Freeform thermal-mechanical Bi-functional Cu-plated diamond/Cu metamaterials manufactured by selective laser melting

Abstract

The leverage of selective laser melting (SLM) successfully fabricate metal matrix composites (MMCs) metamaterials with freeform intricate triply periodic minimal surface (TPMS) structures that are not possibly fabricated by conventional methods and exhibit exceptional mechanical properties. SLM fabricated high precision MMCs metamaterial TPMS structures are of great potential in energy conversion, heat management and lightweight applications. Due to the self-supporting geometric characteristics of TPMS, the metamaterial structures could effectively overcome the manufacturing constraints of SLM. Besides, their freeform capability offers great opportunities to be bi-functional or multi-functional through the selection of materials as well as the design optimization of structure. Diamond can offer unique advantages in the field of heat management due to its outstanding thermal and mechanical properties. The addition of micro-sized diamond particles into copper can tailor its coefficient of thermal expansion (CTE) while enhancing its thermal conductivity (TC). SLM fabricated diamond reinforced copper MMCs metamaterials with TPMS structure could bring outstanding thermal-mechanical bi-functional properties for prospective lightweight thermal management applications. In our previous work, the interfacial bonding issue between diamond particles and Cu matrix was resolved by a coating of copper on micro-sized diamond particle reinforcement. In this present work, 1 vol% Cu-plated diamond/Cu metamaterials with three various TPMS (Gyroid-G, Schwarz Primitive-P, Diamond-D) structures were successfully fabricated via SLM for the first time. Their bi-functional heat transfer and compression behaviors were evaluated by measurement and numerical simulation for three TPMS (G, P, D) structures and TPMS (D) structures with various lattice thicknesses. From the lightweight perspective of three TPMS structures with 0.2 mm wall thickness, the order of these structure is TPMS P structure, TPMS G structure, TPMS D structure (0.2 mm wall thickness, 0.2 P > 0.2 G > 0.2D). If heat transfer performance is an important consideration, The 0.2D structure can be selected from the three TPMS structures. This research also investigated the continuous design of TPMS D structure with various wall thickness and creatively proposed a flexible TPMS design paradigm toward advanced thermal-mechanical bi-functional Cu-plated Diamond/Cu metamaterials via SLM for prospective lightweight thermal management applications.