Molybdenum silicide Chemical Properties

Melting point:

1930°C

Density 

6.31 g/mL at 25 °C(lit.)

solubility 

insoluble in H2O; soluble in HF

form 

powder

color 

Dark gray

Specific Gravity

6.31

Resistivity

21.5 (ρ/μΩ.cm)

Water Solubility 

Insoluble in acids and aqua regia, however, it is soluble in HF and HNO{3}Soluble in nitric acid and hydrofluoric acid. Insoluble in water most acids.

Crystal Structure

Tetragonal

Exposure limits

ACGIH: TWA 10 mg/m3; TWA 3 mg/m3
NIOSH: IDLH 5000 mg/m3

EPA Substance Registry System

Molybdenum silicide (MoSi2) (12136-78-6)

Safety Information

Hazard Codes 

Xn

Risk Statements 

20/21/22

Safety Statements 

36

WGK Germany 

3

TSCA 

Yes

MSDS

• Language:English Provider:SigmaAldrich
• Language:English Provider:ALFA

Molybdenum silicide Usage And Synthesis

Chemical Properties

Molybdenum silicide is dark-gray, crystalline powder. Not affected by air upto 1648°C. Not attacked by most inorganic acidsincluding aqua regia, but very soluble in hydrofluo-ric and nitric acids. Has high stress-rupture strength.

Physical properties

The compound is thermally stable in air up to 1000°C. Corrosion resistant to molten metals such as Zn, Pd, Ag, Bi, and Rb. Corroded by liquid metals Mg, Al, Si, V, Cr, Mn, Fe, Ni, Cu, Mo, and Ce.

Uses

MOLYBDENUM SILICIDE can be considered as an electrically conducting ceramic with primary use in heating elements operating at temperatures above 1,500℃ in air. It is also considered as a material for very high temperature structural applications.

Uses

In electrical resistors, in protective coatings at high temperatures, and in engine parts in space vehicles Molybdenum silicide is used in electric furnaces, glass, steel, electronics and ceramics industries. It finds application in heat treatment materials. It is also used in microelectronics as a contact material. Further, it serves as a dry lubricant.

Application

Molybdenum disilicide (MoSi2) is a ceramic material with excellent high-temperature oxidation resistance and corrosion resistance. It can be used as a substrate material in the fabrication of thermophotovoltaics. MoSi2 can also be used as a protective coating on carbon-carbon composites for potential applications in aerospace and thermonuclear fusion.

Preparation

Molybdenum disilicide is a promising candidate material for high temperature structural applications. Molybdenum silicide is produced in much the same way as ferromolybdenum. A typical mix for the production of molybdenum silicide is 1,000pounds of molybdenum in oxide, 259 pounds of aluminum, 760 pounds of 90-percent ferrosilicon, 166 pounds of 50-percent ferro-silicon, 160 pounds of lime, and 50 pounds of high-grade fluorspar.

Definition

MOLYBDENUM SILICIDE is A cermet.

General Description

This product has been enhanced for energy efficiency.

Hazard

MOLYBDENUM SILICIDE is Toxic material.

Flammability and Explosibility

Not classified

Industrial uses

High-temperature silicides are a new class of materials with potential applications in the temperature range 1200 to 1600 C.The silicide that seems most promising is molybdenum disilicide (MoSi₂) because of its high melting temperature (2200 C) and excellent oxidation resistance. It has a tetragonal crystal structure. A major problem is its absence of ductility at temperatures up to 1000 C. It also has poor high-temperature strength due to the presence of a grain boundary silicon-rich phase that may become viscous at very high temperatures. Recent research has shown that this problem may be solved by the addition of carbon to the material.

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