Compared to 95% alumina, 99% alumina have high dielectric constant.
Features of this material:
- Exceptionally high dielectric strength
- Consistent dielectric constant
- Dense, non-porous and vacuum tight
- Readily accepts moly-manganese metallizing for high temperature brazing
- Electrically and dimensionally stable across a wide temperature range
- Resist chemical attack and abrasion
- Good thermal conductivity
Metallization :
Moly-Manganese metallizing +Ni plating
Applications:
Medical X-ray tubes
Vacuum feedthrus
Vacuum Interrupter
Ceramic to metal seals
Filaments
Assemblies
Material Properties :
| NO | ITEM | Testing condition | Unit | Testing Value | GB/T5593 Specified Value of A-99.5 |
| 1 | Bulk Density | Room Temp | G/cm³ | 3.86 | ≥3.85 |
| 2 | Flexural Strength | Romm Temp | MPa | 368 | ≥300 |
| 3 | Average Coefficient of Linear Expansion |
(20~500)℃ | 1/°℃ | 7.15×10-6 | (6.5~7.5)x10-6 |
| (20~800)℃ | 1/℃ | 7.71×10-6 | (6.5~8.0)x10-6 | ||
| 4 | Dielectric Constant | 20℃ | 10.2 | 9~10.5 | |
| 5 | Dielectric Loos Angle Tangent Value (Dissipation Factor) | 20℃ | 1.9×10-4 | ≤2.5×10-4 | |
| 6 | Volume Resistivity | 100℃ | Ω.cm | 4.5×1014 | ≥1013 |
| 300℃ | Ω.cm | 2.5×1013 | ≥1010 | ||
| 500℃ | Ω.cm | 4.1x101C | ≥10⁸ | ||
| 7 | Chemical Stability | 1:9HC1 | mg/cm² | 0.37 | ≤0.7 |
| 10%NaOH | mg/cm² | 0.04 | ≤0.1 | ||
| 8 | Thermal Stability | (Room Temp.~800)℃ | PASS | PASS | |
| 9 | Airtightness | Pa.M³/s | PASS | PASS | |
| 10 | Dielectric Strength | KV/mm | 36.9 | ≥17 | |
| 11 | Metallization thickness | um | 12.7-38.1 | ||
| 12 | Plating thickness | um | 2.54-10.16 |
