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烧蚀的热标准试验方法  
 【英文标准名称】  Standard Test Method for Heat of Ablation
 【原文标准名称】  烧蚀的热标准试验方法
 【标准号】  ASTM E458-2008
 【标准状态】  Active
 【国别】  美国
 【发布日期】  2008
 【实施或试行日期】  
 【发布单位】  美国材料与试验协会(US-ASTM)
 【起草单位】  E21.08
 【标准类型】  (Test Method)
 【标准水平】  ()
 【中文主题词】  
 【英文主题词】  ablation; cold-wall heat of ablation; effective heat of ablation; heat of ablation; thermochemical heat of ablation; Ablative materials; Heating tests--aerospace materials; Mass
 【摘要】  

General8212;The heat of ablation provides a measure of the ability of a material to serve as a heat protection element in a severe thermal environment. The parameter is a function of both the material and the environment to which it is subjected. It is therefore required that laboratory measurements of heat of ablation simulate the service environment as closely as possible. Some of the parameters affecting the heat of ablation are pressure, gas composition, heat transfer rate, mode of heat transfer, and gas enthalpy. As laboratory duplication of all parameters is usually difficult, the user of the data should consider the differences between the service and the test environments. Screening tests of various materials under simulated use conditions may be quite valuable even if all the service environmental parameters are not available. These tests are useful in material selection studies, materials development work, and many other areas.

Steady-State Conditions8212;The nature of the definition of heat of ablation requires steady-state conditions. Variances from steady-state may be required in certain circumstances; however, it must be realized that transient phenomena make the values obtained functions of the test duration and therefore make material comparisons difficult.

Temperature Requirements8212;In a steady-state condition, the temperature propagation into the material will move at the same velocity as the gas-ablation surface interface. A constant distance is maintained between the ablation surface and the isotherm representing the temperature front. Under steady-state ablation the mass loss and length change are linearly related.

where:
t
 【中国标准分类号】  A54
 【国际标准分类号】  17_200_10
 【页数】  7P.;A4
 【正文语种】  英语
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