Correlations between powder deposition methods and green compact quality: Part i mechanical properties of powders

Influence of three different deposition methods (namely, feed shoe, funnel and rainy) on the compression response of two powders was studied using a medium pressure (<35 MPa) flexible boundary cubical triaxial tester (CTT). The two test powders were: (I) a silicon nitride-based ceramic powder (KY 3500¹), and (2) a microcrystalline cellulose-based pharmaceutical powder (Avicel PH 102²), The fundamental stress-strain engineering parameters of the powders (such as bulk modulus, shear modulus, compression index and swelling index) were determined for each of the three deposition methods at different isotropic pressure values. Analysis of CTT test results showed that deposition methods significantly affected (p<0.05) certain elastic and plastic parameters of the two powders. In case of KY 3500 powder, it was found that the shear modulus and compression index values were sensitive to deposition methods (p<0.05). However, the bulk modulus and swelling (i.e., recovery) index values of KY 3500 were insensitive (p>0.05) to deposition methods, In case of MCC powder, it was observed that all the four engineering parameters were sensitive to deposition methods (p<0.05). Overall, in 11 out of 24 cases, very good correlations (R²>0.90) were observed between the powder’s materials parameters and mean pressure of compaction for both the powders.