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首页> 外文会议>Space Technology amp; Applications International Forum (STAIF-99) ptol January 31-February 4, 1999, Albuquerque Hyatt Hotel, NM >Effects of ambient high temperature exposure on alumina-titania high emittance surfaces for slar dynamic systems
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Effects of ambient high temperature exposure on alumina-titania high emittance surfaces for slar dynamic systems

机译：Slar动力系统的环境高温暴露对氧化铝-二氧化钛高发射率表面的影响

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摘要

SOlar dynamic (SD) space power systems require durable, high emittance surfaces on a number of critical components, such as heat receiver interior surfaces and parasitic load radiator (PLR) elements. To enhance surface char-acteristics, an alumina-titania coating has been applied to 500 heat receiver thermal energy containment canisters and the PLR of NASA Lewis Research Center's (LeRC) 2 kW SD ground test demonstrator (GTD). The alumian-titania coating was chosen because it had been found to miantain its high emittance under vacuum (<= 10~(-6) torr) at high temperatures (1457 deg F (*8257 deg C) for an extended period (approx = 2,700 hours). However, preflight verification of SD systems components such as the PLR, require operation at ambient pressure and high temperatures. Therefore, the purpose of this research was to evaluate the durability of the alumina-titania coating at high temperature in air. Fifteen of sixteen alumina-titania coated Incoloy smaples were exposed to high temperatures (600 deg F (316 deg C) to 1500 deg F(816 deg C) for various durations (2 to 32 hours). Samples were characterized prior to , and after, heat treatment for reflectance, solar absoptance, room temperature emittance and emittance at 1200 deg F (649 deg C). Samples were also examined to detect physical defects and to determine surface chemistry using optical microscopy, scanning electron microscopy, operated with an energy dispersive spectroscopy (EDS) system, and x-ray phototelectron spectroscopy (XPS). Visual examination of the heat-treated smaples showed a whitening of samples exposed to temperatures of 1000 deg F (538 deg C) and above. Correspondingly, the optical properties of these samples had degraded. A sample exposed to 1500 deg F (816 deg C) for 24 hours had whitened and the thermal emittance at 1200 deg F (649 deg C) had decreased from the non-heated value of 0.94 to 0.62. The coating on this sample had become embrittled, with spalling off the substrate noticaeable at several locations. Based on this research it is recommended that preflight testing of SD components with alumina-titania coatings be restricted to temperatures no greater than 600 deg F (316 deg C) in air to avoid optical degradation. Moreover, components with the aluminia-titania coating are likely to experience optical property degradation with direct atomic oxygen exposure in space.
机译：太阳能（SD）空间电源系统要求在许多关键组件上具有耐用的高发射率表面，例如热接收器内表面和寄生负载辐射器（PLR）元件。为了增强表面特性，已将氧化铝-二氧化钛涂层应用于500个热量接收器的热能容器和NASA Lewis研究中心（LeRC）的2 kW SD地面测试演示器（GTD）的PLR。选择氧化铝-二氧化钛涂层的原因是发现它在高温（1457华氏度（* 8257摄氏度））下长时间（约= 10〜（-6）托）在真空下（<= 10〜（-6）托）具有较高的发射率。 2700小时），但是SD系统组件（例如PLR）的飞行前验证需要在环境压力和高温下运行，因此，本研究的目的是评估氧化铝-二氧化钛涂层在空气中的高温耐久性。十六个氧化铝-二氧化钛涂层的Incoloy枫树在不同的持续时间（2-32小时）中暴露于高温（600华氏度（316摄氏度）至1500华氏度（816摄氏度））中，分别在样品之前和之后进行表征，反射率，日光吸收率，室温发射率和1200°F（649°C）时的发射率的热处理。还使用光学显微镜，扫描电子显微镜和能量检测器对样品进行了检测以检测物理缺陷并确定表面化学性质gy色散光谱（EDS）系统和X射线光电子能谱（XPS）。目测检查热处理过的枫木，结果表明样品暴露在1000华氏度（538摄氏度）以上的温度下呈白色。相应地，这些样品的光学性能下降。暴露于1500华氏度（816摄氏度）24小时的样品已经变白，并且在1200华氏度（649摄氏度）的热发射率从0.94的非加热值降低到0.62。该样品上的涂层已经变脆，在几个位置上都明显剥落了基材。根据这项研究，建议将带有氧化铝-二氧化钛涂层的SD组件的飞行前测试限制在不超过600华氏度（316摄氏度）的空气中温度，以避免光学性能下降。此外，具有铝-二氧化钛涂层的组件可能会由于在空间中直接暴露于原子氧而导致光学性能下降。

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