High Purity Alumina Insulating Ring for Electrical Isolation and Spacing
A high purity alumina ceramic insulating ring is a dense Al₂O₃ ring used to separate conductive parts, maintain controlled spacing and provide stable electrical insulation in demanding equipment assemblies. Compared with polymer, metal or lower-grade ceramic spacers, high purity alumina offers stronger heat resistance, better dimensional stability and cleaner ceramic contact in vacuum, plasma, coating and high-temperature environments.
ADCERAX can review standard-friendly and drawing-based insulating rings according to OD, ID, thickness, alumina grade, contact face requirement, groove layout, edge detail and installation condition. For replacement projects, the existing ring drawing, failure mode and assembly stack-up help confirm whether the part should focus on insulation distance, contact-face flatness, edge protection or thermal stability.
Why Use High Purity Alumina for Ceramic Insulating Rings?
Stable Electrical Isolation
High purity alumina provides strong electrical insulation for assemblies where metal-to-metal contact, current leakage or unstable isolation paths must be avoided. It is suitable for insulating ring, spacer ring and ceramic standoff functions in controlled equipment designs.
Controlled Stack-Up Height
A ground or lapped alumina ring can help maintain a repeatable spacing gap between metal parts. This is important when the assembly depends on stable clamp height, contact geometry or rebuild repeatability.
Heat and Vacuum Compatibility
Dense alumina ceramic can be used near high-temperature zones and in selected vacuum or coating equipment where polymer parts may deform, outgas or lose dimensional stability. Final suitability should be reviewed according to temperature, atmosphere and load condition.
Machinable Interface Features
OD, ID, thickness, chamfer, radius, grooves, reliefs, holes and functional faces can be reviewed from the drawing. This allows the insulating ring to match the real fixture stack-up instead of forcing the assembly to adapt to a generic washer.
Reduced Edge and Contact-Face Risk
Protected edges and defined contact surfaces help reduce chipping, rocking, uneven clamp loading and assembly rework. This is especially important for ceramic rings that are repeatedly installed, cleaned or replaced during equipment maintenance.
High-Purity Alumina Insulating Ring 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 | – | – | – | – | – |
The values below are material reference data for alumina ceramic grades. Final material selection should be reviewed according to drawing geometry, operating temperature, insulation requirement, surface finish and assembly load condition.
Custom Size Options for Alumina Ceramic Insulating Rings
| Alumina Insulating Ring | ||
| Item No. | Diameter (mm) | Thickness (mm) |
| AT-HP-JY01 | Customize | |
High-Purity Alumina Insulating Ring Packaging
- Each alumina ceramic insulating ring is individually protected to reduce edge impact, surface scratches and ceramic-to-ceramic contact. Foam positioning, face protection and reinforced packaging can be used for thin or precision-finished rings.
