Installation Precautions for Molybdenum Disilicide Heating Elements:

Molybdenum disilicide heating elements become somewhat soft at high temperatures (above 1500°C) and are hard and brittle at low temperatures. To avoid stress caused by temperature changes and to accommodate thermal expansion and contraction, the industry adopts a free vertical suspension installation method. This method also facilitates the replacement of suspended elements.
When suspending molybdenum disilicide heating elements, the following precautions must be observed:
1. The furnace lining material should be made of corundum bricks, with the mass fraction of Fe2O3 less than 1%, as it interacts with the protective film to form low-melting-point silicates, accelerating element failure.
2. The leakage of hot furnace gas from the cold ends not only increases heat loss but may also burn out the conductive tape clamps and lead wire terminals. Therefore, using stainless steel clamps can effectively extend service life.
3. Since molybdenum disilicide is a brittle material with low bending strength and cannot withstand impact, protective measures should be taken during installation to prevent breakage. When connecting conductive tapes, install the asbestos clamps (or ceramic clamps) first and avoid applying excessive force during tightening.
4. When inserting the elements into the plug bricks, use individually made foam corundum bricks to avoid mechanical stress caused by handling and movement.
5. Insert the plug bricks with the elements into the prepared slots in the furnace roof, ensuring the bricks protrude outside the roof for easy removal.
6. Connect the conductive tapes to the pre-prepared support brackets, avoiding tension and unnatural twisting that could cause mechanical stress.
7. To prevent the asbestos clamps from allowing the elements to sag due to thermal expansion and contraction, apply refractory mortar mixed with water glass at the joints to ensure secure fixation.
8. During suspension, the conical transition area of the heating section should be about 25mm-30mm from the furnace wall. The cold ends should extend 75mm outside the furnace roof, and the lower end of the heating section should be at least 50mm from the furnace bottom.
9. The spacing between molybdenum disilicide heating elements inside the furnace should not be less than the center-to-center distance of the elements themselves.
10. During suspension, ensure the weight balance of both cold ends and the wiring parts to prevent bending deformation of the heating section.