Oxidation resistance of Zr- and Hf-diboride composites containing SiC in air plasma up to 2600 K for aerospace applications

• Published in: Ceramics international Vol. 48; no. 2; pp. 2177 - 2190
• Main Authors: Pellegrini, C., Balat-Pichelin, M., Rapaud, O., Bêche, E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.01.2022; Elsevier
• Subjects: Air plasma; Engineering Sciences; High temperature; Materials; Oxidation; Reactive fluid environment; SiC; UHTC; Oxidation; Air plasma; High temperature; SiC; UHTC
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2021.09.310

Microstructure-controlled and fully-dense ZrB2 and HfB2 composites were elaborated by Spark Plasma Sintering with two different amounts of SiC (20 and 30 vol%) added to improve their oxidation resistance using optimized sintering parameters. Oxidation of several samples in air plasma conditions, at 1000 Pa total pressure and from 1800 K up to 2600 K, was carried out. The mass variation of samples during oxidation duration of 300 s on a temperature plateau was followed. A four-step oxidation mechanism, identified by four singular mass variation behaviors depending on the oxidation temperature ranges, was proposed and detailed. The total normal emissivity was measured on pre-oxidized samples and high values around 0.90 were obtained from 1300 to 1900 K due to the presence of the oxide layer formed in air plasma conditions and this high emissivity is interesting for aerospace applications. -Oxidation resistance in air plasma conditions were studied for (Zr/Hf)B2–SiC composites from 1800 to 2600 K-Materials characterization (SEM, EDS, XRD and Raman spectroscopy) was carried out to understand the different oxidation mechanisms-Thermodynamical calculations can explain the unique behavior of composites between 2050 and 2250 K-Total spectral emissivity was measured in air at 1000 Pa up to 1900 K and total normal emissivity was calculate