Wear occurs between two rubbing surfaces. Severe wear due to seizure under high pressure leads to catastrophic failures of mechanical systems and raises wide concerns. In this paper, a kind of synthetic oil-soluble ultrathin MoS₂ sheets is synthesized and investigated as lubricant additives between steel surfaces. It is found that, with the ultrathin MoS₂ sheets, the wear can be controlled under the nominal pressure of about 1 GPa, whereas the bearable nominal pressure for traditional lubricants is only a few hundred megapascals. It is found that when wear is under control, the real pressure between the asperities agrees with the breaking strength of ultrathin MoS₂. Therefore, it is believed that, because of the good oil solubility and ultrasmall thickness, the ultrathin MoS₂ sheets can easily enter the contact area between the contacting asperities. Then, the localized seizure and further wear are prevented because there will be no metal-to-metal contact as long as the real pressure between the asperities is below the breaking strength of ultrathin MoS₂. In this way, the upper limit pressure the lubricant can work is dependent on the mechanical properties of the containing ultrathin two-dimensional (2D) sheets. Additionally, ultrathin MoS₂ sheets with various lateral sizes are compared, and it is found that sheets with a larger size show better lubrication performance. This work discovers the lubrication mechanism of ultrathin MoS₂ sheets as lubricant additives and provides an inspiration to develop a novel generation of lubricant additives with high-strength ultrathin 2D materials.

中文翻译：

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合成油溶性超薄MoS ₂薄板作为润滑剂添加剂的高压抗磨机理

在两个摩擦表面之间发生磨损。由于在高压下咬死而造成的严重磨损会导致机械系统的灾难性故障，并引起广泛关注。本文合成了一种合成的油溶性超薄MoS ₂片材，并作为钢表面之间的润滑剂添加剂进行了研究。已发现，使用超薄MoS ₂薄板，可以在大约1 GPa的标称压力下控制磨损，而传统润滑剂的可承受标称压力仅为几百兆帕。发现当磨损得到控制时，粗糙之间的实际压力与超薄MoS ₂的断裂强度一致。。因此，据信，由于良好的油溶性和极小的厚度，超薄的MoS ₂片材可以容易地进入接触粗糙度之间的接触区域。然后，由于不存在金属与金属的接触，只要在粗糙之间的实际压力低于极薄的MoS ₂的断裂强度，就可以防止局部的咬住和进一步的磨损。这样，润滑剂可以工作的上限压力取决于所容纳的超薄二维（2D）薄板的机械性能。此外，超薄MoS ₂比较了具有各种横向尺寸的片材，发现具有较大尺寸的片材具有更好的润滑性能。这项工作发现了超薄MoS ₂薄板作为润滑剂添加剂的润滑机理，并为开发新一代具有高强度超薄2D材料的润滑剂添加剂提供了灵感。