In this study, we investigated the low friction mechanism of a diamond-like carbon (DLC) film heated by laser irradiation in a nitrogen gas environment. The friction coefficient decreased from 0.5 to 0.06 when the contact area was heated to 250 °C. Subsequently, we heated the DLC film under non-contact conditions (2 μm distance between DLC film and pin surface) and collected the liquid materials adhered on the pin surface. The adhered materials were revealed to be hydrocarbons with –CH₂– main-chains, as observed using Raman spectroscopy. On the other hand, thermal desorption gas chromatography with mass spectrometry using helium as a carrier gas demonstrated that hydrocarbons such as alkenes and alkanes with relatively high molecular weight were generated from heated DLC. This agreement between the results of the two analysis techniques suggested that the hydrocarbons in the liquid phase at room temperature were generated from the DLC film heated to a high temperature over 250 °C in an inert gas atmosphere. In addition, we confirmed the reduction in the friction coefficient after pre-heating a different location, as well as the dependence of the friction coefficient on the sliding velocity. The results suggest that hydrocarbons (e.g., alkenes or alkanes) generated upon DLC heating could possibly act as a lubricant to reduce the friction coefficient.

Graphical Abstract

中文翻译：

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氮气环境中激光加热产生的液态烃会导致类金刚石碳膜的低摩擦

在这项研究中，我们研究了在氮气环境中通过激光辐照加热的类金刚石碳（DLC）膜的低摩擦机理。当接触面积加热到250°C时，摩擦系数从0.5降低到0.06。随后，我们在非接触条件下（DLC膜与针表面之间的距离为2μm）加热DLC膜，并收集粘附在针表面上的液体材料。发现所粘附的材料是具有–CH _2的烃–使用拉曼光谱法观察到的主链。另一方面，使用氦作为载气的质谱热解吸气相色谱法表明，加热的DLC产生了分子量较高的烯烃，链烷烃等烃。两种分析技术的结果之间的一致性表明，室温下液相中的碳氢化合物是由DLC膜在惰性气体气氛中加热到250°C以上的高温生成的。此外，我们确认了在预热不同位置后摩擦系数的降低以及摩擦系数对滑动速度的依赖性。结果表明，碳氢化合物（例如，

图形概要