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Enhanced corrosion resistance in metal matrix composites assembled from graphene encapsulated copper nanoflakes
- Jin, Baoyin, Xiong, Ding-Bang, Tan, Zhanqiu, Fan, Genlian, Guo, Qiang, Su, Yishi, Li, Zhiqiang, Zhang, Di
- Carbon 2019 v.142 pp. 482-490
- anisotropy, coatings, copper, copper nanoparticles, corrosion, electrical conductivity, electrochemistry, encapsulation, ferric chloride, graphene, microstructure, protective effect, sodium chloride
- Corrosion protection of metals is of great importance due to their widespread use. Graphene (Gr) has shown promising corrosion resistance as a coating for metals, however, its excellent strengthening effect that has been widely shown is suppressed in such coating applications. Here, inspired by positive anti-corrosion role of graphene coating for metal macro-foils, graphene encapsulated Cu (Cu@Gr) micro-/nano-flakes are designed and fabricated, and then used as building blocks for assembling bulk Gr/Cu composites. Thanks to its protective role and strengthening effect of uniformly dispersed graphene in Cu matrix, as compared to bare copper, corrosion rate of the as-fabricated bulk Gr/Cu composites is reduced by 50% in NaCl solution and its yield strength is increased by ∼180% (2.5 vol% Gr) simultaneously, without deterioration on electrical conductivity. The anti-corrosion mechanisms are understood by studying etching behavior of the Cu@Gr flakes in FeCl3 solution, and surface morphology evolution in the samples subjected to salt spray corrosion, and electrochemical corrosion tests. Graphene's anti-corrosion effect is also reflected by an anisotropic corrosion behavior of the Gr/Cu composite because of a “brick-and-mortar” microstructure. The results presented here shed light on expanding metal matrix composite's applications to a wider range and more complex situation by incorporating graphene.