Structure and Thermophysical Properties of Coatings Formed by the Method of Microarc Oxidation on an Aluminum Alloy AK4-1

Abstract

The work presents the results of investigation of the thermal conductivity of the coating formed by the method of microarc oxidation (MAO) on a deformable aluminum alloy AK4-1. The article describes the methodology of the research including the formation of the MAO layer, the study of the structure and composition of the coating and the determination of its coefficient of thermal conductivity. The methodological approach to determining the thermal conductivity is based on measuring the thermal diffusivity of the oxide layer by pulsed laser heating, as well as calculating the heat capacity and density of the coating based on the data of layer-by-layer X-ray phase analysis is proposed. During the calculations, the porosity of the coating was taken into account. In accordance with the proposed procedure, it is established that the MAO layer has a thermal conductivity coefficient of ~ 5 W/(mK). The value obtained is comparable with the known results, but is significantly lower than the values of the thermal conductivity of the single phases constituting the coating. It is assumed that this effect is related to the feature of the structure of the MAO layer.