Study of influence of micro-arc oxidation process duration on the characteristics of thermal control coatings for space applications

Thermal control coatings were obtained on the AMg6 aluminum alloy with the aid of micro-arc oxidation (MAO) process. The dependences of the thickness, roughness, porosity and thermal control properties of the coating on MAO process duration were studied. The thermal control properties (solar absorbance αs and emissivity ε) were investigated by ultraviolet–visible-near infrared spectrophotometer instrument and solar absorption reflectometer. The analysis of thickness, roughness and MAO process duration influence on the thermal control properties of the coating was carried out.

Synthesis and characterization of Co3O4 nanoparticles for use as pigments in solar absorbing paints

This aim of this research is to produce Co3O4 oxide by means of one-step solution novel combustion methods using aspatic acid (C4H7NO4); lysine (C6H14N2O2); tris (hydroximethyl) aminomethane (NH2C (CH2OH)3) and ethylene diamine tetra-acetic acid (C10H16N2O8) as fuels. The pigments were characterized using X-ray diffraction, scanning and transmission electron microscopy, infrared spectroscopy with Fourier transform and UV-VIS-IR Spectrophotometry. The paint based on alkyd resin was made from pigments obtained (Co3O4 oxide). In order to make a comparison of the thermal emittance of the paint, two different formulations were prepared and these coating are named "absorbent paint coating": one that included 1% by weight of aluminum in metallic powder and another, with 1% of copper in metallic powder, respectively. The solar absorbance for the Co3O4 powders, plus quartz cuvette, gave a value of 0.9 in all cases. An extraordinary value of absorption on the coatings between 95 and 96% was noted. These results suggested that the synthesis of combustion in solution makes it possible to obtain a Co3O4 absorbent pigment with different fuels. These syntheses have a low environmental impact because they are one-step processes. All use low amounts of reactive ash obtained at a calcination of about 500 °C. These results suggest the possibility of utilizing this oxide in absorbent solar paints.

An Investigation on the Thermal and Solar Properties of Graphene-Coated Polyester Fabrics

In this study, coatings were made with graphene nanopowder in two different thicknesses (0.1 and 0.5 mm) at three different concentrations (50, 100 and 150 g/kg) on polyester woven fabrics. The effects of the coating thickness and graphene concentration were examined with optical and scanning electron microscopy (SEM) images. The thermal stability properties of the samples were also evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Thermal conductivity was evaluated with two different principles: contact and radiant heat transfer, according to JIS R 2618 and EN ISO 6942, respectively. Solar measurements were performed with a Shimadzu UV-3600 Plus spectrophotometer. The graphene coating improved the thermal stability of the polyester fabrics. The solar absorbance value increased by 80% compared to reference fabrics, and reached approximately 90%. One of the important results was that the thermal conductivity coefficient increased by 87% and 262% for the two coating thicknesses, respectively.

The Effect of Morphologies of Embedded Plasmonic Cu-nanoparticles on Solar Absorption of Perovskite Solar Cells: A Comprehensive Study-=SUP=-*-=/SUP=-

In this work, we aim to reduce the production costs of Perovskite solar cells (PSCs) and achieve high solar absorbance with the inclusion of different shapes of plasmonic nanoparticles within its 200 nm thick Perovskite layer. We have performed an extensive study based on the different morphologies of plasmonic nanoparticles including nanospheres, nanocubes, nanocylinders, nanorods, nanotriangular plates embedded within the film. This geometric study is extended to the different orientations of a particle within the film, with respect to the source of light. Based on our previous study involving different materials of nanoparticles within the perovskite film, copper is selected as a potential candidate to drastically reduce the production costs without compromising the absorption efficiency of the cell. Varying sizes of these copper nanoparticles are placed at the centre of the film to verify the enhancement of the light trapping efficiency of these designed cells. We find that the absorption efficiency of PSCs highly depends upon the corner sharpness and orientation of a nanoparticle within the film, though the average absorption remains analogous to the spherical particles. Since the designed PSC with tailored nanoparticles portray a significant variation in its absorbance efficiency with the change in its geometrical parameters, hence we can choose a specific morphology of the particle, placed at a certain angle within the film to obtain maximum absorbance. The entire study is based on the Finite Difference Time Domain (FDTD) method of simulation. Keywords Perovskite solar cells, solar absorbance, plasmonic Nanoparticles, FDTD

Decoration of an inorganic layer with nickel (hydr)oxide via green plasma electrolysis

Nickel (hydr)oxide decorating MgO matrix via green plasma electrolysis exhibited high solar absorbance but low infrared emissivity.