Fabrication of temperature-selective thermal radiation surfaces utilizing surface texturing

Abstract

Solid surfaces emit electromagnetic (EM) radiation whose wavelength varies with the temperature. Herein, a functional heat sink was developed by creating a temperature-selective heat release surface that raises the radiation flow at a specific temperature. We fabricated periodic V-grooves on an aluminum surface with a pitch dimension in the micron range by micro-cutting (Structure I), and a submicron periodic microstructure on a flat surface using an ultrashort pulsed laser (Structure II). Then, we fabricated a hybrid structure (Structure III) by forming Structure II over Structure I to investigate the effect of the surface microstructure on the radiation performance. Structure I had a high emissivities at certain wavelengths, like blazed grating, due to the reflection of EM waves within the fabricated V-groove. Structure II was found to have an effect similar to holographic grating, and Structure III increased the emissivity of Structure I and shifted the peak emissivity toward higher wavelengths. The radiation flux measured from the sample surface at various temperatures revealed that an increase in the surface area and emissivity were effective in increasing radiation. In particular, in Structure III, the radiation flux was significantly increased and varied with temperature. This indicates that the formation of a finer concavo-convex structure on a periodic structure could enable finer temperature selectivity for emitted radiation.