Self passivating behavior of multilayer SiC under simulated atmospheric re-entry conditions

Oxidation behavior of ZrB2/SiC laminates: Effect of composition on microstructure and mechanical strength

“…The TGA results confirmed the detrimental effect of ZrB 2 on the oxidation resistance at temperatures up to 1600 • C. According to the reaction Eqs. (1) and (2), the oxidation of SiC to silica entails 49.8% weight increase while oxidation of ZrB 2 to zirconia and boria results in 70.9% weight increase, but this last weight increase becomes 9.2% only if boria evaporates. The TGA results showed that the weight gain of the samples dramatically increases with the increase of the ZrB 2 percentage in the specimen in spite of boria evaporation.…”

“…: +39 0110904708. re-entry conditions (oxygen partial pressure decreasing down to few mbar and temperature increasing up to 1550 • C during each test) indicated that the passive mechanism of SiC oxidation prevails over the active one since ceramic laminates made of pure SiC layers survived 100 re-entry cycles and the passive silica layer still covered the specimen surface at the end of the ground experiment. 1,2 On the other hand the sharp profiles of space vehicles and hypersonic aircraft demand materials able to sustain temperatures even exceeding the decomposition temperature of SiC as well as the melting temperature of cristobalite (1725 • C) which, after melting, evaporates.…”

“…23 Oxidation behavior of ZrB 2 and some ZrB 2 /SiC composites (containing from 10 to 30 vol.% of SiC) has been well investigated in the temperature range from 800 to 2000 • C 5,6,[9][10][11][12][13][14][15][16]18,19,21 and recently well reviewed by Fahrenholtz and Hilmas. 20 Pure ZrB 2 undergoes oxidation starting from 800 • C according to the reaction: ZrB 2(s) + 5/2O 2(g) ↔ ZrO 2(s) + B 2 O 3(s,l) (1) The liquid layer of B 2 O 3 grants protection from oxidation up to 1100-1200 • C. Above 1200 • C the volatilization of B 2 O 3 , which exposes the underlying porous ZrO 2 scale, dramatically worsens the oxidation resistance of ZrB 2 . 16,17,20 The addition of SiC particles to a ZrB 2 matrix greatly improves oxidation behavior at high temperatures since it changes the oxide scale microstructure.…”

Thermophysical Properties of Short Carbon Fiber/SiC Multilayer Composites Prepared by Tape Casting and Pressureless Sintering

“…Therefore, this kind of composite layers could be integrated into a multilayer thermal protection system . The outer dense SiC layers are expected to grant excellent oxidation resistance and fairly good heat conductivity in the plane . The C sf /SiC composite layers in the middle of the multilayer architecture could also grant acceptable thermal conductivity in plane and provide decreased thermal conductivity through the TPS thickness.…”

“…Processing ceramics with a multilayer structure is another effective method to improve toughness . SiC multilayer with self‐passivating behavior has been proposed as an oxidation‐resistant component of TPS . Meanwhile, besides the mechanical and oxidation properties, thermal properties, especially thermal conductivity property, are very fundamental for application in thermal protection system .…”