scholarly journals Porous Design of SiCNWs/SiC Nanocomposites with High Strength and Low Thermal Conductivity

2021 ◽  
Author(s):  
Jing Ruan ◽  
Jinshan Yang ◽  
Jingyi Yan ◽  
Xiao You ◽  
Mengmeng Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Chemical Deposition ◽  
High Strength ◽  
Chemical Vapor Infiltration ◽  
Spherical Particles ◽  
Uniform Structure ◽  
Low Thermal Conductivity ◽  
Sic Composites ◽  
Porous Sic

Abstract Porous SiC composites with lightweight, high strength and low thermal conductivity design can be obtained by constructing porous silicon carbide nanowires (SiCNWs) network and controlling chemical vapor infiltration (CVI) process. The SiCNWs network with an optimized volume fraction (13.6%) and uniform structure is prepared by mixing SiCNWs and polyvinyl alcohol (PVA) firstly. SiCNWs reinforced porous SiC composite (SiCNWs/SiC) with a small uniform pore can be obtained by controlling the chemical deposition kinetics. The morphology of the grown SiC matrix, from the spherical particles to the hexagonal pyramid particles, can be influenced by the deposition parameters like temperature and reactive gas concentration. The strength of the lightweight SiCNWs/SiC composites reach 47.8 MPa with a porosity of 64% and thermal conductivity of 1.2 W/(m∙K), which shows the toughening effect and insulation design with low thermal conductivity.

scholarly journals Porous Design of SiCNWs/SiC Nanocomposites with High Strength and Low Thermal Conductivity

2021 ◽  
Author(s):  
Jing Ruan ◽  
Jinshan Yang ◽  
Jingyi Yan ◽  
Xiao You ◽  
Mengmeng Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Chemical Deposition ◽  
High Strength ◽  
Chemical Vapor Infiltration ◽  
Spherical Particles ◽  
Uniform Structure ◽  
Low Thermal Conductivity ◽  
Sic Composites ◽  
Porous Sic

Abstract Porous SiC composites with lightweight, high strength and low thermal conductivity design can be obtained by constructing porous silicon carbide nanowires (SiCNWs) network and controlling chemical vapor infiltration (CVI) process. The SiCNWs network with an optimized volume fraction (13.6%) and uniform structure is prepared by mixing SiCNWs and polyvinyl alcohol (PVA) firstly. SiCNWs reinforced porous SiC composite (SiCNWs/SiC) with a small uniform pore can be obtained by controlling the chemical deposition kinetics. The morphology of the grown SiC matrix, from the spherical particles to the hexagonal pyramid particles, can be influenced by the deposition parameters like temperature and reactive gas concentration. The strength of the lightweight SiCNWs/SiC composites reach 47.8 MPa with a porosity of 64% and thermal conductivity of 1.2 W/(m∙K), which shows the toughening effect and insulation design with low thermal conductivity.

scholarly journals Strong silica-nanocellulose anisotropic composite foams combine low thermal conductivity and low moisture uptake

Cellulose ◽  
2019 ◽  
Vol 27 (18) ◽  
pp. 10825-10836 ◽  
Author(s):  
Pierre Munier ◽  
Varvara Apostolopoulou-Kalkavoura ◽  
Michael Persson ◽  
Lennart Bergström
Keyword(s):  
Thermal Conductivity ◽  
Cellulose Nanofibrils ◽  
High Strength ◽  
Fold Increase ◽  
Silica Particles ◽  
Spherical Particles ◽  
Attractive Alternative ◽  
Low Thermal Conductivity ◽  
Thermal Insulating ◽  
Composite Foams

AbstractWe report the fabrication of anisotropic lightweight composite foams based on commercial colloidal silica particles and TEMPO-oxidized cellulose nanofibrils (TOCNF). The unidirectional ice-templating of silica-TOCNF dispersions resulted in anisotropic foams with columnar porous structures in which the inorganic and organic components were homogeneously distributed. The facile addition of silica particles yielded a significant enhancement in mechanical strength, compared to TOCNF-only foams, and a 3.5-fold increase in toughness at a density of 20 kg m−3. The shape of the silica particles had a large effect on the mechanical properties; anisotropic silica particles were found to strengthen the foams more efficiently than spherical particles. The water uptake of the foams and the axial thermal conductivity in humid air were reduced by the addition of silica. The composite foams were super-insulating at dry conditions at room temperature, with a radial thermal conductivity value as low as 24 mW m−1 K−1, and remained lower than 35 mW m−1 K−1 up to 80% relative humidity. The combination of high strength, low thermal conductivity and manageable moisture sensitivity suggests that silica-TOCNF composite foams could be an attractive alternative to the oil-based thermal insulating materials.

scholarly journals Fabrication of Natural Flake Graphite/Ceramic Composite Parts with Low Thermal Conductivity and High Strength by Selective Laser Sintering

2020 ◽  
Vol 10 (4) ◽  
pp. 1314
Author(s):  
Haihua Wu ◽  
Kui Chen ◽  
Yafeng Li ◽  
Chaoqun Ren ◽  
Yu Sun ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Ceramic Composite ◽  
Selective Laser Sintering ◽  
High Strength ◽  
Laser Sintering ◽  
Post Processing ◽  
Composite Part ◽  
Low Thermal Conductivity ◽  
Powder Composition

The 3D graphite/ceramic composite prototyping parts directly prepared by selective laser sintering (SLS) were porous, which led to poor strength and low thermal conductivity. In order to obtain low thermal conductivity and high strength, its thermal conductivity and compressive strength were adjusted by changing the mixture powder composition and adding post-processing. The result showed that the addition of silicon powder in the mixture powder could significantly improve the compressive strength and thermal conductivity. The addition of expanded graphite was beneficial to the formation of the closed pores in the matrix, which slightly reduced the compressive strength but significantly reduced the thermal conductivity. The 3D graphite/ceramic composite part showed an order of magnitude improvement in compressive strength (from 1.25 to 13.87 MPa) but relatively small change in thermal conductivity (from 1.40 to 2.12 W·m−1K−1) and density (from 0.53 to 1.13 g·cm−3) by post-processing. Reasonable mixture powder composition and post-processing were determined and realized the possibility of fabricating a 3D graphite/ceramic composite part with low thermal conductivity but high compressive strength. Furthermore, it could be used for the repeated casting of steel castings, and through the comparative analysis of casting defects, the prepared graphite/ceramic composite part was expected to replace water glass sand mold.

TGA CHARACTERISTIC AND FABRICATION OF POROUS SiC CERAMICS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2863-2868
Author(s):  
SEONG HOON KIM ◽  
HAN KI YOON ◽  
SEON JIN KIM ◽  
YI HYUN PARK
Keyword(s):  
Particle Size ◽  
Carbon Fibers ◽  
High Strength ◽  
Porous Ceramics ◽  
Pressing Method ◽  
Sic Ceramics ◽  
Length Direction ◽  
Specific Temperature ◽  
Sic Composites ◽  
Porous Sic

The long-range aim of this research is to develop porous ceramics with high strength, excellent thermal resistance and chemical stability at high temperature in environmental industry. The C f / SiC was made by hot pressing method with SiC powder whose particle size is 50nm and less on the average also Al 2 O 3, Y 2 O 3 and SiO 2 as additive. The carbon fibers of oxidation property are investigated by TGA for finding out decarburization point. As a result, decarburization point selected the specific temperature of TGA curve and the C f/ SiC composites occurred perfectly decarburization at carbon fibers so the clearly porous SiC ceramics were formed many holes of 3-5µm diameters through length direction by its reaction.

Elephant ivory: A low thermal conductivity, high strength nanocomposite

2006 ◽  
Vol 21 (1) ◽  
pp. 287-292 ◽  
Author(s):  
Michael B. Jakubinek ◽  
Champika J. Samarasekera ◽  
Mary Anne White
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
High Strength ◽  
Mean Free Path ◽  
Boundary Scattering ◽  
Low Thermal Conductivity ◽  
Recent Interest ◽  
Elephant Ivory ◽  
Nanocomposite Structures ◽  
Structure Properties

There has been much recent interest in heat transport in nanostructures, and alsoin the structure, properties, and growth of biological materials. Here we present measurements of thermal properties of a nanostructured biomineral, ivory. The room-temperature thermal conductivity of ivory is anomalously low in comparison with its constituent components. Low-temperature (2–300 K) measurements ofthermal conductivity and heat capacity reveal a glass-like temperature dependenceof the thermal conductivity and phonon mean free path, consistent with increased phonon-boundary scattering associated with nanostructure. These results suggest that biomineral-like nanocomposite structures could be useful in the design of novel high-strength materials for low thermal conductivity applications.

Thermal Conductivity of Biomorphic Porous SiC Based Ceramics

2010 ◽  
Author(s):  
Nadejda Popovska ◽  
Emad Alkhateeb ◽  
Tanja Kugler ◽  
Andreas P. Fro¨ba ◽  
Alfred Leipertz
Keyword(s):  
Thermal Conductivity ◽  
Single Phase ◽  
Porous Ceramic ◽  
Chemical Vapor ◽  
Composite Ceramic ◽  
Laser Flash ◽  
Ceramic Composites ◽  
Chemical Vapor Infiltration ◽  
Composite Ceramics ◽  
Porous Sic

Biomorphic porous SiC composite ceramics were produced by chemical vapor infiltration and reaction (CVI-R) technique using paper preforms as template. The thermal conductivity of four samples with different composition and microstructure was investigated: a) C-template b) C-SiC, c) C-SiC-Si3N4 and d) SiC coated with a thin layer of TiO2. The SiC-Si3N4 composite ceramic showed enhanced oxidation resistance compared to single phase SiC. However; a key property for the application of these materials at high temperatures is their thermal conductivity. The later was determined experimentally at defined temperatures in the range 298–373K with a laser flash apparatus. It was found that the thermal conductivity of the porous ceramic composites increases in the following order: C-template < C-SiC < C-SiC-Si3N4 < SiC-TiO2. The results were interpreted in regard to the porosity and the microstructure of the ceramics.

Ultra-low thermal conductivity and high strength of aerogels/fibrous ceramic composites

2016 ◽  
Vol 36 (6) ◽  
pp. 1487-1493 ◽  
Author(s):  
Jian He ◽  
Xiaolei Li ◽  
Dong Su ◽  
Huiming Ji ◽  
XiaoJing Wang
Keyword(s):  
Thermal Conductivity ◽  
High Strength ◽  
Ceramic Composites ◽  
Low Thermal Conductivity

Influence of Fabricated Process on Mechanical Properties of Porous SiC-Particle/Si3N4 Composites

2007 ◽  
Vol 336-338 ◽  
pp. 1320-1323 ◽  
Author(s):  
Hong Jie Wang ◽  
Wen Zhang ◽  
Yu Bai ◽  
Guan Jun Qiao ◽  
Ji Qiang Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Powder Compact ◽  
High Strength ◽  
Uniform Structure ◽  
High Porosity ◽  
Gel Casting ◽  
N2 Atmosphere ◽  
Porous Sic ◽  
Sic Particle

In this paper, the mechanical properties of porous Si3N4/SiC composite prepared by different forming method (uniaxial pressing and gel-casting) were compared. Using gelcasting and two steps sintering technology, the porous SiC-particle/Si3N4 composites with a high strength, uniform structure and a relative high porosity were obtained by adding a little amount of nano carbon in slurry. The flexural strength of optimized material reaches to 100MPa and its porosity is more than 60%. But using uniaxial pressing and sintering at N2 atmosphere, because the green bodies have the high density, and the density distribution of a powder compact was not uniform, the flexural strength is not high, and at the same time, the microstructure is not uniform also.

Sign in / Sign up

Export Citation Format

Share Document