Effect of bimodal microstructure on high-temperature properties of nano-reinforced Al2O3-MgO-C refractories

The beneficial effects of adding nanostructured expandable graphite (EG) hybridized yttrium aluminium garnet (EG\YAG) powder as a composite reinforcement in improving the oxidation resistance, hot-strength, and microstructure development in Al2O3-MgO-C refractories were studied. The refractory components reinforced with EG\YAG exhibited more than 60% of oxidation resistance enhancement and as high as 200% increase in hot-strength performance over the standard refractories, formulated without EG\YAG. Correlating the damage parameter (DE) calculations based on ultrasonic measurements with residual strength data (Rc, Rb) showed that there was a progressive increase in Rc and Rb values with consistent reduction in the oxidative damage of EG \YAG reinforced refractories. Analysis indicated that these beneficial features were majorly ascribed to the in -situ development of bimodal microstructure with EG\YAG sintered framework throughout the refractory inte-rior in these new class of reinforced systems. Additionally, the mechanism of toughening and implications of these results to materials design are discussed.

Automated summary

The beneficial effects of adding nanostructured expandable graphite (EG) hybridized yttrium aluminium garnet (EG\YAG) powder as a composite reinforcement in improving the oxidation resistance, hot-strength, and microstructure development in refractories were studied. The refractory components reinforced with EG\YAG exhibited significant enhancement in oxidation resistance and hot-strength performance compared to the standard refractories. The in-situ development of bimodal microstructure with EG\YAG sintered framework was found to be the main reason for these improvements.