# Pressureless Sintered Silicon Nitride

Pressureless sintered silicon nitride is a grade of silicon nitride. The graph bars on the material properties cards below compare pressureless sintered silicon nitride to other non-oxide engineering ceramics (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

## Mechanical Properties

Compressive (Crushing) Strength

2950 *MPa* 430 *x 10 ^{3} psi*

Elastic (Young's, Tensile) Modulus

300 *GPa* 44 *x 10 ^{6} psi*

Flexural Strength

660 *MPa* 95 *x 10 ^{3} psi*

Fracture Toughness

5.6 *MPa-m ^{1/2}* 5.1

*x 10*

^{3}psi-in^{1/2}Knoop Hardness

1450

Poisson's Ratio

0.25

## Thermal Properties

Maximum Temperature: Mechanical

1300 *°C* 2370 *°F*

Maximum Thermal Shock

600 *°C* 1110 *°F*

Specific Heat Capacity

780 *J/kg-K* 0.19 *BTU/lb-°F*

Thermal Conductivity

29 *W/m-K* 17 *BTU/h-ft-°F*

Thermal Expansion

3.2 *µm/m-K*

## Other Material Properties

Density

3.2 *g/cm ^{3}* 200

*lb/ft*

^{3}Dielectric Constant (Relative Permittivity) At 1 MHz

8.0

Dielectric Strength (Breakdown Potential)

18 *kV/mm* 0.7 *V/mil*

Electrical Resistivity Order of Magnitude

11 *10 ^{x} Ω-m*

## Common Calculations

Stiffness to Weight: Axial

52 *points*

Stiffness to Weight: Bending

70 *points*

Thermal Diffusivity

12 *mm ^{2}/s*

## Followup Questions

## Further Reading

Silicon Nitride and the Sialons, Vivien Mitchell, 1993

Handbook of Refractory Carbides and Nitrides: Properties, Characteristics, Processing and Applications, Hugh O. Pierson, 1996

Springer Handbook of Condensed Matter and Materials Data, W. Martienssen and H. Warlimont (editors), 2005

Sintering of Advanced Materials: Fundamentals and Processes, Zhigang Zak Fang (editor), 2010