Study on the Thermodynamics and Kinetics in the Combustion Reaction between Titanium and Boron Powders

2007 ◽  
Vol 351 ◽  
pp. 189-194 ◽  
Author(s):  
K. Wang ◽  
Zheng Yi Fu ◽  
Wei Min Wang ◽  
Yu Cheng Wang ◽  
H. Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Experimental Analysis ◽  
Combustion Temperature ◽  
Raw Materials ◽  
Temperature Range ◽  
Thermodynamics And Kinetics ◽  
Diffusion Controlled ◽  
Calculated Activation

Combustion synthesis of titanium diboride(TiB2) from titanium(Ti) and boron(B) powders was studied by theoretical calculation and experimental analysis. In high temperature range or in low temperature range, the calculated activation energies are 140KJ/mol or 355KJ/mol respectively, which is described by a change from dissolution-precipitation controlled process to diffusion-controlled process. With the increase of particle size of the raw materials, combustion temperature and propagating rate will both reduce. The propagating rate decreases with the addition of diluents. Further increase of diluents may result in a stop of the combustion wave halfway or even a failure of ignition.

Basic Experiment on Lithium Removal Technique

2012 ◽  
Author(s):  
Tomohiro Furukawa ◽  
Yasushi Hirakawa
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Dissolution Rate ◽  
Chemical Reaction ◽  
Pure Water ◽  
Preliminary Investigation ◽  
Testing Temperature ◽  
Temperature Range ◽  
Removal Technique ◽  
Good Agreement

As a preliminary investigation into the establishment of a lithium removal technique for the components used at the International Fusion Materials Irradiation Facility (IFMIF), experiments were performed on the dissolution of lithium in three solvents: ethanol, pure water, and ethanol–water. In these experiments, hemispherical lithium was immersed in the solvents at constant temperatures, and the degree of dissolution was measured continuously from the height of the sample. From the obtained data, the average dissolution rate in the solvents at each testing temperature (10–90 °C) and the amount of hydrogen generated by the chemical reaction were calculated. The average dissolution rates in ethanol, pure water, and ethanol–water at 30 °C were 0.01, 1.6, and 0.43 mm/min, respectively. Although the average dissolution rate increased with the testing temperature in the low-temperature range (10–50 °C) for all solvents, this increase was saturated in the high-temperature range (50–90 °C) in experiments with pure water and ethanol–water as solvents. The volume of gas collected during each experiment was in good agreement with the volume of hydrogen assumed to be generated from the chemical reaction of lithium with the solvents.

Crystallization Characteristics and Thermal Stability of Fluor-Hydroxyapatite Composites with Zirconia

2012 ◽  
Vol 182-183 ◽  
pp. 122-125
Author(s):  
Li Li Wang ◽  
Xiu Feng Wang ◽  
Cheng Long Yu ◽  
Hong Tao Jiang
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Solid State ◽  
Low Temperature ◽  
Solid Solutions ◽  
Tricalcium Phosphate ◽  
Solid State Reaction ◽  
Calcium Fluoride ◽  
Raw Materials ◽  
Thermal Stability Of

Hydroxyapatite (HA) was synthesized in presence of 20wt% m-ZrO2by solid state reaction between tricalcium phosphate(TCP) and Ca(OH)2at 1000 °C for 2h. Similarily, Fluorine hydroxyapatite(FA) was synthesized using tricalcium phosphate and calcium fluoride as raw materials at 1000 °Cfor 3h. The as-prepared HA was mixed with 10%,25%,45%,55%,70wt% FA and the mixture was sintered at 1000°C-1400°C for 2h. The main phase and bulk density was measured. The results show that when the relative amount of FA to HA increased, the decomposition of the composite is decreased gradually because of the formation of thermally stable FHA solid solutions. Low temperature would effect the exchange of ionic between FA and HA,while high temperature would impact synthesis of composites, because high temperature would lead to dissolution of HA ,which has to react with FA. Increase the content of HA would be advantage for synthesis FHA-ZrO2composite.

scholarly journals A Study of Isothermal Curing of PMI Using DMA

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Jing Zhang ◽  
Rui Ye ◽  
Jun Zou ◽  
Jijun Tang ◽  
Hongliang Wang
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Nonequilibrium Thermodynamic ◽  
Fluctuation Theory ◽  
Avrami Equation ◽  
High Temperature Range ◽  
Dynamic Mechanical ◽  
Temperature Range ◽  
Thermodynamic Fluctuation ◽  
Relative Conversion

The isothermal curing of polymethacrylimide (PMI) is studied through the use of dynamic mechanical analysis (DMA). Based on the growth rate of measured dynamic mechanical property, the relative conversion is defined to investigate the evolution of storage modulusE′at different curing temperatures. Hsich’s nonequilibrium thermodynamic fluctuation theory, Avrami equation, and isoconversional methods are used to analyze isothermal cure kinetics of PMI. The results show that there are different increase modes ofE′at low temperature range and high temperature range, respectively. In low temperature range, the relative conversion curves include a transitional stage which is found to be strongly frequency-dependent, but this stage is not observed in the relative conversion curve in high temperature range. During the isothermal curing process, the relative evolution ofE′can be described by Hsich’s nonequilibrium thermodynamic fluctuation theory and Avrami equation. Moreover, the values and evolutions of activation energy are different in two temperature ranges, which suggest that the curing mechanism probably has changed.

Linear red/green ratiometric thermometry of Ho3+/Cr3+ co-doped red up-conversion tungstate materials

2021 ◽  
Author(s):  
Yan Zhao ◽  
Xusheng Wang ◽  
Rui Hu ◽  
Yanxia Li
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Sensitivity ◽  
Temperature Sensing ◽  
High Temperature Range ◽  
Temperature Range ◽  
Co Doped ◽  
Sensing Performance

Existing optical thermometers are faced with the challenges of high sensitivity limited to a very narrow high temperature range, while also lacking low temperature sensing performance. A new linear up-conversion...

Study on Combustion Synthesis and Densification Process for Titanium Diboride and Iron Layered Materials

2007 ◽  
Vol 546-549 ◽  
pp. 1401-1408
Author(s):  
Kun Wang ◽  
Jian Ping Liu ◽  
Zheng Yi Fu ◽  
Wei Min Wang ◽  
Hao Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Combustion Synthesis ◽  
Titanium Diboride ◽  
Raw Materials ◽  
Combustion Process ◽  
Layered Materials ◽  
Propagation Rate ◽  
Interfacial Bonding ◽  
Densification Process ◽  
Temperature Range

The combustion synthesis and densification process for titanium diboride and iron layered materials in the process of Self-propagating high-temperature synthesis of titanium diboride, variation of the initial temperature, amount of diluent and particle size of raw materials had effect on the adiabatic temperature, fraction of melted product and propagation rate of the combustion process, were studied by theoretical calculation and experimental analysis. The result showed that divided by a combustion temperature 3050K, either in the high temperature range or in the low temperature range, the calculated process activation energies were 140 KJ/mol or 355 KJ/mol respectively, which revealed two different reaction process mechanisms. Interfacial bonding between TiB2+Fe cermet and Fe substrate was analyzed by EPMA, which showed interfacial bonding of two-layered product was obtained by the dissolution and the diffusion of Ti in the Fe substrate and joining of Fe binder with Fe substrate. The fractures of joints took place in the TiB2+Fe cermet layer rather than at the interface.

Resource Saving Technology for Plasma Treatment of Molybdenum Ore Tailings

2014 ◽  
Vol 682 ◽  
pp. 515-518 ◽  
Author(s):  
Oleg G. Volokitin ◽  
Nelli K. Skripnikova ◽  
Valentin V. Shekhovtsov
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Plasma Treatment ◽  
Raw Materials ◽  
Silicate Melts ◽  
Low Temperature Plasma ◽  
Resource Saving ◽  
Temperature Plasma ◽  
Mineral Fibers

In the production of mineral fibers it is possible to synthesize high-temperature silicate melts from molybdenum ore tailings using low-temperature plasma. Physicochemical research was carried out in relation to raw materials and melt products.

Effect of Ce3+/Ce4+ Couple on Selective Hydrogenation of Crotonaldehyde over Pt/CeO2 Catalyst

2011 ◽  
Vol 233-235 ◽  
pp. 1592-1596
Author(s):  
Guan Qun Xie ◽  
Yan Hui Dai ◽  
Xi Jing Liu ◽  
Meng Fei Luo ◽  
Xiao Nian Li
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Selective Hydrogenation ◽  
Temperature Reduction ◽  
Crotyl Alcohol

By pretreatment of Pt/CeO2catalysts with high temperature reduction and subsequent low temperature reoxidation, the concentration of Ce3+species in the Pt/CeO2catalysts could be adjusted, while at the same time the Pt particle size remained constant. Thus the pure effect of Ce3+/Ce4+couples on the selective hydrogenation of crotonaldehdye could be explored. The investigation provided direct proofs supporting that Ce3+species favors the crotyl alcohol selectivity.

Non-isothermal thermogravimetric analysis of heavy oil in an O2/CO2 atmosphere

2018 ◽  
Vol 16 (6) ◽  
Author(s):  
Zhiqiang Wang ◽  
Ming Liu ◽  
Xingxing Cheng ◽  
Yusheng He ◽  
Yingjie Hu ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Thermogravimetric Analysis ◽  
Low Temperature ◽  
Oxygen Concentration ◽  
Heavy Oil ◽  
Combustion Process ◽  
Molecular Weights ◽  
Diffusion Controlled ◽  
Temperature Activation

Abstract Although heavy oil is an abundant and promising energy source, its processing and utilization are complicated due to its high density, low hydrogen/carbon ratio, and high asphaltene content. Fortunately, these problems can be mitigated by the application of oxy-fuel combustion. To gain deeper insights into the above technology, the characteristics of heavy oil combustion in an O2/CO2 atmosphere was investigated using non-isothermal thermogravimetric analysis. We demonstrate that the combustion process consisted of four stages. Low-molecular-weight hydrocarbons reacted at low temperature, whereas heavy ones required a higher temperature. Increasing the concentration of oxygen resulted in increased TGA and DSC peak intensities and decreased peak widths, and these peaks were shifted to lower temperatures. Coat-Redfern and Flynn-Wall-Ozzawa methods were used to evaluate the kinetic parameters (E, A) of the oxidation process, showing that the high-temperature activation energy was much higher than the low-temperature one due to the different molecular weights of the oxidized substrates in each region. The reaction was demonstrated to be diffusion-controlled, as reflected by the lower activation energy at high oxygen concentration and high temperature, with the influence of oxygen concentration on QO processes being much more obvious than that on SO ones.

scholarly journals Study on Performance Optimization of Composite Natural Asphalt Modified Gussasphalt Mix

Coatings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 78
Author(s):  
Huadong Sun ◽  
Peng Jiang ◽  
Yongling Ding ◽  
Laixue Pang ◽  
Yinbin Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Performance Optimization ◽  
Temperature Stability ◽  
Superior Performance ◽  
Engineering Properties ◽  
High Temperature Stability ◽  
Temperature Range ◽  
Natural Asphalt ◽  
Modified Binder

In order to systematically study and develop a type of gussasphalt (GA) mix with superior performance, namely GA-10; the effect of Qingchuan Rock Asphalt (QRA) and Trinidad Lake asphalt (TLA) on the GA-10 mix was assessed based on the study of composite natural asphalt modified gussasphalt (CNAMGA) binder. Various analytical tests were used to evaluate the engineering properties, thermal stability and microstructure of CNAMGA mix. The results indicate that the stability of QRA modified binder and TLA modified binder in the normal temperature range and the high temperature range have been improved, and the temperature susceptibility is reduced. The optimal asphalt–aggregate ratio of the GA mix is determined to be 9.7%, which has good high-temperature stability, low-temperature crack resistance and construction workability. The QRA mix has better high-temperature stability than the TLA mix, whereas the low-temperature cracking resistance of the TLA mix is better than that of the QRA mix. The two kinds of GA-10 mix have similar construction workability. The fact that the abundant fine aggregates wrapped in binder fill the coarse aggregates surface contributes to the better adhesion of the GA asphalt concrete. The distribution of aggregate and binder is relatively uniform with fewer pores, and the overall proportion of the binder is greater than that of aggregate.

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