Invasion percolation model of co-interpenetrating ceramic-metal composites

Abstract

An invasion percolation model for simulating the reactive metal infiltration of porous ceramics to form a co-interpenetrating composite is presented. By combining the pore-level dynamics of percolation models with kinetic Monte Carlo phase transformation methods, two thermodynamic driving forces for infiltration are simulated: the applied pressure and the chemical reaction at the ceramic/metal interface. In doing so the model describes both the capillary fingering effects that dominate at high pressures and the evolution of reaction byproduct phases that may cause pore space closure at high temperature. At very high temperature and/or low pressure, a `core-shell' morphology forms. Fingerwidth and pore cluster probabilities are computed to serve as a means for quantifying microstructures. It is demonstrated that the adjustable parameters favourable for the formation of the most highly interconnected composites are high phase transformation rate, low to intermediate invasion pressure, low initial transformation contact angle (low temperature), low kinetic growth rate constant, and low initial matrix porosity. The optimal combinations relating to expected mechanical strength of the composite are presented in the form of Weibull survival probability plots and process maps.