Common heater of resistance furnace

1. Ni Cr alloy electric furnace wire (1000-1200 ℃)

Alloy electric furnace wire is the most widely used heating material with the largest consumption. Its disadvantage is that it is in a very high temperature (hot state) under the working state, and it is easy to burn out due to oxidation reaction in the air; from the aspect of electric heating energy conversion, it causes energy loss due to the generation of part of visible light; the electric furnace wire is often used in spiral state, which will produce inductive reactance effect when electrified.

2. Silicon carbide rod (1300-1400 ℃)

Silicon carbide rod is a kind of non-metallic high-temperature electric heating element, which is made of green high-quality silicon carbide material through light processing. Compared with metal electric heating element, the element has the advantages of high temperature, oxidation resistance, corrosion resistance, long life, small deformation and convenient installation and maintenance. When heated in air, the surface temperature of the heating part can reach 1450 ℃; it is negative from room temperature to 800 ℃, and positive characteristic curve is above 800 ℃. Silicon carbide rod has good chemical stability, acid has no effect on it, but alkali and alkaline earth metal oxides can corrode it under certain temperature conditions. At high temperature, water vapor, hydrogen, halogen and sulfur also have oxidation and erosion effects on them.

3. Silicon molybdenum rod (1600-1700 ℃)

Silicon molybdenum rod electric heating element is a kind of resistance heating element based on molybdenum silicide. A dense quartz glass film is formed on the surface of the sintered molybdenum silicide products when heated to high temperature in the oxidizing atmosphere, which can keep the heating element from oxidation. Therefore, the silicon molybdenum rod element has unique high temperature oxidation resistance. The maximum operating temperature is 1750 ℃. The resistance of the silicon molybdenum rod element does not change with the length of service time (the resistance increases with the increase of temperature, that is, it does not age, so the old and new components can be mixed. Like other ceramic products, the mechanical manufacturing of silicon molybdenum rod is brittle material and easy to fracture at room temperature, but it can be avoided if it is used properly and installed reasonably.

4. Zirconium diboride (above 1700 ℃)

Zirconium diboride composite ceramic heating body is mainly composed of zirconium diboride. In the oxidation atmosphere, the maximum surface temperature is 2050 ℃, and the long-term service temperature range is 100-1900 ℃. In vacuum environment, various inert atmosphere environment and reduction atmosphere, the maximum surface temperature is 2600 ℃ and the long-term service temperature range is 2200-2500 ℃ It has good thermal stability in oxidation atmosphere, vacuum environment and various inert atmosphere. It has good thermal shock resistance and can be used for thermal shock resistance test of ultra-high temperature refractories. This material was researched and applied to resistance furnace by our company, which made great contribution to breaking through 2200 ℃ high temperature.