Ablation mechanism and properties of in-situ SiAlON reinforced BN–SiO2 ceramic composite under an oxyacetylene torch environment

Principles, design, structure and properties of ceramics for microwave absorption or transmission at high-temperatures

“…The ε and tan δ of hot-pressed BN-SiO 2 -Sialon composites both increased with temperature in X band (8.2-12.4 GHz) and Ku band (12-18 GHz). The ε ranged from 4.3 to 5.8, and tan δ increased by an order of magnitude when the test temperature raised from RT to 1200°C [29]. Hot-pressed SiO 2 with 5 wt-% BN nanotubes showed a low ε of 4 [32].…”

“…For MAS coating prepared at 1100°C/3 h, BN-Si 2 N 2 O porous ceramics with various coating thickness of 91-285 μm presented ε of 4.0-4.7 and tan δ of 5.5 × 10 −3 -11.6 × 10 −3 . Unfortunately, the tan δ of the as-sintered various MAS coated BN-Si 2 N 2 O porous ceramics decreased rapidly as the testing frequency raised (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) [32].…”

“…The conventional ceramic materials, such as SiO 2 [24], Si 3 N 4 [25], BN [26], Si 3 N 4 -SiO 2 [27], Si 3 N 4 -BN [28], SiO 2 -BN [29] and Si 3 N 4 -SiO 2 -BN [30], are widely investigated as electromagnetic transparent materials for high-temperature applications in microwave transparent reaction chamber, radome and antenna window due to their low density, high thermo-chemical stability and good thermomechanical properties with respect to creep, oxidation, thermal shock and ablation resistance. However, the mechanical strength and oxidation resistance of these ceramics degrade gradually in air beyond 1500°C due to the softening of protective SiO 2 oxide scale.…”