Viscous flow activation energy adaptation by isothermal spark plasma sintering applied with different current mode

2018 ◽  
Vol 149 ◽  
pp. 125-128 ◽  
Author(s):  
Siyao Xie ◽  
Ruidi Li ◽  
Tiechui Yuan ◽  
Mei Zhang ◽  
Minbo Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Viscous Flow ◽  
Spark Plasma Sintering ◽  
Current Mode ◽  
Flow Activation Energy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Flow Activation

scholarly journals Research on Polymer Viscous Flow Activation Energy and Non-Newtonian Index Model Based on Feature Size

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Yan Lou ◽  
Qunan Lei ◽  
Gang Wu
Keyword(s):  
Activation Energy ◽  
Viscous Flow ◽  
Crystalline Polymer ◽  
Polymer Materials ◽  
Macroscopic Scale ◽  
Feature Size ◽  
Flow Activation Energy ◽  
Microscopic Scale ◽  
Index Model ◽  
Flow Activation

The viscous flow activation energy and non-Newtonian index properties of polymer based on feature size were studied through a series of experiments on the rheological properties of amorphous polymer polymethyl methacrylate (PMMA), semi-crystalline polymer polypropylene (PP), and crystalline polymer high-density polyethylene (HDPE) using capillary die with hole diameters of φ0.3 mm, φ0.5 mm, φ1.0 mm, and φ2.0 mm. The results show that the viscous flow activation energy of PMMA decreases with the feature size under microscopic scale. And the viscous flow activation energy of PP and HDPE increases with hole diameters of the die. Under macroscopic scale, the difference in viscous flow activation energy of all polymer materials is significantly reduced with hole diameters of the die. For the non-Newtonian index of the three polymer materials, it decreases with the feature size under the microscopic scale while it increases or does not change with the feature size under the macroscopic scale. At the same time, for different high polymer materials, the viscous flow activation energy model (SVAE model) and non-Newtonian index model (SNNE model) based on feature size were established. Finally, the accuracy and effectiveness of the SVAE model and the SNNE model are verified by comparing with the traditional model and reference data. The viscous flow activation energy and non-Newtonian index values of the polymer material can be calculated conveniently and accurately.

scholarly journals Effect of Solid Additives on the Rheological Property of Nitroglycerin Plasticized Nitrocellulose

2020 ◽  
Vol 30 (1) ◽  
pp. 14-26
Author(s):  
Le Qi ◽  
Zhongliang Ma ◽  
Jiahao Liang ◽  
Zhongliang Xiao
Keyword(s):  
Activation Energy ◽  
Viscous Flow ◽  
Shear Viscosity ◽  
Energetic Materials ◽  
Energetic Material ◽  
Extrusion Process ◽  
Zero Shear Viscosity ◽  
Flow Activation Energy ◽  
Solvent Content ◽  
Flow Activation

AbstractThe rheological properties of energetic materials comprising nitroglycerin plasticized nitrocellulose were studied using rheological tests in a parallel plate rheometer. The Carreau-Yasuda equation was applied to calculate the zero-shear viscosity, and the dependence of solid additives, temperature and solvent content on zero-shear viscosity was developed. One can study flow characteristics of the energetic materials by observing the zero-shear viscosity instead of the effect of solid additives, temperature and solvent content. Additionally, the relationship between zero-shear viscosity and additives concentration was studied. The Kissinger-Akahira-Sunose (KAS) method was used to obtain the viscous flow activation energy, and the equation to describe the relationship between solid additives concentration and viscous flow activation energy was represented. The Zero-Shear Viscosity (ZSV) test showed that temperature was the predominant effect on the ZSV value at low solvent content, as the concentration of solid additives increased, the ZSV value decreased at low solvent content but increased at high one, however, there is an opposite trend when graphene concentration is above 0.1%. The viscous flow activation energy showed different changing trends with solid concentration that increased at different solvent content. The master curves were obtained by Time-Temperature Equivalence Principle, the viscosity prediction model has been established and showed a good agreement with the experimental data, compared with the test results, the viscosity prediction model is more accurate at low temperature (15°C-25°C). The obtained knowledge of the different equations will form a contribution to the research on extrusion process of this energetic material containing Cyclotrimethylenetrinitramine (RDX) and graphene, and the results obtained by this research have certain practical significance of the extrusion process for this energetic material.

Viscous flow spark plasma sintering of glass microspheres with YAG composition and high tendency to crystallization

2021 ◽  
Vol 41 (2) ◽  
pp. 1537-1542
Author(s):  
Monika Michálková ◽  
Jozef Kraxner ◽  
Milan Parchovianský ◽  
Róbert Klement ◽  
Václav Pouchlý ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Spark Plasma Sintering ◽  
Glass Microspheres ◽  
High Tendency ◽  
Plasma Sintering ◽  
Spark Plasma

Spark plasma sintering of WC – 10 Co nanopowders with various carbon content obtained by plasma-chemical method

2020 ◽  
pp. 73-86
Author(s):  
Yu. V. Blagoveshchenskiy ◽  
◽  
N. V. Isaeva ◽  
E. A. Lantsev ◽  
M. S. Boldin ◽  
...  
Keyword(s):  
Activation Energy ◽  
Carbon Content ◽  
Spark Plasma Sintering ◽  
High Speed ◽  
Diffusion Creep ◽  
Powder Materials ◽  
Plasma Chemical ◽  
Colloidal Graphite ◽  
Plasma Sintering ◽  
Spark Plasma

The features of high-speed sintering of WC – Co nanopowders with various contents of excess carbon (colloidal graphite) were studied. To obtain powders, a process was used that included plasma-chemical and low-temperature syntheses and a chemical-metallurgical method of applying ultrathin cobalt layers by precipitation from a solution of salts. The consolidation of powder materials was carried out by the method of high-speed Spark Plasma Sintering. It was found that an increase in the concentration of free carbon (colloidal graphite) has the greatest effect on the shrinkage and sintering rate at the stage of intense shrinkage of WC-Co nanopowders. It is shown that an increase in the carbon content in the composition of nanopowders leads to a decrease in the value of sintering activation energy at the stage of intense shrinkage.It has been established that the process of nanopowder compaction at the intense shrinkage stage is determined by the intensity of the plastic flow and the grain boundary diffusion of cobalt. It is shown that the mechanism of plastic deformation of the γ-phase based on cobalt corresponds to the Coble diffusion creep. It was found that an increase in carbon content leads to decreased in activation energy at the intense shrinkage and does not significantly affect at stage III of sintering where decrease in the shrinkage intensity is observed. It was shown that a decrease in the sintering activation energy is due to a decrease in the tungsten concentration in the γ-phase.

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