D-values (Dxx) are cumulative particle size percentiles from laser particle size analysis:
Dxx = the particle diameter where xx% of total particle volume/mass is smaller than this size.
1. D10
- Meaning: 10% of all particles (by volume) are finer / smaller than the D10 value; 90% are coarser.
- Function: Represents the fine end / minimum size characteristic of the powder.
- Application: Critical for filtration, ink gloss, battery electrode conductivity, pigment tinting strength.
Example: D10 = 2 μm
Only 10% of particles are below 2 μm; most particles are larger than 2 μm.
2. D50 (Median Particle Size, the most common index)
- Meaning: 50% of particles are smaller, 50% larger than D50.
- Function: The average/median particle size of the entire powder batch, the primary reference parameter for grading powders.
- Application: Standard specification for minerals, fillers, carbon black, battery materials, coatings.
Example: D50 = 10 μm
Half the powder volume is finer than 10 μm, half coarser.
Supplementary Key Comparison
| Parameter | Physical Significance | Main Use Case |
|---|---|---|
| D10 | Fine fraction cutoff | Evaluate ultrafine content, viscosity, surface activity |
| D50 | Median average size | Core product grading standard |
| D90 / D97 | Coarse fraction cutoff | Control oversize impurities, abrasion, sedimentation |
Simple Illustration
If PSD data: D10=3 μm, D50=12 μm, D90=28 μm
- 10 vol% particles < 3 μm
- 50 vol% particles < 12 μm
- 90 vol% particles < 28 μm
Important Note
D-values are volume-based in nearly all industrial laser diffraction instruments (not number count), which matches industrial production and material performance evaluation.
