Iranian Journal of Materials Science and Engineering

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The synthesis of advanced materials from low cost minerals concentrates is a new field of study that has great potential applications. In this paper, the effect of milling time on the temperature of initiation and amount of carbothermic reduction of ilmenite has been investigated. The stoichiometric molar ratio (1:4) of ilmenite to graphite was mixed and mechanically activatedfor 30-70 hours at room temperature. Then homogenized mixture heated for one hour at 1000-1400°C in coal reducing atmosphere. The results show that complete conversion of ilmenite to Fe and TiC can not be achieved in the unmilled powder at 1400°C, while with milling of mixture for 30 hours, complete reduction of ilmenite to Fe and TiC at 1400° C was observed. With increasing milling time from 30 to 70 hours the temperature of complete reduction decreases from 1400 to 1200° C. Leaching of final product in HCI 3% solution dissolve Fe but leave pure titanium carbide intact. Determination of TiC unit cell size from X-ray diffraction pattern shows that unit cell size of synthesized TiC is less than stoichiometric one, which suggests that some oxycarbide phases (TiCxO1-x), is present into the final product.

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Abstract: Nanocrystalline MgAl2O4 spinel powder was synthesized using metal nitrates and a polymer matrix-based composed of sucrose and polyvinyl alcohol (PVA). The precursor and the calcined powders were characterized by simultaneous thermal analysis (STA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). According to XRD results, the inceptive formation temperature of spinel via this technique was between 600°C and 700°C. The average crystallite size of calcined powder at 800°C for 2h was in the range of 8-12nm. In addition, SEM micrograph showed that the synthesized powder had a spherical morphology.

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Abstract:A combination of mechanical activation and Differential Thermal Analysis (DTA) together with X-Ray Diffraction (XRD), and various microstractural characterization techniques were used to evaluate the starting reaction in the combustion synthesis of TiC-Al2O3 composite in TiO2-Al-C system. The mechanical activation was performed on the mixtures of two components of TiO2/Al, Al/C and TiO2/C and then the third component was added according to the stoichiometric reaction for 3TiC+2Al2O3 composite formation. The powder mixtures were heated up to 1450 °C under Argon atmosphere at a heating rate of 10 °C/min. The combustion synthesis temperature was observed to decrease from 962 °C to 649 °C after milling of TiO2/Al mixture for 16 hr. On the contrary, the mechanical activation of Al/C and TiO2/C mixtures for 16 hr made the reaction temperature increase to 995 °C and 1024 °C, respectively. The decrease in reaction temperature as a result of milling the TiO2/Al mixture could be due to an increase of TiO2 and Al interface area as confirmed by TEM micrographs and XRD patterns of milled powder mixture. In addition, DTA experiments showed that for the sample in which TiO2 and Al were mechanically activated the reaction occurred at the temperature even lower than that of Al melting point.

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Abstract: Nano- size alumina particles have been synthesized by mechanical activation of a dry powder mixture of AlCl3 and CaO. Mechanical milling of the above raw materials with the conditions adopted in this study resulted in the formation of a mixture consisting of crystalline CaO and amorphous aluminum chlorides phases. There was no sign of chemical reaction occurring during milling stage as evidenced by x-ray diffraction studies. Subsequent heat treatment of the milled powder at 350ºC resulted in the occurrence of displacement reaction and the formation of Al2O3 particles within a water soluble CaCl2 matrix. The effect of higher temperature calcinations on the phase development in this powder mixture was followed by X-ray diffraction (XRD) analysis and scanning electron microscope ( SEM). Differential thermal analysis (DTA) was used to compare the thermal behavior between the milled and unmilled powders. Perhaps the most important result in this study was the observation of á-Al2O3 phase at a very low temperature of 500ºC.

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Abstracts:

nanoparticles. All the extracts were used separately for the synthesis of gold nanoparticles through the reduction of

aqueous AuCl

gold ions to gold nanoparticles. The ethanol extract of black tea and its tannin free ethanol extract produced gold

nanoparticles in the size ranges of 2.5-27.5 nm and 1.25-17.5 nm with an average size of 10 nm and 3 nm, respectively.

The prepared colloid gold nanoparticles, using the ethanol extract of black tea, did not show the appropriate stability

during storage time (24 hours) at 4

showed no particle aggregation during short and long storage times at the same conditions. To the best of our

knowledge, this is the first report on the rapid synthesis of gold nanoparticles using ethanol extract of black tea and

its tannin free fraction.

In this research the ethanol extract of black tea and its tannin free fraction used for green synthesis of gold4¯. Transmission electron microscopy and visible absorption spectroscopy confirmed the reduction ofoC. In contrast, gold colloids, which were synthesized by a tannin free fraction

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Combustion synthesis is a special thermophysico-chemical process applied for production of intermetallic compounds. In the present work, a reaction–diffusion numerical model was developed to analyze the combustion synthesis of aluminide intermetallics by self-propagating high-temperature synthesis process. In order to verify the reliability of the numerical model, an experimental setup was designed and used to perform the combustion synthesis of nickel and titanium aluminides. The developed model was further used to determine the temperature history of a powder mixture compact during self-propagating high-temperature synthesis. The effect of compact relative density on combustion temperature and wave propagation velocity was also studied.

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Abstract: Nano pore Mordenite membranes were prepared on the outer surface of ceramic tubular tubes via hydrothermal synthesis and evaluated for dehydration pervaporation of water unsymmetrical dimethylhydrazine UDMH mixtures. Highly water-selective mordenite membranes were prepared and the optimum reaction condition was found to be 24 h crystallization time and 170 °C crystallization temperature. Effect of gel composition on separation factor and water flux of the water-UDMH mixtures was investigated. X-ray diffraction (XRD) patterns showed that mordenite is the only zeolite material which presents in the membrane. Morphology of the supports subjected to crystallization was characterized by Scanning electron microscopy (SEM). In PV of the water-UDMH mixtures, the membrane exhibits a hydrophilic behavior, with a high selectivity towards water and a good flux. The best membranes had a water flux of 2.67 kg/m2.h at 27 °C. The best PV selectivity was obtained to be 264.

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Abstract: Nano-structural synthesized materials can be fabricated utilizing intensive milling after combustion synthesis. The Al2O3-TiB2 ceramic composite has been synthesized by aluminothermic reactions between Al, Ti (TiO2), and B (B2O3 or H3BO3). Boric acid (H3BO3) is less expensive than boron oxide, and after being dehydrated at 200°C, boron oxide will be obtained. In this study, Al, TiO2, and boric acid were used as the starting materials to fabricate an Al2O3-TiB2 ceramic composite. After mechanical activation and thermal explosion processes, intensive milling was performed for 5, 10, and 20h to assess the formation of a nano-structural composite. The X-ray phase analysis of the as-synthesized sample showed that considerable amounts of the remained reactants incorporated with the TiO phase were present in the XRD pattern. The results showed that the average crystallite size for alumina as a matrix were 150, 55 and 33 nm, after 5h, 10h, and 20h of intensive milling, respectively. The SEM microstructure of the as-milled samples indicated that increasing the milling duration after combustion synthesis causes a significant reduction in the particle size of the products, which leads to an increase in the homogeneity of particles size. A significant increase in the microhardness values of the composite powders was revealed after intensive milling process.

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Abstract: Microwave processing is one of the novel methods for combustion synthesis of intermetallic compounds and
composites. This method brings about a lot of opportunities for processing of uniquely characterized materials. In this
study, the combustion synthesis of TiAl/Al2O3 composite via microwave heating has been investigated by the
development of a heat transfer model including a microwave heating source term. The model was tested and verified
by experiments available in the literature. Parametric studies were carried out by the model to evaluate the effects of
such parameters as input power, sample aspect ratio, and porosity on the rate of process. The results showed that
higher input powers and sample volumes, as well as the use of bigger susceptors made the reaction enhanced. It was
also shown that a decrease in the porosity and aspect ratio of sample leads to the enhancement of the process.

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The synthesis of mesoporous CuFe2O4 spinel by several nanocasting strategies (i.e., multi-step nanocasting, one step nanocasting, modified solid-liquid), in which copper and iron nitrates are used as precursors and Pluronic P123 as surfactant, is explored. We have also checked the effect of pH, citric acid and sodium citrate in multi-step nanocasting method. The modified solid-liquid method which contains impregnating mesoporous silica by molten state salts in a non-ionic solvent seems to be the best choice to obtain single phase ordered mesoporous copper ferrite. Other methods suffer from the presence of copper oxide or hematite as impurities or lack of integrity in the mesoporous structure. Increasing pH up to 9.5 does not enhance the phase formation inside the pores of the silica matrix. The citric acid yields a fine structure but does not facilitate the phase formation. Adding sodium citrate neither heals the phase formation nor the structure of the final product. Moreover, vinyl- functionalized mesoporous silica exploited in this study as a hard template entraps both metal nitrates in the pores, assisting impregnation procedure

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A method for producing high surface area nano-sized mesoporous alumina from inexpensive Iranian kaolin as raw material is proposed. In this method, first, kaolin was purified for purifying Kaolin, High Grade Magnetic Separation and leaching with HCl and chemical bleaching treatment by using sodium dithionite (Na 2 S 2O4 ) as reducing agent in acidic media (H 2SO 4 ) were used. Purified kaolin was calcined. After that, Al (hydr) oxide from acid -leachates of calcined kaolin was precipitated with ammonia, in presence of polyethylene glycol. Finally, a white powder of nano-sized alumina particles was obtained after calcination. BET surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to characterize the sample. The resulting alumina with relatively high surface area (201.53 m 2 g -1 ) and narrow mean pore diameter (6.91 nm), consists of a particle size distribution ranging from 22 to 36 nm.

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Ceramic-matrix composites containing TiC-TiN have been used in a variety of application because of their superior properties such as high hardness, good wear resistance and high chemical stability. In this research, effect of coke and coke/calcium beds in synthesis of Al 2O3-Ti(C, N) composites using alumino-carbothermic reduction of TiO 2 has been investigated. Al, TiO 2 and active carbon with additives of extra carbon and NaCl and without additives, in separate procedures, have been mixed. Afterwards, mixtures were pressed and synthesized in 1200oC for 4hrs, in coke and coke/calcium beds, separately. Al 2O3-Ti(C,N) composite was synthesized in ternary system of Al-TiO 2 -C with excess carbon and NaCl additives in calcium/coke bed in 1200 . X-ray diffraction patterns (XRD) results showed that existence of calcium in bed resulted in intensification of reduction atmosphere in samples and formation of Ti(C,N) phase enriched from carbon was accelerated. Crystallite sizes of synthesis Ti(C,N) at 1200 °C in reducing conditions were 22-28 nm.

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B4C–Al2O3 composite powder was produced by aluminothermic reduction in Al/B2O3/C system. In this research, microwave heating technique was used to synthesize desired composite. The ball milling of powder mixtures was performed in order to study the effect of mechanical activation on the synthesis process. The synthesis mechanism in this system was investigated by examining the corresponding binary sub-reactions. The self-sustaining reduction of boron oxide by Al was recognized to be the triggering step in overall reaction.

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Boron included aluminium nitride (B-AlN) thin films were synthesized on silicon (Si) substrates through chemical vapour deposition ( CVD ) at 773 K (500 °C). tert-buthylamine (^tBuNH₂) solution was used as nitrogen source and delivered through gas bubbler. B-AlN thin films were prepared on Si-100 substrates by varying gas mixture ratio of three precursors. The structural properties of the films were investigated by X-ray diffraction (XRD) technique and verified the formation of polycrystalline and mixed phases of hexagonal (100), & (110) oriented AlN and orthogonal (002) & cubic (333) oriented BN. The crystallite size was smaller and dislocation density was higher as the deposition was conducted with lowest total gas mixture ratio (25 sccm). Improved surface properties were detected for film deposited using lowest total gas mixture ratio and confirmed by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The composition of films showed the existence of higher concentration of B in the film prepared using lower total gas mixture ratio and confirmed by energy dispersive X-ray Spectroscopy (EDX).

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The field of nanomaterial has greatly advanced in the last decade following a wider range of applications in the fields of electronics, automobiles, construction, and healthcare due to its extraordinary and ever-evolving properties. Synthesis of the nanomaterial plays a crucial role in redefining the current engineering and science field. At the same time, procuring an environment-friendly end product through eco-friendly solutions and sustainable processes is the key to many global problems. Green synthesis of nanomaterials like graphene and its derivatives involves mild reaction conditions and nontoxic precursors because it is simple, cost-effective, relatively reproducible, and often results in more stable materials. This paper primarily focuses on the green synthesis of graphene and its derivatives (graphene oxide & reduced graphene oxide) and geopolymers; a green technology for preparing graphene reinforced geopolymer composites. Various methods used globally for green synthesis of graphene and geopolymer are briefly discussed and this paper tries to integrate these two areas for a green end product. Possible applications of these green composites are also discussed to provide insights on the current growth and developments. 

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Carbon-based chemical substances persistence can contribute to adverse health impacts on human lives. It is essential to overcome for treatment purposes. The semiconducting metal oxide is Zinc Oxide (ZnO), which has excellent biocompatibility, good chemical stability, selectivity, sensitivity, non-toxicity, and fast electron transfer characteristics. The ZnO nanoparticles are more efficient compared to other metal oxide materials. Thus, the nanoparticles are in the present research situation to receive increasing attention due to their potential performance of the human body to feel comfortable. The nanoparticles become more promising for biomedical applications through the development of anticancer agents to recovery different types of malignant cells in the human body. The ZnO nanoparticles can be the future potential materials for biomedical applications. The purpose of this paper is to review the cost-effective approach to synthesize the ZnO nanoparticles. Moreover, these ideas can develop for synthesized ZnO biomaterial to perform easily up-scaled in biomedical applications.

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Indium tin oxide (ITO) nanoparticles were synthesized by green combustion method using indium (In) and tin (Sn) as precursors, and Carica papaya seed extract as novel fuel. This paper highlights effect of tin concentration (5%, 10% and 50%) on microstructural, optical and electrical properties of ITO nanoparticles (NPs). The indium nitrate and tin nitrate solution along with the fuel were heated at 600 °C for 1 h in muffle furnace and obtained powder was calcinated at 650 °C for 3 h to produce ITO NPs. The above properties were investigated using XRD, FTIR, UV-Vis spectroscopy, SEM, TEM and computer controlled impedance analyser. The XRD, SEM and TEM investigations reveals the synthesized NPs were spherical in shape with an increase in average grain size (17.66 to 35 nm) as Sn concentration increases. FTIR investigations confirms the In-O bonding. The optical properties results revealed that the ITO NPs band gap decreased from 3.21 to 2.98 eV with increase in Sn concentration. The ac conductivity of ITO NPs was found to increase with increase in Sn concentration. These synthesised ITO NPs showed the excellent properties for emerging sensor and optical device application.

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Green synthesis refers to the synthesis of nanoparticles using plants and microorganisms. It is preferred over conventional methods as its sustainable, eco-friendly, cost effective and rapid method. The phytochemicals and enzymes present in plants and microorganisms respectively acts as the reducing and capping agent for the synthesis of nanoparticles. Phytochemicals and enzymes have the ability to reduce precursor metal ions into nanoparticles. As the conventional methods involve the use of high energy and toxic chemicals which are harmful to both environment and organisms, these synthesis methods are discouraged. Of the nanoparticles, gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have gained lots of attention owing to their multiple applications and less toxicity. In addition, various in-vitro studies have reported the antimicrobial activity of AgNPs and AuNPs against various microbes. This particular review portrays the methods of nanoparticles synthesis, components of green synthesis, mechanism of green synthesis, antimicrobial activity, other applications and various factors affecting the green synthesis of AgNPs and AuNPs.

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Recently, using calcium phosphates and at the top of them, hydroxyapatite (HA) has been considered in medical and dental applications as an artificial biomaterial due to their chemical and structural similarity to the bodychr('39')s skeletal tissues such as bone and tooth. Because of reinforcement of hydroxyapatitechr('39')s mechanical and biological properties by substitution of OH- groups by F- ions to produce fluorapaptite (FA) has been proven, in this article synthesis methods, properties and medical applications of fluorapatite and its pros and cons in comparison with hydroxyapatite have been reviewed.

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This study investigates the synthesis of Al/MoS₂ nanocomposite coating by the electro spark deposition (ESD) method for its lubricating properties. ESD method was selected because it is a very easy, rapid, and cost-saving method and the resulting coating has a strong bonding with the substrate. As a substrate, a Ti-6Al-4V alloy sheet containing 6.12 % Al, 4.06 % V, 0.19% Fe, and 0.05 % Ni was used. For coating, an aluminum-molybdenum disulfide composite electrode in the form of a cylindrical rod was employed. Three frequencies of 5, 8, and 11 kHz, three current limits of 15, 25, and 35 amps, and three duty cycles of 50, 60, and 70% were used in the coating operation. AFM analysis was used to study the topography, morphology, and calculate roughness. The samples were then subjected to hardness tests. To determine the wear resistance of the samples, pin on disk tests were performed. XRD analysis was performed to identify the phases on the surface of the coated samples. SEM was used to examine the microstructure of the coating before and after wear testing, in order to determine the wear mechanism. The results indicated that the Al/MoS2 nanocomposite coating was synthesized on the substrate surface. The hardness of the reference sample is 353 Vickers, and that of the coated samples is about 200 Vickers. For the reference sample, the roughness was measured at 15.7 nm, and for the coated sample at 268.1 nm. As spark energy increased, the coefficient of friction increased by approximately 0.09. As spark energy increased, the wear rate increased by 27%. A significant increase in the Lancaster coefficient occurred around 5 joules of energy. According to the wear rate results, the sample with the lowest thickness wears 4% less than the sample with the highest thickness. The wear rate of sample 351170 is 78% lower than that of sample 150550.