Kinetics of synthesis of silicon carbide by carbothermal reduction of silicon dioxide

Zhou

Int J Applied Ceramic Tech

et al. 2020

Iron tailings remain the environment-damaging waste from the iron ore, and high porosity porous ceramics are an attractive material to "turn waste into treasure." To improve the thermal conductivity, porous ceramics with high silicon carbide content have been prepared by carbothermal reduction sintering process using argillaceous fine-grained iron tailings with high silica content. The carbothermal reduction reaction mechanism and the components and properties of samples in sintering process are investigated. The results show that reaction components in the tailings are mainly Central Universities. The financial supported by them are greatly appreciated.

Section: Resultsmentioning

confidence: 99%

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

Zhou

Int J Applied Ceramic Tech

et al. 2020

Int J Applied Ceramic Tech

“…When the graphite concentration increases, more sites are available for nucleation of both Si 3 N 4 and SiC. 31,32 Furthermore, both Si 3 N 4 and SiC crystals grow faster (to be discussed later). However, as shown in Table III, the relative quantity of SiC increases when the graphite concentration increases from 3.5C to 4.5C, suggesting that the nucleation rate or growth rate (or both) of SiC increases faster with increase in the graphite concentration than Si 3 N 4 .…”

Section: Formation Of Nanostructured Si 3 N 4 /Sic Powdersmentioning

confidence: 99%

Tailoring the Relative Si₃N₄ and SiC Contents in Si₃N₄/SiC Nanopowders through Carbothermic Reduction and Nitridation of Silica Fume

Suri

Shaw

Zawrah³

2012

This study demonstrates the synthesis of nanostructured Si3N4/SiC composite powders from silica fume, for the first time. The processing approach to convert the waste silica fume to advanced nanocomposites is based on the integrated mechanical and thermal activation (IMTA) process. The synthesized nanostructured Si3N4/SiC powders have crystallite sizes as small as 17 nm for SiC and 42 nm for Si3N4. It has been shown that the carbothermic reduction and nitridation temperature, as well as the graphite concentration in the starting SiO2 + C mixture are the important parameters to obtain Si3N4 and SiC nanopowders and control their crystal sizes. The synthesis conditions to tailor the relative contents of α‐Si3N4 and α‐SiC (changing from as high as 49 vol.% to as low as 21 vol.% α‐SiC) in the final powder mixture have been investigated, and the mechanisms responsible for the observed relationship between processing conditions and the characteristics of the final powder have been identified.

Journal of the American Ceramic Society

“…It is well known that SiC formation from carbothermic reduction at temperatures lower than 16001C occurs through the following overall reaction 8,9,13,[21][22][23][24][25][26][27] : When SiO 2 is in direct contact with C, this overall reaction proceeds in two elementary reactions 8,9,13 SiO 2 ðsÞ þ CðsÞ ¼ SiOðgÞ þ COðgÞ…”

Section: (3) Reaction Pathways Of Carbothermic Reductionmentioning

confidence: 99%

“…However, if SiO 2 is not in contact with C, reaction (4) ceases to function. In this case, it has been proposed that gaseous SiO can be generated through the following reaction 8,9,[23][24][25][26][27] :…”

Section: (3) Reaction Pathways Of Carbothermic Reductionmentioning

confidence: 99%

Synthesis of Silicon Carbide Nanopowder Using Silica Fume

Zhong

Shaw

Manjarres

et al. 2010

Silica fume is a byproduct of producing silicon metal and ferrosilicon alloys, and contains 94–97 wt% SiO2. This study demonstrates, for the first time, that silica fume can be converted to nano‐SiC powder at 1500°C via carbothermic reduction with the aid of high‐energy ball milling of the silica fume plus graphite mixture at room temperature. The nano‐SiC synthesized has particle sizes as small as 30 nm. The effects of the carbothermic reduction temperature and the graphite concentration in the starting SiO2+C mixture on the conversion of SiO2 to SiC have been investigated. The reaction pathways of carbothermic reduction have been identified. A carbon elimination treatment using H2 to remove the free carbon in the nano‐SiC powder has also been proven effective and the extent of carbon elimination depends on the reaction temperature, reaction duration, and quantity of the free carbon present before the carbon elimination treatment.