The choice of ball material is made according to the desired physical and mechanical properties. Ceramic is an increasingly used material for balls due to its exceptional resistance characteristics, which can thus meet many constraints.
At the same time, it generates less friction and offers resistant & lightweight properties allowing it to perform well in high machining precision.
This material is widely used in watchmaking, medical, automotive, high-pressure pumps, high-precision bearings and many other sectors.
- High hardness (> 1,300 Vickers)
- Low density: 3 to 6 kg/dm³
- Friction and wear resistance thanks to a low coefficient of friction
- High modulus of elasticity (200 to 400 GPa)
- Chemical and thermal resistance. Electrical insulation.
- High mechanical strength (flexural strength: approximately 400 to 1,000°C)
- Low porosity (< 0.5%), very high-quality polished surfaces
- Machining and polishing precision. For example, for a 14mm Al2O3 alumina ball, diameter variations can be reduced to less than 0.1 µm with average roughness Ra up to 0,005 µm.
- High-precision, high-speed ball bearings
- Hip prosthesis
- Valves
- Measuring devices
- Reference spheres for coordinate measuring machines
- Probes for coordinate measuring machines
| Physical properties | Sapphire | Ruby | Alumina | HP Silicon Nitride | Zirconia Y-TZP | Tungsten Carbide * | stainless steel * | Steel 100Cr6 * |
|---|---|---|---|---|---|---|---|---|
| Crystal structure | Mono | Poly | Poly | Poly | Poly | Poly | Poly | |
| Chemical formula | Al2O3 | Cr2O3 | Al2O3 | Si3N4 | ZrO2 | Wc (6T10) | ||
| Pureness % | 99,99 % | 99 % | 1,00 | 90 | 90 à 95 | Wc94+C06 | ||
| Density (Kg/dm3) | 3,99 | 3,90 | 3,10 à 3,20 | 6 | 15 | 8 | 7,85 | |
| Hardness (HV) | 2 300 | 1650,00 | 1 600 | 1 100 à 1 500 | 1 550 | 500 to 800 | 762 to 865 | |
| Compressive strength (MPa) | 2 100 | 2400,00 | 3 000 | ≈ 4 000 | 5 300 | - | 2 240 | |
| Elastic resistance (MPa) | - | 280,00 | 400 | - | - | 500 to 1 500 | ||
| Flexural strength (MPa) | 390 | 470,00 | 1 000 | 700 to 1 100 | 1 900 | - | ||
| KIC resilience (MPa.m1/2) | 1 | 4,00 | 6 | 10 | - | 30-80 | ||
| Young's modulus (modulus of elasticity) (GPa) | 430 | 380,00 | 320 | 200 | 610 | 200 | 205 | |
| Coefficient of thermal expansion (10-6 .°K-1) | 5,3 | 5,50 | 3,2 | 10 | 5,5 | 10 à 12 | ||
| Thermal conductivity (W/m°K) | 36 | 29,00 | 40 | 2 | 80 | - | ||
| Heat capacity (J/Kg°K) | 755 | 900,00 | 750 | 500 | 201 | - | ||
| Maximum operating temperature (°C) | 1 800 to 2 000 | 1 500 to 1 800 | 1 200 to 1500 | 1 000 | - | 300 to 600 | 450 | |
| Acid resistance | Very good | Very good | Very good | Good | Limited | Limited | Non-resistant | |
