| 摘要 |
<p>In order to eliminate the oxygen sensitivity of chromium carbide and vanadium carbide particles, vanadium carbide and chromium carbide particles are formed by carburizing a precursor compound at a elevated reaction temperature of about 950 DEG C. Initially, the precursor compound is heated in an inert nitrogen-containing gas to the reaction temperature. Once the reaction temperature is achieved, hydrogen and a carbon-containing gas such as methane or ethylene are used to conduct the carbonization. After the carbonization has been completed, the carbonizing gas is then replaced with an inert nitrogen-containing gas and the product allowed to cool down. The carbonization cycle is adjusted so that the oxygen level is kept to less than 0.35%, while the nitrogen level is kept at about 2%. Powders produced from this process show minimal or no oxygen pickup when exposed to ambient air.</p> |
