颗粒填充型聚合物的导热性能与摩擦磨损性能研究

采用蒙特卡罗可控空间分布算法,生成网链构型的三维代表体积单元(RVE)模型,数值研究了非均匀分布下不同组分氮化铝/石墨/银导热硅脂的导热性能。制备了氮化铝、氮化铝/石墨、氮化铝/石墨/银三种填料体系的导热硅脂,并测试所有样品的热导率和体积电阻率。采用往复摩擦磨损试验机对室温下导热硅脂在钢-钢摩擦副上的载流摩擦磨损性能进行研究。利用扫描电子显微镜(SEM)观察金属表面并利用能谱分析仪(EDS)对表面元素成分进行分析。结果表明:导热填料形貌越丰富,硅脂中的导热网络越致密,氮化铝/石墨/银硅脂的最大热导率可达1.623 W/(m·K),可实现在较少填充量下获得较高热导率;氮化铝/石墨/银有限元模型模拟的结果更贴近实验测量值,可以用来预测球状/片状/棒状颗粒填充导热硅脂的导热性能;氮化铝/石墨/银导热硅脂的载流摩擦磨损性能最优,这归结于其导热性能和导电性能协同减轻电弧对金属表面的侵蚀。

Study on Thermal and Tribological Properties of Particles Filled Polymer Composites

Three-dimensional network configuration representative volume element (RVE) models were built to investigate thermal properties of conductive silicon greases containing different fractions of AlN/C/Ag by applying a Monte Carlo controllable spatial distribution algorithm. Thermal conductive silicon greases containing AlN, AlN/C and AlN/C/Ag were prepared, the thermal conductivity and the volume resistivity of all samples were experimentally measured. The electrical tribological properties were stu-died with a reciprocating friction/wear testing machine under iron/iron contacting at room temperature. SEM and EDS were utilized to observe and analyze the friction area after test. It is found that affluent morphology of conductive fillers will lead to generate compact thermal conductive network, and the thermal conductivity of AlN/C/Ag can be up to 1.623 W/(m·K), which means that the less loading of fillers can obtain higher thermal conductivity. Meanwhile, the simulation result of finite model of AlN/C/Ag has a better agreement with the experimental result at the same mass fraction, which can be used to predict thermal conductivity of silicon greases with sphere/flake/stick fillers. The optimal electrical tribological properties of AlN/C/Ag thermal conductive silicon grease are ascribed to the function of thermal conductivity and electrical conductivity combined, which can be helpful to abate the arc erosion on the friction contacts.