SYNTHESIS OF NANOSIZE SILICON CARBIDE POWDER BY CARBOTHERMAL REDUCTION OF SiO2

2012 ◽  
Vol 05 ◽  
pp. 263-269 ◽  
Author(s):  
M. DEHGHANZADEH ◽  
A. ATAIE ◽  
S. HESHMATI-MANESH
Keyword(s):  
Heat Treatment ◽  
Silicon Carbide ◽  
Phase Composition ◽  
Crystalline Silicon ◽  
High Energy ◽  
Nano Particles ◽  
Process Conditions ◽  
Sample Heat ◽  
State Reduction ◽  
Heat Treated

A mixture of silicon carbide nano-particles and nano-whiskers has been synthesized through solid state reduction of silica by graphite employing high energy planetary ball milling for 25 h and subsequent heat treatment at 1300-1700°C in dynamic argon atmosphere. Effects of process conditions on the thermal behavior, phase composition and morphology of the samples were investigated using DTA/TGA, XRD and SEM, technique, respectively. DTA/TGA analysis shows that silicon carbide starts to form at ~ 1250°C. Analysis of the XRD patterns indicates that the phase composition of the sample heat treated at 1300°C for 2 h mainly consists of SiO 2 together with small amount of β- SiC . Nano-crystalline silicon carbide phase with a mean crystallite size of 38 nm was found to be dominate phase on heat treatment temperature at ~ 1500°C. Substantial SiO 2 was still remained in the above sample. SEM studies reveal that the sample heat treated at 1500°C for 2 h contains nano-particles and nano-whisker of β- SiC with a mean diameter of almost ~ 85 nm. The results obtained were also showed that the characteristics of the synthesized SiC particles strongly depend on the mechanical activation and heat treatment conditions.

scholarly journals Влияние термообработки на электрические характеристики полуизолирующих слоев, полученных с помощью облучения n-SiC высокоэнергетическими ионами аргона

2018 ◽  
Vol 44 (6) ◽  
pp. 11 ◽  
Author(s):  
П.А. Иванов ◽  
А.С. Потапов ◽  
М.Ф. Кудояров ◽  
М.А. Козловский ◽  
Т.П. Самсонова
Keyword(s):  
Heat Treatment ◽  
Silicon Carbide ◽  
Room Temperature ◽  
High Energy ◽  
Room Temperature Resistivity ◽  
Electrical Characteristics ◽  
Near Surface ◽  
Heat Treated ◽  
Argon Ions ◽  
Temperature Resistivity

AbstractIrradiation of crystalline n -type silicon carbide ( n -SiC) with high-energy (53-MeV) argon ions was used to create near-surface semi-insulating ( i -SiC) layers. The influence of subsequent heat treatment on the electrical characteristics of i -SiC layers has been studied. The most high-ohmic ion-irradiated i -SiC layers with room-temperature resistivity of no less than 1.6 × 10^13 Ω cm were obtained upon the heat treatment at 600°C, whereas the resistivity of such layers heat-treated at 230°C was about 5 × 10^7 Ω cm.

Effect of Heat Treatment on the DC Conductivity and Activity Energy of Li2O-Fe2O3-P2O5 Glasses

2007 ◽  
Vol 336-338 ◽  
pp. 1827-1828 ◽  
Author(s):  
Ji Yong Pan ◽  
Jiang Hong Gong
Keyword(s):  
Heat Treatment ◽  
Electrical Properties ◽  
Heat Treating ◽  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Sample Heat ◽  
Heat Treated ◽  
Maximum Conductivity ◽  
Iron Phosphate Glasses ◽  
Activity Energy

Iron phosphate glasses with composition of 20Li2O-32Fe2O3-48P2O5 (in mol%) was prepared by melting, crushing and heat-treating process and the electrical properties were examined. It was found that the sample heat-treated at a temperature close to the glass transition temperature exhibit the maximum conductivity and the lowest activation energy, implying that heat-treatment may play an important role in the electrical properties of the glasses.

The Phase Composition and Structure of Silicon-Carbon Coatings

2019 ◽  
Vol 970 ◽  
pp. 283-289
Author(s):  
Alexander S. Rudenkov ◽  
Alexander V. Rogachev ◽  
Alexander N. Kupo ◽  
Petr A. Luchnikov ◽  
Nataliya Chicherina
Keyword(s):  
Heat Treatment ◽  
Silicon Carbide ◽  
Phase Composition ◽  
Ion Beam ◽  
Ion Source ◽  
Ion Beam Sputtering ◽  
Carbon Coatings ◽  
Silicon Carbon ◽  
Composition And Structure ◽  
Beam Sputtering

The effect of the formation and heat treatment modes of silicon-carbon coatings deposited by ion-beam sputtering of silicon carbide on their morphology, chemical and phase composition is determined. It has been established that an increase in the power of the ion source from 432 W to 738 W leads to a decrease in the sp3/sp2 phase ratio by 1.7 times and an increase in the ratio of Si-C/Si-O bonds by 1.9 times. It is shown that doping of carbon coatings with silicon carbide increases their heat resistance.

Laser-controlled precipitation of gold nanoparticles in silicate glasses

2003 ◽  
Vol 18 (9) ◽  
pp. 2097-2100 ◽  
Author(s):  
Xiongwei Jiang ◽  
Jianrong Qiu ◽  
Huidan Zeng ◽  
Congshan Zhu
Keyword(s):  
Heat Treatment ◽  
Gold Nanoparticles ◽  
Femtosecond Laser ◽  
Optical Switches ◽  
Sample Heat ◽  
Selective Precipitation ◽  
Heat Treated ◽  
All Optical ◽  
Potential Applications ◽  
Controlled Precipitation

We report on the observation of space-selective precipitation of gold nanoparticles in Au2O-doped silicate glass by a method of irradiation with an 800-nm femtosecond laser and further heat treatment. The irradiated region of the glass first became gray in color after irradiation with the femtosecond laser and then turned red after further heat treatment at around 520 °C, indicating that gold nanoparticles have precipitated in the irradiated region of the glass. A possible mechanism has been suggested that the Au+ ions in the region irradiated are reduced to Au0 atoms by the femtosecond laser, and then the Au0 atoms accumulate to form gold nanoparticles with the glass sample heat treated. The observed phenomenon should have potential applications in the fabrication of ultrafast all-optical switches.

OPTIMIZATION of DYNAMIC CH4 GAS HEAT TREATMENT OF NANOCRYSTALLINE STRONTIUM HEXAFERRITE

2012 ◽  
Vol 05 ◽  
pp. 752-759 ◽  
Author(s):  
R. DEHGHAN ◽  
S. A. SEYYED EBRAHIMI ◽  
H. R. KOOHDAR
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Strontium Hexaferrite ◽  
Gas Flows ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Size And Morphology ◽  
Magnetic Nature

In this research the influence of dynamic CH 4 heat treatment on Sr -hexaferrite has been investigated. With the gas heat treatment, the phase composition, particles size and the morphology of Sr -hexaferrite change significantly. Due to this, the hard magnetic nature of the material changes from hard to soft. The strontium hexaferrite powder was prepared by conventional route with calcination of the mixture of strontium carbonate and hematite at 1100°C for 1 hour. Then the resultant Sr -hexaferrite was isothermally heat treated in methane dynamic atmosphere at various temperatures and gas flows for different times. The rate of heating and cooling were 10°C/min. The optimum conditions were obtained at 950°C and 15CC/min flow for 0.5 hour. The effects of gas heat treatment on the phase composition and the particles size and morphology were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibration Sample Magnetometery (VSM) techniques. The results show the decomposition of Sr -hexaferrite and reduction of the resultant hematite mainly to iron. The crystallite size of the resultant iron was also measured below 50nm.

High Purity Ti2AlC Powder Prepared by a Novel Method

2010 ◽  
Vol 658 ◽  
pp. 340-343 ◽  
Author(s):  
Jian Feng Zhu ◽  
Guo Quan Qi ◽  
Fen Wang ◽  
Hai Bo Yang
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
High Purity ◽  
High Energy ◽  
High Energy Milling ◽  
Heat Treated ◽  
Novel Method ◽  
Increasing Temperature ◽  
Milled Powders

Ti2AlC powders with high purity were successfully synthesized via high energy milling and heat treatment of Ti, C and Al powders. The effects of composition and thermal treatment on the formation and purity of Ti2AlC were examined in detail. The results shown a mechanically induced self-propagating reaction (MSR) was triggered to form Ti3AlC2, TiC and TiAlx during the high energy milling. When the as-milled powders were heat treated, Ti2AlC was initially formed by the reaction between TiAl and TiC. With continuously increasing temperature, Ti2AlC was also produced by the reaction between TiAl and Ti3AlC2.

OPTIMIZATION OF Sr-HEXAFERRITE DYNAMIC GASEOUS HEAT TREATMENT BY CARBON MONOXIDE

2008 ◽  
Vol 22 (18n19) ◽  
pp. 3133-3138
Author(s):  
A. YOURDKHANI ◽  
S. A. SEYYED EBRAHIMI ◽  
H. R. KOOHDAR
Keyword(s):  
Heat Treatment ◽  
Carbon Monoxide ◽  
Phase Composition ◽  
Strontium Hexaferrite ◽  
Gas Flows ◽  
Hard Magnetic Material ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Size And Morphology ◽  
Magnetic Nature

In this research the influence of dynamic carbon monoxide heat treatment on Sr -hexaferrite has been investigated. Sr -hexaferrite is a hard magnetic material which under gaseous heat treatment, its phase composition and particles size and morphology change significantly. Due to these changings, the magnetic nature of the material changes from hard to soft. Strontium hexaferrite was prepared by conventional route with calcination of Sr -carbonat and hematite at 1100°C for 1 hour. Then Sr -hexaferrite was isothermally heat treated in carbon monoxide dynamic atmosphere at various temperatures and gas flows for different times. The rate of heating and cooling were 10°C/min. The optimum conditions was obtained at 850°C and 20cc/min flow for 0.5 hour. The effect of gaseous heat treatment on phase composition and particles size and morphology characterized by XRD and SEM. The results show the decomposition of Sr -hexaferrite and reduction of the resultant hematite mainly to iron. The crystallite size of the resultant powder was also measured below 50nm.

SYNTHESIS OF BARIUM HEXAFERRITE/IRON OXIDES MAGNETIC NANO-COMPOSITES VIA HIGH ENERGY BALL MILLING AND SUBSEQUENT HEAT TREATMENT

2012 ◽  
Vol 05 ◽  
pp. 519-526 ◽  
Author(s):  
M.J. MOLAEI ◽  
A. ATAIE ◽  
S. RAYGAN
Keyword(s):  
Heat Treatment ◽  
Milling Time ◽  
Barium Hexaferrite ◽  
High Energy ◽  
Magnetic Composite ◽  
Heat Treated ◽  
Milled Sample ◽  
High Density Recording ◽  
Milling Medium ◽  
Energy Ball

Barium hexaferrite ( BaFe 12 O 19) is a hard magnetic ceramic with superior magnetic properties and in powder form has potential for application in high density recording media. In this research a mechano-chemical approach was applied in order to achieve a nano-structured magnetic composite. Graphite was used to reduce barium hexaferrite in mechanical milling medium under argon atmosphere. Milling was carried out with a ball to powder mass ratio of 35 and rotation speed of 300 rpm. Effects of milling time on phase composition and morphology of the samples were evaluated by XRD and SEM techniques, respectively. XRD results revealed that after 20 hours of milling, nano-composite of BaFe 12 O 19/ Fe 3 O 4/ Fe 2 O 3 was obtained. By extending the milling time to 40 hours, FeO was detected as the dominant crystalline phase with crystallite size of 22 nm. Composite of Fe / FeO / Fe 3 O 4 was synthesized by controlled heat treatment of the 40 hours milled sample. SEM results revealed that particle size in the aforementioned heat treated composite sample reached to about 89 nm and the morphology of the samples changed slightly.

scholarly journals Impact of Pasteurization Process on the Quality and Marination Properties of Onion Juice

2020 ◽  
Vol 8 (3) ◽  
pp. 531
Author(s):  
Hande Demir ◽  
Mustafa Kemal Yıldız ◽  
İsmail Becerikli ◽  
Sevcan Unluturk ◽  
Zehra Kaya
Keyword(s):  
Heat Treatment ◽  
Enzymatic Browning ◽  
Process Conditions ◽  
Incident Intensity ◽  
Sample Depth ◽  
Heat Treated ◽  
Conventional Heat Treatment ◽  
Heat Pasteurization ◽  
K 12 ◽  
Uv C

This study aims to compare UV-C irradiation and conventional heat treatment to produce pasteurized onion juice used as a meat marinating agent. The process conditions maximizing the inactivation of target microorganism Escherichia coli K-12 were; 0.5 mm sample depth, 30 min irradiation, 7.5 mW/cm2 UV incident intensity for UV-C and, 74.5°C and 12 min for heat treatment. Except pH and non-enzymatic browning index, differences between physicochemical properties of raw, UV-C and heat-treated onion juices were significant. Springiness and chewiness of unmarinated beefsteaks were higher compared to the ones marinated with the fresh and pasteurized onion juice (UV-C and heat). Pasteurization of onion juice (UV-C and heat) did not significantly affect general liking scores compared to beefsteaks marinated in untreated onion juice.

Nanocrystalline Formation and Magnetic Properties in Fe2O3–C System by Mechanical Alloying

2021 ◽  
Vol 21 (7) ◽  
pp. 3791-3794
Author(s):  
Chung-Hyo Lee
Keyword(s):  
Heat Treatment ◽  
Solid State ◽  
Mechanical Alloying ◽  
Saturation Magnetization ◽  
Two Phase ◽  
Reaction Heat ◽  
State Reduction ◽  
Heat Treated ◽  
Average Grain Size ◽  
Solid State Reduction

The effect of mechanical alloying (MA) on the solid state reaction of hematite and graphite system with a positive reaction heat was investigated using a mixture of elemental Fe2O3–C powders. The solid state reduction of hematite to Fe3O4 has been obviously observed after 3 hours of MA by a vibrating ball mill. A two-phase mixture of Fe3O4 and remaining Fe2O3 is obtained after 5 hours of MA. Saturation magnetization gradually increases with MA time due to the formation of Fe3O4 and then reaches 23 emu/g after 5 hours of MA. In addition, a Fe3O4 single phase is obtained by MA after 3 hours and subsequently heat treated up to 700°C. X-ray diffraction result shows that the average grain size of Fe3O4 prepared by MA for 5 hours and heat treatment to be in the range of 92 nm. The saturation magnetization of Fe3O4 prepared by MA and heat treatment reaches a maximum value of 56 emu/g for 5 hours MA sample. It is also observed that the coercivity of 5 hours MA sample annealed at 700 °C is still high value of 113 Oe, suggesting that the grain growth of magnetite phase during annealing process tends to be suppressed.

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