Share this page by mail Alumina or zirconia beads: what material should I choose to optimise grinding?
Alumina beads (Al2O3), with a density of 3.9 g/cm³ and a hardness of 17 GPa, are cost-effective and suitable for standard grinding operations, in particular for mineral loads or pigments. Zirconia beads (stabilised ZrO2) have a higher density (6 g/cm³) and a better fracture toughness (7 MPa·m1/2), which improves the effectiveness of the grinding and reduces treatment time. They also cause less contamination and have a better wear resistance. Final Advanced Materials recommends zirconia for intensive or high precision grinding operations, and alumina for more cost-effective applications.
Ceramic beads are available in standard diameters ranging from 0.4 mm to 3.3 mm depending on the applications (grinding, bearings, polishing beads). The smaller beads are used for fine drilling, while the larger diameters are suitable for mechanical applications. The precision tolerances can attain high grades such as G10 to G100 (ISO standard 3290), with a sphericity of less than 0.25 µm for premium grades. The surface roughness (Ra) is 0.02 µm. Final Advanced Materials produces beads of different diameters to meet the strictest industrial requirements.
Stabilised zirconia beads (ZrO₂) have a high density (6 g/cm³), a hardness of 12 GPa and an excellent fracture toughness, enabling them to resist wear and mechanical impacts. They also have a high chemical resistance to acids, bases and corrosive environments and can withstand temperatures as high as 1,050°C. Final Advanced Materials therefore recommends zirconia for industrial valves which are exposed to aggressive environments and which require a reliable and long lasting material.
99.7% alumina beads have a maximum temperature resistance of 1,750°C in continuous service, with a Vickers hardness (HV5) of 1,600 and a compression resistance ranging between 980 and 1,078 N for a 2 mm diameter bead. Stabilised zirconia beads have a maximum temperature resistance of 1,050°C in continuous service, with a Vickers hardness (HV5) of 1,300 and a compression resistance of 2,107 N for a 1.5 mm diameter bead.
The low friction coefficient and dimensional stability of these high temperature beads reduce the wear of mechanical systems. Final Advanced Materials recommends these beads for demanding environments subject to a combination of temperature, abrasion and high mechanical stresses.