Optical Emission Spectroscopy During Plasmatron Testing of ZrB2-SiC Ultrahigh-Temperature Ceramic Composites

Abstract

Optical emission spectroscopy is used to investigate the oxidation of a hot-pressed ZrB 2 -SiC ultrahigh-temperature ceramic composite tested in the 1.2 MW Plasmatron facility at the von Karman Institute for Fluid Dynamics. Time-resolved spectra enable the in situ detection and temporal characterization of electronically excited B, BO, and BO 2 species concentrations directly adjacent to the oxidizing sample surface. The evolution of these boron species correlates well with the transient formation of a complex multilayer oxide scale containing a silica-rich glassy outer layer that limits oxide growth.