Nanostructured alumina particles synthesized by the Spray Pyrolysis method: microstructural and morphological analyses (original) (raw)

Control of structural type and particle size in alumina synthesized by the spray pyrolysis method

Solid State Ionics, 1997

Fine particles of aluminum oxide (amorphous, a, 3' and 0) have been synthesized by spray pyrolysis as a function of both in situ and annealing temperatures and nature of precursors used in the preparation method. A scanning electron micrograph study shows as-received materials constituted by filled spherical particles, the ulterior annealing leading to the formation of small crystallites on the precursor spheres.

Microstructural and morphological analysis of nanostructured alumina particles synthesized at low temperature via aerosol route

Journal of the European Ceramic Society, 2008

Structural and morphological studies in pure and Ce-doped tin dioxide nanoparticles with high stability against particle growth were performed in samples, obtained using the polymeric precursor method and prepared at different annealing temperatures. A Ce-rich surface layer was used to control the particle size and stabilize SnO 2 against particle growth. The formation of this segregated layer can contribute to a decreased surface energy, acting in the driving force, or reducing the surface mobility. Only the cassiterite SnO 2 phase was observed below 1000 C and a secondary phase (CeO 2 ) was observed for the Ce-doped SnO 2 at temperatures higher than 1000 C, when de-mixing process occurs. The evolution of crystallite size, microstrain and morphology of the nanoparticles with annealing temperatures was investigated by X-ray diffraction (XRD), associated to Rietveld refinements, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). #

Effect of Micro-Nano Particle Size Admixture on the Properties of Alumina

2015

Alumina ceramic is widely used because of its excellent chemical, thermo mechanical and dielectric properties. But low fracture toughness and flexural strength have limited some application of alumina ceramics. Size and distribution of particles have impact bearing on the structure and properties of ceramic materials. In this study, to investigate the effect of particle size of alumina, micron and nano-sized alumina particles were mixed in two different ratios, then pressed and sintered using conventional solid state sintering route. To compare the mechanical properties, 100% micro alumina and 100% nano alumina were also prepared. Sintering time was varied to select appropriate sintering cycle. Physical properties like density, apparent porosity and mechanical properties like Vickers hardness (HV), fracture toughness, at room temperature were evaluated. Microstructure was observed by means of a field emission scanning electron microscope (FESEM). It has been observed that improved p...

The Effect of Novel Synthetic Methods and Parameters Control on Morphology of Nano-alumina Particles

Nanoscale research letters, 2016

Alumina is an inorganic material, which is widely used in ceramics, catalysts, catalyst supports, ion exchange and other fields. The micromorphology of alumina determines its application in high tech and value-added industry and its development prospects. This paper gives an overview of the liquid phase synthetic method of alumina preparation, combined with the mechanism of its action. The present work focuses on the effects of various factors such as concentration, temperature, pH, additives, reaction system and methods of calcination on the morphology of alumina during its preparation.

Nanostructured alumina coatings manufactured by air plasma spraying: Correlation of properties with the raw powder microstructure

Journal of Alloys and Compounds, 2010

High energy ball milled nanostructured Al 2 O 3 ("N"), fused/crushed conventional Al 2 O 3 ("C") and sintered nanostructured Al 2 O 3 ("S") powders were air plasma sprayed on 304 stainless steel. The nanostructured powder was composed of nanoparticle agglomerates, whereas the conventional powder consisted of solid granules. The average crystal size of the powders was estimated by X-ray diffraction based methods (the Scherrer equation and the Williamson Hall plot). Deviations between the crystal sizes calculated by the two methods indicated high lattice strain induced by the nanopowder production technique. Sintering of the nanopowder did not cause any considerable grain growth; moreover, the strain was alleviated.

Fuel effects on properties of alumina nanoparticles synthesized by combustion technique

Indian Journal of Pure & Applied Physics, 2016

Alumina nanopowders have been produced by solution combustion synthesis using aluminum nitrate as oxidizer and urea (U), ammonium acetate (AA) and ammonium nitrate (AN) as fuels. The fuel effects on properties of products have been studied. Enthalpy and adiabatic flame temperature are calculated theoretically for each fuel based on thermodynamic concept to determine its exothermicity. Thermogravimetric (TG) analysis has also been carried out to determine the thermal properties of the metal nitrate and fuels. The prepared samples have been characterized by X-ray diffraction (XRD), N 2 adsorption (BET) and scanning electron microscopy (SEM). The results show that by reducing the exothermicity of reaction, alumina nanopowders with smaller crystallite size, finer agglomerate and higher specific surface area are produced.

Preparation of nanosized alumina using a low cost precursor

International Journal of Nanotechnology, 2010

Alpha alumina powders have been prepared by the pyrolysis of sucrose, aluminium nitrate and ammonium nitrate. After spray pyrolysis at 400°C the mixture yields fluffy light brown precursor mass. After grinding followed by heat-treatment at 900°C and 1000°C it produced the alpha-alumina having particle sizes of 42 nm and 55 nm with surface area 12 m 2 /gm and 16 m 2 /gm respectively .The yield per unit time from precursor with ammonium nitrate is 3-4 times that of simple thermal spray pyrolysis without ammonium nitrate. The particle size and crystallite size have been decreased with increase of sucrose commensurated with ammonium nitrate in the reaction mixture. The crystallite sizes are comparable with particle sizes due to poor agglomeration due to excess addition of sucrose and ammonium nitrate.

The microstructure of alumina coatings prepared by aerosol assisted spray deposition

Surface and Coatings Technology, 2004

This paper presents the deposition of alumina coatings using a low cost aerosol assisted spray deposition (AASD) in an open atmosphere at low temperature. AASD is a variant of CVD, which involves spraying atomized precursor droplets into a heated environment where the droplets undergo decomposition and chemical reaction near the heated substrate and produce solid stable coatings. Using the same deposition method but different starting precursor (e.g. solution or suspension), dense or porous deposits could be produced using the AASD method. Dense and thin alumina coatings were deposited using a precursor solution containing aluminium alkoxide. Whereas thick porous alumina deposits were prepared using a suspension of alumina powder in alcohol solution. Such porous alumina deposits could be densified to form thick alumina coatings. Continuous CO laser was used to 2 densify the alumina deposits. The microstructure of the coatings and deposits was characterized using a combination of X-ray diffraction and scanning electron microscope methods. The dense and porous alumina coatings could be deposited by varying the processing conditions. The relationships between the growth behavior and microstructure of the coatings were also discussed.

Synthesisand characterization of alumina- and zirconia-based powders obtained by theultrasonic spray pyrolysis

Journal of Thermal Analysis and Calorimetry, 2007

The ultrasonic spray pyrolysis (USP) technique was used for synthesis of alumina- and zirconia-based powders. The starting agents were aqueous solutions, atomized by the ultrasonic spray generator and pyrolized in the furnace under the open-air conditions. The powders prepared by USP were in the form of solid and hollow aggregates (spheres) consisted of nanosize amorphous grains as determined by the microscopy and the X-ray diffraction techniques. The alumina-based powders were consolidated by the pulse plasma sintering resulting in single-phase materials. Different behavior of solid and hollow particles during the isostatic sintering is found; a higher degree of deformation of spheres is observed in the second case.