Frictional behaviors of graphene, which have been generally investigated on elastic or rigid substrates, are carefully discussed here in metal–graphene systems through molecular dynamics simulations. The nanoscratched process and topography analysis are conducted to study the friction on a composite surface, where the layer number, embedding depth, and interval of graphene are considered as major factors. The friction coefficient of monolayer graphene on an Al surface is obviously higher than the reported results on an elastic or rigid substrate, while the variety of substrates seems to make no much difference to frictional results on multilayer graphene. Graphene is actually helpful for reducing friction on composite surfaces, but the friction coefficient on composite surfaces will rocket from 0.045 to 0.835 with the rise in the embedding depth of graphene, and this range of data is consistent with experimental values measured on Al–graphene composite coatings. Moreover, a larger distance between graphene may lead to an increase in the overall friction coefficient, which can also be proved by electroplating experiments under a low concentration of graphene.

中文翻译：

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纳米划痕Al-石墨烯系统摩擦响应的原子模拟

石墨烯的摩擦行为通常在弹性或刚性基材上进行研究，此处通过分子动力学模拟在金属-石墨烯系统中进行了仔细讨论。进行纳米划痕工艺和形貌分析以研究复合材料表面的摩擦，其中石墨烯的层数、嵌入深度和间隔被认为是主要因素。单层石墨烯在铝表面的摩擦系数明显高于弹性或刚性基板上的报道结果，而基板的种类似乎对多层石墨烯的摩擦结果没有太大影响。石墨烯实际上有助于减少复合材料表面的摩擦，但复合材料表面的摩擦系数会从 0.045 飙升至 0。835 随着石墨烯嵌入深度的增加，该范围的数据与在 Al-石墨烯复合涂层上测量的实验值一致。此外，石墨烯之间较大的距离可能导致整体摩擦系数的增加，这也可以通过低石墨烯浓度下的电镀实验证明。