Efficient Multiscale Strategy for Toughening HfB2 Ceramics: A Heterogeneous Ceramic–metal Layered Architecture

A multiscale structural design was innovatively adopted herein to increase the toughness of monolithic HfB2 ceramics. SiC whiskers (SiCw) and graphene oxide (GO) were used as fillers for the HfB2 matrix, whereas a ductile W foil was introduced as an interlayer to synthesize laminated HfB2-SiCw-rGO/W ceramics. Monolithic HfB2-SiCp (particulate) and laminated HfB2-SiCp/W ceramics were prepared using the same routes and used as controls. Following tape casting and spark plasma sintering at 1800 degrees C, the toughness of the prepared laminated HfB2-SiCw-rGO/W samples was increased to 14.2 +/- 0.6 MPa center dot m(1/2), with minimal sacrifice in flexural strength (421 +/- 16 MPa). Morphological analysis of the fracture surface revealed the synergistic effects of micro-toughening (including bridging and pullout of whiskers and rGO) and macro-toughening (including crack deflection, bifurcation, and delamination) mechanisms responsible for improving the fracture toughness of the laminated HfB2-SiCw-rGO/W composites.