Mullite vs. Synthetic Sapphire
Both mullite and synthetic sapphire are oxide-based engineering ceramics. There are 21 material properties with values for both materials. Properties with values for just one material (7, in this case) are not shown.
For each property being compared, the top bar is mullite and the bottom bar is synthetic sapphire.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 800 | |
| 2700 |
| Elastic (Young's, Tensile) Modulus, GPa | 110 to 170 | |
| 450 |
| Flexural Strength, MPa | 130 to 160 | |
| 1090 |
| Fracture Toughness, MPa-m1/2 | 2.0 | |
| 1.9 |
| Knoop Hardness | 750 | |
| 1860 |
| Poisson's Ratio | 0.25 | |
| 0.28 |
| Tensile Strength: Ultimate (UTS), MPa | 160 | |
| 2470 |
Thermal Properties
| Maximum Temperature: Mechanical, °C | 1680 | |
| 2000 |
| Specific Heat Capacity, J/kg-K | 950 | |
| 760 |
| Thermal Conductivity, W/m-K | 3.5 to 11 | |
| 30 |
| Thermal Expansion, µm/m-K | 5.8 | |
| 5.3 |
Electrical Properties
| Dielectric Constant (Relative Permittivity) At 1 MHz | 6.3 | |
| 10 |
| Dielectric Strength (Breakdown Potential), kV/mm | 16 to 17 | |
| 9.9 |
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 10 to 11 | |
| 17 |
Otherwise Unclassified Properties
| Density, g/cm3 | 2.7 to 3.0 | |
| 4.0 |
Common Calculations
| Stiffness to Weight: Axial, points | 22 to 31 | |
| 63 |
| Stiffness to Weight: Bending, points | 58 to 62 | |
| 64 |
| Strength to Weight: Axial, points | 15 to 17 | |
| 170 |
| Strength to Weight: Bending, points | 22 to 24 | |
| 100 |
| Thermal Diffusivity, mm2/s | 1.4 to 3.7 | |
| 9.9 |
| Thermal Shock Resistance, points | 12 to 19 | |
| 74 |