Calcium zirconium oxide

Particle size distribution (Granulometry)

Description of key information

Based on data from a manufacturer for a variety of samples with varying CaO content (3.7-6.0% w/w), the mass-based median diameter (D50) ranged from 0.55 to 750 µm. Because calcium stabilised zirconia are crushed and sieved to the desired particle size distribution after production, these data can be considered applicable to zirconia with up to 10% CaO w/w (i.e. the upper boundary mentioned in the substance identity profile), for which no data are available at this point in time.

Additional information

Calcium zirconium oxide is typically produced as an ingot or bubble and afterwards the resulting fused material is crushed and sieved to the desired particle size distribution. There are two in-house studies available from Imerys Fused Minerals (manufacturer), in which the particle size distribution is determined for a variety of samples. In the first study, the mass-based median diameter (D50), estimated from mass-based cumulative distribution curves, ranged from about 11 to 750 µm for a series of samples with CaO content between 3.7 and 4.8% w/w. In the second study, mass-based median diameters (D50) were reported to be between 0.55 and 2.0 µm for a series of powders and spray dried granules with a CaO content between 4.5 and 6.0%. No data are included in the dossier for samples with CaO content at the upper range of the substance identity profile (i.e. 10% CaO w/w). However, as confirmed by the manufacturer, the particle size distribution curves for the stabilised zirconia with ca. 5% CaO w/w are also relevant for zirconia with CaO content up to 10% w/w. This is the case because the stabilised zirconia are crushed and sieved to the desired particle size distribution after production, in a similar way.