Due to the depletion of the thermal conductivity reference materials, the National Physical Laboratory (NPL) has certified a new thermal conductivity reference material, NPL code 2I09 that is based on Inconel 600. This batch of material has been thermally and electrically characterised over the temperature range 100 °C to 500 °C. The primary thermal conductivity measurements used to generate the certified values were carried out in the NPL Axial Heat Flow apparatus, which is a UK national standard measurement facility. It is based on a steady-state absolute technique and is suitable for measuring specimens with thermal conductivities in the range 10 W·m −1 ·K −1 to 240 W·m −1 ·K −1 . Comparisons were made between the reference thermal conductivity values and the derived thermal conductivity values obtained from two indirect methods based upon electrical resistivity and thermal diffusivity measurements, respectively. The reference thermal conductivity values of NPL 2I09 compare with those calculated from the measurements of electrical resistivity within 2 % and those calculated from the measurements of thermal diffusivity, specific heat capacity, density and thermal expansion better than 4 %. In addition, the certified thermal conductivity values of the new batch of Inconel 600, the NPL code 2I09, were compared with the representative reference thermal conductivity values of Inconel 600 reported by J Clark and R Tye, and the agreement is within 2 %. The new reference material NPL 2I09 is available from NPL and can be used to calibrate or check apparatus that provides measurements of thermal conductivity which includes the range 14 W·m −1 ·K −1 to 22 W·m −1 ·K −1 covering the temperature range from 100 °C to 500 °C. The overall uncertainty on the certified values is estimated to be within ± 4.8 %, based on a standard uncertainty multiplied by a coverage factor k = 2, providing a level of confidence of approximately 95 %.

中文翻译：

---

NPL 热导率参考材料 Inconel 600 的表征

由于热导率参考材料的枯竭，国家物理实验室 (NPL) 已认证了一种新的热导率参考材料，NPL 代码 2I09，它基于 Inconel 600。这批材料已在整个温度范围内进行了热和电表征范围 100 °C 至 500 °C。用于生成认证值的主要热导率测量是在 NPL 轴向热流装置中进行的，该装置是英国国家标准测量设备。它基于稳态绝对技术，适用于测量热导率范围为 10 W·m -1 ·K -1 至 240 W·m -1 ·K -1 的样品。在参考热导率值和分别基于电阻率和热扩散率测量的两种间接方法获得的导出热导率值之间进行了比较。NPL 2I09 的参考热导率值与电阻率测量值在 2% 以内以及热扩散率、比热容、密度和热膨胀率测量值均优于 4% 的测量值相比较。此外，新批次Inconel 600的认证热导率值（NPL代码2I09）与J Clark和R Tye报告的Inconel 600代表性参考热导率值进行了比较，一致在2%以内。新的参考材料 NPL 2I09 可从 NPL 获得，可用于校准或检查提供热导率测量值的设备，范围包括 14 W·m -1 ·K -1 至 22 W·m -1 ·K -1覆盖温度范围从 100 °C 到 500 °C。基于标准不确定度乘以覆盖系数 k = 2，认证值的总体不确定度估计在 ± 4.8 % 以内，提供大约 95 % 的置信水平。