Erosion of fluorinated diamond-like carbon films by exposure to soft X-rays

Abstract

The effects of soft X-ray irradiation on fluorinated diamond-like carbon (F-DLC) films were investigated using synchrotron radiation (SR). The Vickers hardness of the F-DLC films substantially increased from an initial value of about 290 to about 800 HV at a dose of 50 mA·h and the remained constant at about 1100 HV at doses of more than 300 mA·h. This dose dependence was consistent with those of the film thickness and elemental composition. The depth profile of the elemental composition inside each F-DLC film obtained by the measurement of the X-ray photoelectron spectrum (XPS) during sputtering showed that the composition ratio of fluorine was approximately constant from the surface to the neighborhood of the substrate. Namely, fluorine atoms were desorbed by SR irradiation from not only the surface but also the substrate neighborhood. Modification by SR irradiation was found to occur in the entire F-DLC film of about 200 nm thickness.

A review on diamond-like carbon-based films for space tribology

“…The nanocomposite DLC films are capable of delaying the occurrence of this change and maintaining a relatively low lifetime. For example, although soft X-rays influence the whole F-DLC film instead of just the outermost surface, a low F content contributes to resisting soft X-ray irradiation [104,105]. Similarly, the presence of Si doping could restrict the desorption of hydrogen by X-ray irradiation [106,107].…”

Particle‐Induced Erosional Behaviors of Diamond‐Like Carbon Films

“…[11] Kanda et al studied the erosion of the fluorinated DLC films exposed to soft X-rays and found that the radiation can cause the uniform decrease in fluorine composition from film surface to substrate. [12] However, the erosion behaviors of DLC films caused by hard particles, which can cause severe mass loss, has been rarely reported in literature, leading to the unclear erosion mechanisms of these films.…”