SiC Crystals Derived from β‐SiC Powder Using a Conically Converging Shock‐Wave Technique

Abstract

α‐SiC and β‐SiC crystals are prepared from vapor by sublimation of β‐SiC powder subjected to a conically converging shock‐wave generated by detonating an explosive charge. α‐SiC crystals are mainly 6H modifications and their features are plates, pyramids, needles, and filaments grown in the [0001] direction; 4H‐SiC filaments are also obtained. α‐SiC rods having a triangular cross section develop parallel to the [111] direction.

Characterization of SiC Whiskers from Rice Husks in Argon Atmosphere

“…The reaction ( 6) is followed by reaction (4) to synthesize CO, which in turn reacts with SiO 2 according to reaction (3) and SiO according to reaction (6), and to continue the cycle. Silicon carbide can be formed by heterogeneous nucleation according to reaction (5) by vapor-solid (VS) mechanism at the early stage.…”

“…Silicon carbide (SiC) whiskers have been interested as a reinforcing material for use in plastics, metals and ceramics to produce strong and tougher composite ceramics and light metal alloys because they are fine structure and have a mechanical strength close to theoretical [1,2]. There are several methods to produce SiC whiskers, for example: by reacting metallic silicon and coal tar pitch mixture [3], through reaction of SiO 2 and CH 4 [4], by reduction of methyl trichlorosilane [5], by vaporization of bulk SiC [6], by reacting Si 3 N 4 with carbon [7], by sol-gel techniques or laseror plasma-driven chemical vapor deposition [8], through induction of carbon fiber [9], by thermal decomposition of potentially inexpensive agricultural byproducts such as rice husks and coconut shells [10].…”

“…SiC whiskers offer composites an easy processing, isotropic mechanical properties, and moreover improved resistance to high temperature environments and greater work of fracture [6]. These superior characteristics have attracted much attention not only to the study on SiC whiskers composites but also to the synthesis technologies of SiC whiskers [11].…”

Characterization of Shock-Recovered BaSi2 Powder

“…The formation of different crystal morphologies by gas evaporation and condensation has been reported. Yamada and Tobisawa observed that many varieties of fine crystals of CdS, 38) SiC, 39,40) carbon, 41,42) and ZnO 43) are formed by the conically converging shock-wave technique. For instance, whiskers 0.3 m in diameter and 8 m in length developed in shocked ZnO in addition to plates, spheres, hollows, and star-shaped crystals.…”