Obtaining an Optical Trap Type Surface by Plasma Electrolytic Oxidation

Abstract

High performance solar collectors are those with high selectivity surfaces, high solar radiation absorption and that do not thermally reemit to the external environment. Strategies to enhance this performance might involve surface porosity modification. In this work, a plasma treatment technique called plasma electrolytic oxidation (PEO) has been tested to produce porosity on aluminium surfaces in a controlled manner. The porosity control was made by varying the intensity, frequency and duty cycle of the applied voltage pulses. The aluminium sample was placed in a solution of 1 g/L Na 2 SiO 3. Voltage of 500 V and current density of 0.17 A cm 2 was applied between electrodes. Three duty cycles were used: 33.33%, 50.00% and 67.77%. After treatment, the size, number and distribution of pores were evaluated. These parameters were correlated with both surface reflectance and optical absorbance. It was possible to control the porosity by controlling the electrical parameters of the process. While the mean pore size was directly related to the duty cycle, the inverse occurred for the number of pores. Surface treated with duty cycle of 33.33% presented higher values of absorption for all wavelength range.

Phosphate Porous Coatings Enriched with Selected Elements via PEO Treatment on Titanium and Its Alloys: A Review

“…Other ways of modifying the surface are ion implantation [26][27][28][29][30][31], electrophoretic deposition [32], and laser surface treatment [33][34][35][36]. Development of materials engineering and technology in the following years has allowed new challenges to be posed regarding surface engineering, including, but not limited to, fabrication of porous coatings by the Plasma Electrolytic Oxidation (PEO) or Micro Arc Oxidation (MAO) [37] on light metals and alloys, such as aluminum [38][39][40][41][42][43][44] and its alloys [45][46][47][48][49][50][51][52][53][54], magnesium [38,39,[55][56][57] and its alloys [58][59][60][61][62][63][64], titanium and its alloys [57,[65][66][67][68][6...…”