Development of correlations between process operation, granule structure and product properties - Influence of spray- and process parameters on internal structure and mechanical properties of ceramic granules

点击翻译按钮获取中文摘要

Spray dried ceramic, metallic or hard metal based granules have to meet defined properties and should be well designed for subsequent handling and treatment in powder processing. Especially well designed mechanical properties and homogeneous internal structure of spray dried granules are important for a high quality and reliability of ceramic parts formed by die pressing from ceramic bulk material. Besides the influence of complex spraying suspension properties on resulting granule structure and therefore on the mechanical granule properties, these granule properties will be influenced by spraying and drying parameters too. In second project section of SPP basic correlations between essential formulation parameters and suspension properties as well as correlations between suspension properties and resulting structure and mechanical properties of granules were identified. Previous results have shown, that kind and properties of organic additives have a strong influence on internal structure and resulting mechanical properties of granules. Structure generation is depending on migration and drying behavior of these additives. To analyze these effects a suitable method for quantification of additive distribution within the granules structure is necessary. Therefore an important topic in third project section will be the qualification of the previous developed method for structure quantification. Further key activities are investigations in dependence of granule structure on different spraying and drying conditions. These investigations will base on experimental works in real spray dryers of different size as well as drying experiments at single droplets. Furthermore an inline droplet size measurement within a spray dryer is intended. Within these tests shrinking and drying behavior of ceramic suspension droplets will be analyzed under real process conditions in consideration of varied process parameters. Finally all identified effects of formulation, suspension properties and process parameters on internal structure and mechanical properties will be evaluated. With these results it should be possible to form detailed process knowledge for product design as well as a suitable data set up for modeling of structure generation in spray drying process by other groups within SPP.