ASTM C177-13由美国材料与试验协会 US-ASTM 发布于 2013。
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ASTM C177-13 使用护热板设备测量稳态热通量和热传导特性的标准试验方法的最新版本是哪一版?
最新版本是 ASTM C177-19e1 。
5.1 This test method covers the measurement of heat flux and associated test conditions for flat specimens. The guarded-hot-plate apparatus is generally used to measure steady-state heat flux through materials having a “low” thermal conductivity and commonly denoted as “thermal insulators.” Acceptable measurement accuracy requires a specimen geometry with a large ratio of area to thickness.
5.2 Two specimens are selected with their thickness, areas, and densities as identical as possible, and one specimen is placed on each side of the guarded-hot-plate. The faces of the specimens opposite the guarded-hot-plate and primary guard are placed in contact with the surfaces of the cold surface assemblies.
5.3 Steady-state heat transmission through thermal insulators is not easily measured, even at room temperature. This is due to the fact heat transmission through a specimen occurs by any or all of three separate modes of heat transfer (radiation, conduction, and convection). It is possible that any inhomogeneity or anisotropy in the specimen will require special experimental precautions to measure that flow of heat. In some cases it is possible that hours or even days will be required to achieve the thermal steady-state. No guarding system can be constructed to force the metered heat to pass only through the test area of insulation specimen being measured. It is possible that moisture content within the material will cause transient behavior. It is also possible that and physical or chemical change in the material with time or environmental condition will permanently alter the specimen.
5.4 Application of this test method on different test insulations requires that the designer make choices in the design selection of materials of construction and measurement and control systems. Thus it is possible that there will be different designs for the guarded-hot-plate apparatus when used at ambient versus cryogenic or high temperatures. Test thickness, temperature range, temperature difference range, ambient conditions and other system parameters must also be selected during the design phase. Annex A1 is referenced to the user, which addresses such issues as limitations of the apparatus, thickness measurement considerations and measurement uncertainties, all of which must be considered in the design and operation of the apparatus.
5.5 Apparatus constructed and operated in accordance with this test method should be capable of accurate measurements for its design range of application. Since this test method is applicable to a wide range of specimen characteristics, test conditions, and apparatus design, it is impractical to give an all-inclusive statement of precision and bias for the test method. Analysis of the specific apparatus used is required to specify a precision and bias for the reported results. For this reason, conformance with the test method requires that the user must estimate and report the uncertainty of the results under the reported test conditions.
5.6 Qualification of a new apparatus. When a new or modified design is developed, tests shall be conducted on at least two materials of known thermal stability and having verified or calibrated properties traceable to a national standards laboratory. Tests shall be conducted for at least two sets of temperature conditions that cover the operating range for the apparatus. If the differences between the test results and the national standards laboratory characterization are determined to be significant, then the source of the error shall, if possib......
平板热流计导热仪在绝热材料导热系数测量中应用目前,绝热材料导热系数的测量主要使用护热平板法和平板热流计法两种方法,分别对应国标:GB/T10294-1988《绝热材料稳态热阻及有关特性的测定 防护热板法》;GB/T10295-1988《绝热材料稳态热阻及有关特性的测定(热流计法)》。...
相关标准有GB/T 10294-2008《绝热材料稳态热阻及有关特性的测定 防护热板法》、ASTM C177-19《用护热板仪器法测定稳态热通量和热传递特性的试验方法》及ISO 8302:1991《绝热稳态热阻及有关特性的测定 防护热板法》。...
(根据用户合同要求配)f、试验前应用游标卡尺,测量样品厚度,到0.01mm。或采用其它方式测量样品厚度,检测四个点,取平均值为厚度(单位为毫米)并记录下来供实验时使用。设备自带测厚装置的可忽略此步。g、当试样为泡沫或棉质类易压缩的材质时,请依样品厚度制备三或四个圆柱型固体支柱,以备测试时使用。...
本仪器参考标准:GB/T10295-88 (绝热材料稳态热阻及有关特性的测定 热流计法)及ASTM C518-04用热流计法测定稳态热通量和热传递特性的试验方法。...
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