Near-Field Radiative Heat Transfer Between Materials With Dielectric Coatings Available to Purchase

Radiative heat transfer between materials with dielectric coatings is numerically studied based on the fluctuational electrodynamics and the fluctuation-dissipation theorem. The results show that whereas a dielectric coating (SiC) enhances the far-field radiative heat transfer between two bulk metals, it will suppress the radiative heat transfer in the near-field and the suppression is only for the s-wave contribution. The total radiative heat flux continuously decreases as the coating thickness increases up to 1 μm. A further increase in the coating thickness will cause the total radiative heat flux to increase slightly before it saturates. In addition, a much smaller coating thickness than the coating’s skin depth is enough to significantly change the total radiative heat flux in the near-field region. On the contrary, a thin dielectric coating that supports surface polaritons can greatly enhance the radiative heat transfer between a metal and a dielectric in the case that the coating is on the metal. The large enhancement is due to surface polaritons excited on the two surfaces of the air gap boundaries.