Aluminum Oxide Balls

Aluminum Oxide Balls (Alumina) for Valves and Wear Parts

REDHILL supplies aluminum oxide balls made from high-purity alumina (Al₂O₃). The material combines high hardness, wear resistance and low weight. In addition, alumina acts as an electrical insulator. As a result, engineers consider it for valves, wear parts and selected precision mechanisms.

Reference Properties of 99.5% Alumina

• Alumina content: ≥99.5% Al₂O₃
• Density: About 3.9 g/cm³
• Vickers hardness: About 15–16 GPa
• Flexural strength: About 300–370 MPa, depending on grade and test method
• Compressive strength: About 2,600 MPa
• Elastic modulus: About 370 GPa
• Fracture toughness: About 4–5 MPa·m^1/2
• Thermal conductivity: About 30–32 W/(m·K) at 20°C
• Thermal expansion: About 8.2 × 10⁻⁶/K over 25–1,000°C
• Electrical resistivity: >10¹⁴ Ω·cm at 25°C

These values provide a guide for common alumina grades. However, purity, grain size and processing affect the final properties. Therefore, confirm the exact material grade and any required test values with your inquiry.

Hardness and Wear Resistance

Alumina provides hard contact surfaces that resist abrasive wear. In addition, its high stiffness helps limit deformation under load. As a result, the material suits parts where surface wear affects fit or sealing.

However, alumina remains a brittle ceramic. Therefore, assess impact loads, edge contact and rapid changes in temperature when choosing a ball.

Lower Weight and Electrical Insulation

At the same diameter, an alumina ball weighs about half as much as a steel ball. As a result, it can reduce the mass of moving parts. In addition, alumina offers electrical insulation and a low response to magnetic fields.

However, bearing speed, load capacity and lubrication needs depend on the complete design. Therefore, select the material for the actual mechanism and working conditions.

Applications of Aluminum Oxide Balls

For example, possible uses include:

• Ball check valves and matching seats
• Chemical and metering pump components
• Flow meters and flow control parts
• Specialty bearings and wear contacts
• Mechanisms that need electrical isolation

Chemical and Temperature Limits

Alumina resists many process fluids. However, chemical resistance depends on the fluid, its strength and the working temperature. Therefore, check compatibility with the full process mix.

In addition, use the material grade data and assembly limits to set the working temperature.

Ball Grades and Sizes

• Ball grades: G25, G50 and G100
• Diameters: 0.5 mm–50 mm

Confirm the available combination of size, grade and material before ordering. Finally, send us the diameter, tolerance, quantity and working conditions so we can review your requirements.