October 2000 Morphology and Stacking Faults of p-siC Whisker Synthesized 35 90 109 Fig. 6. TEM micrographs of the three different types of whiskers(a)type A, (b) type B, and(c)type C aligned with the electron beam parallel to the(110) axis). The corresponding electron diffraction patterns are shown as insets in each figure 125 Fig. 7. HREM image of type A whisker Inset shows the corresponding electron diffraction pat te ame morphology as SiC whisker that was synthesized from stacked powder. Here, if carbon monoxide (co)gas is ponsible for the sic formation reaction, the Sic formation ontent might change with the flow rate, because of the gaseous reaction of SiO and co, when the flow of sio gas from the Sio tack to the cb stack is in the same direction as the flow of hydrogen gas. In addition, if CO is used as a reaction gas, SiO, and Sic powders should be formed through the following reactions in Sio(g)+ 3Co(g)- SiC(s)+ 2Co(g) 3SiO(g)+Co(g)- SiC(s)+ 2SiO,(s) However, SiO, and Sic powders were not observed, even near the Fig 8. pe B whisker. Top figure shows a TEM image, reaction boat. Thus, we can conclude that Sic whisker formation IREM image (inset in the HREM image shows reaction occurs directly between the Sio gas and solid carbon. the co diffraction pattern)the same morphology as SiC whisker that was synthesized from the stacked powder. Here, if carbon monoxide (CO) gas is responsible for the SiC formation reaction, the SiC formation content might change with the flow rate, because of the gaseous reaction of SiO and CO, when the flow of SiO gas from the SiO2 stack to the CB stack is in the same direction as the flow of hydrogen gas. In addition, if CO is used as a reaction gas, SiO2 and SiC powders should be formed through the following reactions in the reactor:18 SiO~ g! 1 3CO~ g! 3 SiC~s! 1 2CO2~ g! (5) 3SiO~ g! 1 CO~ g! 3 SiC~s! 1 2SiO2~s! (6) However, SiO2 and SiC powders were not observed, even near the reaction boat. Thus, we can conclude that SiC whisker formation reaction occurs directly between the SiO gas and solid carbon. Fig. 6. TEM micrographs of the three different types of whiskers ((a) type A, (b) type B, and (c) type C aligned with the electron beam parallel to the ^110& zone axis). The corresponding electron diffraction patterns are shown as insets in each figure. Fig. 7. HREM image of type A whisker. Inset shows the corresponding electron diffraction pattern. Fig. 8. Micrographs of type B whisker. Top figure shows a TEM image, and the bottom shows an HREM image (inset in the HREM image shows the corresponding electron diffraction pattern). October 2000 Morphology and Stacking Faults of b-SiC Whisker Synthesized by Carbothermal Reduction 2587