65-80% Al2O3 Mullite (IEC 60672 Type C-620)
C-620 mullite is a grade of mullite. The graph bars on the material properties cards below compare C-620 mullite to other oxide-based 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
800 MPa 120 x 103 psi
Elastic (Young's, Tensile) Modulus
170 GPa 24 x 106 psi
Flexural Strength
160 MPa 23 x 103 psi
Fracture Toughness
2.0 MPa-m1/2 1.8 x 103 psi-in1/2
Knoop Hardness
750
Poisson's Ratio
0.25
Tensile Strength: Ultimate (UTS)
160 MPa 24 x 103 psi
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 Hz
8.0
Dielectric Constant (Relative Permittivity) At 1 MHz
6.3
Dielectric Strength (Breakdown Potential)
17 kV/mm 0.66 V/mil
Electrical Dissipation At 1 MHz
0.0025
Electrical Resistivity Order of Magnitude
11 10x Ω-m
Other Material Properties
Density
3.0 g/cm3 190 lb/ft3
Maximum Temperature: Mechanical
1680 °C 3060 °F
Maximum Thermal Shock
170 °C 340 °F
Specific Heat Capacity
950 J/kg-K 0.23 BTU/lb-°F
Thermal Conductivity
11 W/m-K 6.1 BTU/h-ft-°F
Thermal Expansion
5.8 µm/m-K
Common Calculations
Stiffness to Weight: Axial
31 points
Stiffness to Weight: Bending
62 points
Strength to Weight: Axial
15 points
Strength to Weight: Bending
22 points
Thermal Diffusivity
3.7 mm2/s
Thermal Shock Resistance
12 points
Followup Questions
Further Reading
Mullite, Hartmut Schneider and Sridhar Komarneni (editors), 2005
Ceramic and Glass Materials: Structure, Properties and Processing, James F. Shackelford and Robert H. Doremus (editors), 2008
ASTM C242: Standard Terminology of Ceramic Whitewares and Related Products
IEC 60672-3: Ceramic and glass-insulating materials - Part 3: Specifications for individual materials
Springer Handbook of Condensed Matter and Materials Data, W. Martienssen and H. Warlimont (editors), 2005