(139f) Prediction of Inter-Particle Adhesion Force from Surface Energy and Roughness

It is well known that fine particles do not flow well due to the dominant interparticle adhesion force over the gravitational force. In order to reduce the adhesion force two techniques, dry particle coating and surface silanization, were used to improve the flow behavior of fine cohesive powders (5 ?Ým aluminum). To quantify the inter-particle adhesion force of the pure and surface modified aluminum powders, surface energies of these powders were determined using inverse gas chromatography (IGC). Surface roughness of the particles was obtained with atomic force microscopy (AFM). The Inter-particle adhesion force is calculated using the Derjaguin, Muller, and Toporov (DMT) model. The results indicated that surface modification reduced the surface energy and altered the surface roughness,leading to a dramatic reduction in the inter-particle adhesion force. Meanwhile, flow characterization results of these powders also demonstrated the drastic decrease of interparticle adhesion force. The polar interfacial contributions of the surface free energy showed that the surface modification process increased basicity of the powders in the same trend that the flow properties were improved.