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AFBMA Grade 25 Alumina Balls
Available Configurations
Properties common to all products in this list
| Diameter | Quantity |
|---|---|
| 0.5 mm to 20 mm | 1 piece to 10,000 pieces |
Need custom configurations? Please contact us.
Key Features
AFBMA Grade 25 Alumina Balls are precision aluminum oxide spheres manufactured to Grade 25 dimensional tolerances, combining the hardness, chemical inertness, and wear resistance of technical-grade alumina with certified dimensional precision:
Hardness Approaching Mohs 9
Alumina’s hardness approaching 9 on the Mohs scale gives it a high wear resistance and abrasion resistance under contact loading, outperforming less hard media in the comminution of fine powders in wet and dry ball milling processes.
Very Low Wear Rate Under Abrasive Contact
The combination of high hardness and high compressive strength produces a very low wear rate, minimizing contamination of ground material with ball wear debris — a critical requirement in high-purity milling applications where material purity must be maintained.
Chemical Inertness Across Acids, Alkalis and Organic Solvents
Resistance to attack by most acids, alkalis, and organic solvents extends applicability to grinding in chemically aggressive media where metallic or polymer balls would corrode or dissolve, and to check valve and flow control applications in corrosive fluid handling systems.
High Dielectric Strength and Electrical Insulation
High dielectric strength and electrical insulation properties support use in high-voltage and electromagnetic applications requiring non-conductive structural sphere elements.
Grade 25 Dimensional Tolerances
AFBMA Grade 25 sphericity and diameter tolerance certification provides dimensional reproducibility suited to precision valve seats, calibration reference spheres, and bearing and pivot applications in corrosive or contamination-sensitive environments.
Industrial Applications
AFBMA Grade 25 Alumina Balls are used across grinding, chemical processing, electrical insulation, and precision instrumentation wherever hardness, chemical inertness, and dimensional precision must be combined in a ceramic sphere:
- ✦ Ceramic Grinding Media in Ball Milling
- The standard material for ceramic grinding media in wet and dry ball milling of fine powders, where hardness approaching Mohs 9 outperforms less hard media in comminution efficiency and the very low wear rate minimizes contamination of the ground product with ball debris.
- ✦ Grinding in Chemically Aggressive Media
- Used in ball milling of materials suspended in acids, alkalis, and organic solvents where metallic or polymer grinding media would corrode, dissolve, or contaminate the product, and alumina’s broad chemical inertness maintains both media integrity and product purity.
- ✦ Check Valves and Flow Control in Corrosive Fluid Handling
- Applied as check valve and flow control sphere elements in corrosive fluid handling systems, where chemical inertness in aggressive process media and Grade 25 dimensional precision provide reliable sealing and flow metering performance.
- ✦ High-Voltage and Electromagnetic Applications
- Used as non-conductive structural sphere elements in high-voltage and electromagnetic assemblies where the dielectric strength and electrical insulation of alumina prevent current leakage and electromagnetic interference from the sphere element.
- ✦ Tribological Testing and Calibration Reference Spheres
- Applied in research and precision instrumentation as reproducible, chemically inert reference spheres for tribological testing, calibration of dimensional measurement systems, and precision bearing and pivot applications in corrosive or contamination-sensitive environments.
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 | Standard | ±5% |
|---|---|---|
| Diameter | Precision | See Item |