Reaction-formed silicon carbide

Microstructural characterization using orientation imaging microscopy of cellular Si/SiC ceramics synthesized by replication of Indian dicotyledonous plants

“…[41][42][43][44] The solution-precipitation and interface-controlled mechanisms have similarity with regard to linear dependence of reaction rate on carbon solubility in Si, the C-Si reaction being assumed to be of first order with respect to C concentration. 40 For cellular Si/SiC ceramics, Greil et al 9 attempted to explain the growth of the ␤-SiC layer into C struts with the help of diffusion-controlled mechanism, whereas interpretation of reaction of liquid Si and C of the pyrolyzed wood template in terms of solution-precipitation mechanism has become the theme of the work carried out by Zollfrank and Sieber. 37 The faceted morphology of the layer of reactionformed SiC grains observed in the present study ( Fig.…”

“…9,37 For the reaction mechanism, conflicting interpretations are available. Some authors reported continuous reaction product layers at the interface between C and Si that appeared to grow by a diffusion-controlled process; 34,35 no such continuous product layer was found by others [38][39][40] and it was suggested that the reaction product quickly spalled owing to volume misfit between SiC and C, leading to an interface-controlled reaction directly between Si and C. The other mechanism suggests repeating steps of dissolution of C in liquid Si followed by precipitation of SiC from supersaturated solution of C in Si, occur as the reaction front moves. [41][42][43][44] The solution-precipitation and interface-controlled mechanisms have similarity with regard to linear dependence of reaction rate on carbon solubility in Si, the C-Si reaction being assumed to be of first order with respect to C concentration.…”

Reactive melt infiltration of silicon-molybdenum alloys into microporous carbon preforms

“…6(a), there is an initial incubation period in the reaction (observed via DTA) before the exotherm starts. The cause of this phenomenon has been speculated by various researchers for the case of carbon fiber-liquid silicon reaction [8,20,21]. The exotherm temperature in the case of silicon-3.2 at.% molybdenum alloy is again lower than for the pure silicon.…”

“…Recent studies by various authors [5,8,20,21,23] confirm that the primary silicon carbide dissolves in the molten silicon and then reprecipitates as secondary silicon carbide. Owing to the low coefficients of diffusion of carbon and silicon in silicon carbide, the growth of silicon carbide by solid state reaction at the carbon-liquid silicon interface should be insignificant.…”

“…Research and development on silicon carbide based advanced ceramics and composites has attracted a great deal of attention in recent years [1][2][3][4][5][6][7][8]. The potential applications of these materials include components for advanced propulsion systems, energy conversion devices, and other high-temperature structures.…”