Combustion Synthesis of Cu1-xNixCr2O4 Spinel for Catalytic Applications

2005 ◽  
Vol 498-499 ◽  
pp. 663-668 ◽  
Author(s):  
P.M. Pimentel ◽  
M.F. Ginani ◽  
Antonio Eduardo Martinelli ◽  
D.M.A. Melo ◽  
A.M. Garrido Pedrosa ◽  
...  
Keyword(s):  
Combustion Synthesis ◽  
Catalytic Combustion ◽  
Fine Particles ◽  
Particle Morphology ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Heterogeneous Processes ◽  
Different Temperatures ◽  
Cost Efficient

Transition-metal spinels are efficient catalysts in a number of heterogeneous processes, such as CO oxidation, catalytic combustion of hydrocarbons and oxychlorination of methane. The properties of catalytic materials are highly dependent on the synthesis route. Spinels are often produced at high temperatures by the calcination of precursors such as powder mixtures, slurries or resins. Combustion synthesis is a cost-efficient method used to produce homogeneous and fine particles with high reproducibility. Cu0.8Ni0.2Cr2O4 spinel was obtained by the combustion of metallic nitrates using urea as fuel. The resulting powders were calcinated at different temperatures and characterized by thermogravimetric and particle size analyses, X ray diffraction, and scanning electron microscopy. The effect of urea on the control of the process and particle morphology was investigated. The results revealed the formation of porous powders with increasing crystallinity as the calcination temperature increased. Crystallization of spinel started at 700 oC.

scholarly journals Biochar-Supported FeS/Fe3O4 Composite for Catalyzed Fenton-Type Degradation of Ciprofloxacin

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1062 ◽  
Author(s):  
Yue Wang ◽  
Xiaoxiao Zhu ◽  
Dongqing Feng ◽  
Anthony K. Hodge ◽  
Liujiang Hu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Iron Sulfide ◽  
Magnetic Composite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Magnetite Fe3o4 ◽  
Different Temperatures ◽  
Cost Efficient

The Fenton-type oxidation catalyzed by iron minerals is a cost-efficient and environment-friendly technology for the degradation of organic pollutants in water, but their catalytic activity needs to be enhanced. In this work, a novel biochar-supported composite containing both iron sulfide and iron oxide was prepared, and used for catalytic degradation of the antibiotic ciprofloxacin through Fenton-type reactions. Dispersion of FeS/Fe3O4 nanoparticles was observed with scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). Formation of ferrous sulfide (FeS) and magnetite (Fe3O4) in the composite was validated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ciprofloxacin (initial concentration = 20 mg/L) was completely degraded within 45 min in the system catalyzed by this biochar-supported magnetic composite at a dosage of 1.0 g/L. Hydroxyl radicals (·OH) were proved to be the major reactive species contributing to the degradation reaction. The biochar increased the production of ·OH, but decreased the consumption of H2O2, and helped transform Fe3+ into Fe2+, according to the comparison studies using the unsupported FeS/Fe3O4 as the catalyst. All the three biochars prepared by pyrolysis at different temperatures (400, 500 and 600 °C) were capable for enhancing the reactivity of the iron compound catalyst.

Functionally Graded TiC-Based Cermets via Combustion Synthesis and Quasi-Isostatic Pressing

2005 ◽  
Vol 492-493 ◽  
pp. 63-68 ◽  
Author(s):  
M. Martinez Pacheco ◽  
Marianne Stuivinga ◽  
Eric Carton ◽  
Laurens Katgerman
Keyword(s):  
Combustion Synthesis ◽  
Functionally Graded ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
Powder Mixtures ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Graded Material ◽  
Granulate Medium ◽  
Scanning Electron

Experimental results on the preparation of functionally graded TiC-based cermets obtained by combustion synthesis (also known as Self-Propagating High-Temperature Synthesis, SHS) followed by quasi-isostatic (QIP) pressing in a granulate medium are presented. Pellets of TiC-Fe graded cermets are produced by stacking layers of Ti and C powder mixtures in which the content of a NiFe alloy (50 wt% Ni and 50 wt% Fe) is varied from 5 up to 25 vol %. X-ray diffraction showed that the NiFe alloy did not react with the TiC, thus preserving its special properties. Scanning electron microscopy results show a graded material with pores increasing in size towards the side with the highest ceramic fraction.

scholarly journals Fabrication of Single-Phase NiTi by Combustion Synthesis of Mechanically Activated Powders

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
S. Mousavi Nasab ◽  
M. Aboutalebi ◽  
S. H. Seyedein ◽  
A. Molavi Kakhki ◽  
J. Vahdati Khaki
Keyword(s):  
Combustion Synthesis ◽  
Ignition Temperature ◽  
Ball Mill ◽  
Single Phase ◽  
Milling Time ◽  
Time Profile ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Temperature Time

Single-phase NiTi was fabricated through the thermal explosion mode of combustion synthesis of mechanically activated powders. Combustion and ignition temperatures of combustion synthesis were investigated in different milling times. In this process, equiatomic powder mixtures of nickel and titanium were activated by planetary ball mill and pressed into disk-shaped pellets then heated in a tube furnace, while temperature-time profile was recorded. X-ray diffraction analysis (XRD) was performed on milled powders as well as synthesized samples. Scanning electron microscopy (SEM) was also used to study the microstructural evolution during milling. The results showed that there was a threshold milling time to obtain single-phase NiTi. It was also seen that the ignition temperature and combustion temperature were reduced significantly by increasing milling time.

Effects of sintering temperature on the microstructural properties of Al2O3–Y2O3 powder mixtures

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Serkan Abalı ◽  
Songül Kılınç
Keyword(s):  
Sintering Temperature ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
Yttrium Aluminum Oxide ◽  
X Ray ◽  
Powder Sintering ◽  
Yttrium Aluminum ◽  
Different Temperatures ◽  
The Relationship

Abstract In this study, YAlO3 (YAP) was produced at low temperatures by a powder sintering process. Al2O3–Y2O3 powder mixtures were subjected to heat treatment at different temperatures. The relationship between the sintering temperature and the emergence of new phases was investigated via X-ray diffraction, and supported by energy dispersive X-ray spectroscopy. The crystallization of the monoclinic yttrium aluminum oxide (Y4Al2O9) occurred at 1 000 °C, whereas the yttrium aluminum perovskite (YAlO3) crystallization occurred at 1 100°C. Energy dispersive X-ray spectroscopy analysis showed yttrium content in the sample containing Al2O3–YAlO3 powder sintered at 1100 °C, associated with the YAlO3 phase formed at this temperature. Brunauer–Emmett–Teller surface analysis showed a significant decrease in the pore volume of the sample sintered at 1 100°C.

Effects of dry grinding on two kaolins of different degrees of crystallinity

Clay Minerals ◽  
1991 ◽  
Vol 26 (4) ◽  
pp. 549-565 ◽  
Author(s):  
F. Gonzalez Garcia ◽  
M. T. Ruiz Abrio ◽  
M. Gonzalez Rodriguez
Keyword(s):  
Specific Surface ◽  
Fine Particles ◽  
Degree Of Crystallinity ◽  
Aggregate Formation ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dry Grinding ◽  
Different Temperatures ◽  
Grinding Time

AbstractGrain-size distribution, specific surface, thermal analysis, electron microscopy and X-ray diffraction were used to study the effect of dry grinding on the structure and properties of two kaolins of different degree of crystallinity. Grinding caused particles to fragment and resulted in the formation of stable large spheroidal aggregates of fine particles. These two processes were not clearly separated by a specific grinding time, but occurred in parallel shortly after grinding was started, although aggregate formation persisted at longer grinding times. The variation in the specific surface area during grinding was found to be dependent on these two processes and on the particle size and crystallinity of the initial kaolin. DTA and XRD data and the amount of water released at different temperatures revealed grinding to gradually destroy the kaolinite structure and cause the loss of hydroxyl ions and the formation of others that were subsequently removed at low and medium temperatures. An explanation for the process whereby the new hydroxyl ions are formed is provided.

scholarly journals Effect of sintering temperature on electrical and microstructure properties of hot pressed Cu-TiC composites

2014 ◽  
Vol 46 (1) ◽  
pp. 15-21 ◽  
Author(s):  
S. Islak ◽  
D. Kır ◽  
S. Buytoz
Keyword(s):  
Electrical Conductivity ◽  
Phase Composition ◽  
Sintering Temperature ◽  
Applied Pressure ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
Pressing Method ◽  
X Ray ◽  
Different Temperatures ◽  
Scanning Electron

In this study, Cu-TiC composites were successfully produced using hot pressing method. Cu-TiC powder mixtures were hot-pressed for 4 min at 600, 700 and 800?C under an applied pressure of 50 MPa. Phase composition and microstructure of the composites hot pressed at different temperatures were characterized by X-ray diffraction, scanning electron microscope, and optic microscope techniques. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. With the increasing sintering temperature, hardness of composites changed between 64.5 HV0.1 and 85.2 HV0.1. The highest electrical conductivity for Cu-10 wt.% TiC composites was obtained for the sintering temperature of 800?C, with approximately 68.1% IACS.

Effect of synthesis and activation methods on the character of CoMo/ultrastable Y-zeolite catalysts

2021 ◽  
Vol 19 (1) ◽  
pp. 745-754
Author(s):  
Khoirina Dwi Nugrahaningtyas ◽  
Eddy Heraldy ◽  
Rachmadani ◽  
Yuniawan Hidayat ◽  
Indriana Kartini
Keyword(s):  
Electron Microscopy ◽  
Reduction Process ◽  
Particle Morphology ◽  
Zeolite Catalysts ◽  
X Ray Diffraction ◽  
Y Zeolite ◽  
X Ray ◽  
Irregular Particle ◽  
Transmission Electron ◽  
Pure Metals

Abstract The properties of three types of CoMo/USY catalysts with different synthesized methods have been studied. The sequential and co-impregnation methods followed by activation using calcination and reduction process have been conducted. The properties of the catalysts were examined using Fourier-transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD) with refinement, and surface area analyzer (SAA). The FTIR spectrum study revealed the enhanced intensity of its Bronsted acid site, and the XRD diffractogram pattern verified the composition of pure metals, oxides, and alloys in the catalyst. The SAA demonstrated the mesoporous features of the catalyst. Scanning electron microscopy showed an irregular particle morphology. Additional analysis using the transmission electron microscopy indicated that the metal has successfully impregnated without damaging the USY structure.

scholarly journals A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

scholarly journals Hydrothermal Ageing and Its Effect on Fracture Load of Zirconia Dental Implants

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3103
Author(s):  
Laurent Gremillard ◽  
Agnès Mattlet ◽  
Alexandre Mathevon ◽  
Damien Fabrègue ◽  
Bruno Zberg ◽  
...  
Keyword(s):  
Dental Implants ◽  
Fracture Load ◽  
Accelerated Ageing ◽  
Dental Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dental Restorations ◽  
Different Temperatures ◽  
Mechanical Performances ◽  
Kinetics Of

Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack of confidence in their durability and, in particular, in their ability to resist hydrothermal ageing. In the present study, the ageing kinetics of commercial zirconia dental implants are characterized by X-ray diffraction after accelerated ageing in an autoclave at different temperatures, enabling their extrapolation to body temperature. Measurements of the fracture loads show no effect of hydrothermal ageing even after ageing treatments simulated a 90-year implantation.

scholarly journals Modeling of magneto-conductivity of bismuth selenide: a topological insulator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Field Range ◽  
X Ray ◽  
Bulk Carriers ◽  
Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

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