Durch Benetzbarkeit und Kapillarität getriebene Kornumwandlungsvorgänge und Mikrostrukturentwicklung in Flüssigphasensintern: Effekte der Löslichkeit und der Korngröße

• Antragsteller: Professor Dr. Fathollah Varnik
• Fachliche Zuordnung: Thermodynamik und Kinetik sowie Eigenschaften der Phasen und Gefüge von Werkstoffen ; Glas und Keramik und darauf basierende Verbundwerkstoffe
• Förderung: Förderung von 2015 bis 2019
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 273088361

• Erstellungsjahr: 2020

Zusammenfassung der Projektergebnisse

The main achievements of the project are listed below. • A model was developed to predict the morphology of liquid bridges connecting two spherical solid grains. The theory is shown to be qualitatively in line with simulation results for various liquid volume fractions and contact angles. • It has been shown that curvature-induced stresses enhance the initial sintering stage (solid-solid contact) for sub-micrometer grain sizes. The effect becomes stronger for smaller grains. • The role of coalescence phenomenon and the ways to control it have been elucidated. • Basic questions regarding the coupling between fluid flow and phase field dynamics have been addressed from a theoretical perspective. • Morphology of multiple grain structures has been investigated via numerical simulations after a thorough validation of the model. • The model has been applied to a soft-hard powder mixture using cobalt-tungsten showing that it is capable of predicting porous microstructures for different initial particle configuration. • All the new routines developed during this project are implemented in OpenPhase-software package and is made publicly available. The established work and the developed simulation package can serve as a starting point for future studies of liquid phase sintering with focus on effects arising from properties of individual powder components, their mass ratio, size distribution and variation of process parameters.

Projektbezogene Publikationen (Auswahl)

• "Multi-phase-field method for surface tension induced elasticity", Phys. Rev. B 97, 035410 (2018)
  R. Schiedung, I. Steinbach, F. Varnik
  
• "Controlling bubble coalescence in metallic foams: A simple phase fieldbased approach", Computational Materials Science 173, 109437 (2020)
  S. Vakili, I. Steinbach, F. Varnik
  
• "Diffuse interface models of solidification with convection: The choice of a finite interface thickness", Eur. Phys. J. Special Topics 229, 447 (2020)
  A. Subhedar, P. Galenko, F. Varnik
  
• "Simulation of Capillary-Driven Kinetics with Multi-Phase- Field and Lattice-Boltzmann Method", Modelling Simul. Mater. Sci. Eng. 28, 065008 (2020)
  R. Schiedung, M. Tegeler, D. Medvedev, F. Varnik
  
• "Thin interface limit of the double sided phase field model with convection", Philosophical Transactions A 378, 20190540 (2020)
  A. Subhedar, P. Galenko, F. Varnik