Short-term oxidation of a ternary composite in the system AlN–SiC–ZrB2

Oxidation of ZrB2 powder in the temperature range of 650–800°C

“…This deduction can be also supported by the study on oxidation of AlN-SiC-ZrB 2 composites reported by Brach et al [14]. In the range 700-900 • C, Brach et al [14] indicated the oxidation of AlN-SiC-ZrB 2 composites followed mixed para-linear kinetics, where the linear term was negative, accounting for mass loss due to vaporization of B 2 O 3 . Fig.…”

Effect of AlN Substitutions on the Oxidation Behavior of ZrB2–SiC Composites at 1600°C

“…Clearly, higher levels of AlN do not provide adequate oxidation protection at elevated temperatures. The composites studied by Brach et al had even higher AlN content (~55 vol%) and failed at even lower temperatures (~1300°C). However, the failure mode in their study was different, involving rupturing of the external scale, due to the formation of aluminoborates, which was not observed in this study due to the relatively low Al 2 O 3 content.…”

“…In addition to its potency as a sintering aid, our recent efforts indicated that AlN substitutions affect the oxidation behavior of ZrB 2 –SiC composites . Brach et al have studied the oxidation resistance of AlN–ZrB 2 –SiC composites containing up to 55 vol% AlN . They found that the external layer of the scale ruptures easily at higher temperatures and recommended using the material under 1100°C.…”

“…25 Brach et al have studied the oxidation resistance of AlN-ZrB 2 -SiC composites containing up to 55 vol% AlN. 36 They found that the external layer of the scale ruptures easily at higher temperatures and recommended using the material under 1100°C. While the oxidation resistance of ZrB 2 -SiC composites has been extensively studied over a range of temperatures, the oxidation behavior of ZrB 2 -SiC composites with small amounts of AlN substitutions has not been studied systematically.…”

The effect of a graphite addition on oxidation of ZrB2–SiC in air at 1500°C

“…14-17 When exposed to air, ZrB 2 undergoes stoichiometric oxidation to form crystalline ZrO 2 and B 2 O 3 (l). 18,19 The B 2 O 3 (l) is an effective barrier to the transport of oxygen, leading to passive oxidation behavior with parabolic mass gain kinetics. 16 Rapid evaporation of B 2 O 3 (l) at temperatures above 1100 • C reduces the effectiveness of the diffusion barrier because the ZrO 2 that is left behind has a porous structure and does not protect the underlying ZrB 2 from further oxidation.…”