Chhowalla M, Amaratunga GA
Engineering Department, University of Cambridge, UK.
Nature. 2000 Sep 14;407(6801):164-7. doi: 10.1038/35025020.
The tribological properties of solid lubricants such as graphite and the metal dichalcogenides MX2 (where M is molybdenum or tungsten and X is sulphur or selenium) are of technological interest for reducing wear in circumstances where liquid lubricants are impractical, such as in space technology, ultra-high vacuum or automotive transport. These materials are characterized by weak interatomic interactions (van der Waals forces) between their layered structures, allowing easy, low-strength shearing. Although these materials exhibit excellent friction and wear resistance and extended lifetime in vacuum, their tribological properties remain poor in the presence of humidity or oxygen, thereby limiting their technological applications in the Earth's atmosphere. But using MX2 in the form of isolated inorganic fullerene-like hollow nanoparticles similar to carbon fullerenes and nanotubes can improve its performance. Here we show that thin films of hollow MoS2 nanoparticles, deposited by a localized high-pressure arc discharge method, exhibit ultra-low friction (an order of magnitude lower than for sputtered MoS2 thin films) and wear in nitrogen and 45% humidity. We attribute this 'dry' behaviour in humid environments to the presence of curved S-Mo-S planes that prevent oxidation and preserve the layered structure.
石墨以及金属二硫属化物MX2（其中M为钼或钨，X为硫或硒）等固体润滑剂的摩擦学特性在液体润滑剂不适用的情况下（如空间技术、超高真空或汽车运输领域）对于减少磨损具有技术意义。这些材料的特点是其层状结构之间存在较弱的原子间相互作用（范德华力），使得易于进行低强度剪切。尽管这些材料在真空中表现出优异的摩擦和耐磨性能以及较长的使用寿命，但其在有湿度或氧气存在的情况下摩擦学特性仍然较差，从而限制了它们在地球大气中的技术应用。但是，以类似于碳富勒烯和纳米管的孤立无机类富勒烯空心纳米颗粒形式使用MX2可以改善其性能。在此我们表明，通过局部高压电弧放电方法沉积的空心MoS2纳米颗粒薄膜在氮气和45%湿度环境下表现出超低摩擦（比溅射的MoS2薄膜低一个数量级）和磨损。我们将在潮湿环境中的这种“干”行为归因于弯曲的S-Mo-S平面的存在，这些平面可防止氧化并保持层状结构。
