What are the precautions for use and maintenance of laboratory microwave tube furnaces?

- Mar 10, 2019-

1. After the furnace is used or not used for a long time, it should be baked at 120 ° C for 1 hour, then baked at 300 ° C for 2 hours to avoid cracking of the furnace. The furnace temperature should not exceed the rated temperature to avoid damage to the heating elements and lining. It is forbidden to inject various liquids and dissolved metals directly into the furnace to keep the furnace clean.

2. If the furnace is a corundum furnace tube, according to the physical properties of the corundum material, the temperature rise and fall rate of each temperature zone should not be too fast (≤ 5 °C), and corundum materials are strictly prohibited. The material is above 100 °C. It is beneficial to uniformly release the thermal stress of the furnace tube to prolong the service life of the furnace tube. If the furnace is made of a quartz tube, the temperature of the quartz tube will appear opaque when the temperature is higher than 1000 °C. This is called devitrification (also known as devitrification), which is an inherent defect in quartz tubes, which is normal.

3. The laboratory tube furnace is used under atmospheric conditions, and the gas expands at high temperature, which causes the pressure inside the tube to become larger. The user should open the needle valve in time to vent the gas. Recommended values for safety pressure inside the pipeline: -0.05MPa to 0.05MPa

4. If the furnace body uses a silicon carbon rod as the heating element, the resistance will gradually increase over a long period of time. This phenomenon is called "aging." After the furnace has been running for a period of time, the heating rate and ideal temperature of the furnace will not reach the original value due to the aging of the silicon carbon rod. Please adjust the OPH value appropriately and observe the main current of the ammeter in an appropriate size. When it is necessary to replace individual components for some reason, it is necessary to select a component having an appropriate resistance according to the increase in resistance of other components at that time, and it is not possible to replace the new component at will. If the component is damaged more or the resistance is too large, the furnace temperature cannot be reached and new parts replaced.

5. When using the furnace, since the furnace is cold and requires a large amount of heat absorption, the heating rate in the low temperature section will not be too fast, and the heating rate difference in each temperature section will not be too large. When setting the heating rate, the physical and chemical properties of the sintered material should be fully considered. To avoid spraying, contaminate the furnace tube.

6. Check the contact of the electrical connection part of the temperature control system regularly, paying particular attention to the tight connection of each connection point of the heating element.

7. After the furnace has been used for a period of time, if the vacuum is reduced, replace the high temperature silicone ring between the stainless steel flanges or reinstall the stainless steel flange or replace the vacuum system to increase the overall vacuum of the system.

8. During the working process, the furnace is generally around 300 °C. If the control deviation cannot be eliminated, the temperature display value does not match the program reference value or the swing is too large.