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Application of molybdenum disilicide in electric heating products

wallpapers News 2021-08-03
U-shaped silicon molybdenum disilicide heating rod
U-shaped silicon-molybdenum disilicide heating rod is the most commonly used specification among silicon-molybdenum disilicide heating rod electric heating elements. In electric heating equipment, the element is suspended and installed vertically by supporting chucks to avoid adding mechanical stress to the heating end of the element, otherwise, it is easy to cause the element to break.
Continuous working
Silicon molybdenum disilicide heating rods work continuously at high temperatures for a long time, and the surface film gradually evaporates, so that the rod body undergoes thermodynamic phase equilibrium from the inside to the surface. When the concentration gradient of surface silicon is not enough to form the lowest silicide phase, free molybdenum oxidation and volatilization will occur, and A protective film of quartz glass is formed on the new molybdenum silicide interface. In this way, the volatilization and film formation continue, and the components are continuously reduced until the local minimum cross-section is overloaded and burned out. This is mainly the failure form of silicon molybdenum disilicide heating rods in continuous kilns.
Intermittent work
During the thermal stress process of heating and cooling, the quartz glass film on the surface of the U-shaped silicon molybdenum disilicide heating rod is cracked, collapsed, and thinned due to thermal expansion and contraction. The protective film is re-formed on the new surface of the cracks and collapses. That is, there are pits lower than the surface of the component. After a certain number of alternations, the surface of the component forms a continuous pitted surface with a diameter of 1; 2mm, a depth of 0.2; 0.5mm, and finally burns at the smallest cross-section. This is mainly the failure form of the gap furnace.
About molybdenum disilicide
Molybdenum disilicide MoSi2 is the mesophase with the highest silicon content in the Mo-Si binary alloy system. It is a Dalton-type intermetallic compound with a fixed composition. With the dual characteristics of metal and ceramics, it is a high-temperature resistant material with excellent performance. Excellent high-temperature oxidation resistance, the oxidation temperature is as high as 1600℃, which is equivalent to silicon carbide with medium density (6.24g/cm3) and low thermal expansion coefficient (8.1×10-6K-1).


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