Molybdenum Elements

Molybdenum heating elements, more exactly molybdenum disilicide (MoSi2) elements, are the heating elements used in electric furnaces that run hotter than most other elements can handle. They are common in laboratory furnaces, glass and ceramic kilns, and furnaces for sintering and heat-treating.

How they work

When a MoSi2 element first heats up in air, a thin layer of silica (quartz glass) forms on its surface. This layer protects the element from further oxidation, and if it cracks it re-forms the next time the element is hot. That is why these elements can run for a long time at temperatures where metal wire would burn out.

Main features

• Very high working temperature. Typical element temperatures go up to about 1,700–1,800 °C in air, depending on the grade.
• Long life at high heat. The resistance of MoSi2 changes very little with age, so new and old elements can work together in the same furnace.
• Fast heating. The elements take high power from cold, so the furnace reaches temperature quickly.
• Shapes to fit the furnace. The common shape is a U (two legs), but W shapes, bent elements and different lengths are also made.

Things to know before you buy

• MoSi2 is brittle when cold. Handle and fit the elements with care, and support them as the supplier says.
• At low temperatures (roughly 400–700 °C) the material can slowly break down into powder (“pest” oxidation). Avoid holding the furnace for long in that range.
• The elements have low resistance when cold, so they usually need a transformer or thyristor power control.

Where they are used

• Laboratory and research furnaces
• Sintering of technical ceramics and powder metals
• Glass melting and glass fibre production
• Heat treatment and crystal growth

How to order

To choose the right element, we need a few details: the shape (U, W or other), the heating-zone length, the terminal (cold-end) length, the diameter of the heating and terminal parts, the distance between the legs, and the highest temperature your furnace reaches. If you have an old element or a drawing, send us a photo and the sizes and we will match it.

Contact us for a price and delivery time.