| 摘要 |
<p>A furnace of the Bridgeman type, for making crystals, with a heated wall e.g. cylindrical, and contg. a support for a crucible, incorporates a screen which can be moved axially in a controlled manner between the heated wall and the crucible, so that it masks the crucible as it moves. A process using the furnace consists of filling the crucible with the material being crystallised, while the screen is in its low position, heating the furnace to a temp. above the m.pt. of the substance and constant over the zone of the crucible, and raising the screen slowly until the substance has completely crystallised. The furnace is easier to control and fre from the risk of vibrations or of superheating, than existing furnaces in which the crucible is cooled or the temp. of the furnace wall is varied.</p> |
