The working life of silicon carbide SiC heating elements is important to the end user. How to maximize life of sic heater? STA provide many ways to customer for improving the life. Please be sure to do the following, the working life of silicon carbide heating elements will be become longer and longer.
1. Handle the elements with care – SiC heating elements have low tensile strength and, therefore, are sensitive to mechanical damage from rough handling, dropping (even in the packaging) or forced bending that can occur during storage, unpacking or installation.
2. Match resistance – The purpose of matching resistance of SiC heater is to improve their life and to improve temperature uniformity in the furnace. Silicon carbide heating elements are typically factory tested with the test amperage marked on the shipping box and/or the element. Elements can be connected in parallel (preferred since they tend to come into balance in use), series or series-parallel. The SiC Heating Elements connected in parallel should be matched in resistance within ±20%, while elements connected in series should be matched within ±5%.
3. Choose the proper size SiC heating element for the equipment – If there are any doubts about the size to use, check the design parameters with the original furnace equipment manufacturer.
4. Install carefully – Check that the terminal holes through the insulation are in alignment so that the sic heater slide in without striking the opposite side or are put under tension due to forcing them into position. Be sure to center the elements in the furnace chamber so that no portion of the heating section of the sic heating element is in the brickwork.
5. Pack the silicon carbide heating elements with ceramic fiber to a depth of about 1 inch (25 mm) so as to avoid heat loss, but be sure that the terminal ends of horizontally mounted elements lie flat in the terminal holes and are supported by the furnace walls.
6. Use the lowest voltage that will maintain the desired furnace operating temperature. This will ensure the lowest possible surface temperature of the SiC heating elements and lengthen its service life.
7. Run the correct sic heater watt density for the required furnace atmosphere (Table 1).
8. Perform in-service inspections – Check the amperage as an indication that the silicon carbide heating elements are operating correctly.
9. Maintain matched-resistance circuits at all times. Don’t mix old and new sic heating elements in the same circuit.
10. Be sure that the sic heater are loose in the terminal holes not only when the furnace is cold but also hot.
The max temperature 1650°C is only for Spiral-cut SiC heating-elements, in addition, it is only the temperature of surface sic heater. So the furnace working temperature must be not more than 1400°C.
