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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 103 psi

Elastic (Young's, Tensile) Modulus

290 GPa 43 x 106 psi

Flexural Strength

680 MPa 99 x 103 psi

Fracture Toughness

6.3 MPa-m1/2 5.7 x 103 psi-in1/2

Knoop Hardness


Poisson's Ratio


Shear Modulus

120 GPa 17 x 106 psi

Tensile Strength: Ultimate (UTS)

190 MPa 28 x 103 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


3.3 g/cm3 210 lb/ft3

Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

8.3 kV/mm 0.33 V/mil

Electrical Resistivity Order of Magnitude

14 10x 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 mm2/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