Sapphire Balls

Sapphire Balls – High Hardness and Wear Resistance

REDHILL supplies sapphire balls for parts that need high hardness, low wear and a precise shape. Synthetic sapphire is a single crystal of aluminum oxide. As a result, it combines a hard surface with useful optical properties. In addition, it suits many small parts in measuring tools, valves and sensors.

Key Technical Facts

The values below give a general guide. However, temperature and crystal direction can affect some properties. Therefore, confirm the required material data for your order.

• Crystal structure: Single-crystal corundum.
• Composition: Aluminum oxide, Al₂O₃.
• Purity: 99.99%, subject to the chosen material grade.
• Density: About 3.99 g/cm³.
• Mohs hardness: 9.
• Knoop hardness: About 1,800–2,200, depending on crystal direction.
• Stiffness (Young’s modulus): About 440 GPa, depending on crystal direction.
• Melting point: About 2,050°C.
• Thermal conductivity: About 40 W/(m·K) near 300 K.
• Expansion with heat: The value changes with crystal direction and temperature.
• Electrical resistivity: Typically above 10¹² Ω·cm near room temperature.
• Dielectric constant: Confirm the value for the test frequency, temperature and crystal direction.

However, the melting point does not define the safe working temperature. Therefore, match the material to the heat, load and fluids in your system.

Benefits of Sapphire Balls

Sapphire’s hard surface resists scratches and wear. As a result, the balls can hold their size and shape over long periods.

In addition, sapphire resists many chemicals and acts as an electrical insulator. However, the exact fluid and working temperature still matter.

Sapphire also lets light pass through a wide range of wavelengths. For example, optical grades can work with visible light and parts of the UV and IR ranges. Therefore, choose the grade and surface finish to match your optical system.

Common Uses for Sapphire Balls

The right size and finish depend on the task. For example, common uses include:

• Precision bearings: Sapphire suits selected small bearing designs in instruments.
• Optical systems: Ball lenses help link fibers, light sources and detectors.
• Measuring tools: In addition, designers use sapphire balls in flow meters, scanners and sensors.
• Aerospace and medical equipment: Hard, wear-resistant parts suit many precision devices.

Available Grades and Sizes

Choose the grade and size to match your design. For example, our range includes:

• Grades: G1, G2, G3, G5, G10 and up to G25.
• Sizes: Diameters from 0.16 mm to 25 mm. In addition, ask us about custom sizes.

Finally, send us your drawing, quantity and working conditions. We can then check the size, grade and finish for your project.