Morphologic and Structural Characterization of the CoFe2O4 Synthesized by Combustion Reaction

2010 ◽  
Vol 660-661 ◽  
pp. 904-909
Author(s):  
M.S. Lima ◽  
Jean Pierre La Martini Lima Sousa ◽  
Débora A. Vieira ◽  
Hélio Lucena Lira ◽  
J.M. Sasaki ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Structural Characterization ◽  
Flame Temperature ◽  
Combustion Reaction ◽  
X Rays ◽  
Secondary Phases ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Stoichiometric Proportion

CoFe2O4 powders were synthesized by combustion reaction using glycine as fuel, aiming obtaining nanosized and monophase powders. Thus, different conditions of external heating during the synthesis were investigated. The powders were prepared according to the propellants and explosives theory, using glycine as fuel in the stoichiometric proportion (Φe = 1). During the synthesis the flame temperature and time were measured. The resulting powders were characterized by X-rays diffraction and scanning electronic microscopy (SEM). The results show that the condition in which the synthesis was done it influences in the combustion flame temperature and time and contributes for the obtainment of powders with majority phase without secondary phases. Crystallite size varied of 33 to 50 nm. All powders presented morphology constituted by soft agglomerated formed by nanoparticles.

scholarly journals Tribological Performance of CoCrMo Alloys with Boron Additions in As-Cast and Heat-Treated Conditions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 355
Author(s):  
Marco A. L. Hernandez-Rodriguez ◽  
Diego E. Lozano ◽  
Gabriela M. Martinez-Cazares ◽  
Yaneth Bedolla-Gil
Keyword(s):  
Boron Content ◽  
Tribological Performance ◽  
Secondary Phases ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Hardness Tests ◽  
Heat Treated ◽  
Cocrmo Alloys ◽  
Cast Condition ◽  
Ball On Disc

The present study evaluates the effect of boron additions on the tribological performance of CoCrMo alloys. The alloys were prepared with boron ranging from 0.06 to 1 wt%. The materials were characterized using metallographic techniques, scanning electronic microscopy, and roughness and hardness tests. Tribological evaluation was made by means of ball-on-disc tests for sliding distances of 4, 8 and 12 km. The samples were in the as-cast condition and after a heat treatment at 1200 °C for 1 h, finished by water quenching. The results showed that wear resistance was influenced by the microstructure and the number of secondary phases. The volume loss decreased as the boron content increased. Due to hard phases, abrasion wear was observed. Delamination fatigue was also detected after long sliding distances. Both wear mechanisms diminished in higher boron content alloys.

scholarly journals Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

2007 ◽  
Vol 39 (2) ◽  
pp. 145-152 ◽  
Author(s):  
Z. Andjic ◽  
M. Korac ◽  
Z. Kamberovic ◽  
A. Vujovic ◽  
M. Tasic
Keyword(s):  
Mechanical Properties ◽  
Chemical Method ◽  
Elevated Temperatures ◽  
Hydrogen Atmosphere ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Composite Powders ◽  
Nanocomposite Powders ◽  
Final Composition

In this paper synthesis of a composite based on Cu-Al2O3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electric-mechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al2O3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al2O3. Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-ray-structure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900oC for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al2O3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties. .

Influence of Fuel in the Synthesis of ZnAl2O4 Catalytic Supports by Combustion Reaction

2010 ◽  
Vol 660-661 ◽  
pp. 52-57 ◽  
Author(s):  
Kaline Melo de Souto Viana ◽  
Bruno Brito Dantas ◽  
N.A.S. Nogueira ◽  
J.M. Sasaki ◽  
Normanda Lino de Freitas ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Crystallite Size ◽  
Size Distribution ◽  
Spinel Structure ◽  
Morphological Characteristics ◽  
Combustion Reaction ◽  
Nanosized Particles ◽  
Catalytic Supports ◽  
Stoichiometric Proportion

The aim of this work is to evaluate the influence of fuel in the synthesis of ZnAl2O4 catalytic supports by combustion reaction. For this, it was used the fuels: urea, carbohidrazide, glycine and aniline. The total amount of reagents was calculated according to the theory of propellants and explosive using urea in the stoichiometric proportion (Φe = 1). The structural and morphological characteristics of the powders were evaluated by XRD, FTIR, TEM, SEM and particle size distribution. The results from XRD showed the formation of the normal cubic spinel structure. The powders presented nanosized particles with narrow agglomerates size distribution. The powders prepared with urea showed better value of surface area and smaller crystallite size.

Characterization of Shivirtui Zeolite Modified with Aluminum Oxyhydroxide Nanofibers

2019 ◽  
Vol 942 ◽  
pp. 40-49
Author(s):  
Yulia Murashkina ◽  
Olga B. Nazarenko
Keyword(s):  
Chemical Properties ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Aluminum Oxyhydroxide

Natural zeolite of Shivirtui deposit (Russia) was modified with nanofibers of aluminum oxyhydroxide AlOOH. Aluminum oxyhydroxide nanofibers were produced at the heating and oxidation of aluminum powder with water. The properties of modified zeolite were investigated by means of X-ray diffraction, transmission electronic microscopy, scanning electronic microscopy, low-temperature nitrogen adsorption, thermal analysis, and Fourier transform infrared spectroscopy. It was found that water content in the modified sample of zeolite was about 15 %. Based on the study of the physical and chemical properties, shivirtui zeolite modified with nanofibers of aluminum oxyhydroxide can be proposed for use as a flame-retardant additive to polymers.

Synthesis and Characterization of Magnetite Particles by Co-Precipitation Method

2012 ◽  
Vol 512-515 ◽  
pp. 82-85 ◽  
Author(s):  
Ming Ya Li ◽  
Xu Dong Sui
Keyword(s):  
Spinel Structure ◽  
Bath Temperature ◽  
Precipitation Method ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Magnetite Particles ◽  
Co Precipitation ◽  
Different Diameters

The Fe3O4 nanoparticles with different diameters were prepared by co-precipitation method in this paper. Magnetite particles with different diameters were fabricated by changing the concentration of the reactants and the reaction temperature. The influences of process parameters on the microstructure and properties of magnetic nanopariticles were studied. The obtained samples were characterized by X-ray powder diffraction and scanning electronic microscopy. Besides, vibrating sample magnetmeter was used to characterize the magnetic properties. The results show that all the as-synthesized magnetite nanoparticles are well crystallized and can be indexed into spinel structure. The appearance and magnetism of the particles with different diameter are different from each other. When the ratio of Fe3+ and Fe2+ is 2:1 or 4:3, the product was pure and good crystalline. Furthermore, higher saturation magnetization was obtained in a higher bath temperature.

Preparation and Characterization of NiO Nanoparticles

2015 ◽  
Vol 31 ◽  
pp. 93-102 ◽  
Author(s):  
Farrakh Shahzad ◽  
Karl Ettinger ◽  
Ilse Letofsky-Papst ◽  
Julia Weber ◽  
Peter Knoll
Keyword(s):  
Crystallite Size ◽  
Calcination Temperature ◽  
Ph Value ◽  
Sol Gel ◽  
Systematic Change ◽  
X Rays ◽  
Nio Nanoparticles ◽  
Calcination Time ◽  
Transmission Electron

NiO nanoparticles are successfully prepared by sol-gel technique. A systematic change in preparation parameters like calcination temperature, calcination time and pH value has been done in order to study the influence on crystallite size. The prepared samples are characterized by X-ray diffractometer, Transmission electron microscopy, Energy dispersive x-rays analysis and Raman spectroscopy. It is shown that crystallite size mainly depends on the calcination temperature rather than pH value or calcination time.

Magnetic and Structural Characterization of Nanostructured MgFe2O4Synthesized by Combustion Reaction

2009 ◽  
Vol 27 (6) ◽  
pp. 519-527 ◽  
Author(s):  
S. Da Dalt ◽  
A. S. Takimi ◽  
V. C. Sousa ◽  
C. P. Bergmann
Keyword(s):  
Structural Characterization ◽  
Combustion Reaction

Preparation and Characterization of PbO2 Electrode Modified with Praseodymium

2013 ◽  
Vol 721 ◽  
pp. 37-40 ◽  
Author(s):  
Shu Dong Li ◽  
Feng Wu Wang ◽  
Mai Xu ◽  
Wen Yan Fang ◽  
Xiao Yun Yan
Keyword(s):  
Methylene Blue ◽  
Electrochemical Properties ◽  
Active Surface ◽  
Cyclic Voltammograms ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Bulk Electrolysis

The Ti/PbO2 electrode doped with Pr2O3 was prepared by the electrodeposition method. The X-ray diffraction (XRD) analyses indicated the crystal particles size of Ti/PbO2/Pr2O3 electrode was diminished due to the incorporation of Pr2O3 into the film of PbO2. The scanning electronic microscopy (SEM) revealed that Ti/PbO2/Pr2O3 electrode had smaller particles and larger active surface. The measurement of cyclic voltammograms (CV) revealed Ti/PbO2/Pr2O3 electrode had a better electrochemical properties comparing to Ti/PbO2 electrode. The bulk electrolysis demonstrated that the Ti/PbO2/Pr2O3 electrode presented excellent electrocatalytic performance for degradation methylene blue.

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