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

喷雾干燥的陶瓷、金属或硬金属基颗粒必须满足规定的性能，并应精心设计，以便在粉末加工中进行后续处理和处理。特别是设计良好的机械性能和均匀的内部结构喷雾干燥颗粒是重要的高质量和可靠性的陶瓷零件由陶瓷块材料模压成型。除了复杂的喷雾悬浮特性会影响颗粒结构，从而影响颗粒的力学性能外，这些颗粒的性能也会受到喷雾和干燥参数的影响。在SPP的第二个项目部分，确定了基本配方参数与悬浮性能之间的基本相关性，以及悬浮性能与颗粒结构和力学性能之间的相关性。以往的研究结果表明，有机添加剂的种类和性能对颗粒的内部结构和力学性能有很大的影响。结构的产生取决于这些添加剂的迁移和干燥行为。为了分析这些影响，需要一种合适的方法来定量颗粒结构内添加剂的分布。因此，第三项目部分的一个重要课题将是对先前开发的结构量化方法进行定性。进一步的关键活动是研究颗粒结构对不同喷雾和干燥条件的依赖性。这些研究将基于不同尺寸的实际喷雾干燥机的实验工作以及单液滴的干燥实验。此外，在喷雾干燥机内的在线液滴尺寸测量是有意的。在这些试验中，将分析陶瓷悬浮液滴在考虑不同工艺参数的实际工艺条件下的收缩和干燥行为。最后，将评估所有确定的配方、悬浮性能和工艺参数对内部结构和力学性能的影响。有了这些结果，应该可以为产品设计形成详细的工艺知识，并为SPP内其他小组在喷雾干燥过程中产生的结构建模建立合适的数据。

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.