| 摘要 |
Ablative insulation materials, esp. for cladding space re-entry vehicles, consists of (a) thermosetting binders such as silicones, phenolic resins, polyimide resins, epoxy resins, or urethanes, (b) known additives such as asbestos fibres, carbon fibres, SiO2 or SiC; and (c) a solid gas developing agent which (1) either sublimes or decomposes without melting to form a gas without liberating oxygen at temps. of 150 degrees C in a vacuum (103 torr) to 1200 degrees C, esp. 600 degrees C at ambient press., (2) is compatible with the base material and esp. does not interfere with the curing reaction and (3) is not hygroscopic. The compsn. may also contain (d) a pore-forming agent. The ablative materials give excellent protection and are useful e.g. in re-entry vehicles and rockets. They can be used at ambient temps. of >1650 degrees C and leave a residue of high strength. The materials give almost 100% longer burn-through times c.f. prior art silicone-based materials; the material costs are considerably lower than for previous materials; the mechanical strength of the slag layer formed is considerably higher; and the decomposition of the gas developer gives considerably lower surface temps. |
