Enhanced mechanical and thermal properties in 3D printed Al2O3 lattice/ epoxy interpenetrating phase composites

Interpenetrating phase composites (IPCs) with 3D printed alumina microlattices infiltrated with epoxy have been fabricated. Mechanical analysis shows that the IPCs under quasi-static compression generally exhibit fracture behaviour similar to that of their ceramic-lattice constituent but in a gradual manner. The IPCs with Simple Cubic lattices initiate the fractures at the struts in the outer lattice planes, while IPCs with Octet Truss and Kelvin Cell lattices tend to fracture at their (110) or (111) planes. The compressive strength and energy absorption of IPCs follow the order of Simple Cubic > Kelvin Cells > Octet Truss when the ceramic volume fraction is 0.3. The IPCs display compressive strengths up to 120% higher and energy absorption 100% greater than the iso-strain combined properties of the lattice and epoxy. The factors governing the fracture behaviour and the strengthening and energy absorption mechanisms are thoroughly discussed. Furthermore, the IPCs show much better retention of mechanical strength and dimensional stability at elevated temperatures compared with many commonly used particle or fiber-reinforced epoxy matrix composites.