Operando tribochemical formation of onion-like-carbon leads to macroscale superlubricity.
Operando tribochemical formation of onion-like-carbon leads to macroscale superlubricity.
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DOI：
10.1038/s41467-018-03549-6
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发表时间：
2018-03-21
影响因子：
16.6
通讯作者：
Sumant AV
中科院分区：
文献类型：
--
作者：
Berman D;Narayanan B;Cherukara MJ;Sankaranarayanan SKRS;Erdemir A;Zinovev A;Sumant AV
已知在相对运动期间在滑动界面处的应力诱导反应导致接触材料中的结构或化学改性。然而，在原子水平上的这些改性的性质和在无油环境中副产物的形成仍然知之甚少，并且在预测完整摩擦系统的摩擦学性能方面存在不确定性。在这里，我们表明，即使在干燥的条件下发生摩擦化学反应时，氢化类金刚石碳（H-DLC）表面滑动对二维（2D）二硫化钼沿着与纳米金刚石在干燥的氮气气氛中。结合反应分子动力学模拟的详细实验研究表明，在高接触压力下，硫从解离的二硫化钼中扩散导致纳米金刚石的非晶化，随后转化为洋葱状碳结构（OLC）。OLC在滑动界面处的原位形成提供了减小的接触面积以及相对于H-DLC表面的不相称接触，从而使得能够成功地证明超润滑性。在这里，作者发现了在干燥和无油条件下从2D MoS 2和纳米金刚石中形成洋葱状碳的纳米级摩擦催化剂，在宏观尺度上提供了超润滑性。
Stress-induced reactions at the sliding interface during relative movement are known to cause structural or chemical modifications in contacting materials. The nature of these modifications at the atomic level and formation of byproducts in an oil-free environment, however, remain poorly understood and pose uncertainties in predicting the tribological performance of the complete tribosystem. Here, we demonstrate that tribochemical reactions occur even in dry conditions when hydrogenated diamond-like carbon (H-DLC) surface is slid against two-dimensional (2D) molybdenum disulfide along with nanodiamonds in dry nitrogen atmosphere. Detailed experimental studies coupled with reactive molecular dynamics simulations reveal that at high contact pressures, diffusion of sulfur from the dissociated molybdenum disulfide led to amorphization of nanodiamond and subsequent transformation to onion-like carbon structures (OLCs). The in situ formation of OLCs at the sliding interface provide reduced contact area as well as incommensurate contact with respect to the H-DLC surface, thus enabling successful demonstration of superlubricity Stress-induced tribochemical reactions that reduce friction at sliding interfaces typically require liquid lubricants. Here, the authors discover the nanoscale tribocatalytic formation of onion-like carbon from 2D MoS2 and nanodiamond under dry and oil-free conditions, providing superlubricity at the macroscale.
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影响因子：
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