Jiang Ailong, Shao Anchen, Song Lin, Hua Minghao, Zheng Hongliang, Zhang Xiaofu, Tian Xuelei, Lin Xiaohang
Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, China.
State Key Laboratory of Engine Reliability, Weichai Power Co., Ltd., Weifang 261001, China.
Materials (Basel). 2023 Mar 7;16(6):2158. doi: 10.3390/ma16062158.
To provide the basis for thermal conductivity regulation of vermicular graphite cast iron (VGI), a new theoretical method consisting of shape interpolation, unit cell model and numerical calculation was proposed. Considering the influence of the graphite anisotropy and interfacial contact thermal conductivity (ICTC), the effective thermal conductivity of a series of unit cell models was calculated by numerical calculation based on finite difference. The effects of microstructure on effective thermal conductivity of VGI were studied by shape interpolation. The experimental results were in good agreement with the calculated ones. The effective thermal conductivity of VGI increases in power function with the decrease in graphite shape parameter, and increases linearly with the increase in graphite volume fraction and thermal conductivity of matrix. When the graphite volume fraction increases by 1%, the thermal conductivity of nodular cast iron increases by about 0.18 W/(m·K), while that of gray cast iron increases by about 3 W/(m·K). The thermal conductivity of cast iron has the same sensitivity to the thermal conductivity of matrix regardless of the graphite shape parameter. The thermal conductivity of matrix increased by 15 W/(m·K) and the thermal conductivity of cast iron increased by about 12 W/(m·K). Moreover, the more the graphite shape deviates from the sphere, the greater the enhancement effect of graphite anisotropy on thermal conductivity than the hindrance effect of interface between graphite and matrix. This work can provide guidance for the development of high thermal conductivity VGI and the study of thermal conductivity of composites containing anisotropic dispersed phase particles with complex shapes.
为了给蠕墨铸铁（VGI）的热导率调控提供依据，提出了一种由形状插值、单胞模型和数值计算组成的新理论方法。考虑到石墨各向异性和界面接触热导率（ICTC）的影响，基于有限差分通过数值计算得到了一系列单胞模型的有效热导率。通过形状插值研究了微观结构对VGI有效热导率的影响。实验结果与计算结果吻合良好。VGI的有效热导率随石墨形状参数的减小呈幂函数增加，随石墨体积分数和基体热导率的增加呈线性增加。当石墨体积分数增加1%时，球墨铸铁的热导率增加约0.18W/（m·K），而灰铸铁的热导率增加约3W/（m·K）。无论石墨形状参数如何，铸铁的热导率对基体热导率具有相同的敏感性。基体热导率增加15W/（m·K），铸铁的热导率增加约12W/（m·K）。此外，石墨形状偏离球体越多，石墨各向异性对热导率的增强作用比石墨与基体界面的阻碍作用越大。这项工作可为高导热率VGI的开发以及含复杂形状各向异性分散相颗粒复合材料的热导率研究提供指导。
