Experiment and simulation analysis on thermal shock resistance of laminated ceramics with graphite and boron nitride interfaces

Laminated ZrB2?SiC ceramics with graphite and BN as the interface layers were fabricated by tape casting and consequent hot pressing. The influences of interface materials on the thermal shock resistance of the laminated ceramics were studied by both experimental and theoretical analyses. Experimental results show that the critical temperature differences of G/LZS (laminated ZrB2?SiC/G) and BN/LZS (laminated ZrB2?SiC/BN) were 237 and 99 ?C, respectively. The stress gradients of G/LZS and BN/LZS calculated via finite element analysis were 709 and 809 MPa/mm, respectively. Thus, the thermal shock resistance of G/LZS was higher than that of BN/LZS. Such merits of G/LZS can be explained by the following two reasons: one is the thermal conductivity of the graphite interface layer was higher than that of the BN interface layer; the other is the difference of the thermal expansion coefficient for the graphite interface layer and the matrix layer was lower than that for the BN interface layer and the matrix layer.

Automated summary

Experimental and theoretical analyses showed that the graphite interface layer had a greater impact on the thermal shock resistance of laminated ZrB2-SiC ceramics, mainly due to its higher thermal conductivity and smaller difference in thermal expansion coefficient.