Performance of Elastomeric Silicones in Ablative and Space Environments

1966 ◽  
Vol 39 (4) ◽  
pp. 1247-1257 ◽  
Author(s):  
Clyde L. Whipple ◽  
John A. Thorne
Keyword(s):  
High Vacuum ◽  
Thermal Control ◽  
Heat Fluxes ◽  
Space Environment ◽  
Space Applications ◽  
Wide Range ◽  
Environmental Extremes ◽  
Temperature Ranges ◽  
Space Environments ◽  
Thermal Control Coatings

Abstract Elastomeric silicones are among the best materials available for many ablative and space applications. In ablative applications, these materials protect launching equipment, safeguard various parts of vehicles and spacecraft during flight, and shield re-entering spacecraft. Generally, elastomeric silicones are used where ablative conditions involve low to moderate heat fluxes and shear forces. Ablative characteristics of materials can vary widely depending on polymer type, fillers, and applications techniques, and no one elastomeric silicone will perform in a wide range of ablative missions. A good knowledge of the ablative characteristics of silicone materials is required to select the best candidates for a given application. In the space environment, silicones are often used for seals, thermal control coatings, potting materials, and other applications because they perform well over wide temperature ranges, and because they are inherently stable to high-vacuum and ultraviolet conditions. Data given in this paper illustrate that silicones show little weight loss or loss of properties on exposure to space environmental extremes. Furthermore, these losses can be made almost negligible by proper conditioning of the finished elastomer.

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.

Experimental Study of Flexible Electrohydrodynamic Conduction Pumping for Electronics Cooling

2018 ◽  
Author(s):  
Nicolas Vayas Tobar ◽  
Pavolas N. Christidis ◽  
Nathaniel J. O'Connor ◽  
Michal Talmor ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Flexible Electronics ◽  
Electronics Cooling ◽  
Thermal Control ◽  
Stable Operation ◽  
Space Applications ◽  
Manufacturing Method ◽  
Micro Scale ◽  
Wide Range ◽  
And Performance ◽  
And Control

As modern day electronics develop, electronic devices become smaller, more powerful, and are expected to operate in more diverse configurations. However, the thermal control systems that help these devices maintain stable operation must advance as well to meet the demands. One such demand is the advent of flexible electronics for wearable technology, medical applications, and biology-inspired mechanisms. This paper presents the design and performance characteristics of a proof of concept for a flexible Electrohydrodynamic (EHD) pump, based on EHD conduction pumping technology in macro- and meso-scales. Unlike mechanical pumps, EHD conduction pumps have no moving parts, can be easily adjusted to the micro-scale, and have been shown to generate and control the flow of refrigerants for electronics cooling applications. However, these pumping devices have only been previously tested in rigid configurations unsuitable for use with flexible electronics. In this work, for the first time, the net flow generated by flexible EHD conduction pumps is measured on a flat-plane and in various bending configurations. In this behavioral characteristics study, the results show that the flexible EHD conduction pumps are capable of generating significant flow velocities in all size scales considered in this study, with and without bending. This study also proves the viability of screen printing as a manufacturing method for these pumps. EHD conduction pumping technology shows potential for use in a wide range of terrestrial and space applications, including thermal control of rigid as well as flexible electronics, flow generation and control in micro-scale heat exchangers and other thermal devices, as well as cooling of high power electrical systems, soft robotic actuators, and medical devices.

End of Life and Beginning of Life Thermal Analysis of a Micro Satellite

2015 ◽  
Vol 798 ◽  
pp. 551-555
Author(s):  
Mustafa Turkmenoglu
Keyword(s):  
Thermal Analysis ◽  
Thermal Degradation ◽  
End Of Life ◽  
Satellite Orbit ◽  
Thermal Control ◽  
Low Earth Orbit ◽  
Space Environment ◽  
Bottom Surface ◽  
Solar Panels ◽  
Space Environments

Satellites with passive thermal control system use thermal coatings, secondary and first surface mirrors and paints to maintain the temperatures of their electronic equipment within operating temperatures. Satellite coatings are exposed to harsh space environments like ultraviolet radiation (UV) and atomic oxygen (AO) that cause thermal degradation. As nature of the space environment, degradation of the surface paints and coatings cause increase in temperatures of the equipment in time. Thermal designer must consider the thermal degradation of the coatings and paints and optimize the radiator sizes of the satellite at Beginning of Life (BOL) and End of Life (EOL) of the satellite in order to maintain the temperatures of equipment within their safe operation limits. For this analysis, a micro-class satellite using passive thermal control with surface paints and interface conductance within each equipment has been studied. The satellite top surface (+Z) faces the earth and bottom surface (-Z) faces deep space. The lateral sides of the satellite are covered with honeycomb solar panels and top and bottom surfaces are covered with white paint which act as satellite radiator. The satellite orbit has been considered as 700 km Sun-Synchronous Low Earth Orbit. In this analysis BOL and EOL thermo optical properties have been used to predict the satellite temperatures before and after degradation of paints. Thermal analysis have been performed and predicted temperatures obtained by using THERMICA thermal analysis software.

Effects of a Void Beneath a Kapton Heater Patch in a Vacuum

2004 ◽  
Author(s):  
Ryan A. Schmidt
Keyword(s):  
Heat Flux ◽  
Hot Spot ◽  
Thermal Control ◽  
Heat Fluxes ◽  
Void Size ◽  
Conduction Path ◽  
Space Applications ◽  
Affected Area ◽  
Conduction Pathway ◽  
Substrate Temperatures

The vacuum of space can lead to some interesting heater problems. In many space applications, heater patches consisting of Inconel elements joined together with Teflon sandwiched together between two Kapton layers are bonded to a structure (substrate) to provide thermal control. A void between the heater patch and the substrate can lead to a hot spot due to the loss of conduction path from the heater to the substrate. When the heater is in a vacuum with a void beneath it, heat is transferred to the substrate by radiation and fin effects through the heater and then to the substrate. The localized hot spot can cause heater layers to separate and further reduce the conduction pathway from the affected area and eventually burnout the heater. A large enough void combined with high heater heat fluxes and substrate temperatures can induce heater failures. For this paper the sensitivity of peak temperature with respect to heat flux (power density), substrate temperature, void size, and void location is considered.

Micro-Heat-Sinks for Space Applications

2004 ◽  
Author(s):  
M. Marengo ◽  
S. Zhdanov ◽  
L. Chignoli ◽  
G. E. Cossali
Keyword(s):  
Biomedical Applications ◽  
Heat Pipes ◽  
Thermal Control ◽  
Space Mission ◽  
Small Dimension ◽  
Heat Sinks ◽  
Space Environment ◽  
Space Applications ◽  
Space Requirements ◽  
Further Development

During the space missions, the problems related to the thermal conditioning of devices, to the personnel comfort and to the thermo-mechanical stresses are known and important. Furthermore for a space mission certain priorities are stressed, such as the small dimension and the lightness of thermal equipments. Due to the presence of high temperature gradients, which straightforwardly implies significant heating/cooling powers, these characteristics are sometimes difficult to obtain. The decreasing of the satellites payloads in terms of mass and volume has brought to the necessity of a further development of traditional space technologies, such as heat pipes and radiators. A promising technology is the fabrication of micro-heat-sinks for active and passive thermal control systems suitable for the space environment, which is always an important workshop for future progresses. In fact, miniaturized heat sinks will have a terrestrial large industrial diffusion for electronic component cooling, in propulsion and in the power production for satellites, spacecrafts and airplanes, in various biomedical applications and in cloth conditioning in harsh environmental conditions. The present paper intends to introduce the reader to the standard space requirements, to present some new prospective and experiments to present some new prospective and experimental results and to discuss the use of thermal MEMS for micro- and nano-satellites.

scholarly journals Tailoring Thin-Film/Lacquer Coatings for Space Applications

2000 ◽  
Vol 12 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Wanda C Peters ◽  
George Harris ◽  
Grace Miller ◽  
John Petro
Keyword(s):  
Thin Film ◽  
Thermal Control ◽  
Radiative Properties ◽  
Space Applications ◽  
Solar Absorptance ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Thermal Radiative Properties ◽  
Wide Range ◽  
Specular Surfaces

Thin-film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin-film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission’s thermal control requirements, there is often a need for a variation of solar absorptance (αs), emittance (∊) and/or highly specular surfaces. The utilization of thin-film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of αs/∊ ratios. The radiative properties of thin-film coatings can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin-film application without the cost and difficulty associated with polishing.

Sign in / Sign up

Export Citation Format

Share Document