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

The oxidation of a ZrB2-15vol%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 1600ºC in ambient air were performed on the ZrB2-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 ZrB2-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 SiO2-rich surface layer and an inner ZrO2 layer. Additionally, in the self-heated ribbon specimen a SiC-depleted region was observed below the ZrO2 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 ZrB2-15vol%SiC composite. A conclusion can be drawn that the ribbon method is an alternate option to conventional furnace oxidation.