Thermophysical Data for the Development of Mathematical Models of Solidification

用于开发凝固数学模型的热物理数据

• 批准号: 06044271
• 负责人: NAGATA Kazuhiro
• 金额: --
• 依托单位: TOKYO INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Overseas Scientific Survey.
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044271/
• 关键词: Liquid metal; Alloy; Solidification; Mathematical model; Thermophysical data; Thermal conductivity; Specific heat capacity; Emissivity

Thermophysical data for liquid metals and alloys are very important as input data for mathematical models of solidification. The aim of this collaborative work is to develop methods for measuring thermal conductivities, specific heat capacities and emissivities for liquid metals and alloys.(A) Thermal conductivity measurementThe hot wire method has been improved : The hot wire probe should be coated with insulated substance to avoid current leakage when applied to conducting materials. The probe wires were made of alumel and oxidized thermally, which produced an insulated oxide film on the surface. The thermal conductivity value for mercury measured using this probe is 13W/mK,which is larger than the published value 8.5W/mK.This discrepancy would be due to convection, about which further work should be made. The use of Pt containing Al as probe wires is prospective for measuring on liquid metals at high temperatures.(B) Specific heat capacity measurementThe combination of the drop-calorimeter and levitation method has been proposed to avoid contamination from crucibles : A sample is melted and held at high temperature using the levitaion method and then dropped into a calorimeter. Further investigation is being made about the possibility of this method.(C) Emissivity measurementEmissivity has been measured by comparison between spectral intensities of a liquid sample radiation and of blackbody radiation. The emissivity values for liquid copper and nickel at the wavelength 800nm have been determined to be 0.10 at 1673K and 0.31 at 1873K,respectively. Measurements in infrared wavelengths are also required. The cold crucible technique would be helpful to avoid oxidation and contamination of samples.

液态金属和合金的热物理数据作为凝固数学模型的输入数据非常重要。这项合作工作的目的是开发测量液态金属和合金的热导率、比热容和发射率的方法。(A)热导率测量改进了热线法：热线探头应涂有绝缘物质，以应用于导电材料时避免电流泄漏。探针线由明矾制成，并经过热氧化，在表面产生绝缘氧化膜。使用该探头测得汞的热导率为13W/mK，大于公开值8.5W/mK。这种差异可能是由于对流造成的，对此还需进一步研究。使用含铝 Pt 作为探针线在高温下测量液态金属具有前景。(B) 比热容测量提出了将落热量计和悬浮法相结合以避免坩埚污染：将样品熔化并使用悬浮方法保持在高温下，然后放入量热计中。关于该方法的可能性正在进一步研究。(C)发射率测量通过比较液体样品辐射和黑体辐射的光谱强度来测量发射率。液体铜和镍在波长 800nm 下的发射率值分别确定为 1673K 时的 0.10 和 1873K 时的 0.31。还需要红外波长的测量。冷坩埚技术将有助于避免样品的氧化和污染。