Highly thermally conductive dielectric coatings produced by plasma electrolytic oxidation of aluminum

Abstract

Dielectric materials with high thermal conductivity are of great interest in applications as heat sinks for microelectronics. In this work, an experimentally simple and economic viable technique, the Plasma Electrolytic Oxidation, has been applied to produce dielectric coatings with high thermal conductivity on aluminum substrates. The samples have been prepared in sodium silicate solutions using pulsed DC voltage. Scanning electron microscopy with X-ray energy dispersive spectroscopy, X-ray diffraction, ultraviolet-visible reflectance and impedance spectroscopies, and photoacoustic spectroscopy have been applied to characterize the produced materials. Under certain conditions, samples with electric resistivities as high as 4.6 × 1012 Ω.cm and thermal diffusivity 900% higher than that of Al2O3 or AlN have been grown at room temperature.