Evaluation of spray-dried powder deagglomeration behaviour based on dry laser diffraction analysis

摘要

Powder metallurgy processes need powders with a good flowability. Spray-drying is well-known for improving powder flowability, modifying the shape of particles by formation of spherical agglomerates. However, during industrial processes, pneumatic transport may induce stress leading to powder deagglomeration. In order to study the influence of spray-drying parameters on agglomerates properties, commercial alumina powders of different median sizes (from 0.4 to 8 μm) were put in suspension in water without binder then spray-dried under different conditions (temperature, solid concentration, suspension flow rate). The deagglomeration behaviour of these powders was then examined by dry laser diffraction analysis, using different pressures for the feed powder dispersion. Based on these results, an index is introduced to quantify the deagglomeration properties. It is shown that the initial powder characteristics have a main effect on the deagglomeration behaviour; the spray-drying conditions having a lesser effect.