scholarly journals Reaction Mechanism and Process Control of Hydrogen Reduction of Ammonium Perrhenate

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 640
Author(s):  
Junjie Tang ◽  
Yuan Sun ◽  
Chunwei Zhang ◽  
Long Wang ◽  
Yizhou Zhou ◽  
...  
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Hydrogen Reduction ◽  
Reduction Rate ◽  
Reduction Reaction ◽  
High Density ◽  
Reduction Temperature ◽  
Ammonium Perrhenate

The preparation of rhenium powder by a hydrogen reduction of ammonium perrhenate is the only industrial production method. However, due to the uneven particle size distribution and large particle size of rhenium powder, it is difficult to prepare high-density rhenium ingot. Moreover, the existing process requires a secondary high-temperature reduction and the deoxidization process is complex and requires a high-temperature resistance of the equipment. Attempting to tackle the difficulties, this paper described a novel process to improve the particle size distribution uniformity and reduce the particle size of rhenium powder, aiming to produce a high-density rhenium ingot, and ammonium perrhenate is completely reduced by hydrogen at a low temperature. When the particle size of the rhenium powder was 19.74 µm, the density of the pressed rhenium ingot was 20.106 g/cm3, which was close to the theoretical density of rhenium. In addition, the hydrogen reduction mechanism of ammonium perrhenate was investigated in this paper. The results showed that the disproportionation of ReO3 decreased the rate of the reduction reaction, and the XRD and XPS patterns showed that the increase in the reduction temperature was conducive to increasing the reduction reaction rate and reducing the influence of disproportionation on the reduction process. At the same reduction temperature, reducing the particle sizes of ammonium perrhenate was conducive to increasing the hydrogen reduction rate and reducing the influence of the disproportionation.

scholarly journals Grinding Kinetics of Slag and Effect of Final Particle Size on the Compressive Strength of Alkali Activated Materials

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 714 ◽  
Author(s):  
Evangelos Petrakis ◽  
Vasiliki Karmali ◽  
Georgios Bartzas ◽  
Konstantinos Komnitsas
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Ageing Time ◽  
Reduction Rate ◽  
Curing Temperature ◽  
Alkali Activation ◽  
Final Particle ◽  
Alkali Activated

This study aims to model grinding of a Polish ferronickel slag and evaluate the particle size distributions (PSDs) of the products obtained after different grinding times. Then, selected products were alkali activated in order to investigate the effect of particle size on the compressive strength of the produced alkali activated materials (AAMs). Other parameters affecting alkali activation, i.e., temperature, curing, and ageing time were also examined. Among the different mathematical models used to simulate the particle size distribution, Rosin–Rammler (RR) was found to be the most suitable. When piecewise regression analysis was applied to experimental data it was found that the particle size distribution of the slag products exhibits multifractal character. In addition, grinding of slag exhibits non-first-order behavior and the reduction rate of each size is time dependent. The grinding rate and consequently the grinding efficiency increases when the particle size increases, but drops sharply near zero after prolonged grinding periods. Regarding alkali activation, it is deduced that among the parameters studied, particle size (and the respective specific surface area) of the raw slag product and curing temperature have the most noticeable impact on the compressive strength of the produced AAMs.

Rheology and fluid loss of a polyacrylamide-based micro-gel particles in a water-based drilling fluid

2020 ◽  
Vol 10 (5) ◽  
pp. 657-662
Author(s):  
Gang Wang ◽  
Honghai Fan ◽  
Guancheng Jiang ◽  
Wanjun Li ◽  
Yu Ye ◽  
...  
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Drilling Fluid ◽  
Crosslinking Agent ◽  
Fluid Loss ◽  
Temperature Property ◽  
Water Based ◽  
The Cross

In this paper, the cross-linked micro-gel polymer between acrylamide (AM) and N, N-Methylenebisacrylamide (MBA) was synthesized by dispersion polymerization. The initiator and crosslinking agent concentration were used to control the particle size of micro-gel polymer. The filtration property and mechanism of micro-gel were investigated comprehensively. The characteristics of micro-gel were checked by means of Fourier transform infrared spectroscopy, thermogravimetry, transmission electron microscopy, and particle size distribution, respectively. The results indicated that the cross-linked micro-gel polymer exhibited several outstanding merits, such as thermal stability (up to 200 °C), filtration control and rheological property. Microstructure analysis and particle size distribution examinations showed that the scale of micro-gel polymer was micro, which is in accord with design. Rheological tests demonstrated that the nonlinear structure of micro-gel polymer showed less impact on the apparent viscosity. The anti-high temperature property of micro-gel polymer was better than poly anioniccellulose (PAC) and asphalt widely applied in drilling fluid for anti-high temperature fluid-loss additive. As a result, the cross-linked micro-gel polymer had great potential to be applied in high temperature water-based mud.

Synthesis of hypoxia-high density TZM alloy based on mechanochemistry and particle size distribution theories

2017 ◽  
Vol 698 ◽  
pp. 994-1001 ◽  
Author(s):  
Ping Hu ◽  
Tian Chang ◽  
Zhi-tao Yu ◽  
Fan Yang ◽  
Bo-liang Hu ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
High Density

EFFECT OF COATING CONTENT ON THE PROPERTIES OF A1(OH)3–Y(OH)3/ZrB2 COMPOSITE PARTICLES

2007 ◽  
Vol 14 (03) ◽  
pp. 445-449 ◽  
Author(s):  
JIE-GUANG SONG ◽  
LIAN-MENG ZHANG ◽  
JUN-GUO LI ◽  
JIAN-RONG SONG
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Oxidation Resistance ◽  
Zirconium Diboride ◽  
Resistance Ratio ◽  
Composite Particles ◽  
High Temperature Materials

Zirconium diboride is widely applied to high-temperature materials, but it is easily oxidized at high temperature. To increase the oxidation resistance of zirconium diboride at high temperature, the A 1( OH )3– Y ( OH )3 is coated on the ZrB 2 surface to prepare A 1( OH )3– Y ( OH )3/ ZrB 2 composite particles. In this paper, the effect of coating content on the properties of A 1( OH )3– Y ( OH )3/ ZrB 2 composite particles is investigated. It is analyzed that the particle size and particle size distribution of A 1( OH )3– Y ( OH )3/ ZrB 2 composite particles is increased with the coating content. The dispersion of ZrB 2 particles is largely increased with the coating content of 0%–20%; the dispersion of ZrB 2 particles is similar when the coating content is from 20% to 30%. The oxidation resistance ratio of the ZrB 2 particles with 30% coating content is the best than that of other conditions—it is about three times more than that of the original ZrB 2 particles.

Ultrafine particle size distribution during high velocity impact of high density metals

2012 ◽  
Author(s):  
Giorgio Buonanno ◽  
Luca Stabile ◽  
Andrew Ruggiero ◽  
Gianluca Iannitti ◽  
Nicola Bonora
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
High Velocity ◽  
Ultrafine Particle ◽  
High Density ◽  
High Velocity Impact ◽  
Velocity Impact
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