SiC‐based porous ceramic carriers for heat‐conductive phase change materials through carbothermal reduction method

Porous SiC ceramics with three different pore sizes (∼7, ∼45, and ∼98 μm) and two different porosities (∼54% and ∼63%) were prepared to investigate the effects of pore size on electrical and thermal properties of the porous ceramics. With an increase in pore size from ∼7 to ∼98 μm at the same porosity (∼54%), the electrical and thermal conductivities of the porous ceramics increased from ∼1.01 to ∼2.30 Ω−1·cm−1 and ∼14.3 to ∼26.2 W·m−1K−1, respectively. Similar trends have been obtained in the ceramics with ∼63% porosity. The porous SiC ceramic with larger pore size has smaller pore/strut interface area at the same porosity, which leads to less carrier scattering and phonon‐pore scattering at the pore/strut interfaces, resulting in higher electrical and thermal conductivities, respectively. These results suggest that the electrical and thermal properties of porous SiC ceramics can be successfully tuned by adjusting the pore size and porosity depending on the application.

Section: Introductionmentioning

confidence: 99%

Effects of pore size on electrical and thermal properties of porous SiC ceramics

Das,

Lucio,

Kultayeva

et al. 2023

“…The introduction of porosity into silicon carbide (SiC) ceramics is an extremely versatile and powerful strategy for greatly extending the range of engineering properties offered by SiC ceramic components. The unique combinations of mechanical and thermo-chemical properties of porous SiC ceramics (e.g., low thermal conductivity, high thermal shock resistance, good thermal stability, low thermal expansion coefficient, light weight, excellent mechanical strength, controlled permeability, excellent chemical stability, and good corrosion resistance) [1][2][3][4][5][6][7][8][9][10][11][12] make them promising materials for various industrial applications, such as filtration, [13][14][15] absorption, [16][17][18][19] membrane supports, [20][21][22] catalyst supports, 23,24 thermal insulators, [25][26][27] thermoelectric energy converters, 28 lightweight structural components, 29 and sandwich materials in dual-coolant lead lithium blankets. 30,31 In the past few years, highly contagious viral infections such as COVID-19 and SARS-Cov-2 have caused the challenging medical problems worldwide.…”

Section: Introductionmentioning

confidence: 99%

Electrical, thermal, and mechanical properties of porous silicon carbide ceramics with a boron carbide additive

Kultayeva

Kim

2022

The effects of the boron carbide (B4C) content and sintering atmosphere on the electrical, thermal, and mechanical properties of porous silicon carbide (SiC) ceramics were investigated in the porosity range of 58.3%–70.3%. The electrical resistivities of the nitrogen‐sintered porous SiC ceramics (∼10–1 Ω·cm) were two orders of magnitude lower than those of argon‐sintered porous SiC ceramics (∼101 Ω·cm). Both the thermal conductivities (3.3–19.8 W·m–1·K–1) and flexural strengths (8.1–32.9 MPa) of the argon‐ and nitrogen‐sintered porous SiC ceramics increased as the B4C content increased, owing to the decreased porosity and increased necking area between SiC grains. The electrical resistivity of the porous SiC ceramics was primarily controlled by the sintering atmosphere owing to the N‐doping from the nitrogen atmosphere, and secondarily by the B4C content, owing to the B‐doping from the B4C. In contrast, the thermal conductivity and flexural strength were dependent on both the porosity and necking area, as influenced by both the sintering atmosphere and B4C content. These results suggest that it is possible to decouple the electrical resistivity from the thermal conductivity by judicious selection of the B4C content and sintering atmosphere.

“…Porous silicon carbide (SiC) ceramics have attracted attention not only in the academic field but also industrially due to their remarkable characteristics such as low bulk density, high melting point, high oxidation resistance, bio-inert characteristic, corrosion resistance, high chemical stability, excellent mechanical strength, high specific strength, high thermal shock resistance, tailored thermal conductivity, and controlled permeability. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] These characteristics have made porous SiC ceramics suitable candidates to perform a wide range of engineering applications including membranes for water purification and gas separation, 1,3,5,11,[16][17][18][19] ceramic carriers, 20 lightweight structural materials, 4,6,7,9 hot gas filters, 10,11,[21][22][23][24][25] catalytic supports, [26][27][28] and thermal insulators. [29][30][31][32][33][34]…”

Section: Introductionmentioning

confidence: 99%

Effects of SiC whisker addition on mechanical, thermal, and permeability properties of porous silica‐bonded SiC ceramics

Lucio

Kultayeva

Kim

et al. 2021

The effects of SiC whisker addition into nano‐SiC powder‐carbon black template mixture on flexural strength, thermal conductivity, and specific flow rate of porous silica‐bonded SiC ceramics were investigated. The flexural strength of 1200°C‐sintered porous silica‐bonded SiC ceramics increased from 9.5 MPa to 12.8 MPa with the addition of 33 wt% SiC whisker because the SiC whiskers acted as a reinforcement in porous silica‐bonded SiC ceramics. The thermal conductivity of 1200°C‐sintered porous silica‐bonded SiC ceramics monotonically increased from 0.360 Wm–1K–1 to 1.415 Wm–1K–1 as the SiC whisker content increased from 0 to 100 wt% because of the easy heat conduction path provided by SiC whiskers with a high aspect ratio. The specific flow rate of 1200°C‐sintered porous SiC ceramics increased by two orders of magnitude as the SiC whisker content increased from 0 to 100 wt%. These results were primarily attributed to an increase in pore size from 125 nm to 565 nm and secondarily an increase in porosity from 49.9% to 63.6%. In summary, the addition of 33 wt% SiC whisker increased the flexural strength, thermal conductivity, and specific flow rate of porous silica‐bonded SiC ceramics by 35%, 133%, and 266%, respectively.