High toughness and R-curve behaviour of laminated SiC/graphite ceramics

Abstract Bionic laminated SiC/graphite ceramics were fabricated by tape casting. The mechanical properties and R-curve behaviour of the laminated SiC/graphite ceramics were evaluated and compared with those of monolithic SiC ceramics. The toughness of the laminated SiC/graphite ceramics was 9.48 MPa m1/2, which was 3 times that of the monolithic SiC ceramics (3.56 MPa m1/2). The improvement in the toughness was mainly due to the deflection of the crack at the graphite interface layer and the pull-out of the graphite sheet, which consumed a lot of fracture work. In addition, the laminated SiC/graphite ceramics exhibited rising R-curve behaviour. The excellent damage resistance of the laminated SiC/graphite ceramics was attributed to the indentation surface collapse caused by the porous structure of the graphite interface layer, which consumed quite a large amount energy and reduced the formation of microcracks. Meanwhile, the step-like fracture mode prolonged the crack propagation path and avoided catastrophic damage.