A novel non-selective coating material for solar thermal potential application formed by reaction between sol-gel titania and copper manganese spinel

A method for preparing a novel bixbyite non-selective coating for solar thermal conversion is described. The coating is formed by a thermal reaction between a titania sol-gel precursor with a copper manganese spinel to form a new material, Cu0.44Ti0.44Mn0.84Fe0.28O3, with a bixbyite structure. The effect of temperature and ratio between the two components on the formation of the bixbyite layer (deposited on Inconel by spray-coating) was studied. The absorptance of the films (AM 1.5; 335-2500 nm) with a thickness of 10±2 µm after annealing at 2 h at 650 °C and 750 °C was 97.4% and 94.7%, respectively. This synthesis represents a novel approach in which the final solar thermal coating is formed as a continuous and uniform layer which combines both the absorber and the ceramic binder. The developed material shows promising results for future applications as absorber in solar thermal energy conversion.