Laminated HfC–SiC ceramics produced by aqueous tape casting and hot pressing

Laminated HfC–SiC ceramics with graphite interlayer were successfully produced by aqueous tape casting, laminating and hot pressing, and the properties of slurries, microstructure and mechanical properties were studied in detail. The tape casting slurries exhibit a typical shear-thinning behavior. The flexural strength of the laminated HfC–SiC/graphite ceramics in perpendicular to the lamination direction slightly decreases compared with that of the monolithic HfC–SiC ceramics because of the presence of the weak graphite interlayer. However, the fracture toughness and work of fracture of the laminated HfC–SiC/graphite ceramics in perpendicular to the lamination direction can reach 9.09±0.51 MPa m1/2 and 1037±86 J/m2, which are approximately 2.2 times and 20.3 times higher than those of the monolithic HfC–SiC ceramics, respectively. The synergy of multiple toughening mechanisms, crack deflection, crack bifurcation, delamination crack and the pull out of the matrix layer leads to fairly high toughness and work of fracture of the laminated HfC–SiC/graphite ceramics.