Fabrication and mechanism of 6H-type silicon carbide whiskers by physical vapor transport technique

Shi, Yonggui; Yang, Jianfeng; Liu, Hulin; Dai, Peiyun; Liu, Bobo; Jin, Zhihao; Qiao, Guanjun; Li, Hailiang

doi:10.1016/j.jcrysgro.2012.03.055

Cited by 13 publications

(6 citation statements)

References 32 publications

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“…While the bending strength is about 335.6 MPa, which is higher than the bending strength of using the 50 µm and 175 μm SiC powders. It is well known that the bending strength of the ceramic materials depends largely on the grain size and it decreased with an increase in the grain size, as explained by Carniglia using the Hall-Petch-type relationship [18][19]. In this study, the SiC grain size is mainly the reason which causes the low bending strength.…”

Section: Resultsmentioning

confidence: 61%

“…However, the grain size of 50 µm grade powder is between the 13 µm ~ 80 µm range larger and causes scattered nucleation, the grain size of the 175 µm grade powder is in the range of 43 µm ~110 µm. It is also reported that the proper temperature and the raw material were two key factors in the SiC growth region, the temperature guaranteed the evaporation of the raw materials to form the catalyst and promoted the nucleation and growth of 6H-SiC, while the raw vapour obtained by the heat radiation holes in the carbon fibre felt facilitated the transportation and transition of the vapour specials [19]. In addition, it can also be found in the figure that the size of the grain size is associated with the particle size of the raw materials at the same temperature.…”

Section: Resultsmentioning

confidence: 99%

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FABRICATION OF HIGHLY DENSE PURE 6H-SiC CERAMICS VIA THE PVT METHOD USING SUB-MICRON SiC POWDERS

Liu¹

2020

Ceramics - Silikaty

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The dense SiC ceramics were prepared by the physical vapour transport (PVT) method using three types of SiC powder with different grain size, including a kind of SiC powder with a mean diameter of 500 nm. The effects of the grain size of the raw materials on the bulk density, bending strength and hardness of the SiC ceramics were studied. It was found that with a decreasing grain size, the bulk density and the bending strength of the fabricated SiC ceramics increased, while the Vickers hardness decreased. the effects of the grain size of the raw materials on the nucleation density and the growth rate of the SiC were analysed, and the growth characteristic of the SiC ceramics was systematically explored. The results indicated that the crystal type, the nucleation density and the growth rate were obviously affected by the soaking temperature. When the temperature was higher or lower than 2200 °C, the fabricated ceramics was composed of a 6H-SiC polycrystalline or the mixture of a 6H-SiC and 3C-SiC polycrystalline. Meanwhile, with an increasing temperature, the nucleation density decreased and the growth rate increased. Obviously, by optimising the fabrication process, highly dense 6H-SiC ceramics with a bulk density of 3.07 g•cm-3 and a bending strength of 335.6 ± 10 MPa could be rapidly fabricated by the PVT method using the sub-micron SiC powder.

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Section: Resultsmentioning

confidence: 61%

Section: Resultsmentioning

confidence: 99%

FABRICATION OF HIGHLY DENSE PURE 6H-SiC CERAMICS VIA THE PVT METHOD USING SUB-MICRON SiC POWDERS

Liu¹

2020

Ceramics - Silikaty

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“…At present, various techniques such as physical vapor transport [17], carbothermal reduction [18][19][20][21], one-step thermal reduction method using carbon black and gangue [22], chemical vapor infiltration(CVI) [23], vapor-solid reaction [24], in-situ reaction [25,26], vapor deposition method [27], chemical vapor deposition (CVD) [28], a method with reactive graphite as template [29] and solution method [30], have been utilized to fabricate SiC w . In addition, Chen et al [31] reported a simple technique to produce SiC w on graphite matrix using common and low cost hydrogen silicone oil.…”

Section: Introductionmentioning

confidence: 99%

In-situ growth and characterization of SiC fibers during Si vapor infiltration process without catalysis

Li¹,

Wang

Cheng³

et al. 2016

Ceramics International

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“…They have reported the materials exhibit a resistivity in the 2×10 9 ohm cm range and planar devices from these materials of 4.07×10 -3 cm 2 V -1 electron mobility. Shi et al [2] utilized the physical vapor transport technique to prepare 6H-type silicon carbide whiskers and to investigate the mechanism of nucleation and the growth of SiC whiskers. In the paper, two key factors of (1) the evaporation of raw materials, and (2) the transportation and transition of the vapor species were found.…”

Section: Introductionmentioning

confidence: 99%

“…Even though the process of PVT is an important crystal growth process in applications for acousto-optic materials [1][2][3][4][5][6], until now a better and thorough understanding of convection is required as a basis on the ground for space experiments in the future. This motivation causes us to investigate effects of solutally dominant convection on PVT for a mixture of Hg 2 Br 2 and Br 2 under microgravity environments.…”

Section: Introductionmentioning

confidence: 99%

Effects of Solutally Dominant Convection on Physical Vapor Transport for a Mixture of Hg₂Br₂and Br₂under Microgravity Environments

Kim¹,

Kwon²

2014

Korean Chemical Engineering Research

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The convective flow structures in the vapor phase on earth are shown to be single unicellular, indicating the solutally dominant convection is important. These findings reflect that the total molar fluxes show asymmetrical patterns in a viewpoint of interfacial distributions. With decreasing the gravitational level form 1 g 0 down to 1.0 × 10 -4 g 0 , the total molar fluxes decay first order exponentially. It is also found that the total molar fluxes decay first order exponentially with increasing the partial pressure of component B, PB (Torr) form 5 Torr up to 400 Torr. Under microgravity environments less than 1 g 0 , a diffusive-convection mode is dominant and, results in much uniformity in front of the crystal regions in comparisons with a normal gravity acceleration of 1 g 0 . ated with the total molar flux along the crystal interfacial positions. Unless the two components have molecular weights very close to each other, it is concluded that for 2 ≤ M B ≤ 50, the dominant mode of convection is solutal. For the range of 5 Torr ≤ P B ≤ 100 Torr, the molar fluxes drop significantly, and, for 100 Torr ≤ P B ≤ 400 Torr, decreases slowly, and, for 5 Torr ≤ P B ≤ 400 Torr, the total molar fluxes decay first order exponentially with the partial pressure of component B, PB. ACKNOWLEDGEMENT

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Fabrication and mechanism of 6H-type silicon carbide whiskers by physical vapor transport technique

Cited by 13 publications

References 32 publications

FABRICATION OF HIGHLY DENSE PURE 6H-SiC CERAMICS VIA THE PVT METHOD USING SUB-MICRON SiC POWDERS

FABRICATION OF HIGHLY DENSE PURE 6H-SiC CERAMICS VIA THE PVT METHOD USING SUB-MICRON SiC POWDERS

In-situ growth and characterization of SiC fibers during Si vapor infiltration process without catalysis

Effects of Solutally Dominant Convection on Physical Vapor Transport for a Mixture of Hg₂Br₂and Br₂under Microgravity Environments

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Fabrication and mechanism of 6H-type silicon carbide whiskers by physical vapor transport technique

Cited by 13 publications

References 32 publications

FABRICATION OF HIGHLY DENSE PURE 6H-SiC CERAMICS VIA THE PVT METHOD USING SUB-MICRON SiC POWDERS

FABRICATION OF HIGHLY DENSE PURE 6H-SiC CERAMICS VIA THE PVT METHOD USING SUB-MICRON SiC POWDERS

In-situ growth and characterization of SiC fibers during Si vapor infiltration process without catalysis

Effects of Solutally Dominant Convection on Physical Vapor Transport for a Mixture of Hg2Br2and Br2under Microgravity Environments

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Effects of Solutally Dominant Convection on Physical Vapor Transport for a Mixture of Hg₂Br₂and Br₂under Microgravity Environments