EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The oxidation performance of ZrB2-SiC composites with addition of YB4 or Y2O3 was studied in static oxidation conditions up to 1650°C as well as under dynamic conditions of oxyacetylene torch facility. Ablation tests were performed at temperatures above 2000°C. The oxidation tests revealed quite different behaviour of materials tested under static and dynamic conditions. Static oxidation conditions led to the formation of a typical layered structure of ZrB2-SiC composite with protective silica layer on the surface. The addition of YB4 and Y2O3 resulted in inferior oxidation resistance due to the spallation and deeper degradation, especially at higher oxidation temperatures. However, the analysis of studied composites oxidized using oxyacetylene torch showed, that silica is not anymore present on the surface and the protective function was taken over by outer zirconia layer. Although the YB4 as well as Y2O3 did not improve the oxidation resistance during oxidation in static air, the performance during oxidation in dynamic conditions indicates different results. During ablation at 2000°C, a dense cubic solid solution of ZrxY1-xO1.5+x/2 was formed as the main oxidation product. This compound is very promising to protect the material at even higher temperatures when zirconia already evaporates.