H. Muhlenweg et Ed. Hirleman, LASER DIFFRACTION SPECTROSCOPY - INFLUENCE OF PARTICLE-SHAPE AND A SHAPE ADAPTATION TECHNIQUE, Particle & particle systems characterization, 15(4), 1998, pp. 163-169
Citations number
15
Categorie Soggetti
Materials Science, Characterization & Testing","Engineering, Chemical
The evaluation algorithm employed in laser diffraction spectroscopy is
usually based on the Fraunhofer diffraction theory for spheres. As th
is evaluation theory is limited to spheres only, the measurement of ir
regularly shaped particles results in errors in the evaluated particle
size distribution. To determine the influence of the particle shape,
measurements of arbitrarily shaped particles were simulated, evaluated
and compared with results for spherical particles of the same project
ed area. The detailed investigations showed that the particle's micros
tructure, i.e. its surface roughness, has almost no or only a negligib
le effect on the measurement result. In contrast to this advantageous
outcome, the particle's microstructure, i.e. its axis ratio, affects t
he measurement result greatly and must be taken into account in the ev
aluation method. Based on these results, particles were considered to
be ellipsoids with specific (but negligible) surface structures and a
mathematical adaptation method was developed by extending the evaluati
on theory from spheres to randomly in space oriented ellipsoids. Simul
ations and experiments with reticles verified the need for this adapta
tion technique and its efficiency when applied.