Alumina vs. R30021 Cobalt
Alumina and R30021 cobalt belong to fundamentally different material chemistries. Alumina is a ceramic material, while R30021 cobalt is a metal. Therefore, their performance will be even more dissimilar than would be suggested by the difference in properties. There are 15 material properties with values for both materials. Properties with values for just one material (25, in this case) are not shown. Please note that the two materials have significantly dissimilar densities. This means that additional care is required when interpreting the data, because some material properties are based on units of mass, while others are based on units of area or volume.
For each property being compared, the top bar is alumina and the bottom bar is R30021 cobalt.
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 1920 to 2750 | |
| 1300 |
| Elastic (Young's, Tensile) Modulus, GPa | 220 to 370 | |
| 220 |
| Poisson's Ratio | 0.22 to 0.24 | |
| 0.29 |
| Tensile Strength: Ultimate (UTS), MPa | 210 to 290 | |
| 700 |
Thermal Properties
| Melting Onset (Solidus), °C | 2040 | |
| 1190 |
| Specific Heat Capacity, J/kg-K | 870 to 940 | |
| 450 |
| Thermal Conductivity, W/m-K | 14 to 30 | |
| 15 |
| Thermal Expansion, µm/m-K | 6.7 to 8.2 | |
| 11 |
Otherwise Unclassified Properties
| Density, g/cm3 | 3.4 to 4.1 | |
| 8.4 |
Common Calculations
| Stiffness to Weight: Axial, points | 35 to 53 | |
| 15 |
| Stiffness to Weight: Bending, points | 57 to 62 | |
| 24 |
| Strength to Weight: Axial, points | 14 to 23 | |
| 23 |
| Strength to Weight: Bending, points | 19 to 28 | |
| 21 |
| Thermal Diffusivity, mm2/s | 3.7 to 10 | |
| 3.8 |
| Thermal Shock Resistance, points | 4.9 to 14 | |
| 21 |