坩埚的预热

Preheating of crucible

1.坩埚属陶瓷制品，坩埚壁内存在一定数量的气孔，容易吸潮，所以首次使用坩埚之前在不加料的条件下，坩埚必须进行预热以确保没有湿气残留在坩埚壁中：最好是放在有温度的炉边烘烤24小时以上，在这段时间内，坩埚要转动几次，使其均匀受热，去除坩埚壁内的潮气（或者将适量干燥的木屑放置坩埚闷烧，在不见明火的状态下闷3小时以上，达到最佳预热效果）。以免坩埚升温太快，造成坩埚热膨胀，出现掉底、脱层或爆裂。

The crucible is a ceramic product with a certain number of pores in the crucible wall and is easy to absorb moisture. Therefore, the crucible must be preheated before the crucible is used for the first time under the conditions of none material to ensure that no moisture remains in the crucible wall. It is best to bake on the temperature of the furnace more than 24 hours, during which time, the crucible to turn a few times to make it evenly heated to remove the crucible wall of moisture (or the appropriate amount of wood placed in the crucible combustion 3 Hour or so to achieve preheat effect), so as not to crucible heating too fast, resulting in thermal expansion of the crucible, there fell out, delaminating or burst.

注：潮气一般在75~100度时蒸发的最快，所以在此温度时升温一定要慢；2小时后（视坩埚具体受潮情况适当延长100℃之内的预热时间）坩埚预热至150~200度并保温一小时，之后每小时升温150度。由于在315~650度的温度范围内坩埚壁会出现快速氧化，氧化不仅会缩短坩埚的寿命，而且会由于热导率降低影响其使用性能，因此坩埚无需在此温度区间内停留过久的时间。

Note: Moisture is generally 75 to 100 degrees when the fastest evaporation, so the temperature at this temperature must be slow; 2 hours later(depending on the crucible specific moisture situation within the appropriate extension of the warm-up time within 100 ℃) crucible preheated to 150 to 200 degrees and heat for one hour, then 150 degrees per hour temperature. Oxidation not only shortens the life of the crucible due to the rapid oxidation of the crucible wall in the temperature range of 315-650 ° C, but also affects the serviceability due to the decrease of the thermal conductivity, so the crucible does not need to stay in this temperature range for too long.

2.坩埚经过第一次预热后通常如连续使用无需再次预热，除非坩埚再次暴露于潮湿的环境中。

The crucible, after the first warm-up, is usually used without continuous reheating unless the crucible is again exposed to a humid environment.

3.坩埚预热后，操作人员需要在不加料的状态下快速升温到850~950度，并保温半小时，再降到正常的使用温度，然后加料。（加热坩埚使其温度高于正常工作温度会延长坩埚的使用寿命。）通常使坩埚加热至815~930度，会有助于坩埚的釉料保护，如果有可能，这种高温加热可以每周都进行一次

After the crucible is preheated, the operator needs to quickly raise the temperature to 850-950 ° C without heating the raw material, and keep the temperature for half an hour, and reduce to the normal operating temperature then add raw material. (Heating the crucible above its normal operating temperature will prolong the service life of the crucible.) Usually the crucible heated to 815 ~ 930 degrees, will help protect the crucible glaze, if possible, this high-temperature heating can be carried out once a week.