Lu Liu,Guobing Ying,Dong Wen,Yuexia Li,Kaicheng Zhang,Huihua Min,Cong Hu,Cheng Sun,Cheng Wang
Two-dimensional (2D) nanomaterials based on MXenes have gained increasing importance in the field of strength reinforcement. However, the easy oxidation of MXenes has long been deemed unfavorable for reinforcement in high-temperature processing. Herein, high-shear mixing was used in present work for simple and efficient dispersion of MXenes in copper powders. Partial MXene sheets were also in-situ oxidized to TiO 2 particles to form nail board-like structure reinforcement (NSR) during spark plasma sintering (SPS) process at 600 °C, which allowed one to significantly improve the yield strength of copper matrix by up to 70.3%. Experimental characterization and modeling simulations enabled one to identify second phase strengthening as the main reason for increased yield strength of the composites. In particular, the mechanical engagement of NSR played an important role in strengthening. Meanwhile, the hardness of TiO 2 particles on NSR was found to be higher than that of the copper matrix, leading to enhancement in compressive yield strength. Also, the presence of MXene sheets on NSR slightly reduced the resistance of copper matrix composites . In sum, these findings look promising for designing novel MXene reinforced metal matrix composites with improved mechanical properties.
The development of a material with high ampacity to allow current to flow through narrow channels is one of the most promising ways to address the progressive miniaturization and light weight of electronic devices. The efficient synergistic electron transmission by compounding 1D/2D carbon materials with a metal matrix via various methods in recent years has attracted great research interest due to their potential utilization in electronics. In this study, a copper (Cu) matrix with a 3D nitrogen (N) doped-multi-walled carbon nanotubes (MCNTs) interface with prominent physical features is reported and fabricated, involving the use of nano-self-assembly-heat-modification by adopting polyethyleneimine-nano-Cu and carboxyl MCNTs. Young's modulus was enhanced from 28.8 to 92.2 GPa due to a higher efficiency of stress transfer and interfacial adhesion, and the hardness fitted by Gauss distribution was increased by ∼69% (∼39.7 HRC). Toward the stability after a modification of vacuum reduction sintering, the initial oxidation temperature (T d ) was increased largely from 232 °C to 286 °C, and thermal conductivity was enhanced eminently from 358 to 548 W/(m K) due to more efficient electron/phonon motion. Moreover, synergistic electron transmission endowed the final Cu-N-CNTs with a higher ampacity (7.23–16.98 × 10 4 A cm −2 ), which could be further observed by the time-evolution of electrical resistivity under a constant current density. The improved physical features state that the assembled 3D N-CNTs interface possesses prominent characteristics and potential for directing the deep applications of 1D or 2D carbon materials in electronic science.
We developed a layered composite with directional distributed reduced graphene oxide (RGO) in a copper matrix through a double-slot multi-step electrodeposition method, playing to the advantage of in-plane thermal conductivity of RGO. The resulting RGO/Cu composite has superior thermal conductivity up to 545 W m −1 K −1 (150% of copper), which was determined by the growth behavior of the RGO flake on the copper substrate through adjusting electrodeposition time. By analyzing the structure, distribution status and its relationship with thermal conductivity, three factors including of structural integrity of RGO, thermal conduction network and interfacial effect between RGO layers were proposed. With the increase of deposition time, the restoration of RGO lattice structure and the formation of a complete thermal conduction network both promoted the phonon transmission, which was beneficial to the improvement of thermal conductivity. The multi-layer stacking of RGO, however, could generate the interlayer interfacial effects, resulting in the phonon scattering and unfavorable to the thermal conductivity. Therefore, proper adjustment of RGO deposition time resulted in excellent thermal conductivity of RGO/Cu composite, meeting the demands for the heat dissipation performance of the instrument.
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