Oxidation pathway and kinetics of titania slag powders during cooling process in air

2021 ◽  
Vol 28 (6) ◽  
pp. 981-990
Author(s):  
Wen-chao He ◽  
Xue-wei Lü ◽  
Cheng-yi Ding ◽  
Zhi-ming Yan
2019 ◽  
Vol 38 (2019) ◽  
pp. 567-575 ◽  
Author(s):  
Qingfu Tang ◽  
Dong Chen ◽  
Bin Su ◽  
Xiaopeng Zhang ◽  
Hongzhang Deng ◽  
...  

AbstractThe microstructure evolution of U-Nb alloys during solidification and consequent cooling process was simulated using a cellular automaton (CA) model. By using this model, ϒ phase precipitation and monotectoid decomposition were simulated, and dendrite morphology of ϒ phase, Nb microsegregation and kinetics of monotectoid decomposition were obtained. To validate the model, an ingot of U-5.5Nb (wt.%) was produced and temperature measuring experiment was carried out. As-cast microstructure at different position taken from the ingot was investigated by using optical microscope and SEM. The effect of cooling rate on ϒ phase precipitation and monotectoid decomposition of U-Nb alloys was also studied. The simulated results were compared with the experimental results and the capability of the model for quantitatively predicting the microstructure evolution of U-Nb alloys during solidification and consequent cooling process was assessed.


1984 ◽  
Vol 62 (4) ◽  
pp. 729-735 ◽  
Author(s):  
John W. Bunting ◽  
Glenn M. Kauffman

The kinetics of disproportionation and ferricyanide ion oxidation of the 10-methylacridinium cation have been measured spectrophotometrically over the pH range 9–14 in.20% CH3CN – 80% H2O (v/v) and ionic strength 1.0 at 25 °C. Disproportionation is kinetically second-order in total acridine species. The pH–rate profile is consistent with the rate-determining reaction of one acridinium cation with the pseudobase alkoxide anion derived from a second acridinium cation. Ferricyanide ion oxidation is kinetically first-order in each of ferricyanide ion and total acridine species. The pH–rate profile requires three distinct pathways for the ferricyanide ion oxidation of the 10-methylacridinium cation. For pH < 9.7, rate-determining attack of ferricyanide ion on the neutral pseudobase predominates, while for pH > 12.8 the predominant oxidation pathway involves reaction of ferricyanide ion with the pseudobase alkoxide ion. Between pH 9.7 and 12.8, the major oxidation pathway involves initial disproportionation of the acridinium cation followed by ferricyanide ion oxidation of the 9,10-dihydro-10-methylacridine product. This latter route accounts for a maximum of 69% of the total ferricyanide ion oxidation at pH 11.1.


2014 ◽  
Vol 508 ◽  
pp. 110-113
Author(s):  
Rong Hua Zhang ◽  
Biao Wu ◽  
Xiao Ping Zheng

The temperature and duration of β1→α+β2 transformation of Ti-6Al-4V alloy in cooling process were measured by differential scanning calorimetry, and transformation activation energy and Avrami exponent of β1→α+β2 were also calculated. The results show that the cooling rate is in the range of 在5~20°C/min, the transformation temperature and the transformation duration β1→α+β2 transformation of Ti-6Al-4V alloy decreased with the increasing cooling rate, its transformation activation energy decreased with the increasing phase transformation volume fraction, and Avrami exponent was between 1 and 2 at 660°C.


2017 ◽  
Vol 24 (2) ◽  
pp. 229-233 ◽  
Author(s):  
Xuan-wei Lei ◽  
Ji-hua Huang ◽  
Shu-hai Chen ◽  
Xing-ke Zhao

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Hsiu-Jung Chiu ◽  
Ruey-Shi Tsai ◽  
Jieh-Ming Huang

Abstract The miscibility and crystallization kinetics of the blends of poly(e- caprolactone) (PCL) and bezoxazine (B-m) resin was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that PCL/B-m blends were miscible in the melt. Thus the blend exhibited a single glass transition temperature (Tg), which increased with increasing B-m composition and the crystal equilibrium temperature (Tmo) depressed with the addition of B-m from the Hoffman-Weeks equation analysis. The freezing crystallization temperature (Tfc) for the nonisothermal crystallization on the cooling process, and the spherulitic growth and overall crystallization rates of PCL for the isothermal crystallization were depressed with the addition of B-m component, attributing it to the dilution of PCL concentration due to the addition of B-m.


2015 ◽  
Vol 47 (1) ◽  
pp. 666-674 ◽  
Author(s):  
Dong Wang ◽  
Zhi Wang ◽  
Tao Qi ◽  
Lina Wang ◽  
Tianyan Xue

1998 ◽  
Vol 76 (6) ◽  
pp. 1078-1082 ◽  
Author(s):  
Hong Yong Sohn ◽  
Ling Zhou
Keyword(s):  

Author(s):  
J. F. DeNatale ◽  
D. G. Howitt

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.


Author(s):  
R. J. Lauf

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.


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