Abstract
For the purpose of determining the optimum temperature and relating factors for vapor deposition of zirconium carbide, the deposition rates were measured with a thermo-balance.
Deposition was observed at emperatures above 770°C and the (100) planes were developed in parallel with the surface of graphite substrate. The both planes of (110) and (100) were found relatively distinct at above 840 and 1200°C, respectively. The deposition took place within 0.4 sec. after the two reacting gas streams were mixed together. The deposition rates were proportional to the linear velocity of hydrogen and the concentrations of zirconium tetrachloride and hydrocarbons. The increase of the rates with temperature became slower at higher temperatures owing to the pyrolysis of hydrocarbons.
Higher rates were given by paraffins and naphthenes. However, the highest rates were found in the range of their concentrations of 0.3-0.7vol.% (indicated as reduced value to propane); and the rates were rather decreased by carbon deposition beyond that range.
Benzene was out of the above regularity, owing to its large anti-pyrolytic property. Its growth rate was 0.3-0.8μ/min. under the optimum condition at 1200-1300°C.
