Two-faced liquid silicon

Nature India ◽  
2011 ◽  
Keyword(s):  
Author(s):  
K Das Chowdhury ◽  
R. W. Carpenter ◽  
W. Braue

Research on reaction-bonded SiC (RBSiC) is aimed at developing a reliable structural ceramic with improved mechanical properties. The starting materials for RBSiC were Si,C and α-SiC powder. The formation of the complex microstructure of RBSiC involves (i) solution of carbon in liquid silicon, (ii) nucleation and epitaxial growth of secondary β-SiC on the original α-SiC grains followed by (iii) β>α-SiC phase transformation of newly formed SiC. Due to their coherent nature, epitaxial SiC/SiC interfaces are considered to be segregation-free and “strong” with respect to their effect on the mechanical properties of RBSiC. But the “weak” Si/SiC interface limits its use in high temperature situations. However, few data exist on the structure and chemistry of these interfaces. Microanalytical results obtained by parallel EELS and HREM imaging are reported here.


2014 ◽  
Vol 33 (4) ◽  
pp. 363-368 ◽  
Author(s):  
Halvor Dalaker ◽  
Merete Tangstad

AbstractThe interactions between carbon and nitrogen in liquid silicon have been studied experimentally. High purity silicon was melted in silicon nitride crucibles under an Ar atmosphere with a graphite slab inserted in the crucible prior to melting as a carbon source. The system was thus simultaneously equilibrated with Si3N4 and SiC. Samples were extracted in the temperature range 1695–1798 K and analyzed using Leco.It was observed that the simultaneous saturation of nitrogen and carbon caused a significant increase in the solubilities of both elements. The interaction parameters were derived as The solubility of carbon in liquid silicon as a function of temperature and nitrogen content was found to follow: And the solubility of nitrogen in liquid silicon found to follow:


2018 ◽  
Vol 53 (2) ◽  
pp. 214-228 ◽  
Author(s):  
Yue Zha ◽  
Jing Li
Keyword(s):  

2012 ◽  
Vol 108 (6) ◽  
Author(s):  
J. T. Okada ◽  
P. H.-L. Sit ◽  
Y. Watanabe ◽  
Y. J. Wang ◽  
B. Barbiellini ◽  
...  

2011 ◽  
Vol 66 (1-2) ◽  
pp. 134-138
Author(s):  
Marco Antonio Béjar ◽  
Rodrigo Mena ◽  
Juan Esteban Toro

Biomorphic SiC/Si composites were produced from pine and beech wood, and the corresponding electrical conductivity was determined as a function of the temperature. Firstly, wood preforms were pyrolized at 1050 °C in nitrogen. Then, the pyrolized preforms were impregnated with liquid silicon and kept at 1600 °C for 2 h in vacuum. The SiC/Si composites were obtained due to the produced carbothermal reaction. As expected, the resulting electrical conductivity of these composites increased with the temperature and with the silicon content.


1993 ◽  
Vol 88 (5) ◽  
pp. 381-385 ◽  
Author(s):  
James R. Chelikowsky ◽  
N. Binggeli

1979 ◽  
Vol 72 (2) ◽  
pp. 153-154 ◽  
Author(s):  
N.M. Kéita ◽  
S. Steinemann

1982 ◽  
Vol 13 ◽  
Author(s):  
D. Barbierf ◽  
M. Baghdadi ◽  
A. Laugier ◽  
A. Cachard

ABSTRACTIn this work Pulsed Electron Beam Annealing has been used to Sctivaye As implanted in (100) and (111) silicon (140 keV- 1015 cm−2 ). With a selected electron beam energy deposition profile excellent regrowth layer quality and As activation has been obtained in the 1.2–1.4 J/cm2 fluence range. As redistribution is conistent with the melting model assuming a diffusivity of 10−4 cm2/s in liquid silicon. As losses might slightly reduce the carrier concentration near the surface in the case of (100) silicon. However a shallow and highly active N+ layer have been achieved with optimized PEBA conditions.


2008 ◽  
Vol 23 (5) ◽  
pp. 1237-1248 ◽  
Author(s):  
Jesse C. Margiotta ◽  
Dajie Zhang ◽  
Dennis C. Nagle ◽  
Caitlin E. Feeser

Fully dense and net-shaped silicon carbide monoliths were produced by liquid silicon infiltration of carbon preforms with engineered bulk density, median pore diameter, and chemical reactivity derived from carbonization of crystalline cellulose and phenolic resin blends. The ideal carbon bulk density and minimum median pore diameter for successful formation of fully dense silicon carbide by liquid silicon infiltration are 0.964 g cm−3 and approximately 1 μm. By blending crystalline cellulose and phenolic resin in various mass ratios as carbon precursors, we were able to adjust the bulk density, median pore diameter, and overall chemical reactivity of the carbon preforms produced. The liquid silicon infiltration reactions were performed in a graphite element furnace at temperatures between 1414 and 1900 °C and under argon pressures of 1550, 760, and 0.5 Torr for periods of 10, 15, 30, 60, 120, and 300 min. Examination of the results indicated that the ideal carbon preform was produced from the crystalline cellulose and phenolic resin blend of 6:4 mass ratio. This carbon preform has a bulk density of 0.7910 g cm−3, an actual density of 2.1911 g cm−3, median pore diameter of 1.45 μm, and specific surface area of 644.75 m2 g−1. The ideal liquid silicon infiltration reaction conditions were identified as 1800 °C, 0.5 Torr, and 120 min. The optimum reaction product has a bulk density of 2.9566 g cm−3, greater than 91% of that of pure β–SiC, with a β–SiC volume fraction of approximately 82.5%.


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