Research and development of advanced aluminium/graphite composites for thermal management applications

Thermal management materials are continuously gaining importance as a consequence of everlasting evolution in performance of electronic and electric devices. In particular, by improving the heat exchanger’s materials' properties (i.e. thermal conductivity) it is possible to boost further performance and miniaturization of such devices. Due to their high thermal conductivity, Copper and Aluminium are currently the most commonly used materials for thermal management applications. However, the mismatch in thermal expansion between Cooper/Aluminium and Silicon is limiting the heat transfer at the interface between the electronic chip and the heat exchanger. Furthermore, Copper is indeed characterized by a high thermal conductivity but at the same time its high density (8.9 g/cm3) increases weight of the final product, which in most of the cases does not meet specific application requirements. High cost of these materials is another constraint which limits their application. Due to aforementioned facts, monolithic metals used as thermal management materials cannot simultaneously satisfy characteristics of high thermal conductivity, low thermal expansion and low density. As an answer to this demand, an ongoing research is observed to investigate advanced composites as an alternative to conventional monolithic structures. Among variety of compositions, the Aluminium-Graphite reinforced metal matrix composite seems to be a promising solution due to its superior thermal properties and low cost. Several variants of composites are presented in this thesis, starting with a study and simulation of their properties, production process and refinement, finalized with experimental measurements of thermal and mechanical properties of the final compositions. Conducted research and development works led to interesting results – created composites outrun pure Aluminium’s thermal conductivity while keeping adequate mechanical properties: very low coefficient of thermal expansion and density.