Oct 30

Particle size distribution analysis

X-rays imaging at high resolution allows visualization and quantification of any type of sample, including particles and powders. X-ray computed tomography in the micro and even nano scale is now possible, as a service facility in Stellenbosch University. Here we present the advantages of using the method for particles and powder characterization.

The full 3D data set is first analyzed in greyscale slice images. These images immediately show the user the general morphology of the grains of interest, also showing internal features such as porosity or dense inclusions within particles. The slice images are equivalent to “thin sections” through the middle of the scan field of view, and you can “scroll through the object” without any special software. In the sugar grains we see no internal porosity or density variations, but many flat surfaces on the particles. In the 3D image, the largest 3 sugar grains are selected from analysis and extracted to view them seperately in 3D.

sugar slice

sugar 3D

The concrete powder shows very irregular shapes with pores inside some particles. A particle size distribution analysis is performed, and the histogram shown below. In addition to particle volume or diameter, every particle has its 3D surface area, X,Y,Z projection area, longest axis length, sphericity factor, etc. calculated. All this additional information can be very useful and is not possible with any other technique such as surface analysis “topography” SEM or laser methods, all of these have some limitations in providing real shape information in true 3D. The only limitation to X-ray CT is the field of view and resolution. Best resolution is 500-1000 nm which is possible using a 1 mm sample size, and makes possible quantitative size distribution analysis of 10 – 1000 micron particle diameters.

concrete powder slice

concrete powder analysis

particles size distr

High quality nanoCT scans produce the best results, these take between 2-4 hrs per sample without any post processing. We can provide standard analysis such as particle size distribution analysis, within 1 hr after the scan. Analysis results (size distribution) can be e-mailed (CSV file) while volume data (10 Gb) is sent on hard drive with a free 3D viewer program. Academic rates are R550 per hour, excl 7% admin fee and VAT, commercial R1250 ph.

Samples can be physically delivered to our labs (via courier) – for powders we need approx 2 x 2 x 2 mm for quantitative particle size distribution from 10-1000 micron

This page is available as brochure: particle analysis

Analysis performed in VGStudioMax 2.2