Chemical vapor deposition of silicon carbide whiskers activated by elemental nickel

Chemical vapor deposition of silicon carbide whiskers from the thermal decomposition of methyltrichlorosilane was performed at 1300 degrees C on Ni-coated graphite substrates with an emphasis on the thickness effect of the activating Ni coatings on the growth characteristics of the whiskers obtained. The results showed that the addition of Ni is essential for the successful preparation of whiskers. As a result of the difference in the thermodynamic and kinetic processes fur the breakup of Ni coatings during heating, the number of discrete particles formed was found to decrease with increasing coating thickness,while the diameter of the particles demonstrated an increasing trend. Those particles then acted as a liquid-forming agent for the successful operation of the vapor-liquid-solid mechanism for whisker growth. The nucleation density, length, and aspect ratio of the whiskers thus resulting was found to decrease with increasing Ni coating thickness, but the diameter showed an opposite tendency. In summary, the growth characteristics and quality of the whiskers deposited were strongly affected by the particles formed as a result of the breakup of Ni coatings, which in turn were greatly influenced by the thickness of the Ni coatings. (C) 1999 The Electrochemical Society. S0013-4651(97)10-100-8. All rights reserved.