What is the MoSi2 Heating element ?
1800 type silicon molybdenum rod is a resistive electric heating element made of molybdenum disilicide . When used in a high temperature oxidizing atmosphere, like other Si -based high temperature resistant materials, a layer of MoSi2 will rapidly form on the surface of the MoSi2 under high temperature and oxygen atmosphere . The bright and dense quartz (SiO2) glass film can protect the inner layer of the silicon molybdenum rod from being further oxidized, so the silicon molybdenum rod element has a unique high temperature oxidation resistance. In an oxidizing atmosphere, the maximum operating temperature is about 1700 ℃, and the resistivity of MoSi2 increases rapidly with the increase of temperature. Under normal circumstances, the resistance of the element does not change with the length of use, so the old and new silicon molybdenum rod heating elements can be mixed. It must be pointed out that the silicon molybdenum rod heating element should not be used in the temperature range of 400°C to 700°C, so under this unfavorable condition, the element will be oxidized at low temperature and the element will be destroyed.
Properties of silicon molybdenum rods ( MoSi2 )
1. Recrystallization temperature 1800℃
2. Normal temperature : high hardness, high brittleness, high temperature resistance
3. High temperature deformation, vertical installation is more common
4. Good resistance to temperature sudden change ( resistance to sudden change )
5. The chemical properties are stable and do not react with acidic materials
6. But at high temperature, it will react with alkaline earth metals or low melting point acid salts
7. Generally , a fire blocking device is installed at the outlet of the heating element to reduce heat loss
8. The shape is "U" , so there is enough expansion space at the bottom when installing
Atmosphere influence:
A. When used in NO2, CO2 , O2 and air , the temperature control should be less than 1700℃
B. When used in Ne , Ar , He , the temperature control should be less than 1650℃
C. When used in SO2 , the temperature control should be less than 1600℃
D. Use in CO , N 2 , temperature control should be less than 1500 ℃
E. When used in wet H2 , the temperature control should be less than 1400 °C, and when used in dry H2 , the temperature control should be less than 1350 ° C
Resistance temperature characteristics of silicon molybdenum rod ( MoSi2 )
The resistivity of molybdenum disilicide heating components increases rapidly with increasing temperature. Under normal operating conditions, component resistance generally does not change with age . Therefore , old and new components can be mixed.