Heat dissipation properties of oxide layers formed on 7075 Al alloy via plasma electrolytic oxidation

The paper demonstrated the microstructure and radiation characteristics of the oxide layers on 7075 Al alloy samples which were subjected to plasma electrolytic oxidation (PEO) process in the couples of the electrolytes with containing particles of either carbon nanotube (CNT) or yttria-stabilized zirconia (YSZ), or titania (TiO2). For this purpose, a series of PEO coatings were conducted at a current density of 100 mA/cm2. Surface observation revealed that a number of CNT, YSZ, and TiO2 were incorporated successfully in the oxide layer. Moreover, the size and distribution of the micro-pores caused by plasma discharge were changed markedly as compared to Al alloy coated by PEO process using a particle-free electrolyte. The oxide layer formed in the electrolyte with CNT showed the highest heat emission properties among all conditions tested in this study.