PSI - Issue 65

A.M. Kazakov et al. / Procedia Structural Integrity 65 (2024) 114–120 Kazakov A.M., Korznikova G.F., Korznikova E.A. / Structural Integrity Procedia 00 (2024) 000–000

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2.2. Interfacial bonding

The quality of the interface between graphene and copper is critical in ensuring efficient thermal transport across the composite. Stronger interfacial bonding reduces thermal resistance and allows heat to flow more freely between the materials. Techniques like spark plasma sintering and molecular-level mixing have been employed to enhance this bonding, significantly improving the thermal performance of the composites. There are several methods to enhance interfacial bonding in copper-graphene composites. Using nanoporous graphene can help generate copper nanoislands on the graphene surface, facilitating atomic diffusion bonding at low temperatures, Song et al. (2022). This approach can significantly increase the interfacial shear strength between graphene and copper. The next way to improve interfacial bonding is adding elements like Cr and Mg to the copper matrix. Cr can form finely dispersed chromium carbide particles at the interface, significantly improving bonding strength, Lu et al. (2022). Graphene modification can also be used to enhance interfacial bonding in the composite. Decorating graphene surfaces with metal particles (e.g., Cu, Ni, Ag) can enhance interfacial binding and mechanical properties (Lu et al., 2022). Another way is to use graphene oxide as a binder. Graphene oxide can act as a surfactant and "glue" to strengthen bonding between the thermal conductivity coating and the copper matrix (Hu et al., 2024). It can also interact with graphene through π–π conjugation, achieving uniform dispersion. Finally, boron-doped graphene may provide better interfacial bonding compared to oxygen functionalization, while maintaining excellent mechanical and physical properties, Hidalgo-Manrique et al. (2019), Savin et al. (2015), Lisovenko et al. (2016). Despite this, there are still some challenges that researches face in this field. Obtaining effective interfacial bonding is difficult due to the poor affinity of graphene to metals. Copper does not wet graphene, and covalent bonding is not possible as no reactions occur between Cu and graphene. In unmodified copper-graphene systems, weak mechanical adhesion and van der Waals interactions are the primary bonding mechanisms (Hidalgo-Manrique et al., 2019). Proper consideration of the above-mentioned factors and the use of various simulation methods, Babicheva et al. (2022), Babicheva et al. (2019), can be the key to overcome the existing difficulties. For example, Kazakov et al. (2023) implemented the molecular dynamics method to investigate thermal conductivity in copper graphene composites with different configurations of graphene layers relative to copper, and its dependence on composite density. Figure 3 shows the results of the work.

Fig. 3. The dependence of coefficient of thermal conductivity k on composite density ρ and graphene effect on thermal properties for different composite architecture (Kazakov et al., 2023).

2.3. Fabrication method

The method used to fabricate copper-graphene composites greatly impacts their thermal properties. There are many different methods to produce graphene-metal composites, which can be classified as powder metallurgy methods, electrochemical methods, chemical vapor deposition (CVD) and some novel approaches.