Tunable nanostructures of SiHfBCN hierarchical porous ceramics with high strength and well-defined ductility

Abstract

This paper presents a rapid and versatile fabrication process using the self-assembly of block copolymers to create both SiCN and SiHfBCN hierarchical porous ceramics. The multifarious three-dimensional micellar networks of gels, adjusted through regulating preceramic polymer content, can facilitate the production of nanotemplated preceramic polymers, and tunable nanostructure and porosity. The resulted ceramics feature interconnected nanoscale ceramic pillars. The synergistic effect of the nanostructures with low defect potential and the flexural mechanism of ceramic strut networks with high aspect ratio, endows the SiHfBCN hierarchical porous ceramics with exceptional mechanical properties. These include compressive strength of up to ∼262 MPa, ∼10 % recoverable strain, and high energy absorption (%_P: ∼39 %). Moreover, they demonstrate excellent thermal stability and enhanced compressive strength (up to ∼363 MPa) following annealing at 1200 °C. These remarkable properties make the ceramics ideal for applications requiring high-temperature resistance, thermal insulation, energy absorption, and more, in extreme conditions.