Stress formation during heating in supercritical drying

2001 ◽  
Vol 279 (2-3) ◽  
pp. 110-118 ◽  
Author(s):  
Betul Unlusu ◽  
Sermin G. Sunol ◽  
Aydin K. Sunol
Keyword(s):  
Supercritical Drying ◽  
Stress Formation

scholarly journals Design of Aerogels, Cryogels and Xerogels of Alginate: Effect of Molecular Weight, Gelation Conditions and Drying Method on Particles’ Micromeritics

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1049 ◽  
Author(s):  
Rosalía Rodríguez-Dorado ◽  
Clara López-Iglesias ◽  
Carlos García-González ◽  
Giulia Auriemma ◽  
Rita Aquino ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Textural Properties ◽  
Supercritical Drying ◽  
Processing Parameters ◽  
Storage Conditions ◽  
Drying Methods ◽  
Drying Method ◽  
Molecular Weights ◽  
Nanostructured Particles

Processing and shaping of dried gels are of interest in several fields like alginate aerogel beads used as highly porous and nanostructured particles in biomedical applications. The physicochemical properties of the alginate source, the solvent used in the gelation solution and the gel drying method are key parameters influencing the characteristics of the resulting dried gels. In this work, dried gel beads in the form of xerogels, cryogels or aerogels were prepared from alginates of different molecular weights (120 and 180 kDa) and concentrations (1.25, 1.50, 2.0 and 2.25% (w/v)) using different gelation conditions (aqueous and ethanolic CaCl2 solutions) and drying methods (supercritical drying, freeze-drying and oven drying) to obtain particles with a broad range of physicochemical and textural properties. The stability of physicochemical properties of alginate aerogels under storage conditions of 25 °C and 65% relative humidity (ICH-climatic zone II) during 1 and 3 months was studied. Results showed significant effects of the studied processing parameters on the resulting alginate dried gel properties. Stability studies showed small variations in aerogels weight and specific surface area after 3 months of storage, especially, in the case of aerogels produced with medium molecular weight alginate.

Luminescent anodized silicon aerocrystal networks prepared by supercritical drying

Nature ◽  
1994 ◽  
Vol 368 (6467) ◽  
pp. 133-135 ◽  
Author(s):  
L. T. Canham ◽  
A. G. Cullis ◽  
C. Pickering ◽  
O. D. Dosser ◽  
T. I. Cox ◽  
...  
Keyword(s):  
Supercritical Drying

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

Influence of Heat Treatment on Residual Stress Formation in the Wear-Resistant Steel 60–Steel 15–Steel 60 Bimetal Material

2021 ◽  
Vol 12 (1) ◽  
pp. 5-9
Author(s):  
N. N. Sergeev ◽  
A. N. Sergeev ◽  
S. N. Kutepov ◽  
A. E. Gvozdev ◽  
A. G. Kolmakov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Resistant Steel ◽  
Wear Resistant ◽  
Stress Formation

A novel approach to alginate aerogels: carbon dioxide induced gelation

RSC Advances ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 7812-7818 ◽  
Author(s):  
P. Gurikov ◽  
S. P. Raman ◽  
D. Weinrich ◽  
M. Fricke ◽  
I. Smirnova
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Drying ◽  
Novel Approach

A novel process, carbon dioxide induced gelation, opens new pathways towards hydrogels and can be coupled with supercritical drying to produce aerogels.

scholarly journals Nanotechnologies: a review of inventions and utility models. Part IV.

2020 ◽  
Vol 12 (5) ◽  
pp. 275-284
Author(s):  
L.A. Ivanov ◽  
A.D. Ishkov ◽  
Zh.V. Pisarenko ◽  
Q. Wang ◽  
P.S. Prokopiev
Keyword(s):  
Mechanical Strength ◽  
Supercritical Drying ◽  
Community Services ◽  
Raw Material ◽  
Gelling Agent ◽  
Ceramic Fiber ◽  
Polymer Concrete ◽  
Protection Method ◽  
Nano Coating ◽  
Wide Range

The article provides an abstract review of patents. The results of creative activity of scientists, engineers and specialists, including inventions in the field of nanotechnology and nanomaterials, being implemented, allow achieving a significant effect in construction, housing and community services, and related sectors of the economy. For example, the invention “Heat-insulating material based on air gel” can be used to obtain heat-insulating materials for a wide range of applications. The required technical result, which consists in improving the thermal insulation properties of the material in a wide temperature range, increasing the absorbing properties of electromagnetic radiation in the IR spectrum, increasing the mechanical strength and flexibility, as well as reducing crumbling, is achieved in an air gel-based material containing a fibrous substrate with a density of 0.001–0.1 g/cm3, consisting of silica and/or glass and/or basalt fibers with a diameter of 0.1–5 microns, which is impregnated with an air gel obtained on the basis of silicon dioxide from alkoxysilane with the introduction of a gelling agent and followed by supercritical drying. The introduction of nanomaterials gives an additional reinforcing effect, which increases the mechanical strength of the final material and significantly reduces the crumbling of the air gel. The final material can be provided with an additional layer of fibrous substrate to increase its vibration resistance. This is especially true when using the proposed material for civil and industrial construction in seismically active zones, as well as in aircraft and rocketry. The specialists can also be interested in the following inventions in the area of nanotechnologies: nano-coating protection method for electrical connectors, preparation method of nanometric size metal oxide additives that reduce the temperature of sintering, raw material mixture for the manufacture of fine-grained polymer concrete (modified with microsilica), installation for the synthesis of carbon-containing nanomaterials, a method for producing silver nanoparticles, a method for producing nanocrystalline cubic tungsten carbide, a composition with carbon nanotubes for obtaining a carbon blank for high-density SiC/C/Si ceramics and a method for producing articles from SiC/C/Si ceramics, composite membrane for drying natural and technological gas mixtures based on graphene oxide intercalated with hydroxylated fullerene derivatives, compositions containing nanometric copper, carbon-ceramic fiber-reinforced composite material and a method for its production, a method for producing nanoparticles of aluminum oxide et al.

scholarly journals COMPUTATIONAL MICROSTRUCTURE-BASED ANALYSIS OF RESIDUAL STRESS EVOLUTION IN METAL-MATRIX COMPOSITE MATERIALS DURING THERMOMECHANICAL LOADING

2021 ◽  
Vol 19 (2) ◽  
pp. 241
Author(s):  
Ruslan Balokhonov ◽  
Varvara Romanova ◽  
Eugen Schwab ◽  
Aleksandr Zemlianov ◽  
Eugene Evtushenko
Keyword(s):  
Residual Stress ◽  
Metal Matrix ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Matrix Composites ◽  
Two Phase ◽  
Irregular Shapes ◽  
The Matrix ◽  
Stress Formation ◽  
Mechanical Fragmentation

A technique for computer simulation of three-dimensional structures of materials with reinforcing particles of complex irregular shapes observed in the experiments is proposed, which assumes scale invariance of the natural mechanical fragmentation. Two-phase structures of metal-matrix composites and coatings of different spatial scales are created, with the particles randomly distributed over the matrix and coating computational domains. Using the titanium carbide reinforcing particle embedded into the aluminum as an example, plastic strain localization and residual stress formation along the matrix-particle interface are numerically investigated during cooling followed by compression or tension of the composite. A detailed analysis is performed to evaluate the residual stress concentration in local regions of bulk tension formed under all-round and uniaxial compression of the composite due to the concave and convex interfacial asperities.

Fabrication of Carbon Aerogels

2006 ◽  
Vol 11-12 ◽  
pp. 19-22 ◽  
Author(s):  
Y.N. Feng ◽  
Lei Miao ◽  
Yong Ge Cao ◽  
T. Nishi ◽  
Sakae Tanemura ◽  
...  
Keyword(s):  
Pore Size ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Limited Range ◽  
Molar Ratio ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Catalyst Content ◽  
Fabrication Parameters ◽  
Pyrolysis Processes

RF (Resorcinol-Formaldehyde) aerogels and carbon aerogels were prepared through the sol-gel method following the routes of polymerization, gelation, supercritical drying and pyrolysis processes. The influence of fabrication parameters on the textural structure of the samples, e.g., specific surface area, pore size, and pore size distribution, etc., were systematically investigated. With a decrease in the R/F molar ratio, or an increase in the catalyst content within a limited range, the porosity of the nanostructure materials increases. The optimal temperature of pyrolysis for RF aerogel was investigated by TGA (Thermogravimetric Analysis).

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