Abstract
Non-isothermal, isothermal and cyclic oxidation behavior of hot pressed ZrB 2–20 (vol.%) SiC (ZS) and HfB 2–20 SiC (HS) composites have been compared. Studies involving heating in thermogravimetric analyzer have shown sharp mass increases at 740 and 1180 °C for ZS, and mass gain till 1100 °C followed by loss for HS. Isothermal oxidation tests for 1, 24 and 100 h durations at 1200 or 1300 °C have shown formation of partially and completely stable oxide scales after ∼24 h exposure for ZS and HS, respectively. X-ray diffraction, scanning electron microscopy and energy or wavelength dispersive spectroscopy has confirmed presence of ZrO 2 or HfO 2 in oxide scales of ZS or HS, respectively, besides B 2O 3–SiO 2. Degradation appears more severe in isothermally oxidized ZS due to phase transformations in ZrO 2; and is worse in HS on cyclic oxidation at 1300 °C with air cooling, because of higher thermal residual stresses in its oxide scale.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
