Alumina vs. Machinable Glass-ceramic
Alumina belongs to the oxide-based engineering ceramics classification, while machinable glass-ceramic belongs to the glass and glass-ceramics. There are 24 material properties with values for both materials. Properties with values for just one material (3, in this case) are not shown.
For each property being compared, the top bar is alumina and the bottom bar is machinable glass-ceramic.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 1920 to 2750 | |
| 310 |
| Elastic (Young's, Tensile) Modulus, GPa | 220 to 370 | |
| 67 |
| Flexural Strength, MPa | 260 to 430 | |
| 96 |
| Fracture Toughness, MPa-m1/2 | 3.7 to 7.2 | |
| 2.5 |
| Knoop Hardness | 960 to 1660 | |
| 250 |
| Poisson's Ratio | 0.22 to 0.24 | |
| 0.29 |
| Tensile Strength: Ultimate (UTS), MPa | 210 to 290 | |
| 84 |
Thermal Properties
| Maximum Temperature: Mechanical, °C | 650 to 1730 | |
| 760 |
| Specific Heat Capacity, J/kg-K | 870 to 940 | |
| 790 |
| Thermal Conductivity, W/m-K | 14 to 30 | |
| 1.2 |
| Thermal Expansion, µm/m-K | 6.7 to 8.2 | |
| 21 |
Electrical Properties
| Dielectric Constant (Relative Permittivity) At 1 Hz | 8.0 to 9.0 | |
| 6.0 |
| Dielectric Constant (Relative Permittivity) At 1 MHz | 7.8 to 11 | |
| 6.4 |
| Dielectric Strength (Breakdown Potential), kV/mm | 8.9 to 12 | |
| 27 |
| Electrical Dissipation At 1 Hz | 0.00031 to 0.0011 | |
| 0.0049 |
| Electrical Dissipation At 1 MHz | 0.00049 to 0.0013 | |
| 0.0050 |
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 6.2 to 14 | |
| 14 |
Otherwise Unclassified Properties
| Density, g/cm3 | 3.4 to 4.1 | |
| 2.7 |
Common Calculations
| Stiffness to Weight: Axial, points | 35 to 53 | |
| 14 |
| Stiffness to Weight: Bending, points | 57 to 62 | |
| 51 |
| Strength to Weight: Axial, points | 14 to 23 | |
| 8.8 |
| Strength to Weight: Bending, points | 19 to 28 | |
| 16 |
| Thermal Diffusivity, mm2/s | 3.7 to 10 | |
| 0.56 |
| Thermal Shock Resistance, points | 4.9 to 14 | |
| 4.3 |