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Alumina Rod
Available Configurations
Properties common to all products in this list
| Diameter | Length |
|---|---|
| 1 mm to 20 mm | 2 mm to 1000 mm |
Need custom configurations? Please contact us.
Key Features
Alumina Rod (Al₂O₃) is a fully dense, high-purity engineering ceramic combining the highest compressive strength, continuous service ceiling, electrical insulation, and chemical resistance of any widely available oxide ceramic in a precision rod form:
Very high compressive strength
Compressive strength of 2200–2600 MPa is among the highest of any engineering ceramic available as standard rod stock, allowing alumina rods to carry substantial compressive loads as furnace supports, pusher rods, and structural spacers without deformation or fracture under the sustained mechanical loads of high-temperature kiln and sintering furnace service.
Continuous service ceiling of 1700°C
The maximum continuous service temperature of 1700°C exceeds that of most other engineering ceramics and all engineering metals, making alumina rod the standard choice for furnace support, thermocouple protection, and structural elements in sintering and crystal growth systems where operating temperatures are well above the range of refractory metals and superalloys.
Full electrical insulation
Volume resistivity exceeding 10¹⁴ Ωcm provides full electrical insulation across the service temperature range, qualifying alumina rods as insulating spacers, stand-offs, and support elements in high-voltage electrical assemblies and high-temperature electrochemical systems where conductive supports would short the assembly.
Zero porosity and full chemical resistance
Zero apparent porosity eliminates moisture absorption and ensures consistent performance in oxidizing, reducing, and chemically aggressive atmospheres. Alumina is chemically resistant to most acids and alkalis at room and elevated temperature, allowing rod use in corrosive process environments where metallic rods would corrode and porous ceramics would absorb process fluids.
Dimensional stability under combined thermal and mechanical load
The high stiffness and fully dense microstructure ensure that rods maintain their geometry and surface finish reliably under sustained combined mechanical and thermal loading, a critical requirement for precision spacers, alignment elements, and metrology fixtures where creep or deformation under load would compromise the assembly.
Industrial Applications
Alumina rod is used wherever the combination of extreme compressive strength, a 1700°C service ceiling, full electrical insulation, and chemical inertness is required from a single ceramic rod component:
- ✦ Furnace support and pusher rods in high-temperature kilns and sintering furnaces
- Used as furnace support and pusher rods in high-temperature kilns and sintering furnaces operating to 1700°C, where the combination of very high compressive strength, thermal stability, and chemical resistance to the process atmosphere and sintered materials qualifies alumina rod over metallic and lower-melting-point ceramic alternatives.
- ✦ Insulator rods in high-voltage electrical assemblies
- Applied as insulating rods in high-voltage electrical assemblies and vacuum furnace electrode systems, where the combination of full electrical insulation, mechanical strength to support electrode structures, and thermal stability at operating temperatures qualifies alumina over polymer and lower-temperature ceramic insulators.
- ✦ Wear-resistant guide rods in abrasive material handling
- Used as guide and contact rods in abrasive material handling systems, where the high hardness and wear resistance of alumina provide substantially longer service life than metallic guides in contact with abrasive particulates, powders, and process streams that would rapidly erode steel or other metal alternatives.
- ✦ Precision spacers and alignment elements in optical and metrology instruments
- Applied as precision spacers and alignment rods in optical assemblies and metrology instruments, where the combination of dimensional stability under thermal cycling, full electrical insulation, and chemical inertness allows alumina rods to maintain precise spacing and alignment without thermal expansion mismatch or chemical interaction with adjacent components.
- ✦ High-temperature mechanical testing fixtures and electrochemistry research
- Used in research as high-temperature mechanical testing fixtures, electrode supports in high-temperature electrochemical cells, and as reference ceramic specimens for hardness and modulus calibration studies where a well-characterized, fully dense oxide ceramic is required.
Material Properties
| Element | Value |
|---|---|
| Acids - concentrated | Good |
| Acids - dilute | Good |
| Alkalis | Good |
| Halogens | Good |
| Metals | Good |
| Element | Value |
|---|---|
| Dielectric constant | 9-10.1 |
| Dielectric strength( kV mm⁻¹ ) | Oct-35 |
| Volume resistivity( Ohmcm ) | >10¹⁴@25 |
| Element | Value |
|---|---|
| Apparent porosity( % ) | 0 |
| Water absorption - saturation( % ) | 0 |
| Density( gcm⁻³ ) | 3.9 |
| Element | Value |
|---|---|
| Melting point( C ) | 2100 |
| Upper continuous use temperature( C ) | 1700 |
| Specific heat( J K⁻¹ kg⁻¹ ) | 850-900@25°C |
| Thermal conductivity( W m⁻¹ K⁻¹ ) | 26-35@20°C |
| Coefficient of thermal expansion( x10⁻⁶ K⁻¹ ) | 8@20-1000°C |
| Element | Value |
|---|---|
| Tensile modulus( GPa ) | 300-400 |
| Hardness - Knoop( kgf mm⁻² ) | 2100 |
| Hardness - Vickers( kgf mm⁻² ) | 1500-1650 |
| Shear strength( MPa ) | 330 |
| Tensile strength( MPa ) | 260-300 |
| Element | Value |
|---|---|
| Compressive strength( MPa ) | 2200-2600 |
Tolerances
| Diameter | +20% / -10% | |
|---|---|---|
| Length | <100mm | ±1mm |
| Length | >=100mm | +5 / -1% |