12033-76-0Relevant articles and documents
Hydrolysis-induced aqueous gelcasting of β-SiAlON-SiO2 ceramic composites: The effect of AlN additive
Ganesh, Ibram,Sundararajan, Govindan
, p. 3180 - 3189 (2010)
Dense β-SiAlON-SiO2 (SiO2520, 40, 50, 60, and 80 wt%)ceramic composites have been prepared from β-Si4Al 2O2N6 and fused silica by sintering at 15001-1750°C for 3-4 h. For comparison purposes, a powder mixture consisting 60 wt% β-Si4Al2O2N6 and 40 wt% fused silica has been consolidated following a new near-net shape technique based on hydrolysisinduced aqueous gelcasting (GCHAS) and sintered for 3 h at 1750°C. In the GCHAS process, consolidation of suspensions containing 50 vol% solids was achieved by adding a polymerization initiator, a catalyst, and AlN powder equivalent to 1-5 wt%Al2O3. Thin-wall radomes consolidated by GCHAS (using AlN equivalent to 5 wt% Al2O3 in the suspension) have exhibited green strengths 420 MPa. The sintered materials were characterized for various properties including hardness, fracture toughness, mass loss, shrinkage, coefficient of thermal expansion, and dielectric constant. The Si2N2O formed from a powder mixture of 60 wt% β-Si4Al2O2N6 and 40 wt% fused silica at 1750°C for 3 h exhibited a flexural strength of B140 MPa, Young's modulus of 214 GPa, coefficient of thermal expansion of 3.5×10 -6°C-1, hardness of 1390 kg/mm2, fracture toughness of 4.2MPa .m1/2, and a dielectric constant of 5.896 and tan δ of 0.002 at 17 GHz.
Spark plasma sintering of nanosized amorphous silicon nitride powder with a small amount of sintering additive
Hotta, Mikinori,Shinoura, Takanori,Enomoto, Naoya,Hojo, Junichi
, p. 1544 - 1546 (2010)
Dense and fine-grained β-Si3N4 ceramics were successfully obtained with a small amount of sintering additives, 1.5 mass% Y2O3 and 0.5 mass% Al2O3, using nanosized amorphous Si3N4 powder by spark plasma sintering at temperatures of 1500°-1800°C and a pressure of 30 MPa under N 2. The β-Si3N4 ceramics were composed of equiaxed grains with an average size of 300 nm. A higher sintering temperature was required for the densification of submicrometer-sized α-Si 3N4 powder with the small amount of the additives. The use of nanosized amorphous Si3N4 powder accelerated the densification and the transformation to the β-phase.
Carbothermal synthesis of silicon nitride: Effect of reaction conditions
Durham,Shanker,Drew
, p. 31 - 37 (1991)
Conditions for carbothermal synthesis of α-Si3N4 are presented with special emphasis on the reaction temperature, C:SiO2 ratio, and precursor mixing. With pure precursors, the conversion temperature is 1500° to 1550 °C. An
Formation process of calcium-α SiAlON hollow balls composed of nanosized particles by carbothermal reduction-nitridation
Hotta, Mikinori,Tatami, Junichi,Komeya, Katsutoshi,Zhang, Cheng,Meguro, Takeshi,Terner, Mark R.,Cheng, Yi-Bing
, p. 860 - 864 (2008)
Carbothermal reduction-nitridation (CRN) of SiO2-Al 2O3-CaO powders was performed under various firing conditions to investigate the formation process of Ca-α sialon hollow balls composed of nanosized particles. Scanning electron microscopy and transmission electron microscopy observations of the samples obtained at different firing temperatures confirmed that solid spherical particles were formed at the early stage of the reaction, and nanosized particles were subsequently produced on the surface of these solid balls. From X-ray diffraction and energy-dispersive spectrometry analyses, it was found that the solid balls initially formed at 1450°C were mainly amorphous and contained Si, Al, Ca, O, and a small amount of N. Further nitridation at 1450°C gradually converted the solid balls into Ca-α sialon hollow balls over time. The results revealed that the formation of Ca-α sialon hollow balls depends on the formation of solid balls from the Si-Al-Ca-O liquid phase at the initial stage of the CRN process.
Arias, Alan
, (1981)
Direct electrochemical preparation of nanostructured silicon carbide and its nitridation behavior
Vishnu, D. Sri Maha,Sure, Jagadeesh,Kim, Hyun-Kyung,Kim, Ji-Young,Kumar, R. Vasant,Schwandt, Carsten
, p. D731 - D742 (2019/01/03)
Silicon carbide was synthesized from mixtures of SiO2 and graphite by applying the concept of the FFC-Cambridge process and several fundamental aspects of the synthesis route were investigated. Porous disks composed of powders of SiO2 and graphite in molar ratios of 1:0.5, 1:1 and 1:1.5 were prepared by sintering in inert atmosphere and subjected to electro-deoxidation in molten CaCl2 at 1173 K under a range of experimental conditions. Disks of molar ratio 1:1.5, reduced at an applied voltage of 2.8 V for a duration of 6 h, yielded exclusively phase-pure SiC of nanowire morphology as the reaction product, while the other precursor compositions provided significant amounts of calcium silicides. Voltages lower than 2.8 V gave mixtures of SiC with elemental Si and graphite, and voltages higher than that gave CaSi alone. Shorter electro-deoxidation times led to incomplete reduction and allowed for the identification of CaSiO3 as a transient phase. Based on the experimental results a multipath reaction mechanism is proposed, consisting of the electrochemical reduction of SiO2 and CaSiO3 to Si and the subsequent in-situ carbonization of the Si formed to SiC. The effect of N2 at high temperature on the electrochemically synthesized SiC was investigated and the formation of nanowire Si2N2O was observed. Overall, the process presented is a facile single-step and low-temperature method for the synthesis of SiC with possible commercial prospects.
