Installation of SiC Heating Elements
1.SiC heating elements is brittle as ceramics,so that the buyer need to be careful when you receive the goods from shipment of air freight.No permit for hard shock or knock.
2.The first thing before installation is to test the resistance of the elements,or we could see if there is mark on the elements showing the resistance,if yes,we no need to make double testing.
3. The resistance should be same or similar in a group electric circuit,the outer diameter is ≥Φ12mm, the difference tolerance is ≤0.2 Ω; when ≤Φ 8mm, ≤0.5 Ω.
4. Temperature control is very important in heating processing—to keep the temperature in a suitable level. Frequently observing the control equipment to see if they are normal to avoid uneven heating in hot zone and unregular oxidation in cold zone.
5. When the elements aging,the voltage should be increased to maintain the furnace normal temperature.If the furnace temperature can’t reach standard requests by increasing voltage to the maximum,then we need to stop furnace and change the way of electrical connection and then continue to work.
6. As for a new furnace,usually 1/2 of the nominal full-load voltage used for a certain time to protect silicon carbide element from weaken or fracturing.If everything is ok,then increase voltage as required heat up schedule, but do not exceed full-load voltage.
7. If the furnace is new or has not been used for a long time, it must be dried before operation,better to use old SiC rods or other heating elements to do the drying.
8. In the course of furnace heating operation, if any individual heating element need to be replaced, you need to choose a elements with suitable resistance which is same or similar to the ones in its group,please refer to list3.
9. Water vapor can increase the aging processing.So that if there is water come out in the processing of heating,we need to leave an air hole in the furnace.
10. The SiC heating elements rods should be keep dry in storage. If the sprayed aluminum film is find decomposed because of the moisture,film should be double sprayed or wrapped with several layers of aluminum foil.
11. Elements should be better to be continuously working, which could longer its lift-time.
12. Atmosphere in the furnace is important. The element becomes brittle in hydrogen. And to keep alkali, alkaline metal, silicate and boride away from the heating SiC elements.
Installation of MoSi2 Heating Element
- MoSi2 heating element is very crisp and hard under room temperature and become plastic under high temperature. Therefore, it’s the best way for U type element to hang it vertically.It can avoid stress directly to the Hot zone of the element when the temperature changes, otherwise, the element will be broken easily. If it needs to be hang horizontally, please keep a support refractory to the elements.
- Please put the element bottom into the furnace chamber to avoid partially overheating.
- The lead wire should be a little longer than the linear distance between the element and the generating line to avoid putting the stress to the element.
- Please don’t tighten the screw of clamps too much at one time. Considering the element’s plasticity,the screws can be tightened again when the element heats up to high temperature.
- The temperature of the clip should be less than 200℃; the contact voltage between the clip and the element should be less than 0.1V.
- The distance between the lower end of the clip and the upper surface of the brick should be more than 50mm, to avoid the radiation heat conducting to the clip.
- To avoid damage,the element with size of Φ6/12mm couldn’t be used under current of 170A for a long time; And the element with size of Φ9/18mm couldn’t be used under current of 300A for a long time.