scholarly journals Synthesis of fibre reinforced Al2O3−SiO2 aerogel composite with high density uniformity via a facile high-pressure impregnation approach

2017 ◽  
Vol 11 (3) ◽  
pp. 185-190 ◽  
Author(s):  
Gang Yang ◽  
Yonggang Jiang ◽  
Junzong Feng ◽  
Sizhao Zhang ◽  
Jian Feng
Keyword(s):  
Thermal Conductivity ◽  
High Pressure ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Aerogel Composite ◽  
Sio2 Aerogel ◽  
The Mean

Alumina-silica (Al2O3?SiO2) aerogel composite, with low density, low thermal conductivity and hightemperature stability, is attracting increased interest in the field of thermal insulation application. In this paper, a novel way to fabricate fibre reinforced Al2O3?SiO2 aerogel composite via a facile high-pressure impregnation approach was reported. Two Al2O3?SiO2 aerogel composites, HPe and LPe, were synthesized via high-pressure and low-pressure impregnation approach, respectively. The effects of the impregnation approach on the aerogel composites performance were studied, and the impregnation model was established. The results showed that the as-prepared HPe exhibited higher density uniformity, better high-temperature stability, higher specific surface area and lower thermal conductivity. It was also shown that the effect of impregnation approach on the mean density and morphology of the aerogel composites is negligible. However, the standard deviation of density (0.00857) and mean thickness shrinkage (9.98%) of HPe were 37.8% and 15.4% lower than that of LPe, respectively. The specific surface area (884.1m2/g) of HPe was 43.5% higher than that of LPe. The thermal conductivity of HPe at 1100?C was 2.74% lower than that of LPe. The impregnation model of the aerogel composites presented that the density uniformity and thermal conductivity of HPe were improved obviously, because there were less large pores in HPe than in the LPe.

Synthesis of AnataseTiO2 Having High Specific Surface Area from a Gel Precursor

2011 ◽  
Vol 485 ◽  
pp. 279-282
Author(s):  
Keiko Fukushi ◽  
Sae Nakajima ◽  
Kazuyoshi Uematsu ◽  
Tadashi Ishigaki ◽  
Kenji Toda ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Temperature Stability ◽  
High Specific Surface Area ◽  
High Temperature Stability ◽  
X Ray Diffraction ◽  
Dialysis Treatment ◽  
X Ray ◽  
Transmission Electron

Anatase TiO2 having high temperature stability and specific surface area was synthesized using a gel precursor in very mild conditions. The precursor gel was obtained by dialysis treatment of Na16Ti10O28–HNO3 solution. The samples were characterized by X-ray diffraction analysis, transmission electron microscopy, Brunner–Emmett–Teller method for specific surface area measurements, and thermogravimetric analysis.

scholarly journals Structure, specific surface area and thermal conductivity of the snowpack around Barrow, Alaska

2012 ◽  
Vol 117 (D14) ◽  
pp. n/a-n/a ◽  
Author(s):  
Florent Domine ◽  
Jean-Charles Gallet ◽  
Josué Bock ◽  
Samuel Morin
Keyword(s):  
Thermal Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area

The whole-aperture pore-structure characteristics of marine-continental transitional shale facies of the Taiyuan and Shanxi Formations in the Qinshui Basin, North China

2019 ◽  
Vol 7 (2) ◽  
pp. T547-T563 ◽  
Author(s):  
Jiyuan Wang ◽  
Shaobin Guo
Keyword(s):  
High Pressure ◽  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Gas Adsorption ◽  
Pore Morphology ◽  
Qinshui Basin ◽  
Mercury Intrusion ◽  
Structure Characteristics

To systematically study the whole-aperture pore-structure characteristics of the marine-continental transitional shale facies in the Upper Palaeozoic Taiyuan and Shanxi Formations of the Qinshui Basin, we have collected a total of 11 samples for high-pressure mercury intrusion, low-pressure gas adsorption ([Formula: see text] and [Formula: see text]), nuclear magnetic resonance (NMR), and field-emission scanning electron microscopy with argon-ion polishing experiments to determine the pore morphology and distribution characteristics of shale samples in detail and to perform quantitative analyses. Then compared the pore-development characteristics of the Taiyuan Formation samples with those of the Shanxi Formation to determine which is preferable. The experimental results indicate that the shale samples of the Qinshui Basin mainly develop three types of pores: organic pores, intergranular pores, and microfractures. High-pressure mercury intrusion and gas-adsorption experiments indicate that the pore-size distributions exhibit multiple peaks. The samples contained varying proportions of macropores, mesopores, and micropores, among which the former two are dominant, accounting for approximately 85% of the total pore volume, whereas micropores account for only 15%. However, mesopores and micropores dominate the specific surface area; between them, the micropores are much more prevalent, accounting for more than 99% of the total specific surface area. Macropores contribute less than 1% of the specific surface area and therefore can be neglected. The pore morphology resembles the slit type parallel platy pores with a ballpoint pen structure. The NMR [Formula: see text] spectra have multiple-peak values. In addition, the large difference between the curved areas before and after centrifugation indicates that the samples contain a large proportion of mesopores and macropores, which is consistent with the results presented above. The results demonstrate that the development of pores in the Taiyuan Formation is better than that in the Shanxi Formation.

The formation of ice between hydrotalcite particles measured by thermoporometry

Clay Minerals ◽  
1996 ◽  
Vol 31 (2) ◽  
pp. 263-277 ◽  
Author(s):  
M. K. Titulaer ◽  
H. Talsma ◽  
J. B. H. Jansen ◽  
J. W. Geus
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Shape Factor ◽  
Mean Value ◽  
Nitrogen Sorption ◽  
Ice Volume ◽  
The Mean

AbstractThermoporometry (TPM) was applied to hydrotalcite precipitates prepared with carbonate, bicarboxylic acids and chloride. It was used to measure the formation of an ice body between the hydrotalcite particles. Before TPM could be applied, the dried hydrotalcite precipitate had to be soaked for two weeks in water. The mean value of a factor F measured by TPM, which described the shape of the ice body in hydrotalcite, was 1.7. This value was between those of a purely cylindrical (F = 2) and a purely spherical ice body (F = 1), indicating the formation of ice lenses. From the radius of the ice body, Rn, ice volume, Vn and shape factor F, the corresponding specific surface area of the hydrotalcite particles could be assessed. The TPM indicated that the distance between the separate hydrotalcite crystals in water, which is equal to 2(Rn+0.9) nm, was a function of the type of anion incorporated at the interlayer, such as chloride and bicarboxylic acid. The pore volume and surface area of the hydrotalcite particles measured by TPM were compared with those determined by the traditional nitrogen sorption technique on dried hydrotalcite. It appeared that sorption of N2 yielded much lower values than TPM. This difference was interpreted as being due to slow penetration of N2 through the dried hydrotalcite samples to the interparticle voids.

Design of SAW Specific Gas Sensor with High Sensitivity

2013 ◽  
Vol 303-306 ◽  
pp. 137-142
Author(s):  
Jin Yi Ma ◽  
Jing Yang ◽  
Bo Du ◽  
Lu Wang ◽  
Hong Min Jiang ◽  
...  
Keyword(s):  
High Temperature ◽  
Acoustic Wave ◽  
Specific Surface ◽  
Surface Area ◽  
Gas Sensor ◽  
Temperature Stability ◽  
High Sensitivity ◽  
Response Speed ◽  
High Temperature Stability ◽  
The Relationship

To improve the temperature stability, response speed and sensitivity of surface acoustic wave (SAW) gas sensor, the relationship between the sensing region of the resonator for SAW gas sensor and the sensitivity of sensor is studied, a specific resonator with big space topology structure is proposed. A SAW resonator with high temperature stability is investigated from the viewpoint of piezoelectric material, cut type and fabrication process. A nano-wire bundle based SAW gas sensor with big specific-surface-area is proposed.

scholarly journals The Effect of 200 MPa Pressure on Specific Surface Area of Clay

2015 ◽  
Vol 36 (4) ◽  
pp. 3-6 ◽  
Author(s):  
Ewa Koszela-Marek
Keyword(s):  
High Pressure ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pressure Effect ◽  
Laboratory Studies ◽  
Adsorption Method ◽  
Pressure Tests ◽  
Soil Skeleton

Abstract The paper presents the results of laboratory studies of the 200 MPa pressure effect on specific surface area of clay. The original high-pressure investigation stand was used for the pressure tests. Determination of the specific surface area was performed by the methylene blue adsorption method. The results of the specific surface area test were compared for non-pressurized clays and for clays pressured in a high-pressure chamber. It was found that the specific surface area of pressurized soil clearly increased. This shows that some microstructural changes take place in the soil skeleton of clays.

Characteristics of Silica Aerogel Composites Synthesized by Ambient Drying Method

2007 ◽  
Vol 544-545 ◽  
pp. 673-676 ◽  
Author(s):  
Chang Yeoul Kim ◽  
Jong Kyu Lee ◽  
Byung Ik Kim
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
Pore Diameter ◽  
High Specific Surface Area ◽  
Ambient Atmosphere ◽  
Drying Method ◽  
Aerogel Composite ◽  
Exchange Surface

Aerogel has its advantages of light density of 0.003-0.35 g/cm3 and its high specific surface area, 600-1000m2/g, mean pore diameter ~20nm. However, aerogel has its disadvantages of fragility and high cost. To overcome the mechanical fragility, we synthesized aerogel composite blankets with glass wools by drying at ambient atmosphere. Colloidal silica sol was first prepared by ion exchanging sodium silicate through amberlite column. Then, glass wool was soaked into the pH-controlled silica aerogel and then gelated. Ageing of silica aerogel composite was conducted in purified water and solvent exchange/surface modification was simultaneously processed in hexane and TMCS solution. After drying at 60oC and heat-treatment at 230oC, we evaluated the properties of aerogel composite, its apparent density and specific surface area.

scholarly journals Thermal conductivity of polyvinylpolymethylsiloxane aerogels with high specific surface area

RSC Advances ◽  
2019 ◽  
Vol 9 (14) ◽  
pp. 7833-7841 ◽  
Author(s):  
Lukai Wang ◽  
Junzong Feng ◽  
Yonggang Jiang ◽  
Liangjun Li ◽  
Jian Feng
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Heat Insulation ◽  
High Specific Surface Area

The traditional SiO2 aerogels are difficult to apply in the fields of energy storage and heat insulation due to their poor mechanical properties.

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