Synthesis of nano-porous ZNO as pigment for white silicone thermal control coating and investigation of structure, optical and thermal properties

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vahid Heydari ◽  
Zaker Bahreini ◽  
Majid Abdouss
Keyword(s):  
Near Infrared ◽  
Uv Light ◽  
Thermal Control ◽  
Ideal Condition ◽  
Solar Absorptance ◽  
Content Type ◽  
Scattering Coefficients ◽  
Oxide Particles ◽  
Thermal Control Coatings ◽  
First Time

Purpose The harsh environment of space, especially radiation of direct solar rays, can potentially raise the temperature of the spacecraft to harmful levels. Thermal control coatings (TCCs) fix the thermal condition of the spacecraft acceptable for its components. This is possible by diffusely reflecting all effective ultraviolet (UV), visible (VIS) and near infrared (IR) (NIR) wavelengths of solar radiation and emmition of IR energy. The most commonly used TCCs have used ZnO as a pigment, but absorption of the UV light by ZnO pigment can change the ideal condition of these TCCs. The aim of his study is the using the porous ZnO particles as pigment to prevent the UV absorption. Design/methodology/approach To enhance the efficiency of these coatings, in the present study, nano-porous zinc oxide particles were synthesized and used as pigments for white TCCs. Findings The results revealed that the proposed TCC (TPZ), Thermal control coating with porous ZnO had better reflection (scattering) and emittance properties in comparison with the coating using ZnO as a pigment (TZ coating); so this coating had a solar absorptance value equal to 0.141, whereas this value for TZ was 0.150. Furthermore, TPZ showed higher thermal emittance (0.937) in comparison with TZ (0.9). These changes were because of the improvement in the refractive index, shape and surface area of the pigments. The general trend of the scattering coefficients for the prepared coating, as calculated from the Kubelka–Munk equation, showed that scattering was more efficient in the UV region, as compared with the TCC containing ZnO pigments. Originality/value This type of pigment for the first time is evaluated in TCCs.

Research of Strontium Silicate Modified Zinc Oxide Thermal Control Coatings

2013 ◽  
Vol 821-822 ◽  
pp. 1236-1239 ◽  
Author(s):  
Xiaoan Yue ◽  
Zheng Quan Zhang ◽  
En Ze Wang ◽  
Song Qin Xia
Keyword(s):  
Zinc Oxide ◽  
Optical Properties ◽  
Thermal Management ◽  
Near Infrared ◽  
Composite Coatings ◽  
Thermal Control ◽  
The Novel ◽  
Infrared Band ◽  
Thermal Control Coatings ◽  
Strontium Silicate

Thermal control coatings (TCCs) play an important role in thermal management of spacecrafts and satellites by their thermo-optical properties. In this research, the novel TCCs were prepared by incorporating the self-made strontium silicate and zinc oxide into the potassium silicate binder. The effects of strontium silicate on phase composition, microstructure and optical performance of TCCs were studied using scanning electron microscope and spectroreflectometer. The results show that: strontium silicate can improve near infrared band (1000~2400nm) spectra reflectance. Compared with traditional zinc oxide TCCs, the novel composite coatings enhance the reflectance , and improve the optical properties.

Optical Absorption Properties of Nanotitanium Dioxide Doped ZnO/Silicone Thermal Control Coating

2007 ◽  
Vol 546-549 ◽  
pp. 1725-1728
Author(s):  
Wei Qin ◽  
Xiao Hong Wu ◽  
Gui Mei Zhao ◽  
Xiao Ming Lai ◽  
Li Gong Zhang
Keyword(s):  
Optical Properties ◽  
Visible Region ◽  
Wavelength Region ◽  
Thermal Control ◽  
Infrared Region ◽  
Absorption Properties ◽  
Solar Absorptance ◽  
Doped Zno ◽  
Thermal Control Coatings ◽  
Control Principle

As a kind of white paint, ZnO/silicone thermal control coatings are used commonly in space. In order to implement more effective thermal control in space, nanotitanium dioxide was doped to the coatings. In this paper, different percent of nanotitanium dioxide was appended to the coatings, and thermal control principle was discussed. Optical properties of these coatings were discussed by spectrophotometry and infrared reflectometer. The experimental results show that solar absorptance (αs) of nanotitanium dioxide doped ZnO/silicone thermal control coating is lower in all wavelength region than the coatings without doping, especially in visible region and infrared region. The total solar absorptance of 1% nanotitanium dioxide doped coating is 0.09, which decreases by 36% than the undoped coating..

Low-energy Electron Exposure Effects on the Optical Properties of ZnO/K2SiO3 Thermal Control Coating

2002 ◽  
Vol 17 (7) ◽  
pp. 1766-1771 ◽  
Author(s):  
X. D. Wang ◽  
S. Y. He ◽  
D. Z. Yang
Keyword(s):  
Electron Energy ◽  
Near Infrared ◽  
Thermal Control ◽  
Low Energy ◽  
Energy Electron ◽  
Spectral Irradiance ◽  
Paramagnetic Resonance ◽  
Solar Absorptance ◽  
Before And After ◽  
Low Energy Electron

An experimental investigation was undertaken to study low-energy electron exposure effects upon ZnO/K2SiO3 thermal control coating. The specimens were exposed to 10-, 30-, 50-, and 70-keV electrons, respectively. The spectral reflectance of each specimen was measured in situ before and after electron exposures. The solar absorptance was calculated by assuming a Johnson solar spectral irradiance distribution. Electron paramagnetic resonance and photoluminescence measurements were made before and after electron exposures to explain physical changes induced by the electron exposures. All the specimens exhibited a reflectance decrease throughout the visible and the near-infrared regions, and also the induced optical degradation was found to be electron energy dependent, with increased damage for increasing electron energy. It is believed that the optical degradation of ZnO/K2SiO3 thermal control coating, induced by the low-energy electron exposures, is mainly due to the ionization process of the ZnO pigment.

White Anodic Coatings on Aluminum Alloy with Low Ratio of Solar Absorptance to Infrared Emittance

2007 ◽  
Vol 336-338 ◽  
pp. 643-646
Author(s):  
Wei Qin ◽  
Bo Cui ◽  
Xiao Hong Wu ◽  
Zhao Hua Jiang
Keyword(s):  
Optical Properties ◽  
Aluminum Alloy ◽  
Low Cost ◽  
Thermal Control ◽  
Space Environment ◽  
Space Applications ◽  
Solar Absorptance ◽  
Thermal Control System ◽  
Thermal Control Coatings

White anodic coatings are gained by growth in situ on the aluminum alloy. The coatings possess stable optical properties, excellent adhesive power, low cost, stability in the space environment, and so on, which can be widely used in the thermal control system of spacecrafts. In this article, the developed Al2O3 thermal control coatings that had a low solar absorptance and a high infrared emittance were gained in the electrolyte of sulfuric acid. The influences of various process parameters, such as electrolyte temperature, current density, anodizing time, on the optical properties of the coatings were investigated. AFM and XRD were used to characterize the microstructure of the coatings. Experimental results show the anodic coatings could reach a solar absorptance value lower than 0.20 and an infrared emittance higher than 0.80. Therefore, the coatings can be applied as important thermal control coatings for space applications.

Black Anodized Thermal Control Coating on LY12 Aluminum Alloy

2011 ◽  
Vol 233-235 ◽  
pp. 2166-2171 ◽  
Author(s):  
Mei Yu ◽  
Wu Jiang ◽  
Jian Hua Liu ◽  
Song Mei Li
Keyword(s):  
Aluminum Alloy ◽  
Oxide Film ◽  
Thermal Control ◽  
Anodic Oxide ◽  
Open Circuit ◽  
Anodic Oxide Film ◽  
Solar Absorptance ◽  
Porous Oxide ◽  
Thermal Control Coatings ◽  
Galvanostatic Conditions

The black thermal control coatings were prepared by etching anodic oxide film and coloring with an organic ATT dyestuff on the LY12 aluminum alloy. The anodic oxide film on aluminum alloy was formulated in 20% aqueous solution of sulfuric acid in galvanostatic conditions. The microstructure of the anodized coating was studied by scanning electronic microscope (SEM). Open circuit potential (OCP) was applied to study the etching of porous oxide layers in the immerging acid solution. The influence of coloring on the optical properties of the coating was investigated. Results showed that the solar absorptance and infrared emittance increased by increasing coloring times.

Optical properties and radiation stability of thermal control coatings based on doped zirconium dioxide powders

2004 ◽  
Vol 19 (2) ◽  
pp. 535-541 ◽  
Author(s):  
M.M. Mikhailov ◽  
A.S. Verevkin
Keyword(s):  
Electromagnetic Radiation ◽  
Zirconium Dioxide ◽  
Diffuse Reflectance ◽  
Satellite Orbit ◽  
Thermal Control ◽  
Radiation Stability ◽  
Simultaneous Action ◽  
Solar Absorptance ◽  
Trivalent Cations ◽  
Thermal Control Coatings

The effect of the doping by compounds with bivalent and trivalent cations (BN, Al2O3, MgO + SiO2) on the diffuse reflectance spectra (ρλ) and the integral solar absorptance (as) and their changes at irradiation (with 30 keV electrons, 3 keV protons, and electromagnetic radiation that imitates solar spectra) of the reflecting thermal control coatings based on ZrO2 powders is examined. The coating based on untreated ZrO2 pigment and the coatings based on the pigments treated with 1 and 3 mass% of Al2O3 nanopowder were subjected to simultaneous action of electrons, protons, and electromagnetic radiation that imitates action of these irradiations on geostationary satellite orbit. After that, the comparative investigations of the changes in spectral reflectance and solar absorptance of these coatings were carried out.

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

2021 ◽  
Vol 2144 (1) ◽  
pp. 012006
Author(s):  
К A Anikin ◽  
A V Apelfeld ◽  
I O Kondratskiy
Keyword(s):  
Near Infrared ◽  
Thermal Control ◽  
Space Applications ◽  
Solar Absorption ◽  
Process Duration ◽  
Micro Arc Oxidation ◽  
Infrared Spectrophotometer ◽  
Thermal Control Coatings ◽  
Amg6 Aluminum Alloy ◽  
Solar Absorbance

Abstract 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.

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