Modeling the effect of particle size on the activation energy and ignition temperature of metallic nanoparticles

2012 ◽  
Vol 159 (1) ◽  
pp. 416-419 ◽  
Author(s):  
Tran X. Phuoc ◽  
Ruey-Hung Chen
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Ignition Temperature ◽  
Metallic Nanoparticles ◽  
Effect Of Particle Size

scholarly journals Effects of temperature gradient and particle size on self-ignition temperature of low-rank coal excavated from inner Mongolia, China

2019 ◽  
Vol 6 (9) ◽  
pp. 190374 ◽  
Author(s):  
Yongjun Wang ◽  
Xiaoming Zhang ◽  
Hemeng Zhang ◽  
Kyuro Sasaki
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Temperature Gradient ◽  
Ignition Temperature ◽  
Coal Particle ◽  
Critical Value ◽  
Low Rank ◽  
Low Rank Coal ◽  
Coal Particles ◽  
Effects Of Temperature

This study investigates the effects of temperature gradient and coal particle size on the critical self-ignition temperature T CSIT of a coal pile packed with low-rank coal using the wire-mesh basket test to estimate T CSIT based on the Frank–Kamenetskii equation. The values of T CSIT , the temperature gradient and the apparent activation energy of different coal pile volumes packed with coal particles of different sizes are measured. The supercriticality or subcriticality of the coal is assessed using a non-dimensional index I HR based on the temperature gradient at the temperature cross-point between coal and ambient temperatures for coal piles with various volumes and particle sizes. The critical value I HRC at the boundary between supercriticality and subcriticality is determined as a function of pile volume. The coal status of supercritical or subcritical can be separated by critical value of I HR as a function of pile volume. Quantitative effects of coal particle size on T CSIT of coal piles are measured for constant pile volume. It can be concluded that a pile packed with smaller coal particles is more likely to undergo spontaneous combustion, while the chemical activation energy is not sensitive to coal particle size. Finally, the effect of coal particle size on T CSIT is represented by the inclusion of an extra term in the equation giving T CSIT for a coal pile.

scholarly journals Magnetizing Roast for Chalcopyrite: Effect of Particle Size and Dilution

1984 ◽  
Vol 1 (3) ◽  
pp. 115-122
Author(s):  
Irina Makarow ◽  
Thomas Agrafiotis ◽  
James A. Finch
Keyword(s):  
Particle Size ◽  
Ignition Temperature ◽  
Copper Ferrite ◽  
Effect Of Particle Size ◽  
Magnetic Product

In excess oxvgen, 0-37 μm CuFeS2 became magnetic at a temperature of 280ºc. The magnetic product is copper ferrite, CuO.Fe203. The ‘magnetizing’ temperature increased with particle size apparently following the trend reported for the ignition temperature. Dilution increased the magnetizing temperature; 80% dilution by PbS, MoS2 or SiO2 increases the temperature from 280ºC to over 420ºC. Sinterina was a concurrent reaction. Nevertheless, a chalcopyrite/ galena mixture after roasting and gentle grinding was readily separated on a Davis tube.

Effect of Particle Size on Oxidation Reaction Kinetics Parameter of Cu2O Powders

2011 ◽  
Vol 284-286 ◽  
pp. 726-729 ◽  
Author(s):  
Zai Yuan Li ◽  
Yu Chun Zhai ◽  
Myongil Pang
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Apparent Activation Energy ◽  
Reaction Kinetics ◽  
Oxidation Reaction ◽  
Raw Materials ◽  
Particle Sizes ◽  
Oxide Powders ◽  
Effect Of Particle Size ◽  
Kinetics Parameter

The 0.4mol•L-1CuSO4liquor and 5mol•L-1NaOH liquor were prepared by CuSO4·5H2O and NaOH as raw materials. The Cu2O powders were prepared by dextrose reducer and PVP dispersant. The Cu2O oxidation reaction DTA-TG-DTG curves were obtained by SDT 2960 simultaneous DSC-TGA analysis apparatus. The mensuration condition were that rise temperature velocity 15°C·min-1and deoxidize gas air. The Cu2O oxidation reaction kinetics was calculated by DTA-TG-DTG curves data. The results indicate that the cuprous oxide powders shape were spherical, their particle’ sizes were 100,200,1000nm. Their apparent activation energy were 164.38, 175.54, 282.65 KJ·mol-1, the apparent activation energy increase with Cu2O particle’ size. Their frequency factors were 1.22×1013, 1.40×1013, 2.88×1020, the frequency factors increase with particle’ size Cu2O. Their reaction progressions were 1.02, 1.00, 0.96, the reaction progression increase with Cu2O particle’ size decreased.

scholarly journals Effect of Particle Size and pH Value of Slurry on Chemical Mechanical Polishing of SiO2 Film

2022 ◽  
Author(s):  
Fan Xu ◽  
Weilei Wang ◽  
Aoxue Xu ◽  
Daohuan Feng ◽  
Weili Liu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Chemical Mechanical Polishing ◽  
Ph Value ◽  
Removal Rate ◽  
Mechanical Action ◽  
Sio2 Film ◽  
Mechanical Polishing ◽  
Chemical Action ◽  
Effect Of Particle Size

Abstract This study investigated the effects of particle size and pH of SiO2-based slurry on chemical mechanical polishing for SiO2 film. It was found that the removal rates and surface roughness of the material was highly dependent on the particle size and pH. As the particle size varied, the main polishing mechanism provided the activation energy to mechanical erasure. In addition, pH affected the particle size and Zeta potential, which had an important effect on the strength of the mechanical and chemical action of the chemical mechanical polishing. The change in mechanical action greatly influenced the removal rate. According to the experimental results, the best polishing of SiO2 film was achieved with 40 nm particle size SiO2 abrasives when the pH was 4.

Thermogravimetric Study of the Effect of Particle Size on the Spontaneous Combustion of Indonesian Low Rank Coal

2013 ◽  
Vol 330 ◽  
pp. 101-105 ◽  
Author(s):  
Muksin Saleh ◽  
Yulianto Sulistyo Nugroho
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Spontaneous Combustion ◽  
Moisture Loss ◽  
Low Rank ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Isothermal Method ◽  
Size Groups ◽  
Effect Of Particle Size

Low-temperature oxidation of two Indonesian low rank coals was characterized by Thermogravimetric analysis (TGA). The effect of particle size on the spontaneous combustion of coal was examined. Coals were classified to-599+299, -299+249, -249-150, -150+76 and-76 μm size groups and through non-isothermal method scanned from 24 to 600°C at heating rate 5°C/min with air flow rate 50 mL/min. DTA thermogram shows that the transition temperatures decrease by decreasing the particle size. Furthermore, the weight loss increases by decreasing particle size. It is indicated that the propensity of coal to spontaneous combustion increase with decreasing particle size. The moisture loss activation energy and oxidation activation energy were calculated by an integral method using the Coats-Redfern formula. The results show that the propensity for spontaneous combustion of two coal samples (judged by the activation energy) increases by decreasing particle size.

Particle Size Effect on FeS Spontaneous Combustion Characters in Petroleum

2014 ◽  
Vol 608-609 ◽  
pp. 971-975
Author(s):  
Man Yang ◽  
Xian Feng Chen ◽  
Yu Jiao Shang ◽  
Ren Dong Bao
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Reaction Mechanisms ◽  
Spontaneous Combustion ◽  
Oxidation Kinetic ◽  
Mesh Size ◽  
Particle Size Effect ◽  
Particle Sizes ◽  
Heating Rates ◽  
Effect Of Particle Size

In order to evaluate the effect of particle size on FeS Spontaneous Combustion Characters, four different grain diameters of FeS particles (100, 170, 220, 320-mesh) were detected in the experiment. The reaction process at heating rates of 5°C /min in air flow from 30°C to 900°C were studied by TG-DSC and oxidation kinetic analysis. The activation energies of samples were calculated by the Coats-Redfern method. It is found that four reaction mechanisms are involved in FeS spontaneous combustion for different particle sizes; the activation energy values change from 307.4 to 398.05 kJ/mol; larger size particles have higher activation energy values; so grain diameters larger than 100-mesh size samples are less inclined to be oxidized and self-ignited.

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