# 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). 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

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}* 5.7

*x 10*

^{3}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 Temperature: Mechanical

1200 *°C* 2190 *°F*

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

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

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