The Alumina Ceramic Tube Using

18-03-2020

The Alumina Ceramic Tube Using

alumina tube

1. The maximum service temperature of high purity alumina furnace tubes shall not exceed 1700℃, and the long-term service temperature shall be below 1650℃.

2. The high temperature area of high purity alumina furnace tube shall be protected from impurities, especially metal debris and nonmetallic mineral raw materials containing K2O, Na2O, CaO, SiO2, etc. Otherwise, low temperature eutectic materials will be easily formed and corundum tube will be damaged.

3. When using high-purity alumina furnace tubes, sharp temperature rise and fall shall be avoided as far as possible, especially corundum tubes shall be prevented from being directly inserted into high-temperature furnaces. When lowering the temperature, it should be cooled naturally after the temperature is lowered to 300 degrees. The rate of raising and lowering the temperature should be controlled to about 5 degrees. Air cooling or indirect cooling with cooling water is not allowed.

4. Alumina ceramic tube shall be installed vertically as far as possible to reduce creep deformation at high temperature if the process or equipment allows. Try to avoid vibration under high temperature or heating. When installing or using, minimize the support of high-temperature heating area or contact with other objects.

5. In order to reduce cracking of high-purity alumina furnace tubes, local quenching and sudden heating of high-purity corundum furnace tubes should be avoided, especially the hot alumina tubes should be prevented from being directly placed on firebricks or refractory fiber blankets at normal temperature, otherwise it is easy to crack. At the same time, it is also avoided that the sintered material with high temperature and large heat storage capacity will touch the wall in the corundum furnace tube. If it needs to move, the temperature gradient during the movement should preferably be controlled within 200℃.

6, In the process of use, if need to introduce protective gas into the furnace tube, please pay attention to don't too fast cold air flow, when cold keep 10~20 bubbles per minute at the outlet end is appropriate, under high temperature, due to gas expansion, bubble quantity will increase, don't reduce the air intake, avoid too little air intake when cooling water back into the furnace tube, causing the furnace tube burst;

7. In order to avoid breakage of high purity alumina ceramic furnace tubes due to large temperature gradient changes as far as possible, it is recommended that the position of the tube plug (or reflection screen) in the furnace tubes should not overlap with the position of the heat insulation cotton (or heat insulation support) outside the tube. According to the use experience, pulling out some of the tube plug will correspondingly improve the service life of corundum tubes.

8. High purity alumina furnace tubes are brittle and hard materials. The service life of alumina tubes is different for different service conditions and process methods. It is greatly influenced by service temperature, temperature rise and fall rate, atmosphere, volatilization of sintered materials, ambient temperature, etc. It is hoped that users can combine their own process characteristics and summarize a set of operation specifications that are most suitable for use conditions.




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