Ablation behavior of laminated Graphite/ZrB 2 -SiC ceramics in two different directions

Laminated Graphite/ZrB2-SiC ceramics were fabricated by tape casting and hot pressing. The ablation properties of the ceramics in the parallel and the perpendicular directions were studied using an oxyacetylene torch. The mass ablation rates were 8.1 ± 0.4 mg/s in the parallel direction and 0.2 ± 0.1 mg/s in the perpendicular direction. The linear ablation rates were 3.1 ± 0.2 µm/s in the parallel direction and 1.2 ± 0.1 µm/s in the perpendicular direction. Thus, the ablation resistance of the laminated Graphite/ZrB2-SiC ceramics in the perpendicular direction was higher than that in the parallel direction. This anisotropy was mainly attributed to the lower surface temperature in the perpendicular direction resulted from higher thermal conductivity, as well as the orientation of the weak graphite interface layer perpendicular to the ablation surface.