What Is a High Purity Alumina Ceramic Insulation Frame?
A high purity alumina ceramic insulation frame is a machined Al₂O₃ structural insulator used to separate conductive parts, support assemblies and maintain electrical isolation in high-voltage, vacuum, laser and industrial equipment. It is selected when polymer, glass or metal-supported insulation parts cannot meet the required temperature resistance, dielectric stability, dimensional accuracy or cleanliness level.
ADCERAX supplies drawing-based alumina insulation frames with reviewed material grade, outer size, aperture geometry, mounting holes, flatness, edge design and surface finish according to the operating environment.
Why Use Alumina Ceramic for Insulation Frames?
High-purity alumina ceramic is often selected for insulation frames because it combines electrical insulation, thermal stability and mechanical support in one rigid component. It is especially useful when the frame must separate conductive parts, keep stable geometry and fit into compact high-voltage or controlled-atmosphere assemblies.
Stable Electrical Insulation
Dense alumina ceramic helps separate conductive parts in high-voltage, pulsed power and compact module assemblies. Compared with many polymer or composite insulation materials, alumina provides stronger insulation stability under heat, electrical stress and long-term equipment operation.
Reliable Shape Stability During Thermal Cycling
For equipment exposed to repeated heating and cooling, alumina maintains its shape better than many softer insulation materials. This helps the frame keep hole alignment, aperture position and contact surfaces stable during long-term use.
Cleaner Performance in Vacuum or Gas-Filled Systems
High-purity alumina can be selected for vacuum, laser and gas-filled equipment where low contamination risk and clean surfaces are important. It helps reduce the risk of material degradation, surface residue or insulation instability caused by less stable insulation materials.
Mechanical Support for Precision Assemblies
A machined alumina ceramic frame can support electrodes, connectors, optics mounts, housings or positioning references. Its rigid structure helps maintain assembly spacing and mechanical alignment when the surrounding module requires both insulation and support.
High Purity Alumina Ceramic Insulation Frame Properties
| Property | Unit | 96% Al₂O₃ | 99% Al₂O₃ | 99.5% Al₂O₃ | 99.6% Al₂O₃ | 99.7% Al₂O₃ | 99.8% Al₂O₃ | 99.9% Al₂O₃ | 99.99% Al₂O₃ |
| Alumina content | % | 96 | 99 | 99.5 | 99.6 | 99.7 | 99.8 | 99.9 | 99.99 |
| Density | g/cm³ | 3.6-3.75 | 3.83 | 3.89 | 3.91 | 3.92 | 3.93 | 3.94 | 3.98 |
| Color | – | white | Ivory | Ivory | Ivory | Ivory | Ivory | Ivory | Ivory |
| Water absorption | % | 0 | 0 | – | 0 | 0 | 0 | 0 | 0 |
| Young’s modulus (Elastic modulus) | GPa | 300 | 350 | 375 | 356 | 357 | 358 | 359 | 362 |
| Shear modulus | GPa | – | – | 152 | – | – | – | – | – |
| Bulk modulus | GPa | – | – | 228 | – | – | – | – | – |
| Poisson’s ratio | – | – | – | 0.22 | – | – | – | – | – |
| Compressive strength | MPa | 1910 | 2210 | 2600 | 2552 | 2554 | 2556 | 2558 | 2570 |
| Flexural strength | MPa | 260 | 300 | 379 | 312 | 313 | 314 | 315 | 320 |
| Fracture toughness | MPa·m¹ᐟ² | – | – | 4 | – | – | – | – | – |
| Hardness | GPa | 14.5 | 17 | 17 | 23 | 24 | 25 | 26 | 30 |
| Thermal conductivity | W/m·K | 22 | 24 | 35 | 32–37 | 33–38 | 34–39 | 35–40 | 36–42 |
| Thermal shock resistance ΔT | °C | – | – | – | 222 | 223 | 224 | 225 | 228 |
| Maximum use temperature (no load) | °C | 1450 | 1680 | ≤1750 | 1755 | 1760 | 1765 | 1770 | 1800 |
| Coefficient of thermal expansion | 10⁻⁶/°C | 7.6 | 7.6 | 8.4 | – | – | – | – | – |
| Volume resistivity | Ω·cm | >1×10¹⁴ | >1×10¹⁴ | >1×10¹⁴ | >1×10¹⁴ | >1×10¹⁴ | >1×10¹⁴ | >1×10¹⁴ | >1×10¹⁴ |
| Dielectric constant (relative permittivity) | – | 9.2 | 9.5 | 9.8 | 9.83 | 9.84 | 9.85 | 9.86 | 9.92 |
| Dielectric strength | kV/mm | 15 | 19 | 16.9 | 23.2 | 23.4 | 23.6 | 23.8 | 24 |
| Dissipation factor (loss factor @ 1 kHz) | – | – | – | 0.0002 | – | – | – | – | – |
Custom Alumina Ceramic Insulation Frame Specifications
| Custom Alumina Ceramic Insulation Frame Specifications | |||||
| Item No. | Outer Size | Aperture / Window | Thickness | Hole / Slot Design | Surface Finish |
| AT-HP-K01 | Custom | Custom | Custom | Custom | As-sintered, ground or polished |
How to Select the Alumina Grade for an Insulation Frame
For most custom insulation frame projects, purity should not be selected by number alone. The frame size, mounting force, aperture shape, surface finish, operating temperature, voltage condition and cleaning method often have a stronger influence on service reliability. ADCERAX can review whether a 99.5% or 99.8% alumina grade is more suitable before quotation.
| Grade Direction | When It Is Usually Considered |
|---|---|
| 96% alumina | Cost-sensitive industrial insulation parts where ultra-clean surfaces are not required. |
| 99% alumina | General high-temperature and electrical insulation parts with better stability than lower-grade ceramics. |
| 99.5% alumina | Precision insulation frames requiring stronger dielectric stability and cleaner surfaces. |
| 99.8% alumina | High-voltage, vacuum, laser or precision module assemblies where insulation stability and low contamination risk are more important. |
| 99.9%+ alumina | Only when the application clearly requires a higher purity grade and ADCERAX confirms availability before quotation. |
Mounting Notes to Reduce Cracking and Insulation Failure
Ceramic insulation frames are strong under compression but sensitive to point loading and bending stress. For large frames or thin wall sections, the mounting design should distribute load evenly and avoid forcing the ceramic into a misaligned metal housing. If the operating voltage, pulse mode or temperature profile changes, the frame design should be reviewed before reuse.
| Risk | Recommended Prevention |
|---|---|
| Corner cracking | Use larger internal radii, protected edge design and avoid sharp stress concentration. |
| Screw over-tightening | Use torque-controlled fastening and load-spreading washers or metal plates. |
| Uneven contact surface | Confirm flatness and remove burrs from mating metal parts before installation. |
| Thermal shock | Avoid sudden temperature changes beyond the reviewed design condition. |
| Surface contamination | Keep ceramic surfaces clean and avoid oil, metal particles or conductive dust. |
| Electric field concentration | Review aperture spacing, edge chamfer and clearance distance during design. |
High Purity Alumina Insulation Frame Packaging
- Each alumina ceramic insulation frame is individually separated using foam or soft interlayers to avoid ceramic-to-ceramic contact.
- Parts are packed in clean PE bags and then located in custom cut foam or honeycomb cartons to minimize movement during transport.
