For powder materials, we typically use a laser particle size analyzer (based on the light scattering equivalent principle) to test their particle characteristics and particle size distribution.
Generally, we look at test results to determine the D50 and D90 values. It helps us evaluate the performance of the material. But what if there’s no analysis done by others— how can we interpret the data ourselves?
First, let’s understand particle size distribution.
Particle size distribution describes how particles of different sizes are distributed in a powder. It also reflects the uniformity of particle size. It is typically illustrated in two ways: frequency distribution (differential distribution) and cumulative distribution.
Differential Distribution Graph
Differential Distribution
This shows the percentage of particles at each particle size range within the whole particle population (as shown in the graph above).
The black line indicates that particles with a size of 0.4 μm account for 7% of the total. The green line shows that particles of 1.05 μm account for 2.5%. From the graph, we can see that the powder has particle sizes ranging from 0.1 μm to 15 μm. Particles around 0.4 μm and 3 μm dominate. The particle uniformity isn’t very good—this could be by design. It could be due to poor dispersion, where smaller particles agglomerate to form larger ones.
Cumulative Distribution
This shows the percentage of particles smaller or larger than a certain particle size (integrated distribution). Below is a combined graph of differential and cumulative distributions—the red line and the right-hand y-axis form the cumulative distribution.
Combined Differential and Volume Distribution Graph
Let’s now explain the cumulative distribution, focusing on commonly seen values in reports: D10, D50, and D90.
D10: This means 10% of the particle volume is made up of particles smaller than this size. In the graph, the blue line shows that 10% of the total volume is made up of particles smaller than 0.9 μm.
D50: Also called the median diameter or median particle size, this is a typical value representing the particle size distribution. It means that 50% of particles are larger than this size, and 50% are smaller. In the graph, the black dashed line shows that particles larger and smaller than 3 μm each make up 50%.
D90: As indicated by the pink line, this means 90% of the particles are smaller than 7 μm, and so on.
Although the laser particle size analyzer is very practical and widely used, it also has limitations. If we want a more accurate understanding of the particle size and shape, we need to use scanning electron microscopy (SEM) for direct observation and analysis of the material’s morphology and particle size.
En Polvo épico Machinery, we specialize in precision particle size control. Whether you’re targeting narrow distributions or specific D50 values, our advanced jet milling and clasificación systems help you achieve consistent, reliable results. We provide not only equipment, but also deep expertise in particle analysis, helping customers understand and optimize their powder properties for better product performance.
