## 3 Results and Discussion
Previous studies [4; 16] have shown that tape-casting is a colloid process that could leave fewer defects in the green body compared to the conventional dry-press method because the colloid process allows particles to be well-dispersed to avoid agglomerates. Since ceramics are a brittle material that is sensitive to defects, this would improve the strength of the final products. For liquid-phase-sintered SiC, the inter-granular crack deflection was the main toughening mechanism [17; 18]. The phase formed in the grain boundary of the liquid phase sintering SiC (in this study, the phase was YAG) was weaker than SiC, so the cracks tended to propagate along the grain boundary rather than through the grain [15]. Moreover, the residual stress generated by the thermal mismatch of the phase in the grain boundary further weakened the grain boundary, facilitating the inter-granular crack deflection [15; 16]. The crack deflection elongated the cracking path, leading to the high toughness of the liquid phase sintered SiC, compared to that of the solid-state sintered SiC. The degree of the inter-granular fracture reflected the effect of the inter-granular crack deflection. A higher inter-granular fracture indicated a weaker grain boundary, and the liquid phase sintered SiC with a higher degree of the inter-granular fracture tended to have higher toughness but lower strength and lower Vickers hardness, compared to the SiC with a lower degree of the inter-granular fracture [19; 20]. In this study, the laminated SiC showed a low degree of inter-granular fracture, so the strength and Vickers hardness of the pure-matrix sample remained high among the liquid phase sintered SiC (approximately 450-650 MPa in strength and 18-20 GPa in Vickers hardness). The price for the high strength and hardness of the pure-matrix SiC was the reduced toughness. The toughness of the pure-matrix SiC (with 8 wt.% Al\({}_{2}\)O\({}_{3}\)-Y\({}_{2}\)O\({}_{3}\)) was 6.9 MPa\(\cdot\)m\({}^{1/2}\), lower than that of the SiC prepared by [PERSON] [15]. Their SiC with 5-10 wt.% Al\({}_{2}\)O\({}_{3}\)-Y\({}_{2}\)O\({}_{3}\) additives was sintered pressureless but reached a toughness of 7.0-7.5 MPa\(\cdot\)m\({}^{1/2}\). However, the toughness of the pure-matrix SiC was still higher than the SSIC due to the crack deflection effect. The introduction of the interface layer to the laminated ceramics in this study was to promote the energy absorption ability of the material. According to [PERSON]'s study [6], the interface layer with a combination of SiC and BN (approximately 1:1 in weight) would facilitate the crack kinking and delamination cracking in the interface layer during fracturing and the crack would propagate step-like. In this study, the uniform-layered sample (10 matrix layers to 1 interface layer) had improved toughness compared to the pure-matrix sample. A step-like cracking path is observed in Figure 7, showing strong delamination cracking and crack kinking effect. The gradient-layered structure sample, however, did not have this effect and had similar toughness as the pure-matrix sample. The ballistic results are shown in Table 3. In the CA test, all of the samples resisted the shot and were not completely penetrated by the bullets. The B  
Figure 7: Optical image of the side-view of the gradual-layered sample after the three-point-bending test. layered, gradual-layered, pure-matrix, and SSIC samples was 7.2 mm, 5.6 mm, 9.1 mm, and 11.2 mm, respectively. All three types of the laminated SiC had decreased BFS depths compared to the SSIC sample. The BFS depth of the gradual-layered sample after ballistic impact, which was the least in this study, was 50% less than that of the SSIC. In the SA test, all three laminated ceramics resisted three hits and were not completely penetrated, showing good multi-hit resistance. The maximum BFS depth of the uniform-layered sample was 16.4 mm, slightly higher than that of gradual-layered and pure-matrix samples (both were 15.7 mm).