Toughening of laminated ZrB2–SiC ceramics with residual surface compression

Laminated ZrB2–SiC ceramics with residual surface compression were prepared by stacking layers with different SiC contents. The maximum apparent fracture toughness of these laminated ZrB2–SiC ceramics was 10.4 MPam1/2, which was much higher than that of monolithic ZrB2–SiC ceramics. The theoretical predictions showed that the apparent fracture toughness was strongly dependent on the position of the notch tip, which was confirmed by the SENB tests. Moreover, laminated ceramics showed a higher fracture load when the notch tip located in the compressive layer, whereas showed a lower fracture load as the notch tip within the tensile layer. The toughening effect of residual compressive stresses was verified by the appearance of crack deflection and pop-in event. The influence of geometrical parameters on the apparent fracture toughness and residual stresses was analyzed. The results of theoretical calculation indicated that the highest residual compressive stress did not correspond to the highest apparent fracture toughness.

► Laminated ZrB2–SiC ceramics with residual surface compression were prepared. The distribution of the residual stresses in the laminated ZrB2–SiC ceramics was firstly investigated according to lamination theory.
► The influence of geometrical parameters on apparent toughness and residual stresses was firstly analyzed.
► Crack propagation and toughening mechanism of the laminated ceramics were investigated. The residual compressive stresses weaken the crack propagation driving force and enhance the crack growth resistance, which leaded to crack deflection.