Silicon Nitride ( Si3N4 ) - Hot Pressed Silicon Nitride - Supplier Data by Goodfellow

Background

Hot pressing of Silicon Nitride produces a material of virtually zero porosity. This hard, grey ceramic is, however, still very lightweight. Silicon Nitride shows good resistance to wear and abrasion.

It shows very little oxidation at elevated temperatures, and high hardness and strength above 1000 °C. One of its main assets is its resistance to thermal shock, due to the low thermal expansion coefficient.

This material can be diamond ground to precise tolerances. Silicon Nitride is used in gas turbine situations, as diesel engine components and as an electrical insulator.

Key Properties

The key properties of Silicon Nitride ( Si3N4 ) are tabulated below.

Table 1. Key properties

Chemical Resistance
Acids – concentrated Fair
Acids – dilute Good
Alkalis Good-Poor
Halogens Good
Metals Fair
Electrical Properties
Dielectric constant 10
Volume resistivity ( Ohm.cm ) 1012-1015 @ 25 °C
Mechanical Properties
Compressive strength ( MPa ) 2000-3500
Hardness - Vickers ( kgf.mm-2 ) 1700-2200
Shear strength ( MPa ) 480-960
Tensile modulus ( GPa ) 280-310
Tensile strength ( MPa ) 400-580
Physical Properties
Apparent porosity ( % ) 0
Density ( g.cm-3 ) 3.11
Thermal Properties
Coefficient of thermal expansion ( x10-6 K-1 ) 3.3 @ 20-1000 °C
Specific heat ( J.K-1.kg-1 ) 680-800 @ 25 °C
Sublimation point ( °C ) 1900
Thermal conductivity ( W.m-1.K-1 ) 15-43 @ 20 °C
Upper continuous use temperature ( °C ) 1100-1650

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