Research Project 5
Kinetics of Structure Formation of Complex Nanoparticles in Model Flowreactors
Nanoparticles can show a complex structure, such score-shell or structured aggregates, which allows to realize novel material properties and joint properties. The fundamental processes during particle formation and agglomeration can oft difficult be interpreted, as the nanoparticles in the aerosol to be investigated are rather different in their size, form and agglomerate structure and their interaction as well as the coating and sintering processes strongly depend on these properties. At the same time, it is a great challenge to monitor the resulting changes and processes in an unambiguous way.
This project aims at an investigation of these fundamental properties in a better defined manner, by providing aerosols in form of well-defined core-particles, spherical or aggregated, by means of size-fractionation and in-flight sintering. Then a thermal restructuring is initiated in a flow reactor, this can be sintering process increasing the primary particle size or a coating process. Applying online measurement techniques such as SMPS, CPMA, DAPS und ELPI the resulting changes are analyzed as function of the reaction conditions and materials system, and the processes are analyzed with help of models. This technique is modified and adopted to low-pressure reactors, to clarify the particle structure as function of the reaction conditions. Conventional particle dynamical models are not able to described the formed structures, as they describe only the particle volume and not structure or composition. For that reason, Monte-Carlo simulation techniques are being applied, which allow to described multivariate properties of particles and aggregates of particles.
Goal of this project is to clarify, to quantify and to model the processes taking place during the structuring of complex particle systems in the gas phase. Materials will be investigated which have relevance for TP3 and TP4: Fe and Si particles and their oxidation products.