Graphene-and-Copper Artificial Nacre Fabricated by a Preform Impregnation Process: Bioinspired Strategy for Strengthening-Toughening of Metal Matrix Composite

Abstract

Metals can be strengthened by adding hard reinforcements, but such strategy usually compromises ductility and toughness. Natural nacre consists of hard and soft phases organized in a regular "brick-and-mortar" structure and exhibits a superior combination of mechanical strength and toughness, which is an attractive model for strengthening and toughening artificial composites, but such bioinspired metal matrix composite has yet to be made. Here we prepared nacre-like reduced graphene oxide (RGrO) reinforced Cu matrix composite based on a preform impregnation process, by which two-dimensional RGrO was used as "brick" and inserted into "□-and-mortar" ordered porous Cu preform (the symbol "□" means the absence of "brick"), followed by compacting. This process realized uniform dispersion and alignment of RGrO in Cu matrix simultaneously. The RGrO-and-Cu artificial nacres exhibited simultaneous enhancement on yield strength and ductility as well as increased modulus, attributed to RGrO strengthening, effective crack deflection and a possible combined failure mode of RGrO. The artificial nacres also showed significantly higher strengthening efficiency than other conventional Cu matrix composites, which might be related to the alignment of RGrO.

Ultrahigh Electrical Conductivity of Graphene Embedded in Metals

“…However, these rather sophisticated methods make the transfer of any molecular‐level, superior carrier transport properties to macroscopic bulk materials difficult. Not surprisingly, the electrical conductivity of most reported graphene (or graphene derivative)‐reinforced metal matrix composites does not surpass that of the pure metal matrices . In this work, we demonstrate that graphene sheets deposited by chemical vapor deposition (CVD) and embedded inside metal matrices (Cu, Ag, and Al) can provide local, ultrahigh electrical conductivity inside the composite material that is up to three orders of magnitude higher than that of most conductive pure metals at room temperature, showing a remarkable potential for enhancing the electrical conductivity of metals.…”

Strength of Graphene-Coated Ni Bi-Crystals: A Molecular Dynamics Nano-Indentation Study

“…In the following, we will base our analysis on the averaged data. Forces (μN) 30° hm [1] 30° hm [2] 30° hm [3] 30° hm [4] 30° hm [5] average (a) Since, in all our studies, we use the same indenter and target material, we can use the force-depth curves to identify the material response. In particular, the momentary contact pressure-given by the quotient of the force and the cross-sectional area of the indenter at a specified depth-contains no further information than the force-depth curves.…”

“…Graphene-metal nanocomposites are an interesting class of materials which exhibit improved mechanical properties [1]. In these, graphene-with its high in-plane elastic modulus and yield strength-is used as reinforcement component for ductile metals [2][3][4][5]. The increase in strength in the nanocomposite materials is usually attributed to the presence of interfaces that act as barriers to the propagation of dislocations [6][7][8][9].…”

Preparation and Mechanical Property of Graphene-reinforced Copper Matrix Composites

“…由于石墨烯固有的优异力学性质, 研究人员通 过不同工艺制备的石墨烯铜基复合材料的强度得到 非常明显的提高。但是随着金属材料强度的提高, 塑性和韧性通常会下降, 强度韧性呈明显的倒置 关系。在石墨烯铜基复合材料中, 石墨烯作为增强 相使得铜基体的强度显著增大, 但是其韧性和延展 性却大大降低, 这也是制约石墨烯铜基复合材料实 际工业应用的主要瓶颈之一。近年来, 层状结构由 于构型相对简单、制备方法多样且能实现金属基复 合材料性能指标的最优化配置而备受关注。其中, Xiong 等 [57] 受到仿生贝壳结构启发, 通过化学途经 复制冷杉木结构先制备出层状多孔铜结构, 然后浸 渗氧化石墨烯溶液, 制备出还原氧化石墨烯铜基复 合层状材料, 展示出高强度和高韧性, 如图 5 所示。 除此之外, Zhang 等 [58] 通过原位合成法制备了 一种具有三维石墨烯网格/铜构型(3D GN@Cu@Cu) 的石墨烯增强铜基复合材料。该工艺首先在原位上 合成三维石墨烯网格/铜粉末(3D GN@Cu), 使得纳 米铜颗粒紧密地结合在三维石墨烯网格粉末上。然 后, 进一步地在三维石墨烯网格粉末上包裹铜, 形 成具有 3D GN@Cu@Cu 结构的石墨烯/铜粉末, 最后热压成型, 如图 6 所示。实验结果表明此种工 艺获得的石墨烯增强铜基复合材料具有高强度和强 韧性。 图 5 具有仿生贝壳结构的石墨烯铜基复合材料的制备过程示意图 [57] Fig. 5 Schematic representation of fabricating RGrO-and-copper artificial nacre [57] 图 6 三维石墨烯网格/铜复合材料的制备过程示意图 [58] Fig.…”