銅の導電性が驚異的に向上(An Electrifying Improvement in Copper Conductivity)

2023-12-21

2023-12-20 パシフィック・ノースウェスト国立研究所(PNNL)

◆米国エネルギー省（DOE）太平洋西北国立研究所の研究者らは、電気線の製造において、グラフェンを銅に18ppm添加することで、温度係数の低下を11%達成し、室温の電気伝導性を損なうことなく、電気モーターや産業用機器の効率向上が可能であることを示しました。
◆これは通常の金属の振る舞いに反しており、新しい製造プロセス「ShAPE™」を使用して実現されました。この発見により、電力供給の効率向上や電気自動車のモーター効率の向上が期待され、特許出願も行われました。

＜関連情報＞

摩擦押出し銅-グラフェン複合材の前例のない電気的性能 Unprecedented electrical performance of friction-extruded copper-graphene composites

Bharat Gwalani, Xiao Li , Aditya Nittala, Woongjo Choi, Md. Reza-E-Rabby, Julian Escobar Atehortua, Arun Bhattacharjee, Mayur Pole, Joshua Silverstein, Miao Song, Keerti Kappagantula
Materials & Design Available online: 9 December 2023
DOI:https://doi.org/10.1016/j.matdes.2023.112555

Highlights

•Copper-graphene feedstock films shear-extruded to bulk copper-graphene wires.
•Adding 18 ppm graphene decreased C11000 TCR by ∼11 % and increased conductivity by ∼1.4 %.
•Microstructure with graphene present as agglomerates and flakes possibly responsible for electrical properties.

Abstract

Copper-graphene composites show remarkable electrical performance surpassing traditional copper conductors albeit at a micron scale; there are several challenges in demonstrating similar performance at the bulk scale. In this study, we used shear assisted processing and extrusion (ShAPE) to synthesize macro-scale copper-graphene composites with a simultaneously lower temperature coefficient of resistance (TCR) and improved electrical conductivity over copper-only samples. We showed that the addition of 18 ppm of graphene decreased the TCR of C11000 alloy by nearly 11 %. A suite of characterization tools involving scanning and transmission electron microscopy along with atom probe tomography were used to characterize the grain size, crystallographic orientation, structure, and composition of copper grains and graphene additives in the feedstock and processed samples. We posit that the shear extrusion process may have transformed some of the feedstock graphene additives into higher defect-density agglomerates while retaining the structure of others as mono-to-tri-layer flakes with lower defect density. The combination of these additives with heterogeneous structures may have been responsible for the simultaneous decrease in TCR and enhanced electrical conductivity of the copper-graphene ShAPE composites.