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 m edium pressure (<35 MPa) flexible boundary cubical triaxial tester (CTT). T he two test powders were: (1) a silicon nitride-based ceramic powder (KY 35 00(1)), and (2) a microcrystalline cellulose-based pharmaceutical powder (A vicel PH 102(2)). The fundamental stress-strain engineering parameters of t he powders (such as bulk modulus, shear modulus, compression index and swel ling index) were determined for each of the three deposition methods at dif ferent isotropic pressure values. Analysis of CTT test results showed that deposition methods significantly affected (p<0.05) certain elastic and plas tic 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 depos ition methods (p<0.05). However, the bulk modulus and swelling (i.e., recov ery) index values of KY 3500 were insensitive (p>0.05) to deposition method s. In case of MCC powder, it was observed that all the four engineering par ameters were sensitive to deposition methods (p<0.05). Overall, in 11 out o f 24 cases, very good correlations (R-2>0.90) were observed between the pow der's materials parameters and mean pressure of compaction for both the pow ders.