# SiAlON

SiAlON is a non-oxide engineering ceramic. It has a moderately high fracture toughness among non-oxide engineering ceramics. In addition, it has a very low thermal conductivity and a moderately high density. The graph bars on the material properties cards below compare SiAlON to other non-oxide engineering ceramics (top) and the entire database (bottom).

## Mechanical Properties

Compressive (Crushing) Strength

2620 *MPa* 380 *x 10 ^{3} psi*

Elastic (Young's, Tensile) Modulus

290 *GPa* 43 *x 10 ^{6} psi*

Flexural Strength

680 *MPa* 99 *x 10 ^{3} psi*

Fracture Toughness

6.3 *MPa-m ^{1/2}* 5690

*psi-in*

^{1/2}Knoop Hardness

1700

Poisson's Ratio

0.23

Shear Modulus

120 *GPa* 17 *x 10 ^{6} psi*

Tensile Strength: Ultimate (UTS)

190 *MPa* 28 *x 10 ^{3} psi*

## Thermal Properties

Maximum Thermal Shock

300 *°C* 570 *°F*

Specific Heat Capacity

880 *J/kg-K* 0.21 *BTU/lb-°F*

Thermal Conductivity

19 *W/m-K* 11 *BTU/h-ft-°F*

Thermal Expansion

3.6 *µm/m-K*

## Other Material Properties

Density

3.3 *g/cm ^{3}* 210

*lb/ft*

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

9.3

Dielectric Strength (Breakdown Potential)

8.3 *kV/mm* 0.33 *V/mil*

Electrical Resistivity Order of Magnitude

14 *10 ^{x} Ω-m*

## Common Calculations

Stiffness to Weight: Axial

50 *points*

Stiffness to Weight: Bending

67 *points*

Strength to Weight: Axial

16 *points*

Strength to Weight: Bending

22 *points*

Thermal Diffusivity

6.4 *m ^{2}/s*

Thermal Shock Resistance

13 *points*

## Followup Questions

## Further Reading

Silicon Nitride and the Sialons, Vivien Mitchell, 1993

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015