Solar Absorbing Surfaces of Anodized Dendritic Tungsten

Anodization of textured tungsten is shown to have merit either in creating a solar absorber of extremely high absorptance when applied to a large dendritic surface, or in enhancing the solar absorptance-to-emittance ratio when applied to smaller hillock topographies. The angular dependence of the absorption is reduced by the anodization coating, which consists of a thin conformal coating of WO
3
. The surface is stable up to temperatures of 520 K in air.