Preparation and characterization of graphene/metal composites
Licentiate thesis, 2021
In this regard, the emphasis of this study was to investigate a scalable and simple method to obtain such MMC via powder metallurgy. Specifically, gas atomized copper powder was functionalized with 3-aminopropyl-triethoxysilane (APTES) in toluene (APTES-Cu), resulting in a positively charged surface; then aqueously dispersed and negatively charged graphene oxide (GO) could then be self-assembled on the surface APTES@Cu via electrostatic interaction (Cu@APTES-Cu). The thickness of GO layers and morphology on the powder was controlled by modulating APTES grafting duration and APTES concentration in toluene. Cu@APTES-Cu powders were thermally annealed before compaction and sintering in inert atmosphere.
The results show that surface modification of metal powders serves as a scalable and versatile approach to coat graphene on metal particles for the preparation of graphene/metal composites. Surface modification of copper with 0.2 vol% APTES in toluene for 30 minutes was sufficient to obtain composite powders with incomplete GO coating, which nonetheless demonstrated improved hardness. However, cold working of sintered composites was essential to densify the porous structure created by reduced GO during sintering. On the other hand, sintered composite samples that exhibited higher thermal conductivity than copper was obtained with higher APTES and GO loading. After thermal annealing, these thicker GO coatings were found to improve thermal conductivity in sintered composites by acting as thermal bridges between individual composite particles. Despite incomplete sintering of these composites, a 20% increase in thermal conductivity was attainable. Finally, both polarization scans and etching measurements in concentrated HCl and ammonium persulfate (APS) indicate that the GO coating decomposes on the outer surface during sintering. However, the reduced GO coating can retard corrosion of the internal composite structure by diffusion inhibition.
metal matrix composite
Kristoffer Harr Martinsen
Chalmers, Industrial and Materials Science, Materials and manufacture
Martinsen, K. H, Sun, J, Kovtun, A, Bojestig, E, Hansson, J, Liu, Y, Liu, J, Klement, U, Hryha, E, Nyborg, L, Palermo, V Coating graphene on Cu for improved thermal, mechanical properties annd printability for additive manufacturing
Martinsen, K. H, Sun, J, Xia, Z, Kovtun, A, Klement, U, Hryha, E, Nyborg, L, Palermo, V Dual anticorrosion protection of Cu by silanes and graphene with controlled thickness
Graphene Core Project 2 (Graphene Flagship)
European Commission (EC) (EC/H2020/785219), 2018-04-01 -- 2020-03-31.
Manufacturing, Surface and Joining Technology
Metallurgy and Metallic Materials
Composite Science and Engineering
Chalmers Materials Analysis Laboratory
Areas of Advance
Thesis for the degree of licentiate of engineering / Department of Materials Science and Engineering, Chalmers University of Technology: Technical Report IMS-2021-8
Virtual Development Laboratory (VDL), Chalmers tvärgata 4C, Campus Johanneberg
Opponent: Xiaoyan Zhang, Chalmers University of Technology