Flow characterization of fine powders using material characteristic parameters

Instantaneous flow properties of fine cohesive powders, i.e. limestone, glass-ballotini, alumina and talc, are evaluated using Jenike shear tester. The results are analysed in the light of elastic-plastic interparticle contact deformation theory incorporating fundamentals of fine powder adhesion and consolidation in flow behavior characterization. Thus, unconfined yield strengths (σc) of the given samples at various consolidation levels are evaluated solely on the basis of material characteristic parameters, i.e. angle of internal friction (øi), stationary angle of friction (øst), isostatic tensile strength of an unconsolidated powder (σ0) along with characteristic pre-consolidation influence (σM,st) and subsequently predicted flow functions (ffc) are compared with those evaluated experimentally. The correlation coefficient values for the comparison are found to be in the range of 0.96-0.99, indicating the satisfactory nature of the above parameters in explaining the flow behavior. Further, compressibility indices and elastic-plastic contact consolidation coefficient (K) characterizing powder cohesiveness are calculated using experimental data.