hand, Hot press and Resin Transfer Molding (RTM) processes were conducted to fabricate woven jute fabric composites. Water absorption tests were also carried out in this study for woven jute fabrics composites using various fibre volume fractions and polymers. The tensile properties (tensile strength, Young’s modulus and strain to failure) were determined by varying span length in case of single fibres. Tensile properties were carried out for woven jute fabric composites before and after water absorption test. Scanning Electron Micrograph (SEM), Fourier Transformation Infra Red (FT-IR) and Thermo Gravimetric Analysis (TGA) were also carried out to determine the physical properties of fibres in order to correlate with their strength; Young’s modulus and strain to failure and physical properties were observed in terms of composites. The study has revealed that with increasing test span length of single fibres, Young’s modulus increases and tensile strength as well as strain to failure decreases. This is because no extensometer could be used in this test set-up and machine displacement (denoted by α) is used for the modulus determination. It is also attributed that larger span length helps to minimize the machine displacement compared to smaller ones. At longer span lengths, the relative effect of slippage in the clamps is smaller. The Young’s modulus and strain to failure were corrected by using newly developed equations. Among all fibres, bamboo fibres had the highest Young’s modulus values. Jute fibre had smoother surface and good thermal properties (burnt at ≈ 2560C) compared to other three examined fibres. In case of UD composites, analytical results showed good agreement with theoretical values. In comparison between jute and bamboo fibre UD composites, it is observed that bamboo fibre showed better results in terms of tensile strength and jute fibre showed better values in terms of Young’s modulus. Bamboo fibre showed superior flexure strength with longitudinal distribution while jute fibre composite showed the good results in strength with transverse fibre distribution. Fibre distribution was not aligned uniformly for both bamboo and jute fibre in UD composites and in case of jute fibre composites some fibre have broken during processing. Composite containing higher percentages of fibre showed good tensile and impact behaviour. 4 ply shows better flexural properties for both polyester and polyvinylchloride (PVC) composite. Both tensile and flexural properties decreased after water absorption. It is observed from the SEM image that fibre at first debonded during loading tensile force and then fibre pulled out from the composite. Jute/Polyester composites showed better flexural properties. Tendency of resistance to water absorption of polyvinylchloride composite was higher than that of polyester composites because of its interfacial bonding. SEM images suggested that there is a good interlocking between jute and polyester composite compare to jute-PVC composite interlocking.
Characterization of anomalous Fe-Ni alloy coating by electrodeposition and its properties
(Department of Materials and Metallurgical Engineering, BUET, 2008-06) Aminul Islam, Md.; Moniruzzaman, Dr. Md.
Iron-nickel (Fe-Nil alloys are of great commercial interest as thcy possess low thennal cxpansion, soft mab'llctic and widc spectrum of physical properties. Attcmpts have been made to explain the anomalous mechanism of Fe-Ni alloy codeposition and researchers have proposed several models. Main focus of this work is to invcstil':ate the enect and the inlefaction of complexinl': agenl~ on the propertics of electrodeposited Fe-Ni alloy coating as well as the special characteristic of anomalous natlll"e. The Fe-Ni films were deposited from eight different baths; two of them were simple, coutaming NIS04, Fe504, Na1SO., H,BO.l as main ingredients and another six were complex, containiug ascorbic acid, saccharin and citric acid as complexing agent along with the main ingradicllls in varying compositiou. Fe-Ni alloy coatings were etectrodepositcd on Cu substrate at room tcmperature in the cum:nt density raub'e of20- 140 mNcml. Th", effects of current density, pH and bath composition on the coating appearance, composition, hardness, corroSIon resistance, morphologies and magnetization were studied. Chemical analysts, Mil..-TOhardness,Corrosion resistance, M0'Phologics and Magnetization of the coatings were studied by means of Conventional Wet Method, Mierohardness Tester, Salt Immersion Test, Scanning Electron Microscope (SEM) and Vibrating Sample Magnetometer (VSM) respectively. It was observed that coating obtaliled al higher cllrrent denSity with higher bath pH was blackish (examined with naked eye) while lower current density with higher pH or h'gher current density with lower pH resulted In uniform and bright coatings. The Ni percentage of the coating as well as its VHN increased with increasing current density for SImple baths but the reverse situations occurred for complex baths. Addition of complexing agents suppresscd the anomalous characteristics of the Fe-Ni alloy eJectrodeposition. The corrosion rate decreased with increasing Ni content of the films. Formation of protective NiO layer is supposed to inerease the corrosion resistance of high Ni content thin film Thus, the properlle~ of electrodeposited Fe-Ni alloy are strongly influenced by the electrolytic composition and deposition parameters. Tile filtn 7 obtained from simple baths did 1I0t exhibit smooth surface and the coating developed sharp line microcracks due to the internal stress developed during depositlOn in it. No cracks were observed and the coating gram size became finer for the coatings from complex baths compared to the simple baths. A clear morphological modification was observed due to the addition of eompJexing agent. The saturation magneti£ation of the electrodeposited Fe-Ni coating was fOlmd to decrease with increasing Ni content which is in good agreement with suppression of ferromagnetic character of the films. The highest saturation magneti7<1tionwas seen 131.13 cmwg among the coatings studied which is very close to the acceptable limit (135 emu/g). Charactenzatioll of Fe-Ni alloy plating parameters with its properties was attempted.
Characterization of chemically modified jute fiber for polymer composites
(Department of Materials and Metallurgical Engineering (MME), 2011-03) Sweety Shahinur; Hasan, Dr. Mahbub
Jute fiber reinforced composite as moderate structural materials have attracted the attention of material scientists all over the world because of their low cost, easy availability, light weight, renewability and biodegradability. In addition, low density and high specific strength of jute reinforced polymer composites make them the most suitable candidates for low load bearing applications. In this research work, control and chemically treated jute fibers were characterized by thermal, mechanical and structural testing. The effects of treatments on the physical, chemical and mechanical properties of the fiber have been studied. Reaction parameters such as time and temperature have been investigated for all chemical treatments. The control jute fibers were chemically treated to make the fiber rot retardant, fire retardant and water retardant. FTIR spectroscopy analyses were done for all retardant treatments and the results show the evidence of positive reaction. The tensile properties (Tensile strength, Young’s modulus, and strain to failure) of both control and chemically treated jute fibers were studied by varying fiber span length (5mm, 15 mm, 25 mm and 35 mm). The effect of span length on those properties was also studied. Chemical concentration on the treated and control fiber have been studied by the thermal properties in terms of differential scanning calorimetric (DSC) and thermal gravimetric analysis (TGA). All the studies are made for the top, middle and bottom portion of the jute fiber. In order to observe the crystalline properties and surface morphology, x-ray diffractometry (XRD) and atomic force microscopy (AFM) have been carried out respectively. Both the control and chemically treated fibers were incorporated as reinforcing agents in maleic anhydride grafted polypropylene (MAgPP) matrix composites through hot compression molding under specific pressure and temperature. The effect of fiber content on the mechanical properties of composites was studied by preparing composites with different percentage of fiber loading (20wt%, 25wt% and 30wt %) for each type of jute fiber. Tensile, three points bend and impact tests were conducted on all treated and control jute MAgPP composites. The Young’s modulus, tensile strength, strain to failure, flexural strength, and flexural modulus increased in case of control, RR, FR and WR compared to matrix. Since scanning electron micrographs of the single fiber and fracture surface of composites were taken to examine the variation in failure mode and to investigate the interfacial adhesion and bonding between fiber and matrix. Improve interfacial interactions were found for treated jute composites. Water absorption tests were carried out on rot, fire and water retardant fibers and their composites to investigate the chemical effect on the moisture absorption of hydrophilic jute and its composite. Reduced water absorption was found in case of rot and water retardant treated fiber and their composites.
Characterization of ilmenite of Cox's Bazar heavy mineral deposit
(Department of Materials and Metallurgical Engineering, BUET, 2003-07) Rabaya Begum; Kurny, Dr. A. S. W.
Ilmenite and l1ltile are natural sources of Ti02 and titanium metal. Rutile, naturally occuring pure Tin, i, prefen-ed to ilmenite as a raw materia!. Due to rapid decrease ;n sup1'l} of rutile, the necessity of alternate sources of rutile cannot be ov~relllpha,i7ed_ As a l'esult, investigatlOns are bcmg carried out throughout the world on the lIpgradation of low-gmde ilmenite 10 rutile. C()n.
Characterization of Ilmenite of Moheshkhali heavy mineral deposit
(Department of Materials and Metallurgical Engineering, BUET, 2001-09) Nazmun Nahar Shams; Kurny, Dr. A. S. W.
limenite is ~ promising altern~te oourCc of rutile from whIch Ille end prodllCl TiO, c~n be prodllced. Due 10 lapid decrease in supply of nalural TiO!, Ihe necessity of alternale ';Oufces ofrutJlc c~nnol k l"crclllpilasized . .1\0~ le,lill In\'~sllgations Jrc b~ing ctiLriedoul Ihroughout the '''!Hld on th,' llpgradalLOJI of low gradc ilrnetlite 10 ["lLlileconsequently it is l1ec~,,,aIY to id~l1lify the best po,~ible route for the upgradatlon af ilmenitc to whal i~ known i\S synlhellc rUlile. RutJle, ilmcnitc and 1eucoxenc, an "llcmtlOn product of l1memtc arc the main mineral ,ources ofl':laniulll and its oxide, Ilmenite may contain other min~:-als hke hematite, magnetite ',tC LIIil.l structure Thc wcathering re,ulls show that 'he TiOl content incrcases ",iih increasing ag~ So dctailcd analy,i, of weathcring elfect, on ilmenite to a parli~ular placer ,kposil is essenlial not only for its q&alitativc asses,ment 10 adopt better explOItation techniques but also for improving tht tcchnique of production of ,y"thelic fUlIk. Ilmenite of this present ,ludy wa' separJted li'(1[nMohcshkhali he","v mincral deposit at (he Bcach Sand ExploratlOn Cenler, Cox's Bazar. Thi, ilmcnite sal11pl~ \Va.s rraction~tcd magnetically by isodynamic magnetic s~p"ralor. Plcsctlce or dillcrem phascs III ~ach magnetic fracta1l1 "crc itlvestig,ned by x-raJ' diffl'tudyindlcatcs that alteration does not exist in this partlculiJr hcavy mincral collected from Mobeshkhali,
Characterization of tensile failure behavior of natural single fibre composite by acoustic emission technique
(Department of Materials and Metallurgical Engineering (MME), 2012-07) Saiful Alam, Md.; Gulshan, Dr. Fahmida
In the present days among the different non-destructive testing methods Acoustic Emission is a suitable tool for detecting and evaluating and for better understanding the damage mechanism and failure behavior in composites during mechanical loading. Methodology was developed for natural single fibre tensile test with Acoustic Emission (AE) to assess or monitor the tensile failure behavior of natural single fibre especially for bamboo single fibre. Series of experiment performed with this methodology. Before the final failure of fibre during tensile test few (one or two) load drop observed from the time vs load graph. From AE parameter such as Amplitude, Energy, duration etc. significant information of corresponding to that load drops found. These AE signals from the load drop may occur from the failure such as debonding between two elementary fibre or from join of elementary fibre at edge. The value of load at first load drop was not found consistent for different sample (for a particular sample the value is 8N, Stress: 517.51 MPa). Final breaking of fibre gives saturated level AE amplitude of preamplifier (99.9 dB) for all samples. Therefore it was not possible to think up exact AE energy value for final breaking. The other AE signal of AE may occur for the micro failure mechanism. Same methodology was used for tensile test of three single fibres, which gives clear indication of load drop before the final breaking of first and second fibre. Moreover, tensile test of single fibre composite (bamboo single fibre/epoxy) was performed to identify the individual fibre and matrix failure mechanism in composites using AE technique. Experimental data from AE for SFC test shows that many of them have a clear correlation between acoustic emission amplitude and failure mechanisms in single fibre composite.
Characterization of zinc based high temperature solder alloys with chromium and molybdenum additions
(Department of Materials and Metallurgical Engineering (MME), 2017-02) Khairul Islam, Md.; Sharif, Dr. Ahmed
Initiative of development and characterization of Pb free high temperature solders was taken. Two systems such as Zn-xMo (x= 0.4, 0.6 and 0.8 wt% Mo) and Zn-xCr (x= 0.2, 0.4 and 0.6 wt% Cr) were chosen for this study. Samples of the selected compositions were fabricated through casting in a permanent metal mold. Their microstructural, thermal, mechanical and electrical characteristics were determined using several analytical techniques such as Scanning Electron Microscope (SEM), Differential Thermal Analyzer (DTA), X-Ray Diffractometer (XRD), Thermomechanical Analyzer (TMA), Universal Testing Machine (UTM), Hardness tester, Conductivity Meter etc. Experimental findings revealed that with the addition of Mo and Cr particles grain refinement occurred in both Zn-xMo and Zn-xCr systems which was evident in the scanning electron micrographic images. Energy-dispersive X-ray spectroscopy (EDS) spots in several zones of the microstructure confirmed the presence of Mo and Cr particles throughout the respective structures. XRD analysis showed a very little or no shift in the peak pattern compared to standard Zn pattern indicating no new phase formation. However, crystallite size calculation using Scherrer equation showed that, average crystallite size decreases with increasing Mo content and it ranged from around 34.0-29.4 nm in case of Zn-xMo system, while the average crystallite size of Zn-xCr system ranged between 29.7 and 28.8 nm. Brinell hardness showed an incremental trend with increasing Mo content. Similar results were obtained in Zn-xCr system. Brinell hardness number of Zn-xCr increased from 33.98 in Zn-0.2 Cr to 42.74 in case of Zn-0.6 Cr alloy. Similarly, hardness increased from 29.71 to 41.28 in case of Zn-0.4 Mo to Zn-0.8 Mo respectively. Tensile strength of unalloyed zinc increased from 31.09 MPa to 33.04 MPa when alloyed by 0.8% Mo. In a similar manner, strength of Zn-Cr solders increased from 40.53 to 47.07 MPa due to an increase in 0.4% Cr than that of the former. Fractographic analysis of the tensile fracture surfaces with SEM indicated mixed (neither completely ductile nor completely brittle) fracture mode of both Zn-xMo and Zn-xCr systems. Coefficient of thermal expansion (CTE) of Zn-Cr system was found to vary from 4.5-5×10-5 (1/ºC) while in Zn-Mo system it was 4.14-2.64×10-5 (1/ºC). Electrical conductivity of both Zn-xMo and Zn-xCr decreased with increasing Mo and Cr contents respectively. The relative conductivity of Zn-xMo and Zn-xCr varied from 27.35 to 26.55 and 25.3 to 22.7 %IACS (International Annealed Copper Standard) respectively in the selected composition range. DTA results suggested that onset of melting started at temperature below the melting temperature of pure Zn. It was found that, the onset temperature of melting of all three compositions of the Zn-xMo system was around 416ºC whereas, the finishing temperature of melting was around 423ºC indicating a melting range of around 7ºC. On the other hand, DTA graphs exhibited that, the onset of melting of the Zn-xCr alloys started at around 412ºC and it finished near about at 418ºC showing a melting/solidification range of about 6ºC. From the experimental findings it can be said that Zn-xMo as well as Zn-xCr systems might be promising candidate for high temperature solders in replacement of Pb based solders.
Chemical and structural characterization of Bangladesh zircon and its application
(Department of Materials and Metallurgical Engineering, BUET, 1999-08) Sumsun Naher; Haseeb, Dr. A. S. M.
Zircon is one of the most important among the heavy minerals occurring in the beach sand along the coastal belt of Bangladesh. The prescnt work attcmpts to make chemical and mineralogical eharaeten7..ation of zircon benelkiated at the Cox's Bazar Pilot Plant of Bangladesh Atumk Energy Commission (BAEC). The mineral is investigated by means of chemical analysis, optical microscopy and X-ray diffraction (XRD). Potentiality of Bangladesh zircon as a raw material for zirconia, opacilier and re1i:actury brick production is also examined. From the chemical analysis it is found that Bangladesh zircon has 95.88% purity. The main impurity in Bangladesh zircon is titanium oxide (3.01%). This is followed by iron oxide (0.42%). Tnlce amounts of other oxides are also found. From the mineralogical study it is found that Bangladesh zircon have an elongated, prismatk shape with pyramidal termination in half of the grains and the rest are more or less rounded. Some fractured and irregular grains arc also found. Bulk sample of Bangladesh zircon in the as-received condition shows golden yellowish brown color. However, individual grains were found tu be almost colorless an d tnmsperent under polari7ed light. XRD study confmned good crystallinity in the sample. Under the microscope, it is found that in Bangladesh zircon, zircon grains constitute 94% and tutal impurities amount to 6%. This result agrecs fairly well with the chemical analysis resuIL~. The main impurities in thc prcsent sample of Bangladesh zircon are found to'be oxides of titanilUTl(both rutile and ilmcnite). This is also consistent with the finding~ uf chemical analY8is. Further, monazitc was identified as an important impurity under the microscopc. Most of the impurities found in Bangladesh zircon exist as discrete minerals. As a result, it should be possible to remove these impurities fairly casily by physical mineral processing methods and thereby impnwe the grade of Bangladesh zircon. The iron bearing coating found on ,orne zircon grains can be removed by acid washing. In the disintegration cxperiments, it has been found that the heating pcriod of 30 minutes is not sufficient to result in eomplele di8inlegration of Bangladesh zircon into zirconia even at the highest temperature (1500"C) and the largest sodium oxide concentration (30%) used in the present 8tudy. Practical experiments have demonstrated that Bangladesh zircon i~ quite 8atisfactory for preparation of zircon flour in ce"lmic indmtries. Zircon flour made from 13angladesh zircon can effectively replace imported zircon 110ur, if adequate size reduction and purification is earned ouL Bangladcsh zircon can also be used successfllily ji,r preparation ofrelmdory bricks for high temperature use.
Comparative study of ion nitriding behaviour of stainless steels
(Department of Materials and Metallurgical Engineering, BUET, 1993-05) Zahedul Huq, Md.; Kurny, Dr. A. S W.
For abstracts please see full text
Conversion of coke fired furnace to gas fired furnace
(Department of Materials and Metallurgical Engineering, BUET, 1973-12) Md. Mohafizul Haque; Ibrahim, Dr. M.
For abstracts please see full text
Creating three-dimensional hydrogel architectures for biomedical applications
(Department of Materials and Metallurgical Engineering, 2019-06-22) Raihan, Atahar.; Gulshan, Dr. Fahmida
Hydrogels are water-soluble polymers which can contain a huge amount of water inside them. This property of hydrogels has attracted specific interests in biomedical fields such as 3D organ/tissue printing, wound dressing, drug delivery, trans-dermal systems, dental materials, implants, injectable polymeric systems, ophthalmic applications, hybrid-type organs, contact lenses etc. Three-dimensional (3D) printing of hydrogels can be considered as a significant advancement in this regard because this may fascilate the use of hydrogels. In this research work, a hydrogel of poly(acrylic acid)- cysteine (PAA-cysteine) conjugates was 3D printed. The hydrogel synthesized was chosen after in-depth literature study. PAA-cysteine conjugates were synthesized by the covalent attachment of L-cysteine to poly(acrylic acid) (PAA). Synthesis followed by purification of the hydrogel. The reaction mixture was dialyzed using Spectra/Por® 2 membrane (MWCO: 12-14 kD) for 3 days in a fume hood under stirring at room temperature. After that, the dialyzed sample was transferred into petri dishes and freeze-dried for two days and stored in a closed desk until use. Swelling test was performed to get the swelling ratio of poly(acrylic acid)- cysteine (PAA-cysteine) conjugated hydrogel. The swelling ratio was found to be ~290% of the dry weight of the hydrogel. This high swelling ratio is very exciting for biomedical application. After that printing of hydrogel was tried. It was very challenging as hydrogel possesses a significant portion of porosity inside them. Inkjet printing and fused deposition modeling (FDM) printing technology were applied for the printing purpose. Inkjet printing was performed successfully with the synthesized hydrogel. A Standard operating procedure (SOP) was prepared for the use of FDM printer. But FDM printing was not possible due to the difficulty in finding the melting point of the hydrogel. Different biomolecules (proitens, amino acids etc.) can be delivered in vivo through the printed hydrogels. This work can be considered as a precursor to facilitate the use of hydrogels in biomedical applications. Keywords: hydrogel, swelling ratio, 3D printing, inkjet printing, fused deposition modeling (FDM).
Deposition of thin films of ZnO by sol gel method and their characterization
(Department of Materials and Metallurgical Engineering, BUET, 1999-03) Sayed Ansar Md. Tofail; Ebsanul Haque, Dr.
Thin films of zinc oxide have been deposited on Pyrex glass substrate by using sol gel process and characterized by means of different charactcrizatioll techniques including optical microscopy, X-ray diffractometry (XRD), thermogravimetry and spectrophotometry. The sol has been prepared by reacting zinc acetate and ethylene glycol and dissolving the resultant solution in npropanol. Glycerol was added to the sol to increase its stability. A proton acceptor like diethyl amille was added to assist hydrolysis of zinc acetate. Thin films of zinc oxide were cast on the substrate by dip coating method and gelled in humid air. The as deposited film was annealed at various temperatures ranging from 150 C to 450 C for 15 minutes at each set temperature. It has been found that the cleanliness of the glass substrate, the humidity during the gelation of the film as well as the time and temperature of the heal treatment affect the appearance and the morphology of the film. Cleaning of the glass substrate for the successful deposition of the film was achieved by the use of deionized water, acetic acid and absolute ethanol. Relative humidity less than 50% during the deposition of the film on to the glass substrate was found to be favorable for yielding good transparent film. It has been found that annealing of the film pyrolyzes gelled film to zinc oxide, drives out moistures and other volatiles and at higher temperatures decomposes the metalorganic complexes. The amorphous as-deposited film transforms to polycrystalline as a result of annealing above 275 C and the XRD peaks become sharper and more intense with the increase in annealing temperature, The films annealed at higher temperature, especially those annealed above 400 C, are denser and less porous and annealing leads to the increase in the size of the ZnO crystallites in them. The thin films of ZnO formed are randomly oriented without showing any preferred orientation. The ZnO crystallites have the hexagonal wurtdte structure, with e = 5.271 A and a = 3.285 A. The average thickness of the films from thermogravimetric analyses has been found to be about I ,.un after annealing at 450 C for 15 minutes and the film and the film exhibited about 80% transmission.
Design and fabrication of biocompatible copper based shape memory alloy by spark plasma sintering
(Department of Materials and Metallurgical Engineering (MME), 2022-07-03) Auditee, Majumder Momo; Gulshan, Dr. Fahmida
Copper based shape memory alloys are at the forefront of R&D for biomedical applications due to their good shape recovery, ease of fabrication, excellent thermal and electrical conductivity, antibacterial properties, and corrosion resistance. Spark plasma sintering (SPS) is a consolidated powder metallurgy process, which offers biocompatibilities to the materials by controlling grain growth, forming desired phases and controlled number of porosities. In the present study, two type of shape memory alloys- CuAlNi and NiTiCu have been fabricated by the SPS method. Studying the ternary phase diagram of the alloys, the composition has been chosen. The SPS parameters have been determined through multiple trials. CuAlNi and NiTiCu alloys have been sintered respectively at 475℃and 730℃.The present study aims to find out the effectiveness oflower sintering temperature and pressure for sintering the shape memory alloys. After selecting the material and experimental parameters, the sample powders have been prepared by wet ball milling at lower ball powder ratio (BPR) and lower milling hour. DSC analysis of the powder has been done to find out the melting point of the alloy powders and the temperatures for different phase formations. XRD, SEM and EDS analysis of the sintered CuAlNi and NiTiCu samples have been carried out to identify the phases and to see the morphology of the samples. Micro hardness of the sintered alloys has been measured and static corrosion test have been done on the sample to find out the corrosion rate. The DSC analysis of the alloy powders provides evidence that successful sintering of CuAlNi and NiTiCu is possible at lower SPS and ball milling parameters. XRD, SEM and EDS results also confirm the presence of desired phases in the sintered alloys. The Vickers hardness values of CuAlNi and NiTiCu refer to the further modification of CuAlNi sample is required whereas the hardness of NiTiCu alloys already have the desired values. The corrosion rates of presently studied CuAlNi alloys are lower. But corrosion resistance of NiTiCu samples in the present study requires further improvement.