- Industry Convention
For tabular alumina powders used in refractories, ceramics, and other fields, a single numerical particle size marking (e.g., 3 μm, 5 μm, 10 μm) defaults to the D50 median particle size measured by a laser particle size analyzer. This value represents the particle diameter at which the cumulative volume percentage of the powder reaches 50%, and it is the core index for evaluating the overall particle size distribution, filling performance, and reactivity of the powder.
- Distinction from Other Particle Size Indicators
If the marking refers to other indicators such as D10 or D90, it must be explicitly specified (e.g., “D10=10 μm” or “D90=10 μm”), rather than simply writing “10 microns”.
- D10: The particle size corresponding to 10% cumulative volume, reflecting the proportion of fine particles in the powder.
- D90: The particle size corresponding to 90% cumulative volume, indicating the upper limit of coarse particle size in the powder.
Additionally, if the 10-micron specification refers to sieve pass rate (e.g., residue on 10 μm sieve ≤ 5%), the sieve specification and residue ratio will also be clearly indicated in the product parameters to avoid confusion with D50. - Practical Application Significance
Tabular alumina marked with D50=10 μm has a moderately fine particle size distribution, which can balance filling effect and anti-agglomeration performance. It is widely used in formulations of microporous refractories and ceramic blanks to optimize product microstructure and improve thermal shock resistance and mechanical strength.
