Influence of Grain Size on Thermal Conductivity of SiC Ceramics

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

Download Full-text

Effect of Initial Alpha-SiC Content on Thermal Conductivity of Silicon Carbide Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.616.23 ◽

2014 ◽

Vol 616 ◽

pp. 23-26 ◽

Cited By ~ 2

Author(s):

Kwang Young Lim ◽

Tae Young Cho ◽

Young Wook Kim ◽

Seung Jae Lee

Keyword(s):

Thermal Conductivity ◽

Grain Size ◽

Room Temperature ◽

Phase Content ◽

Sic Ceramics ◽

Α Phase ◽

Average Grain Size ◽

Carbide Ceramics ◽

Equiaxed Grains ◽

Silicon Carbide Ceramics

By using α-and/or β-SiC powders, the effects of initial α-phase content on the microstructure and thermal properties of the SiC ceramics sintered with Y2O3 and Sc2O3 were investigated. When α-SiC powder was used, the microstructure consisted of large equiaxed grains and small equiaxed grains. The average grain size decreased with increasing α-SiC content in the starting composition. The thermal conductivity decreased with increasing α-SiC content in the starting composition. Such results suggest that the grain growth of SiC ceramics is beneficial in increasing the thermal conductivity of liquid-phase sintered SiC ceramics. The thermal conductivity of SiC ceramics processed from a 90% β-SiC-10% α-SiC powder mixture was 159 W/m∙K at room temperature.

Download Full-text

THE EFFECT GRAIN-SIZE COMPOSITION ON THERMAL CONDUCTIVITY OF SANDY SOILS

Construction and Geotechnics ◽

10.15593/2224-9826/2020.2.02 ◽

2020 ◽

Vol 11 (2) ◽

pp. 19-27

Author(s):

A. V Zakharov ◽

S. E Makhover

Keyword(s):

Thermal Conductivity ◽

Grain Size ◽

Sandy Soil ◽

Alternative Energy ◽

Radiant Energy ◽

Sandy Soils ◽

Size Composition ◽

Experiment Planning ◽

Pore Filling ◽

Grain Size Composition

Today the issue of energy saving is acute. The main sources of energy are radiant energy of the Sun, wind energy, energy of moving water. Therefore, the issue of solving alternative energy sources is relevant. The article aims to solve the problem by using low-potential heat of the soil mass by means of energy-efficient building constructions - foundations. It is necessary to know the thermal characteristics of soils for this. At the moment, methods for determining the thermophysical properties of inert materials with subsequent practical application in the field of construction have been widely studied, but no one of these methods takes into account the grain-size composition. Thus, the study of the connection between the thermal conductivity and the grain-size composition of the soil is important. The aim of the work is to Estimation of thermal conductivity of sandy soils based on grain-size composition. This article presents an analysis of the dependence of the thermal conductivity of the sandy soil of its grain-size composition. The matrix of experiment planning is made; the methodology and technological sequence of the experiment were tested. Statistical processing of the obtained experimental data was carried out. Based on a series of test experiments, it was concluded that there are two factors competing in its thermal conductivity: an increase in λ due to an increase in the degree of pore filling and a decrease in total heat conductivity due to a decrease in the degree of pore filling. These results suggest that grain-size composition has an impact on the thermal conductivity of the sandy soil. During the experiment, the dependence of the thermal conductivity of sandy soils on their grain-size composition was experimentally established.

Download Full-text

Thermal Diffusivity and Conductivity of La0.7Ca0.3-xSrxMnO3 (x=0 to 0.10)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.501.319 ◽

2012 ◽

Vol 501 ◽

pp. 319-323

Author(s):

Hasan A. Alwi ◽

Lay S. Ewe ◽

Zahari Ibrahim ◽

Noor B. Ibrahim ◽

Roslan Abd-Shukor

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Grain Size ◽

Transition Temperature ◽

Thermal Diffusivity ◽

Electrical Properties ◽

Room Temperature ◽

Electronic Contribution ◽

Insulator Metal Transition ◽

Thermal And Electrical Properties

We report the room temperature thermal conductivity κ and thermal diffusivity α of polycrystalline La0.7Ca0.3-xSrxMnO3 for x = 0 to 0.1. The samples were prepared by heating at 1220 and 1320oC. The insulator-metal transition temperature, TIM and thermal diffusivity increased with Sr content. Phonon was the dominant contributor to thermal conductivity and the electronic contribution was less than 1%. Enhancement of electrical conductivity σ and thermal diffusivity for x ≥ 0.08 was observed in both series of samples. The grain size of the samples (28 to 46 µm) does not show any affect on the thermal and electrical properties.

Download Full-text

Effect of grain size on low-temperature electrical resistivity and thermal conductivity of pure magnesium

Materials Letters ◽

10.1016/j.matlet.2018.07.037 ◽

2018 ◽

Vol 229 ◽

pp. 261-264 ◽

Cited By ~ 13

Author(s):

Xin Tong ◽

Guoqiang You ◽

Yuhan Ding ◽

Hansong Xue ◽

Yichang Wang ◽

...

Keyword(s):

Thermal Conductivity ◽

Grain Size ◽

Electrical Resistivity ◽

Low Temperature ◽

Pure Magnesium

Download Full-text

Effects of AlN Content and Sintering Atmospheres on the Thermal Conductivity of Hot-Pressed SiC Ceramics

Transactions of the Indian Ceramic Society ◽

10.1080/0371750x.2021.1952110 ◽

2021 ◽

pp. 1-6

Author(s):

Jingren Li ◽

Wenzhong Lu ◽

Hai Jiang

Keyword(s):

Thermal Conductivity ◽

Sic Ceramics

Download Full-text

Thermal Conductivity of Si₃N₄ Ceramics Fabricated From Carbothermal-reduction-derived Powder

10.21203/rs.3.rs-910628/v1 ◽

2021 ◽

Author(s):

Yuelong Wang ◽

Xingyu Li ◽

Haoyang Wu ◽

Baorui Jia ◽

Deyin Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Fracture Toughness ◽

Grain Size ◽

Flexural Strength ◽

Grain Boundaries ◽

Carbothermal Reduction ◽

Secondary Phase ◽

Gas Pressure ◽

Gas Pressure Sintering

Abstract Si3N4-based ceramic (Si3N4-5wt%Y2O3-3wt%MgO) was obtained from carbothermal-reduction-derived powder combined with gas pressure sintering. The phase, microstructure, thermal conductivity and mechanical properties of Si3N4 ceramics were comprehensively analyzed. Dense Si3N4 ceramic with uniform grain size was obtained after sintering at 1900°C for 7 h under a N2 pressure of 1.2 MPa. The secondary phase consisted of Y4Si2O7N2 and Y2Si3O3N4 was found to gather around triangular grain boundaries. The thermal conductivity, flexural strength, hardness and fracture toughness of the Si3N4 ceramics were 95.7 W·m-1·k-1, 715 MPa, 17.2 GPa and 7.2 MPa·m1/2, respectively. The results were compared with product derived from commercial powder, the improvement of thermal conductivity (~8.3%) and fracture toughness (~4.3%) demonstrating the superiority of Si3N4 ceramics prepared from carbothermal-reduction-derived powder.

Download Full-text

Effect of Grain Size and Film Thickness on the Thermoelectric Properties of Flexible Sb2Te3 Thin Films

Advances in Materials Science and Engineering ◽

10.1155/2019/6954918 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 12

Author(s):

Pornsiri Wanarattikan ◽

Piya Jitthammapirom ◽

Rachsak Sakdanuphab ◽

Aparporn Sakulkalavek

Keyword(s):

Thin Films ◽

Thermal Conductivity ◽

Electrical Conductivity ◽

Grain Size ◽

Film Thickness ◽

Seebeck Coefficient ◽

Thermoelectric Properties ◽

Flexible Substrate ◽

Rf Magnetron Sputtering ◽

Mean Free Path

In this work, stoichiometric Sb2Te3 thin films with various thicknesses were deposited on a flexible substrate using RF magnetron sputtering. The grain size and thickness effects on the thermoelectric properties, such as the Seebeck coefficient (S), electrical conductivity (σ), power factor (PF), and thermal conductivity (k), were investigated. The results show that the grain size was directly related to film thickness. As the film thickness increased, the grain size also increased. The Seebeck coefficient and electrical conductivity corresponded to the grain size of the films. The mean free path of carriers increases as the grain size increases, resulting in a decrease in the Seebeck coefficient and increase in electrical conductivity. Electrical conductivity strongly affects the temperature dependence of PF which results in the highest value of 7.5 × 10−4 W/m·K2 at 250°C for film thickness thicker than 1 µm. In the thermal conductivity mechanism, film thickness affects the dominance of phonons or carriers. For film thicknesses less than 1 µm, the behaviour of the phonons is dominant, while both are dominant for film thicknesses greater than 1 µm. Control of the grain size and film thickness is thus critical for controlling the performance of Sb2Te3 thin films.

Download Full-text