Fuel effects on properties of alumina nanoparticles synthesized by combustion technique (original) (raw)
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Effect of Adiabatic Flame Temperature on Nano Alumina Powders during Solution Combustion Process
Transactions of the Indian Ceramic Society, 2011
Nano ceramic alumina powders are synthesized by solution combustion synthesis using aluminium nitrate as oxidizer and urea as fuel with different fuel to oxidizer ratio. The variation of adiabatic flame temperatures are calculated theoretically for different fuel/oxidizer ratio according to thermodynamic concept and correlated with the observed flame (reaction) temperatures. A "multi channel thermocouple setup connected to computer interfaced Keithley multi meter 2700" is used to monitor the thermal events occurring during the process. The combustion products, characterized by XRD, show that the powders are composed of polycrystalline oxides with crystallite size of 32 to 52 nm. An interpretation based on maximum combustion temperature and the amount of gases produced during reaction for various fuel to oxide ratio has been proposed for the nature of combustion and its correlation with the characteristics of as-synthesized powder.
SYNTHESIS OF ALUMINA NANOPOWDER USING MIXED FUEL BY SOLUTION COMBUSTION APPROACH.docx
The combustion synthesis is a technique using Glycine and urea as fuels and aluminium nitrate as an oxidizer to produce alumina nano powder. The combustion reaction shows the variation of gases produced and combustion temperature with variation in fuel to oxidizer ratio. Amorphous structure is observed for as-synthesized powder using glycine alone. Crystallinity can be obtained by further calcination at desired temperature. Crystalline alumina powder can be obtained by using urea as a fuel. By using the mixed fuel (Glycine+Urea), there will be sufficient energy for combustion and good crystalline alumina powder can be obtained. The obtained alumina powder is free from organic residues. X-ray diffraction shows the formation of pure alumina powder. SEM (Scanning Electron Microscope) studies show the morphology of the powder.
Specific Surface Area Increment of Alumina Nanoparticles Using Mineral Fuels in Combustion Synthesis
Journal of Nanostructures, 2012
Ammonium carbonate and ammonium sulfate have been proposed and used as two new fuels for synthesizing gamma alumina nanoparticles. The prepared samples have been characterized by X-ray diffraction (XRD), 2 N adsorption (BET) and Transmission electron microscopy (TEM). A comparison has been made between the properties of the nanoparticles synthesized by these two fuels and other conventional fuels. These two mineral fuels showed to be suitable for replacing organic fuels in combustion synthesis because they reduce the size and increase specific surface area of alumina nanoparticles effectively.
Solution Combustion Preparation Of Nano-Al2O3: Synthesis and Characterization
The aluminum oxide materials are widely used in ceramics, refractories and abrasives due to their hardness, chemical inertness, high melting point, non-volatility and resistance to oxidation and corrosion. The paper describes work done on synthesis of α-alumina by using the simple, non-expensive solution combustion method using glycine as fuel.Aluminum oxide (Al2O3) nanoparticles were synthesized by aluminum nitrate 9-hydrate as precursor and glycine as fuel. The samples were characterized by high resolution transmission electron microscopy (HRTEM), field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD) and electron dispersive spectroscopy (EDS). As there are many forms of transition aluminas produced during this process, x-ray diffraction (XRD) technique was used to identify α-alumina. The diameter of sphere-like as-prepared nanoparticles was about 10 nm as estimated by XRD technique and direct HRTEM observation. The surface morphological studies from SEM depicted the size of alumina decreases with increasing annealing temperature. Absorbance peak of UV-Vis spectrum showed the small bandgap energy of 2.65 ev and the bandgap energy increased with increasing annealing temperature because of reducing the size.
Main objective of present work is to study the efficiency of mixed fuel towards solution combustion synthesis of alumina powder, which otherwise prepared by single fuel and study of properties of final product with mixed fuel approach. Two different fuels, glycine and urea, along with aluminium nitrates have been used to prepare nanophase alumina powder. Different fuel to oxidizer ratios and different percentage combination of two fuels were used to prepare six samples. In all samples, nanoscale particle size obtained. Parameter which continuously changes the results of various characterisations is percentage combination of two fuels. In case where percentage of urea is higher than glycine reaction takes place with high exothermicity and hence crystallinity in product phase, whereas glycine promotes amorphous character. With mixed fuel approach, crystallinity can be enhanced easily, by calcinations of powder product at low temperature, because due to mixed urea and glycine, there is already some fraction of crystallinity observed. Overall mixed fuel approach has ability to produce nanophase alumina powder with wide range of particles size.
Combustion synthesis technique for synthesis of Aluminium oxide using urea as fuel and Aluminium Nitrate as an oxidizer is found to be easy & economical route & is able to produce Nano phase alumina powder. In present experiment urea is found to have outstanding potential towards solution combustion. Exothermicity is excellent and exothermic flame temperature increase with increase in oxidizer/ fuel ratio. A well defined crystalline structure and Nano scale particles size found after XRD and SEM analysis. Overall Urea-Nitrate combustion synthesis has an outstanding potential for producing pure Alumina powder. Crystallinity is excellent in case of urea, which leads to use in applications require high strength crystalline material.
AlN nanoparticles were synthesized by carbothermal reduction method using a combustion synthesis precursor derived from aluminum nitrate, glucose, and urea mixed solution. Effects of urea on the combustion temperature of solutions, the particle size and morphology of precursors, the intermediate formed -alumina, and the synthesized AlN were studied in detail. The results indicated that the homogeneous mixture of amorphous (Al2O3 + C) precursor might be prepared by selecting an optimum molar ratio of urea to aluminum nitrate (U/Al) in solution by combustion synthesis method. Furthermore, a regular variation in the particle size and morphology of precursors had been observed with increasing (U/Al). The nitridation products, synthesized at 1500 ◦C, retained the characteristics of -alumina in the precursors. The nitridation products, prepared with (U/Al = 0.5–2), comprised of well-distributed spherical particles of AlN with the average size ranging from 30 to 80 nm. Moreover, the nitridation reactivity of products with (U/Al = 0.5–2) had been found at 99%, which was significantly higher than that of the nitridation products prepared with (U/Al = 0.3, 2.5, 3) and without urea.
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/characterization-of-alumina-porous-nano-structure-with-adjusting-fuel-ratio-via-modified-auto-combustion-method https://www.ijert.org/research/characterization-of-alumina-porous-nano-structure-with-adjusting-fuel-ratio-via-modified-auto-combustion-method-IJERTV3IS080564.pdf Nano-alumina particles (Al 2 O 3-NPs) was prepared via modified auto-combustion method (MACM) using optimum ratio of citric and nitric acid as fuel. Al 2 O 3-NPs were annealed at 750 o C, 900 o C and 1200 o C for 2h. Effect of salt molar weight to fuel (SMW/F) on structure was investigated by X-ray diffraction (XRD). The XRD results revealed that the samples produced at 900 o C and 1200 o C were crystalline with a cubic and rhombohedral structure, respectively. In order to figure out the particle aggregation state, nano-particles size distribution and porosity surface, transmission electron microscopy (TEM), dynamic light scattering (DLS) and BET analysis technique were investigated, respectively. The results show that SMW/F=2.1 can be used as an optimum ratio for polymerization and stabilizer in ACM. KyewordsAuto-combustion, Nano-alumina porous, Dynamic light scattering.
Influence of fuel in the microwave assisted combustion synthesis of nano α-alumina powder
Microwave assisted combustion synthesis is used for fast and controlled processing of advanced ceramics. Single phase and sinter active nano crystalline alpha alumina powders were successfully synthesized by different fuel-to-oxidant molar ratios using aluminium nitrate as an oxidiser, glycine as a reducing agents and millipore water as a solvent by microwave assisted combustion synthesis. Thermodynamic modelling of the combustion reaction shows that as the fuel-to-oxidant ratio increases, the amount of gases produced and adiabatic flame temperature also increases. The precursor powders were investigated by thermogravimetry (TG) analyses. The as prepared precursors calcined at 900 to 1200°C in air atmosphere were characterized for their structure and morphology. The thermal analyses (TG/DSC), X-ray diffraction (XRD) and Fourier transform infra red (FT-IR) results demonstrate the effectiveness of the microwave assisted combustion synthesis. The transmission electron microscopy (TEM) observations show the different morphologies of as-prepared powders and shows the particle sizes in the range of <50 nm. The results confirm that the homogeneous, nano scale alumina powders derived by microwave assisted combustion have high crystalline quality and the morphology of the as-prepared precursor powders.