Property Table of Al₂O₃
June 17, 2025
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| Categories | Item | Values |
| General | Chemical composition | Al₂O₃ |
| Crystal form | Hexagonal | |
| Melting point | 2050℃ | |
| Thermal | Coefficient of expansion | Parallel optical axis: 6.7×10^{-6}, perpendicular optical axis: 5.0×10^{-6} |
| Specific heat | 0.18 Cal/g∙mo.K (25℃) | |
| Mechanical | Density | 3.98～4.1 g/cm³ |
| Hardness | Mohs 9; Micro (Hv) ≥ 1700 kg/mm² | |
| Elastic modulus | 340-380 G Pa | |
| Compression strength | 2.1 G Pa | |
| Tensile strength | 0.19 G Pa | |
| Optical | Refractive index | Parallel optical axis: 1.769; perpendicular optical axis: 1.76 |
| Transmittance | 83% ( 300nm～5000nm ) | |
| Electrical | Resistivity | 25℃ > 10^{14} Ω∙cm; 500℃ 10^{11} Ω∙cm |
| Dielectric constant | 11.5 (1MHz) | |
| Chemical | Corrosion resistance | At room temperature, it's not affected by acid or base; at 300℃ it can be corroded by HF |
