Selective active oxidation in HAFNIUM BORIDE (cas 12007-23-7)-silicon carbide composites above 2000 °C

Add time:07/30/2019    Source:sciencedirect.com

The oxidation behavior of an ultra-high temperature ceramic (UHTC) based on HfB2 with 20vol% SiC and was studied following two 10 min arc-jet test cycles with nominal heat flux of 350 W cm−2, stagnation pressure of 7 kPa, and a sustained peak surface temperature of 2360 °C. Microstructure characterization revealed a modified, layered structure comprising ∼390 μm of porous HfO2 at the surface and an underlying ∼740 μm porous region containing un-oxidized HfB2 over the bulk UHTC, unaffected below the oxidation front. The SiC presumably undergoes active oxidation, as commonly reported for temperatures above ∼1600 ± 100 °C. However, unlike typical of exposures below ∼2000 °C no molten silicate phase was present at the surface to mediate the exchange of oxidant and gaseous reaction products. Additionally, a HfC impurity phase oxidizes concurrently with SiC rather than HfB2. A thermodynamic analysis is provided to explain the observed behavior and the differences with lower temperature scenarios in the literature.

We also recommend Trading Suppliers and Manufacturers of HAFNIUM BORIDE (cas 12007-23-7). Pls Click Website Link as below: cas 12007-23-7 suppliers

Prev:Insight into the elastic, electronic properties, anisotropy in elasticity of Manganese Borides
Next:Development of Refractory and Rare Earth Metal Borides & Carbides for High Temperature Applications)