Mullite Coatings on SiC and C/C–Si–SiC Substrates Characterized by Infrared Spectroscopy

Abstract

Mullite (3Al2O3·2SiO2) coatings on SiC substrates and SiC precoated carbon/carbon composite (C/C‐Si‐SiC) substrates were produced by pulsed laser deposition (PLD) using pressed mullite powder targets. The layers can be characterized efficiently by IR reflection spectroscopy in the spectral range between 650 and 5000 cm−1. The deposited coatings turn into mullite upon oxidation in air at temperatures between 1400° and 1600°C. Fabry‐Perot interferences indicate a high quality and homogeneity of the mullite coating/SiC substrate interface. Amorphous SiO2 gradually forms during prolonged heating or at higher temperatures.