Abstract
The thermal control coating was produced on AA7075 by pulsed DC plasma electrolytic oxidation (PEO) process in an aqueous electrolyte containing 3 g/l sodium silicate (Na2SiO3) and 6 g/l potassium hydroxide (KOH) along with 4 g/l nanoparticles of Cupric oxide (CuO) or Titanium oxide (TiO2) or CuO and TiO2 with equal mass. PEO coatings were fabricated with different electrolyte compositions with a current density of 150 mA/cm2 and a frequency of 1000 Hz for 6 min. The phase composition, surface morphology, and thickness of the coating were assessed using X-ray diffraction (XRD), scanning electron microscope (SEM), and eddy current thickness gauge, respectively. Thermal diffusivity of the coated sample was measured by the laser flash apparatus and the practical adhesive strength between the substrate and coating layer was evaluated by the scratch test. It was perceived that all the coated samples exhibited superior thermal control properties compared to the bare aluminium and the CuO particles incorporated PEO coating showed the highest thermal diffusivity (80.18 mm2/sec at 30 °C) compared to other PEO coated samples. The nano TiO2 and nano CuO incorporated PEO coatings shown the least porosity compared to the PEO coating without nanoparticles and the scratch testing critical loads are 13.58 N and 9.53 N, respectively.
Published Version
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