Black zirconia composites with enhanced thermal, optical and mechanical performance for solar energy applications

Abstract

This work discusses developing new black zirconia (ZrO2) composites with high efficiency and optimal properties as a volumetric solar receiver via low cost processing. The major aim is optimizing a new high temperature material with high durability, optical and thermal properties for solar energy applications. This was achieved by blackening of zirconia and producing black zirconia composites through addition of Fe2O3 and MnO2 instead of using coating. Fe2O3 is added to the white zirconia with different content (0–30 wt%) to promote its dark color and enhance its properties. 5 wt% MnO2 is added to assist the blackening and the sintering processes. The different ZrO2/Fe2O3 (0–30 wt%)/MnO2 composites are produced by pressureless sintering method at a temperature of 1700 °C for 2 hrs. Optical, thermal and mechanical performances of the obtained composites are optimized to ensure its suitability and sustainability as solar absorber material. Results indicated that highly dense composites with homogenous microstructural features are attained. Increment of Fe2O3 content has a substantial effect on promoting the thermal and solar to thermal efficiencies of the obtained composites. Composite with 30 wt % Fe2O3 showed the highest solar absorbance in the UV, visible and near IR regions. It recorded the best light emission efficiency with the highest photoluminescence performance. Black ZrO2/Fe2O3/MnO2 composites could be a promising candidate as solar receiver material for thermal solar plants than other reported carbide and nitride materials.