| 摘要 |
PURPOSE:To accomplish the title calcination intended to improve product precision through such processes that a ceramic is put to temperature rise at a high rate in its initial calcination stage, and in the next stage, temperature is raised at a slower rate than that in the first stage to advance the calcination followed by temperature rise at a higher rate than the second stage and the resulting ceramic is held at a maximum temperature for a specified time. CONSTITUTION:A ceramic such as of Si3N4 is first put to rapid temperature rise to about 1200 deg.C at a rate of 10 deg.C/min in a low-pressure inert gas atmosphere. In the next stage, temperature is raised to 1200-1400 deg.C or so under increased inert gas pressure. In the third stage, the ceramic is raised in the temperature at a rate of 0.5 deg.C/min to 1400-1650 deg.C or so to advance its sintering with its rapid shrinkage suppressed. In the final stage, temperature is raised from ca.1650 deg.C to a maximum temperature at a rate of 2 deg.C/min and the resultant ceramic is held at the maximum temperature for a specified time, thus giving a highly densified ceramic sintered compact. l. temperature 2. time 3. gas pressure. |
