The flow behavior of the liquid/powder mixture, theory and experiment II: Effect of the friction force

The analytical theoretical formula for calculating the unconfined yield shear strength (fc) of the powder/oil mixture obtained earlier in our previous paper [1] is modified, taking into account the work required not only to rupture the liquid bridge, but also to move particles relative to each other against the inter-particle friction force. This formula is valid for powder/oil mixtures with homogeneously distributed oil, as well as for dry powders. Experimental results obtained for dry narrowly sized silica particles in a Schulze cell agree with the developed formula, suggesting experimental value for the friction coefficient and accounting for the effect of the roughness on the adhesion and friction forces.