The focus of this study is to establish a characterization method determining the powder flowability in context of tableting. At first, flowability of different materials is measured using the ring shear tester, and its prediction from particle size is established. Next, the model die-filling system is presented which is a modified version of previous studies. Using this system, flowability of different materials is measured at varying die speeds. A new curve fit to assess die fill ratio vs die speed is suggested improving predictability, and a novel flowability metric, "Die Fill Index" (DFI), is derived. The DFI is appropriate to describe flowability for most of the tested materials, and sensitivity of a material with respect to tableting speed. A correlation is generated predicting DFI from particle size. Additionally, it is shown that model die filling is the preferable method to assess flowability for tableting compared to ring shear tester.

No abstract

No abstract

In the sieve section of a paper producing machine, where the formation of paper occurs, a polyethylene sieve is guided over a set of ceramic blades to remove the water in the paper slurry. These sieves are running with velocities of 70 km/h and more. The high velocities lead to defects in the tissue structure of the sieve as well as on the blades. Moreover the presence of high abrasive particles like kaolin and carbonates in the paper slurry as well as its corrosive characteristics enforce the material wear. Present solutions include bulk ceramic blades but they cause defects on the sieves and they are quite expensive. New solutions are desired where these bulk ceramic blades can be replaced by intelligent coating systems that on one hand exhibit an extraordinarily high wear resistance but can minimize the wear of the PE sieve on the other hand. The presentation gives first results obtained by different types of ceramic and cermetic coating systems manufactured by thermal spray technology.