Carbothermal synthesis of TiC whiskers via a vapor-liquid-solid growth mechanism

TiC whiskers were synthesized via a vapor-liquid-solid (VLS) growth mechanism in the temperature region 1200 degrees-1600 degrees C in a protecting argon atmosphere. The starting materials consisted of TiO2, carbon, nickel, and an alkalimetal chloride, such as NaCl, used as a precursor for chlorine. The overall chemical reaction was based on a straightforward carbothermal reduction process, but the reactions that actually took place were more complex and involved formation of gaseous TiClx species, which were transported to the nickel catalyst. The formation of TiC whiskers depended on the processing conditions used, mixing procedure of the precursor materials applied, and properties of precursor materials chosen, e.g., their particle sizes. A route for synthesizing TiC whiskers at a yield of 80-90 vol% was established. The whiskers mere similar to 1 mu m in diameter and 10-30 mu m in length; they were straight and had smooth surfaces. The main impurities were TiC particles, minor amounts of unreacted carbon, and remnants of the nickel catalyst.