Enhanced oxidation resistance of ZrB2/SiC composite through in situ reaction of gadolinium oxide in patterned surface cavities

Micro-cavities on the surface of dense ZrB2/20 vol.% SiC composites, machined by ultra-fast laser ablation, were filled with Gd2O3 nanopowder and oxidized in static air at 1600 °C. Optimized rectangular pattern of cavities, 10 μm diameter and deep, 20 μm apart conferred improved oxidation resistance compared to the untreated ZrB2/20 vol.% SiC due to the formation of glasses of higher viscosity with lower oxygen diffusivities. Reduction of the oxidized depth was revealed by a significant decrease of 10 μm (60%) in the extent of the protective layer. The filled-cavity strategy leads to better protection against oxygen diffusivity into the composite without altering the bulk properties.