Surface growth for molten silicon infiltration into carbon millimeter-sized channels: Lattice–Boltzmann simulations, experiments and models

Abstract

The process of liquid silicon infiltration is investigated for channels with radii from 0.25 to 0.75 [mm] drilled in compact carbon preforms. The advantage of this setup is that the study of the phenomenon results to be simplified. For comparison purposes, attempts are made in order to work out a framework for evaluating the accuracy of simulations. The approach relies on dimensionless numbers involving the properties of the surface reaction. It turns out that complex hydrodynamic behavior derived from second Newton law can be made consistent with Lattice-Boltzmann simulations. The experiments give clear evidence that the growth of silicon carbide proceeds in two different stages and basic mechanisms are highlighted. Lattice-Boltzmann simulations prove to be an effective tool for the description of the growing phase. Namely, essential experimental constraints can be implemented. As a result, the existing models are useful to gain more insight on the process of reactive infiltration into porous media in the first stage of penetration, i.e. up to pore closure because of surface growth. A way allowing to implement the resistance from chemical reaction in Darcy law is also proposed.

Microwave heating controlled reactive melt infiltration for graphite‐Si‐SiC ceramics manufacturing

“…Reactive melt infiltration of Si‐C systems is a very complex process which involves many interacting physical mechanisms, including phase transition, reactions, temperature changes, and geometry modifications . The process can be described through the following sequence of steps: the preform and the silicon are heated by an external source, silicon melts and evaporates, silicon vapor reacts with the graphite surface forming a precursor solid layer of SiC and the liquid silicon starts to infiltrate.…”

Vapor‐mediated melt infiltration for synthesizing SiC composite matrices

“…The preceding mechanism is at variance with that previously reported for reaction of bulk Si liquid with solid or porous C, which broadly involves dissolution of the C into the Si and precipitation of SiC 15–18 . In one proposed variant, a thin layer of porous SiC first forms on the C surface; the melt then dissolves the C beneath the SiC and additional SiC is precipitated on the existing surface 17,19 . Once the pores are sealed, the reaction rate is controlled by solid‐state diffusion through the original layer.…”

New advanced SiC-based composite materials for use in highly oxidizing environments: Synthesis of SiC/IrSi3

“…As reported by [53], the infiltration kinetics can be analyzed by following the evolution of the height of infiltration (h inf) (i.e. infiltration depth), usually described by linear, parabolic or other laws [54,55]. It is possible to calculate h inf by assuming that a spherical cap geometry of the molten drop is preserved during infiltration process.…”