Effect of Powder Morphology on Thermal Conductivity for TiB₂ Particle Dispersed Aluminum Composites Fabricated by Spark Plasma Sintering

Abstract

In recent years, the use of Al matrix composites with high heat dissipation has grown because of the increased heat generation of high-power semiconductors. These composites must have excellent thermal conductivity, excellent mechanical properties over a wide temperature range, and the ability to suppress thermal expansion. In this study, TiB₂ particles were selected as the additive to pure aluminum, the composites of which were fabricated by sintering. The objective of this study was to clarify the relation between particle dispersibility and thermal conductivity. Initially, TiB₂ particles and Al powder were mixed dry and wet with ethanol to form mixed powders, and 10 vol.% TiB₂ particles dispersed pure Al matrix composites were fabricated using the spark plasma sintering (SPS) process. Subsequently, dispersibility was evaluated using the LN2DRver method, followed by particle size distribution, and thermal conductivity. Consequently, we were able to quantitatively assess the difference in dispersibility caused by the mixing method. Moreover, the experimental thermal conductivity was corrected using the relative density, and a slight difference was noted between wet and dry processes. Furthermore, the relation between dispersibility and thermal conductivity was calculated by simulation. The thermal conductivity increased as the dispersibility decreased, and as the volume fraction of TiB₂ particles in the pure Al matrix increased, the thermal conductivity improved significantly.