Oxidation-resistant ZrB2-SiC composites at 2200 °C

Oxidation resistance tests were carried out on hot-pressed Zi-B-2-20 vol%SiC using an oxyacetylene torch. The temperature of the oxidized specimens exceeded 2200 degrees C. The mass and linear oxidation rates of the ZrB2-20 vol%SiC composites for 10 min were -0.23 mg/s and 0.66 mu m/s, respectively. The surface layer appeared dense and adherent with the exception of a few burst bubbles and craterlets. No macro-cracks or spallation were detected after oxidation, suggesting that these composites possess a super oxidation resistance. The microstructure of the surface and cross-section of the oxidized specimens were studied by scanning electron microscopy along with energy dispersive spectrometry and X-ray diffraction. The oxidation mechanism was also discussed. (c) 2007 Elsevier Ltd. All rights reserved.