Mullite vs. Fused Silica
Mullite belongs to the oxide-based engineering ceramics classification, while fused silica belongs to the glass and glass-ceramics. There are 21 material properties with values for both materials. Properties with values for just one material (8, in this case) are not shown.
For each property being compared, the top bar is mullite and the bottom bar is fused silica.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 800 | |
| 1100 |
| Elastic (Young's, Tensile) Modulus, GPa | 110 to 170 | |
| 73 |
| Flexural Strength, MPa | 130 to 160 | |
| 67 |
| Knoop Hardness | 750 | |
| 570 |
| Poisson's Ratio | 0.25 | |
| 0.17 |
| Tensile Strength: Ultimate (UTS), MPa | 160 | |
| 50 |
Thermal Properties
| Maximum Temperature: Mechanical, °C | 1680 | |
| 1080 |
| Specific Heat Capacity, J/kg-K | 950 | |
| 720 |
| Thermal Conductivity, W/m-K | 3.5 to 11 | |
| 1.4 |
| Thermal Expansion, µm/m-K | 5.8 | |
| 0.5 |
Electrical Properties
| Dielectric Constant (Relative Permittivity) At 1 MHz | 6.3 | |
| 3.8 |
| Dielectric Strength (Breakdown Potential), kV/mm | 16 to 17 | |
| 30 |
| Electrical Dissipation At 1 MHz | 0.0025 | |
| 0.00011 |
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 10 to 11 | |
| 14 |
Otherwise Unclassified Properties
| Density, g/cm3 | 2.7 to 3.0 | |
| 2.2 |
Common Calculations
| Stiffness to Weight: Axial, points | 22 to 31 | |
| 18 |
| Stiffness to Weight: Bending, points | 58 to 62 | |
| 63 |
| Strength to Weight: Axial, points | 15 to 17 | |
| 6.3 |
| Strength to Weight: Bending, points | 22 to 24 | |
| 14 |
| Thermal Diffusivity, mm2/s | 1.4 to 3.7 | |
| 0.85 |
| Thermal Shock Resistance, points | 12 to 19 | |
| 97 |