Fabrication and characterisation of a novel biomimetic anisotropic ceramic/polymer-infiltrated composite material

Objective: To fabricate and characterise a novel biomimetic composite material consisting of aligned porous ceramic preforms infiltrated with polymer. Method: Freeze-casting was used to fabricate and control the microstructure and porosity of ceramic preforms, which were subsequently infiltrated with 40–50% by volume UDMA-TEGDMA polymer. The composite materials were then subjected to characterisation, namely density, compression, three-point bend, hardness and fracture toughness testing. Samples were also subjected to scanning electron microscopy and computerised tomography (Micro-CT). Results: Three-dimensional aligned honeycomb-like ceramic structures were produced and full interpenetration of the polymer phase was observed using micro-CT. Depending on the volume fraction of the ceramic preform, the density of the final composite ranged from 2.92 to 3.36 g/cm³, compressive strength ranged from 206.26 to 253.97 MPa, flexural strength from 97.73 to 145.65 MPa, hardness ranged from 1.46 to 1.62 GPa, and fracture toughness from 3.91 to 4.86 MPa m^1/2. Significance: Freeze-casting provides a novel method to engineer composite materials with a unique aligned honeycomb-like interpenetrating structure, consisting of two continuous phases, inorganic and organic. There was a correlation between the ceramic fraction and the subsequent, density, strength, hardness and fracture toughness of the composite material.