Synthesis of Rod-Like High-Purity β-Sialon Powder by a Novel Carbothermal Reduction-Nitridation Method with a Nanocasting Procedure

β-Sialon/Ti(C,N) composites were prepared using low and middle grade bauxite and ilmenite as raw material,while coke as reducing agent in high purity nitrogen atmosphere through carbothermal reducrion-nitridation(CRN).The main phases of low and middle grade bauxite are kaolinire(Al2O3•2SiO2•2H2O) and (Al2O3•H2O)2 and ilmenite mainly contain ilmenite(FeTiO3) and rutile(TiO2).The reaction products of bauxite are the β-Sialon(Z=3,Si3Al3O3N5) while those of ilmenite are TiC and Fe.The results showed that the main phases are β-Sialon,Ti(C,N),Al2O3 and Fe when the reaction temperature is at 1400°C holding for 4 hours(10wt% ilmenite and 90wt% bauxite as raw material).However,β-Sialon decomposes into 21R at 1450°C and into 15R and AlN at 1500°C.So 1400°C is selected as the proper temperature to synthesize β-Sialon/Ti(C,N) composites.At 1400°C,the β-Sialon crystals with the largest quantity grow well and show long column in shape.With the increase of the reacrion temperature β-Sialon begin to decompose,the β-Sialon crystals change to short columnar,with the number decreasing quickly.

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Synthesis of Silicon Carbide Powders from Methyl-Modified Silica Aerogels

Applied Sciences ◽

10.3390/app10186161 ◽

2020 ◽

Vol 10 (18) ◽

pp. 6161

Author(s):

Kyoung-Jin Lee ◽

Yanggu Kang ◽

Young Hun Kim ◽

Se Won Baek ◽

Haejin Hwang

Keyword(s):

Silicon Carbide ◽

High Purity ◽

Silica Aerogel ◽

Carbothermal Reduction ◽

Single Phase ◽

Phase Evolution ◽

Silica Aerogels ◽

Methyl Groups ◽

Modified Silica ◽

Lower Temperature

β-silicon carbide (SiC) powders were synthesized by the carbothermal reduction of methyl-modified silica aerogel/carbon mixtures. The correlations between the phase evolution and morphologies of the SiC powders and the C/SiO2 ratio were investigated. At a C/SiO2 ratio of 3, β-SiC formed at 1425 °C and single-phase SiC powders were obtained at 1525 °C. The methyl groups (-CH3) on the silica aerogel surfaces played important roles in the formation of SiC during the carbothermal reduction. SiC could be synthesized from the silica aerogel/carbon mixtures under lower temperature and C/SiO2 ratios than those needed for quartz or hydrophilic silica. The morphology of the SiC powder depended on the C/SiO2 ratio. A low C/SiO2 ratio resulted in β-SiC powder with spherical morphology, while agglomerates consisting of fine SiC particles were obtained at the C/SiO2 ratio of 3. High-purity SiC powder (99.95%) could be obtained with C/SiO2 = 0.5 and 3 at 1525 °C for 5 h.

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Synthesis Ca-α-SiAlON powder by carbothermal reduction nitridation of colloidal sol-gel derived powder precursor

Ceramics International ◽

10.1016/j.ceramint.2019.05.320 ◽

2019 ◽

Vol 45 (14) ◽

pp. 17567-17573 ◽

Cited By ~ 1

Author(s):

M. Amin ◽

N. Ehsani ◽

R. Mozafarinia

Keyword(s):

Carbothermal Reduction ◽

Sol Gel ◽

Powder Precursor ◽

Sialon Powder

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Preparation of Ultrafine β-Sialon Powder by Citrate Sol-Gel and Carbothermal Reduction Nitridation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.927 ◽

2007 ◽

Vol 336-338 ◽

pp. 927-929 ◽

Cited By ~ 1

Author(s):

Hai Jun Zhang ◽

Hai Tang Zhang ◽

Jin Qi Miao ◽

Zi Liang Wang ◽

Quan Li Jia ◽

...

Keyword(s):

Particle Size ◽

Isoelectric Point ◽

Carbothermal Reduction ◽

Sol Gel ◽

Formation Temperature ◽

Nitriding Temperature ◽

Mean Particle Size ◽

The Mean ◽

Sialon Powder ◽

Crystal Seed

Ultrafine β-sialon powder is synthesized by citrate sol-gel and carbothermal reduction and nitridation (CRN) process. The presence of small amounts of β-sialon as crystal seed can obviously accelerate the formation of final β-sialon product and lower its formation temperature. The effects of nitriding temperature on the formation of the final β-sialon are investigated. The mean particle size of the prepared β-sialon powder is 100 ~ 150 nm. The β-sialon precursor gel and the ultrafine β-sialon powder are characterized by XRD, TG-DTA and SEM. The isoelectric point of ultrafine β-sialon is pH 2.46.

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Fabrication and Analysis of β-Sialon Whiskers from Fly Ash by Carbon Thermal Reduction-Nitridation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.723.610 ◽

2015 ◽

Vol 723 ◽

pp. 610-614

Author(s):

Jing Zhang ◽

Jiang Long Yu ◽

Huan Zhao ◽

Jun Shuai Liu

Keyword(s):

Fly Ash ◽

Reaction Time ◽

Carbon Content ◽

Reaction Temperature ◽

Carbothermal Reduction ◽

Thermal Reduction ◽

Optimal Temperature ◽

Nitridation Process ◽

Best Parameter ◽

Sialon Powder

β-Sialonwhiskers which the molecular structuralformula of β-Sialonis Si3Al3O3N5(z = 3) were synthesized from fly ash and graphite under appropriate technological conditions by carbothermal reduction–nitridation process. The effects of carbon content, reaction temperature and reaction time on synthesis ofβ-Sialonwere analysed by XRD, SEM techniques. The results proved that, the condition of the carbon content over 80% is the best parameter to promote theβ-Sialon powder production. Compared to other kinds of temperature, 1430 °C is the optimal temperature to promoteβ-Sialon powder generation. Compared to 3h, holding time of 6h is promoting theβ-Sialon powder generation.The main morphology of β-Sialon was rod-like whisker.

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