• Charpentier, L.
• Balat-Pichelin, Marianne J. H.
• Helber, B.
• Nickel, K.
• Chazot, O.
• Panerai, F.

Abstract

This paper reports the experimental results of oxidation studies for the determination of the transition between passive and active oxidation of two silicon carbide-based materials produced by Herakles-Safran (France) and MT Aerospace (Germany). The transition between active and passive oxidation is determined for both materials using two different plasma facilities-a low enthalpy one and a high enthalpy one-and the experimental results lead to the same transition law. Characterization by SEM of the oxidized samples (surface and cross-section) is shown. Mass loss rates in active oxidation conditions are reported for both Herakles and MT Aerospace materials. Moreover, samples exposed to heat fluxes exceeding 1.2 MW/m 2 and low pressures show a spontaneous jump at surface temperature near 2100 K, rapidly leading to temperatures above 2400 K. Under these conditions, the SiC coating at the sample surface is entirely eroded and the bare carbon fibers of the substrate are left exposed to the incoming flow. The temperature jump phenomenon is described by means of infrared temperature measurements and real time visible recordings of the surface. Space-and time-resolved optical emission spectroscopy and SEM analysis of the samples are used to discuss and explain the chemical processes occurring at the surface.

Topics

• impedance spectroscopy
• surface
• Carbon
• scanning electron microscopy
• carbide
• Silicon