Details

Autor(en) / Beteiligte

• Alfano, D
• Scatteia, L
• Monteverde, F
• Beche, E
• Balat-Pichelin, M

Titel

Microstructural characterization of ZrB2–SiC based UHTC tested in the MESOX plasma facility

Ist Teil von

• Journal of the European Ceramic Society, 2010-08, Vol.30 (11), p.2345-2355

Ort / Verlag

Elsevier

Erscheinungsjahr

2010

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The microstructures of ZrB2-SiC and ZrB2-HfB2-SiC ultra high temperature ceramics, subjected to a high temperature plasma environment, were investigated. Both materials were tested in the MESOX facility to determine the recombination coefficient for atomic oxygen up to 1750 C in subsonic air plasma flow. Surfaces were analysed before and after testing to gain a deeper insight of the surface catalytic properties of these materials. Microstructural analyses highlighted oxidation induced surface modification. The oxide layers were composed of silica with trace amounts of boron oxide and zirconia if the maximum temperature was < about 1550 C and zirconia for higher temperatures. The differences in the oxide layer composition accounted for the different catalytic behaviour. The presence of a borosilicate glass layer on the surface of the ZrB2-SiC materials guaranteed atomic oxygen recombination coefficients that were lower than the coefficients measured when only zirconia was present. The oxidation processes of ZrB2-HfB2-SiC materials, associated with catalytic tests carried out up to 1550 C, led to the formation of hafnia and silica, and zirconia. The higher recombination coefficients measured in the case of ZrB2-HfB2-SiC materials were correlated with the presence of hafnia which was characterised by a higher catalytic activity compared to zirconia. The investigated materials demonstrated a low catalytic activity over the inspected temperature range with maximum values of recombination coefficients close to 0.1.