title: Pull-off force of coated fine powders under small consolidation.
abstract: In this paper, a three-dimensional model taking into account the contact deformation and surface area coverage (SAC) of nanoadditives is proposed to predict the force required to separate two contacting particles (the pull-off force) under consolidation stress up to 10 KPa, for cornstarch, a Geldart group C powder, sparsely and densely dry-coated with nanosilica. The experimental pull-off force measurement is conducted in a Seville powder tester. Comparison of the predicted results with the experimental results indicates (1) that the pull-off force of sparsely coated cornstarch is larger than that of densely coated cornstarch due to the greater hardness and small particle radius of fumed silica; (2) there is not a continuous variation in the pull-off force with the coverage of silica; on the contrary, values of the pull-off force of sparsely coated samples are grouped in similar range, while the values of the pull-off force of densely coated samples are grouped in another range of lower values. (3) Within a range, the SAC does not have a big effect on the pull-off force for sparsely coated samples and only a slight effect for densely coated samples (4) the pull-off force increases with increasing consolidation force due to larger deformation in the contact area; (5) under consolidation stresses up to 10 KPa, the deformation of the cornstarch particles is not large enough to fully embed the nanosized silica.
authors.affiliation: New Jersey Center for Engineered Particulates (NJCEP), New Jersey Institute of Technology, University Heights, Newark, New Jersey 07102-1982, USA.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Chen
authors.forename: M A S
authors.initials: MA
authors.lastname: Quintanilla
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Jose M
authors.initials: JM
authors.lastname: Valverde
authors.forename: Rajesh N
authors.initials: RN
authors.lastname: Dave