| Molybdenum was deposited onto nickel substrate by chemical vapor deposition from MoCl_5 and H₂ gas mixture. Effects of temperature, flow rate of the gas, and MoCl_5 partial pressure on the deposition rate, microhardness, and x-ray pattern were thoroughly investigated. The deposition rate of Mo was found to be zero order reaction and was increased with increasing temperature, flow rate of the gas, and MoCl_5 partial pressure It was apparent that the reaction mechanism changes at 900℃, at temperatures lower than 900℃ the activation energy is 35.8Kcal/mole, whilst at temperatures higher than that is 3.6Kcal/mole. In the region of diffusion control, the deposition rate of Mo was proportional to the square of total flow rate. The microhardness of deposited layer was increased and the preferred orientation(220) distinctively appeared with increaing above three factors, (reaction temperature, flow rate of the gas, and Mocl_5 partial pressure) however, the former was highest and the latter was lowest at 800℃. |
|
