When an application needs electrical insulation, heat resistance and dimensional stability, alumina ceramic tubes are often a practical material choice. HERUN manufactures straight tubes, insulating sleeves, rods and custom tube-like components according to drawings or samples.
Material Property Comparison
| Material | Hardness | Fracture toughness | Flexural strength | Max use temperature | Thermal conductivity | Electrical insulation | Relative cost |
|---|---|---|---|---|---|---|---|
| 95%-99% alumina (Al2O3) | 12-20 GPa | 3-5 MPa m^0.5 | 300-450 MPa | 1500-1700 C | 20-35 W/m K | Excellent | Low to medium |
| 99.5%-99.7% alumina | 16-20 GPa | 3-4 MPa m^0.5 | 300-400 MPa | 1600-1700 C | 25-35 W/m K | Excellent | Medium |
| Silicon nitride (Si3N4) | 14-18 GPa | 5-7 MPa m^0.5 | 700-1000 MPa | 1000-1200 C | 20-35 W/m K | Good | High |
Typical values for comparison — request a datasheet for guaranteed specifications.
Typical Applications
- Thermocouple protection tubes and sensor sleeves.
- Electrical insulating tubes for furnace and heating equipment.
- High-temperature guides, spacers and support tubes.
- Laboratory equipment and analytical instrument ceramic tubes.
Material and Purity Selection
95% alumina is often used for cost-effective insulation and structural ceramic parts. Higher purity alumina can be selected when temperature, contamination control or electrical performance requirements are stricter. The right grade depends on the real working environment.
Tube Design Considerations
Long thin tubes are sensitive to straightness, wall thickness and handling damage. For precision assemblies, define the critical diameter and length tolerance. If only one end or one bore area is critical, the drawing should mark it clearly to control grinding cost.
Information Needed for Quotation
- Outer diameter, inner diameter, length and wall thickness.
- One-end closed or open-end design if applicable.
- Operating temperature, electrical requirement and atmosphere.
- Quantity, tolerance, surface finish and packing requirement.
Related Pages
FAQ
What are alumina ceramic tubes used for?
Alumina ceramic tubes are used for high-temperature insulation, thermocouple protection, furnace supports, wire guides, heating equipment and other industrial assemblies.
Can alumina tubes work at high temperature?
Yes. Alumina can work at high temperatures, but the usable limit depends on purity, load, atmosphere, thermal cycling and part design.
What details are needed for a custom ceramic tube quote?
Outer diameter, inner diameter, length, tolerance, wall thickness, material grade, quantity and working temperature are the most useful details for quotation.