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Molybdenum Disilicide Powder Is Used to Produce MoSi2 Heaters and Thermocouple Protection Tubes

Like tungsten disilicide (WSi2) powder, molybdenum disilicide powder is also an inorganic compound composed of one transition metal atom (both tungsten and molybdenum are transition metal elements) and two non-metallic silicon atoms. 

It is a black powder, and the chemical formula is MoSi2, the molecular weight is 152.11, the purity is as high as 99.9%, the crystal structure is square, and the CAS number is 12136-78-6.

The main components of MoSi2: Si (T.C) total silicon 36%~38%, the rest is molybdenum content; MoSi2 impurity content: free silicon (F.Si) 0.1%, Fe0.03%, Al0.01%, N0. 01%, C0.03%, O0.15%. MoSi2 powder commonly used particle size specifications: 300 mesh, 400 mesh, 500 mesh, 3.5~2.6μm, 2.3~1.5μm.

In terms of physical and chemical properties, molybdenum disilicide is a gray metallic solid with a melting point of about 2030°C and a density of about 6.26g/cm3. It is insoluble in most acids except nitric acid and hydrofluoric acid. It has low thermal expansion coefficient (8.1×10-6K-1), good electrical and thermal conductivity, dual characteristics of metal and ceramics, high temperature oxidation resistance and other characteristics. 

Specifically, at high temperatures greater than 1000 °C, a silicon dioxide passivation layer can be formed on its surface to prevent further oxidation, and it has a very high Young's modulus, but it is brittle at low temperatures, and in an environment exceeding 1200 °C will lose creep resistance.

About production process, MoSi2 powder can be obtained by direct reaction of Mo powder and Si powder. MoSi2 parts can be made by cold pressing sintering or hot pressing.

In terms of use, heating elements made of molybdenum disilicide powder are mainly used in the production of glass, steel, electronic components, ceramics and other products in electric melting furnaces. In addition, the substance can also be used as a surface coating material for high temperature resistant ceramics, thermocouple protection tubes or evaporating appliances.

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