Numerical study for the percolation threshold and transport properties of porous composites comprising non-centrosymmetrical superovoidal pores

Abstract

The aggressive media can be transported into the composite through the connected pores, which will damage the microstructure and then lead to a subsequent reduction in the strength and serviceability of composite. In the statistical physics, the continuum percolation model is usually used to study the system-spanning connectivity in the porous composite. It is widely believed that the dimensionless excluded volume Vdex of discrete pore is of great importance in the evaluation of the global percolation threshold ϕc of porous network. The porous networks of composites are normally composed of overlapping symmetrical spheres. However, the actual shape of pores in composite is asymmetrical. In this work, the dimensionless Vdex of discrete superovoidal pores are theoretically and numerically calculated. Then, the quantitative relationship between components (pore shape) and microstructures (global percolation threshold ϕc) of porous networks comprising superovoids is established by a dimensionless excluded volume based empirical approximation. It is observed that the porous composites comprising symmetrical pores are more difficult to form the system-spanning connected porous path than the composites consisting of non-centrosymmetrical pores. Moreover, the transport properties of composites considering their microstructures (i.e., the thresholds ϕc) are theoretically predicted by the continuum percolation-based generalized effective medium theory (CP-GEMT) and the theoretical values are validated by comparing with the experimental results.