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1. Obtaining an Optical Trap Type Surface by Plasma Electrolytic Oxidation

Author

Hugo Fernandes Medeiros da Silva, Tarciana Dieb Toscano, Kelly Cristiane Gomes, José Felix da Silva Neto, Francine Alves da Costa, and Clodomiro Alves Junior

Subjects
PEO, pulsed, duty cycle, optical trap, Materials of engineering and construction. Mechanics of materials, TA401-492
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 Na2SiO3. Voltage of 500 V and current density of 0.17 A cm2 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.

Published
2018
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2. Obtaining an Optical Trap Type Surface by Plasma Electrolytic Oxidation

Author

Hugo Fernandes Medeiros da Silva, Tarciana Dieb Toscano, Kelly Cristiane Gomes, Francine Alves da Costa, Clodomiro Alves Júnior, and José Felix da Silva Neto

Subjects
Materials science, 020209 energy, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, optical trap, Aluminium, 0202 electrical engineering, electronic engineering, information engineering, General Materials Science, Absorption (electromagnetic radiation), Porosity, Materials of engineering and construction. Mechanics of materials, Mechanical Engineering, Plasma electrolytic oxidation, Condensed Matter Physics, pulsed, chemistry, Mechanics of Materials, Duty cycle, PEO, Electrode, duty cycle, TA401-492, Current density, Intensity (heat transfer)
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 Na2SiO3. Voltage of 500 V and current density of 0.17 A cm2 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.

Published
2017

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