Analysis of the heat conduction mechanism for Al2O3/Silicone rubber composite material with FEM based on experiment observations

Based on the microcosmic configuration of samples on cross-section, a three-dimensional particle random distribution model of spherical Al2O3/SIR composites was built. Through sample measurement and model calculation, the effects of volume fraction, particle size and binary filling schemes of the Al2O3 fillers on thermal conductivity of the composites were studied. The particle contact probability which aiming at single sized particles filling case and different sized particles filling case were proposed to quantitatively characterize the formation probability of heat conduction path in the materials. Increasing the volume fraction of fillers can increase the contact probability of filler particles. When the volume fraction of Al2O3 fillers exceeds a certain threshold, the thermal conductivity of composites increases slightly first and then decreases with the increment of particle size. For Al2O3/SIR composites filled with different particle size fillers, as the volume fraction of the reinforced fillers with small particle size increases, the thermal conductivity of composites rises. As the particle size of the reinforced fillers increases, the thermal conductivity rises first and then reduces. The optimal volume ratio between the main fillers and reinforced fillers will be affected by the total filling content of the Al2O3 fillers.