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Pressure Sintered (Hot Pressed) Silicon Nitride

Hot pressed silicon nitride is silicon nitride in the hot isostatic pressed (HIP) condition. The graph bars on the material properties cards below compare hot pressed 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

2810 MPa 410 x 103 psi

Elastic (Young's, Tensile) Modulus

310 GPa 45 x 106 psi

Flexural Strength

810 MPa 120 x 103 psi

Fracture Toughness

6.2 MPa-m1/2 5.6 x 103 psi-in1/2

Knoop Hardness


Poisson's Ratio


Tensile Strength: Ultimate (UTS)

510 MPa 74 x 103 psi

Thermal Properties

Maximum Temperature: Mechanical

1330 °C 2420 °F

Maximum Thermal Shock

750 °C 1380 °F

Specific Heat Capacity

720 J/kg-K 0.17 BTU/lb-°F

Thermal Conductivity

31 W/m-K 18 BTU/h-ft-°F

Thermal Expansion

3.2 µm/m-K

Other Material Properties


3.2 g/cm3 200 lb/ft3

Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

18 kV/mm 0.7 V/mil

Electrical Resistivity Order of Magnitude

12 10x Ω-m

Common Calculations

Stiffness to Weight: Axial

53 points

Stiffness to Weight: Bending

69 points

Strength to Weight: Axial

44 points

Strength to Weight: Bending

44 points

Thermal Diffusivity

13 mm2/s

Thermal Shock Resistance

37 points

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