Alumina vs. Mullite
Both alumina and mullite are oxide-based engineering ceramics. There are 24 material properties with values for both materials. Properties with values for just one material (2, in this case) are not shown.
For each property being compared, the top bar is alumina and the bottom bar is mullite.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 1920 to 2750 | |
| 800 |
| Elastic (Young's, Tensile) Modulus, GPa | 220 to 370 | |
| 110 to 170 |
| Flexural Strength, MPa | 260 to 430 | |
| 130 to 160 |
| Fracture Toughness, MPa-m1/2 | 3.7 to 7.2 | |
| 2.0 |
| Knoop Hardness | 960 to 1660 | |
| 750 |
| Poisson's Ratio | 0.22 to 0.24 | |
| 0.25 |
| Tensile Strength: Ultimate (UTS), MPa | 210 to 290 | |
| 160 |
Thermal Properties
| Maximum Temperature: Mechanical, °C | 650 to 1730 | |
| 1680 |
| Maximum Thermal Shock, °C | 200 to 300 | |
| 170 to 230 |
| Specific Heat Capacity, J/kg-K | 870 to 940 | |
| 950 |
| Thermal Conductivity, W/m-K | 14 to 30 | |
| 3.5 to 11 |
| Thermal Expansion, µm/m-K | 6.7 to 8.2 | |
| 5.8 |
Electrical Properties
| Dielectric Constant (Relative Permittivity) At 1 Hz | 8.0 to 9.0 | |
| 8.0 |
| Dielectric Constant (Relative Permittivity) At 1 MHz | 7.8 to 11 | |
| 6.3 |
| Dielectric Strength (Breakdown Potential), kV/mm | 8.9 to 12 | |
| 16 to 17 |
| Electrical Dissipation At 1 MHz | 0.00049 to 0.0013 | |
| 0.0025 |
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 6.2 to 14 | |
| 10 to 11 |
Otherwise Unclassified Properties
| Density, g/cm3 | 3.4 to 4.1 | |
| 2.7 to 3.0 |
Common Calculations
| Stiffness to Weight: Axial, points | 35 to 53 | |
| 22 to 31 |
| Stiffness to Weight: Bending, points | 57 to 62 | |
| 58 to 62 |
| Strength to Weight: Axial, points | 14 to 23 | |
| 15 to 17 |
| Strength to Weight: Bending, points | 19 to 28 | |
| 22 to 24 |
| Thermal Diffusivity, mm2/s | 3.7 to 10 | |
| 1.4 to 3.7 |
| Thermal Shock Resistance, points | 4.9 to 14 | |
| 12 to 19 |