Oxidation of ZrB2/SiC: Comparison of furnace heated coupons and self-heated ribbon specimens

The oxidation of a ZrB-15vol%SiC composite was compared for specimens heated with a conventional furnace to a self-supportive self-heated ribbon specimen resistively heated in a novel table-top apparatus. Cyclic oxidation experiments at 1600°C in ambient air were performed on the ZrB-SiC samples with the two methods. A complex multi-layer oxide scale was observed for both cases. The structure of the oxide scale of the ZrB-SiC sample tested in the table-top apparatus was similar to the oxide scale formed by standard furnace oxidation testing. For both methods the oxide scale consisted of a SiO-rich surface layer and an inner ZrO layer. Additionally, in the self-heated ribbon specimen a SiC-depleted region was observed below the ZrO layer. The thicknesses of the oxide scales were estimated, 27 ?m for the ribbon method and c 30 ?m for the furnace heated. The two different methods give comparable results for the ZrB-15vol%SiC composite. A conclusion can be drawn that the ribbon method is an alternate option to conventional furnace oxidation.