Dry Coating is a novel technique to prepare engineered particles and it helps reduce the adhesion force of very fine powders and improve their flowability and fluidizability. However, at present, the mechanism of the fluidizability improvement due to nano-additives is not well understood. Since particles are compressed at least by the weight of particles above themselves when stored, transported and processed, it is important to account for such low consolidation when proposing a mechanism of the improvement in fluidizability or flow. In this work, a three dimensional model taking into account the contact deformation and Surface Area Coverage of nano-additives is proposed to predict the pull-off force, the force required to separate two contact particles, under consolidation stress up to 10,000 Pa for sparsely and densely dry coated group C powder cornstarch. Sparse coating demonstrates that two dry coated particles contact each other through contact of silica and cornstarch, while dense coating illustrates that two dry coated particles contact each other by silica-silica contact. The pull-off force measurement is conducted in a Seville Powder Tester (SPT), which uses gas flow either to fluidize to erase memory of the powder or to compress the bed in order to subject it to a controllable consolidation stress. The analytical results have good agreement with the experiment results indicating: (1) the pull-off force of sparsely coated cornstarch is larger than that of densely coated cornstarch due to the greater hardness of fumed silica; (2) the pull-off force increases with increasing the consolidation force due to larger deformation in contact area; (3) under consolidation stress less than 10,000 Pa the nanosized silica is not fully embedded in the cornstarch because the deformation of cornstarch is not big enough though it increases with raising the consolidation force and decreasing the surface area coverage (SAC).

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