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Properties and Uses of Molybdenum Disilicide

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Update time : 2020-12-30 09:19:21

What is molybdenum disilicide?

The crystal of molybdenum disilicide (MoSi2) has a tetragonal structure. It is an intermediate phase with the highest silicon content in the Mo-Si binary alloy system. It is a Dalton intermetallic compound with a fixed composition. It is gray with metallic luster. It has good electrical and thermal conductivity, excellent mechanical properties and high temperature oxidation resistance. It can be used as a heating element and has better performance than silicon carbide. Its early application was as a high-temperature and corrosion-resistant coating protection material on the surface of a metal substrate. It was first applied to the coating of gas turbine parts, jet engine combustion chambers and missile combustion chambers. Nowadays, the main industrial applications of molybdenum disilicide materials are in the production of high-temperature heating elements and thermocouple protection tubes.

Molybdenum disilicide properties:

Crystallographic properties: It belongs to a tetragonal crystal structure with a density of 5.9-6.3g/cm. Pure molybdenum disilicide has no phase change before it reaches the melting point and has good thermal stability. Within the upper limit of its effective temperature range, the rise and fall of temperature will not be destroyed by changes in crystallographic properties.

Thermodynamic properties: melting point up to 2030°C, high thermal conductivity (similar to SiO), and small thermal expansion coefficient. These characteristics are necessary conditions for the production of high-temperature heating elements or thermocouple protection tubes, and help to increase the thermal shock resistance of their products .

Electromagnetic properties: low resistivity (2×10-5Ω·cm), high electric rate, and it is a good conductor. This material is an excellent material for manufacturing heating elements, thermocouple thermoelectrodes and temperature protection tubes (when used as thermocouple protection tubes, please pay attention to insulation).

Mechanical properties: The tensile strength and bending strength are not lower than that of general metal materials and some oxide materials (such as Al2O3), and the hardness and compressive strength are higher than that of metals. Compared with metal, the biggest disadvantage is poor impact toughness, so it belongs to brittle material like general ceramic products. Therefore, in the actual production process, a small amount of metal bond is added under the condition of not affecting its own high-temperature oxidation resistance to make cermet.

Chemical properties: The chemical state is acidic. It is insoluble with most acids and alkalis at room temperature. Except for oxide ceramics, MoSi2 is the most stable of all refractory compounds. Since the solubility of silicon in molybdenum is about 1% (1800°C), it determines the oxidation stability temperature of MoSi2 below 1700°C.

Molybdenum disilicide itself is not resistant to high-temperature oxidation, but at 1300~1600°C, a thin and dense silicon dioxide glassy protective layer is formed on its surface to inhibit continued oxidation. MoSi2 is not only stable in oxidizing media, but also can be used to high temperatures in reducing, neutral, inert and some strong corrosive atmospheres. For example, in N2, CO2, SO2 and other media, the highest temperature can reach 1600℃.

Uses of molybdenum disilicide:

At present, the most widely used silicide product with the largest industrial production is molybdenum disilicide, and its main products are high-temperature heating elements and thermocouple protection tubes.

TRUNNANO (aka. Luoyang Tongrun Nano Technology Co. Ltd.) is a trusted global chemical material supplier & manufacturer with over 12 years’ experience in providing super high quality chemicals and Nano materials. The MoSi2 powder produced by our company has high purity, fine particle size and impurity content. Lower, please contact us if necessary.

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