scholarly journals Effect of particle size on the pore characterization and strength of porous cordierite-mullite ceramics prepared by a pore-forming in-situ technique

2013 ◽  
Vol 45 (2) ◽  
pp. 165-172 ◽  
Author(s):  
W. Yan ◽  
N. Li ◽  
J. Tong ◽  
G. Liu ◽  
J. Xu
Keyword(s):  
Particle Size ◽  
Pore Size ◽  
Average Particle ◽  
Pore Characterization ◽  
Effect Of Particle Size ◽  
Median Pore ◽  
Porous Cordierite ◽  
Mullite Ceramics ◽  
In Situ Technique

The porous cordierite-mullite ceramics were prepared by the pore-forming in-situ technique. The characterizations of porous cordierite-mullite ceramics were determined by an X-ray diffractometer (XRD), a scanning electron microscopy (SEM), and a microscopy measured method, etc., and the effect of particle size on phase composition, pore characterization and strength were investigated. It?s found that particle size affects strongly the formations of cordierite and mullite, and then changes the pore characterization and strength. With the decrease of the particle size, the sintering temperature at which the formations of cordierite and mullite take place extremely fast decreases, the pore size distribution becomes from bi-peak mode to mono-peak mode, the porosity and the median pore size decrease but strength increases. The most opposite mode is the specimen sintered at 1400 ?C from the grinded powder with an average particle size of 10.2 ?m, which consists of cordierite, mullite and minor spinel, and has a high apparent porosity (40 %), a high compressive strength (58.4 MPa), a small median pore size (6.3 ?m) and well-developed necks between particles.

scholarly journals Effect of Al(OH)3 content on the microstructure and strength of porous cordierite-mullite ceramics prepared by an in-situ pore forming technique

2018 ◽  
Vol 50 (2) ◽  
pp. 205-215 ◽  
Author(s):  
Qingjie Chen ◽  
Wen Yan ◽  
Nan Li ◽  
Xiaoli Lin ◽  
Zhenyan Zhang ◽  
...  
Keyword(s):  
Phase Composition ◽  
Pore Size ◽  
Size Distribution ◽  
Porous Ceramics ◽  
X Ray ◽  
Neck Size ◽  
Median Pore ◽  
Porous Cordierite ◽  
Mullite Ceramics

Five porous cordierite-mullite ceramics with similar porosity and different neck characteristics were prepared from Al(OH)3, magnesite, silica and clay using an in-situ pore-forming technique. The phase composition, pore and neck characteristics and strength of the porous ceramics were investigated by an X-ray diffractometer (XRD), a scanning electron microscopy (SEM) and a microscopy measured method, etc. The experimental results showed that Al(OH)3 content had a significant effect on the pore size distribution and neck characteristics (neck size distribution, total value of neck size and phase composition) and then affecting the strength. With an increase in Al(OH)3 content, the median pore size decreased, the total length of necks and the uniformity of neck size increased, also the mullite content of necks increased, resulting in the increase of strength of the porous cordierite-mullite ceramics. When the Al(OH)3 content was 64.9 wt%, the porous cordierite-mullite ceramics had the best performance of high apparent porosity of 45.1 % and high compressive strength of 55.9 MPa.

scholarly journals Effect of particle size on microstructure and strength of porous spinel ceramics prepared by pore-forming in situ technique

2011 ◽  
Vol 34 (5) ◽  
pp. 1109-1112 ◽  
Author(s):  
WEN YAN ◽  
NAN LI ◽  
YUANYUAN LI ◽  
GUANGPING LIU ◽  
BINGQIANG HAN ◽  
...  
Keyword(s):  
Particle Size ◽  
Effect Of Particle Size ◽  
In Situ Technique

Effect of particle size on in-situ desulfurization for oxy-fuel CFBC

Fuel ◽  
2021 ◽  
Vol 291 ◽  
pp. 120270
Author(s):  
Seo Yeong Kang ◽  
Su Been Seo ◽  
Eun Sol Go ◽  
Hyung Woo Kim ◽  
Sang In Keel ◽  
...  
Keyword(s):  
Particle Size ◽  
Effect Of Particle Size

scholarly journals Effect of soil textural characteristics on longitudinal dispersion in saturated porous media

2021 ◽  
Vol 69 (2) ◽  
pp. 161-170
Author(s):  
Mojtaba G. Mahmoodlu ◽  
Amir Raoof ◽  
Martinus Th. van Genuchten
Keyword(s):  
Particle Size ◽  
Dispersion Coefficient ◽  
Average Particle Size ◽  
Longitudinal Dispersion ◽  
Average Particle ◽  
Sand Sample ◽  
Average Pore ◽  
Advection Dispersion ◽  
Strong Positive Relationship

Abstract This study focuses on the effects of soil textural heterogeneity on longitudinal dispersion under saturation conditions. A series of solute transport experiments were carried out using saturated soil columns packed with two filter sands and two mixtures of these sands, having d50 values of 95, 324, 402, and 480 µm, subjected to four different steady flow rates. Values of the dispersion coefficient (D) were estimated from observed in-situ distributions of calcium chlo-ride, injected as a short nonreactive tracer pulse, at four different locations (11, 18, 25, 36 cm). Analyses of the observed distributions in terms of the standard advection-dispersion equation (ADE) showed that D increased nonlinearly with travel distance and higher Peclet numbers+. The dispersion coefficient of sand sample S1 with its largest average particle size (d 50) was more affected by the average pore-water velocity than sample S4 having the smallest d 50. Results revealed that for a constant velocity, D values of sample S1 were much higher than those of sample S4, which had the smallest d 50. A correlation matrix of parameters controlling the dispersion coefficient showed a relatively strong positive relationship between D and the Peclet number. In contrast, almost no correlation was evident between D and porosity as well as grain size. The results obtained with the four sandy matrices were consistent and proved that the dispersion coefficient depends mainly on the particle size.

scholarly journals Effect of Particle Size on the HDS Activity of Molybdenum Sulfide

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Carola Contreras ◽  
Fernanda Isquierdo ◽  
Pedro Pereira-Almao ◽  
Carlos E. Scott
Keyword(s):  
Particle Size ◽  
Heavy Oil ◽  
Molybdenum Sulfide ◽  
Vacuum Gas Oil ◽  
Particle Sizes ◽  
Heavy Oils ◽  
Gas Oil ◽  
Oil Reserves ◽  
Effect Of Particle Size

More than half of the total world oil reserves are heavy oil, extra heavy oil, and bitumen; however their catalytic conversion to more valuable products is challenging. The use of submicronic particles or nanoparticles of catalysts suspended in the feedstock may be a viable alternative to the conversion of heavy oils at refinery level or downhole (in situ upgrading). In the present work, molybdenum sulfide (MoS2) particles with varying diameters (10000–10 nm) were prepared using polyvinylpyrrolidone as capping agent. The prepared particles were characterized by DLS, TEM, XRD, and XPS and tested in the hydrodesulfurization (HDS) of a vacuum gas oil (VGO). A correlation between particle size and activity is presented. It was found that particles with diameters around 13 nm show double the HDS activity compared with the material with micrometric particle sizes (diameter ≈ 10,000 nm).

Effect of Particle Size upon Pt/SiO2Catalytic Cracking ofn-Dodecane under Supercritical Conditions: In situ SAXS and XANES Studies

ChemCatChem ◽  
2016 ◽  
Vol 9 (1) ◽  
pp. 99-102 ◽  
Author(s):  
Sungwon Lee ◽  
Sungsik Lee ◽  
Mrunmayi D. Kumbhalkar ◽  
Kamila M. Wiaderek ◽  
James Dumesic ◽  
...  
Keyword(s):  
Particle Size ◽  
Supercritical Conditions ◽  
Effect Of Particle Size

In situ cracking of silica beads in the SEM and TEM — Effect of particle size on structure–property correlations

2015 ◽  
Vol 270 ◽  
pp. 337-347 ◽  
Author(s):  
J. Paul ◽  
S. Romeis ◽  
M. Mačković ◽  
V.R.R. Marthala ◽  
P. Herre ◽  
...  
Keyword(s):  
Particle Size ◽  
Structure Property ◽  
Sem And Tem ◽  
Silica Beads ◽  
Effect Of Particle Size ◽  
Property Correlations

Fabrication of Porous SiAlON Using Fe2O3 as Pore Former

2014 ◽  
Vol 804 ◽  
pp. 267-270
Author(s):  
Qing Wen Duan ◽  
Rong Zhen Liu ◽  
Hai Yun Jin ◽  
Jian Feng Yang ◽  
Zhi Hao Jin
Keyword(s):  
Particle Size ◽  
Porous Materials ◽  
Pore Size ◽  
Fracture Mode ◽  
Size Effects ◽  
Pore Diameter ◽  
Bending Strength ◽  
Thermal Reduction ◽  
Pore Former ◽  
Median Pore

Porous SiAlON ceramics were fabricated by carbo-thermal reduction nitridation method using Fe2O3 as pore former. Particle size effects of Fe2O3 were reported in this paper. The results showed that composites were composed by SiAlON, AlN and Iron Silicon phases. The median pore diameter of Sialon was affected by the composition and particle size of Fe2O3. The fracture mode of this material was intergranular. With the increase of Fe2O3 additions, the porosity of this materials increased. The bending strength of this material was reversely proportional to Fe2O3 particle size. The maximum bending strength of Porous materials with 30wt.% Fe2O3 additions (with a porosity about 65% and the pore size is about 1μm) could reach 22 MPa. The porous Sialon ceramics with a smaller pore size exhibited a higher bending strength.

scholarly journals Aggregation of Nanochemical Microcrystals in Urine Promotes the Formation of Urinary Calculi

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yanting Lou ◽  
Wei He ◽  
Zhengyao Song
Keyword(s):  
Particle Size ◽  
Pore Size ◽  
Average Particle Size ◽  
Colorimetric Method ◽  
Urinary Calculi ◽  
Control Group ◽  
Average Particle ◽  
Public Attention ◽  
Flame Atomic Absorption ◽  
Experimental Group

With the increasing incidence and recurrence rate of urinary calculi, urinary calculi have become a serious health risk, and the research on urinary calculi has become the focus of public attention. At present, the research results on the formation mechanism of urinary calculi are not ideal, and there is no unified conclusion. In order to further study the influencing factors of the formation of urinary calculi and provide new ideas for the prevention and clinical treatment of urinary calculi, the influence of agglomeration of nanochemical microcrystals in urine on urinary calculi was studied in this paper. In this study, fresh morning urine was collected from 10 urological stone patients and 10 healthy controls without urological stone in the urology department of a hospital. After processing the experimental specimens, we first use flame atomic absorption spectrometry and alcian blue colorimetric method to detect the content of Ca2+ and citrate in the urine and then use the nanoparticle size analyzer to detect the microcrystals in the urine. Diameter, distribution, degree of aggregation and potential, and finally HRTEM observation to observe the morphology, chemical composition, and element composition of the nanocrystals. The results showed that the content of Ca2+ and lemon hydrochloric acid in the urine of the experimental group was lower than that of the control group. The particle size of the nanocrystals increased with the increase in the pore size of the membrane. The average particle size of the experimental group increased gradually from 163 ± 31 nm to 3219 ± 863 nm, while the average particle size of the control group increased from 183 ± 65 nm to 997 ± 522 nm. The mean value of the potential decreased with the increase in the pore size of the filter membrane. The change amplitude of the experimental group was 6.57 mV, while the change amplitude of the control group was only 1.75 mV. In the composition of nanocrystals, element O accounts for the most, accounting for 42.54% of all elements. This indicates that the aggregation of nanocrystals in urine will lead to the rapid increase in the size of nanocrystals, which will eventually lead to the formation of stones.

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