Volatility diagram of ZrB₂‐SiC‐ZrC system and experimental validation

Abstract

A volatility diagram of zirconium carbide (ZrC) at 1600, 1930, and 2200°C was calculated in this work. Combining it with the existing volatility diagrams of ZrB 2 and SiC, the volatility diagram of a ternary ZrB 2 -SiC-ZrC (ZSZ) system was constructed in order to interpret the oxidation behavior of ZSZ ceramics. Applying this diagram, the formation of ZrC-corroded and SiC-depleted layers and the oxidation sequence of each component in ZSZ during oxidation and ablation could be well understood. Most of the predictions from the diagrams are consistent with the experimental observations on the oxidation scale of dense ZrB 2 -SiC-ZrC ceramics/coatings after oxidation at 1600°C or ablation at 1930 and 2200°C. The reasons for the discrepancy are also briefly discussed. K E Y W O R D S microstructure, oxidation, volatility diagrams, ZrB 2 -SiC-ZrC

New insight into the formation and oxygen barrier mechanism of carbonaceous oxide interlayer in a multicomponent carbide

“…Returning to the diffusion barrier nature of the carbonaceous oxide interlayer, the as‐formed carbon may particularly be associated with the oxygen barrier effect. To deepen the understanding of the as‐formed carbon, volatility diagrams of HfC, ZrC and TiC were constructed here according to the reported method 27,39‐41 . As a valuable tool for oxidation behavior study, volatility diagram shows the thermodynamically predicted stable solid phase, the concomitant gaseous species, and their vapor pressures at different oxygen partial pressures and temperatures 40 .…”

“…To deepen the understanding of the as-formed carbon, volatility diagrams of HfC, ZrC and TiC were constructed here according to the reported method. 27,[39][40][41] As a valuable tool for oxidation behavior study, volatility diagram shows the thermodynamically predicted stable solid phase, the concomitant gaseous species, and their vapor pressures at different oxygen partial pressures and temperatures. 40 However, these diagrams are isothermal plots, 40 as in the case of the underlying interface, aforementioned temperature gradient across the oxide layer need to be taken into account.…”

ИЗУЧЕНИЕ СТРУКТУРЫ ПОЛИФАЗНЫХ КЕРАМИЧЕСКИХ КОМПОЗИТАХ ZrB2-ZrC-SiC-BN-CNT

“…Следует ожидать, что синергетическое действие механизмов увеличения ударной вязкости, реализующихся на разных структурных уровнях, обеспечит нивелирование присущей керамическим материалам имманентной хрупкости. [5][6] Цель исследований в рамках данной работы -изучение структуры полифазных керамических композитах ZrB 2 -ZrC-SiC-BN-CNT.…”

Zirconium-Doped Hybrid Composite Systems for Ultrahigh-Temperature Oxidation Applications: A Review

“…An experimental result was presented by Li et al, where SiC and nanocarbon tubes had been used to form a protective cost over ZrB 2 during oxidation delaying oxidative decomposition of ZrB 2 into zirconia and boria. It is inferred from the values of vapor pressures that the important eventthe evaporation of boriaoccurs at a temperature 1000 °C higher for HfB 2 when compared to ZrB 2 . , .In addition, Zou et al, have made a detailed study on the oxidative behavior of a ternary system of ZrB 2 –SiC–ZrC, where, at an oxidative temperature of 1930 °C, the domination of gaseous species of boron oxides vary with the partial pressure of oxygen, i.e., partial pressure of oxygen ( P (O 2 )) of 10 –8 Pa. Oxidation of the system inversely varies with P (O 2 ) up to 10 –6 Pa. ZrC was the first to oxidize, followed by SiC enveloping ZrB 2 and ZrO 2 . Upon further increasing the P (O 2 ), exceeding 10 –6 Pa SiC was passively oxidized, which is characteristic to SiC, but finally the SiO 2 ( l ) formed from the oxidation of SiC was driven off due to its vulnerability to fluid dynamics at high temperature, leading to the onset of ZrB 2 depletion.…”