目的 基于阿蒙顿固体摩擦理论和静电力理论，利用原子力显微镜和开尔文显微镜研究晶界对单层多晶MoS2和MoSe2纳米片摩擦性能的影响。方法 用化学气相沉积法制备单层多晶MoS2和MoSe2，结合摩擦力显微镜模块、开尔文显微镜模块，在单层多晶MoS2和MoSe2不同区域上（500 nm×500 nm），研究晶界对其摩擦性能的影响。结果 对于单层多晶MoS2和MoSe2，有明显晶界区域的粗糙度、接触电势差和粘附力要大于无明显晶界区域或无晶界区域。有明显晶界区域的摩擦系数大于其他区域，无明显晶界区域的摩擦系数大于无晶界区域。结论 探针在晶界处滑动时，受到棘轮效应和压电效应的双重作用，导致探针更大的变形量与更多的能量耗散，因此有明显晶界区域的摩擦力显著增大。对于晶界不明显的区域，其摩擦力仅受压电效应的作用，也会有所增大。对于无晶界的区域，因探针滑动时不会受到棘轮效应和压电效应的作用，其摩擦力相对较小。

Based on Amonotons’ solid friction and the electrostatic force theory, the effect of grain boundary on the friction properties were studied by using atomic force microscope and Kelvin microscope for molybdenum disulfide and molybdenum diselenide nanosheets. The polycrystalline MoS2 and MoSe2 with monolayer were prepared by chemical vapor deposition, and the effect of grain boundary on the friction properties were measured in different regions (500 nm×500 nm) by friction microscopy module and Kelvin microscopy module. For the monolayer polycrystalline MoS2 and MoSe2, the roughness, contact potential and adhesive force in the obvious grain boundary area for the morphology map were larger than those in the non-obvious grain boundary region or the non-grain boundary region. The friction coefficient in the obvious grain boundary region was larger than that in other regions, and the friction coefficient in the non-obvious grain boundary region was larger than that in the non-grain boundary region. When the probe slided on the grain boundary, it was affected by both the ratchet effect and piezoelectric effect, and they leaded to the larger deformation and more energy dissipation. Therefore, there is higher friction in the obvious grain boundary region. For the increased friction in the non-obvious grain boundary region, it was only affected by piezoelectric effect. For the non-grain boundary regions, the friction were relatively small because the probe couldn’t affected by the ratchet effect and piezoelectric effect.