Measurement of Adhesion Force of Powder Particles by Powder Bed Tensile Strength Method

Abstract

The adhesion force of silica sand, limestone and copper powder beds were measured with the split cell type tensile strength measurement method, which had been developed by Ashton, Farley and Valentin⁴⁾, and later modified by the authors. The effect of porosity change on the strength of powder bed, σ_z, was measured and correlated with the function of porosity, (1-ε) k, which had been proposed by Rumpf⁵⁾⁶⁾ in Eq. (1).
These results reveal that the relation between σ_z and (1-ε) k does not follow the proportionality which is shown in Eq. (1), and so the adhesion force at a contact point, H, is also affected quite severely by the compacting conditions as are shown in Figs. 4, 5, 6.
The effect of compression force was investigated with two different compacting methods, compression and tapping. The results show that the adhesion force of the powder bed by compression is usually larger than that by tapping at same porosity as are shown in Figs. 4, 5.
From these results and another consideration which the authors made⁴⁾, it is suggested that the adhesion force of powder is affected not only by the factors which Rumpf analysed but also by the change of contacting condition, perhaps contact area, at the contact point of particles.