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首页> 美国政府科技报告 >Performance Characterization of Polyimide-Carbon Fiber Composites for Future Hypersonic Vehicles
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Performance Characterization of Polyimide-Carbon Fiber Composites for Future Hypersonic Vehicles

机译：聚酰亚胺 - 碳纤维复合材料在未来高超声速飞行器中的性能表征

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The Air Force, Army, and Navy have initiated research and development progress to develop hypersonic vehicles in the Mach 5-15 range. Two broad categories are being considered, namely: (i) vehicles that fly at low altitudes for short times (minutes) over distances of hundreds of miles and (ii) flights that are global and cover lower space orbits over periods of hours. Specifically, the Air Force for future vehicles need to be able to reach anywhere in the world in one hour (Vista 25 program). The primary structures of hypersonic vehicles need to be lightweight, strong and thermally durable for the duration of the flight (or for multiple flights in the case of reusable vehicles). Transition-metal carbides, referred to as ultra-high temperature (UHT) materials, are interesting because they are refractory materials with the highest known melting points (that in many cases exceed 2600 deg C). Applications for UHT materials such as hypersonic flight, atmospheric re-entry, and rocket propulsion, with temperatures exceeding 3000 deg C, challenge the survivability of many known materials currently in use. Unfortunately, the synthesis of the refractory transition-metal carbides requires high temperatures that can exceed 1700 deg C. The in-situ synthesis of transition- metal carbides, in an argon atmosphere using transition-metal halide salts solution-processed with polymer matrices, is described here as a low temperature method for making UHT carbides. For example, tantalum carbide (Tm = 3880 deg C) can be produced at temperatures as low as 1000 deg C with high yield (>80%). This relatively low temperature procedure is relatively universal in terms of the variety of transition metals (Ta, Hf, Nb, etc.) that can be used, making it very useful for a wide variety of high temperature applications. The AFR-PEPA-N polyimide-carbon fiber composite system developed by AFRL and AFOSR sponsored programs is the leading candidate as the starting material for this conversion process.

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