Professor Eckart Schnack from University of Karlsruhe in Germany recently visited WIT where he gave a lecture on ‘Phase-Field Modelling of the Isothermal Chemical Vapour Infiltration Process of MTS’.
Phase-field modelling is a widely used method to predict phase transition during solidification, where a continuous phase-field parameter is introduced to denote the phase state in the process. It can effectively avoid the discontinuity of the physical parameters and the difficulty in the exact track of the boundary in the sharp interface method. Meanwhile the process of isothermal chemical vapour infiltration (ICVI) is a complex physical-chemical process of the deposition of solid material from the gas phase. In order to optimize the ICVI process, it is crucial to understand and simulate the gas-to-solid phase transformation.
In his lecture, phase-field modelling was developed in the chemical vapour infiltration process of silicon carbide (SiC) from methyltrichlorosilane (MTS). The interface between solid and gas was described as a diffuse interface region with a small height and a continuous phase-field parameter was introduced to describe the state of any point in the region. A set of differential equations was developed based on mechanical and thermodynamic laws and the Landau-Ginzburg type equation for the phase-field parameter was deduced based on the free energy of the diffuse region. The mass transport of the species was modified with the phase-field parameter. Finally, the numerical solution for these highly complex nonlinear systems was given for the space-time dependent problems in the 2D ICVI process.
The lecture generated a lively discussion.
Wessex Institute