This study assessed the influences of fluorine introduced into DLC films on the structural and mechanical properties of the sample. In addition, the effects of the fluorine incorporation on the compressive stress in DLC films were investigated. For this purpose, fluorinated diamond-like carbon (F-DLC) films were deposited on cobalt-chromium-molybdenum substrates using radio-frequency plasma-enhanced chemical vapor. The coatings were examined by Raman scattering (RS), Attenuated total reflectance Fourier transform infrared spectroscopic analysis (ATR-FTIR), and a combination of elastic recoil detection analysis and Rutherford backscattering (ERDA-RBS). Nano-indentation tests were performed to measure hardness. Also, the residual stress of the films was calculated by the Stony equation. The ATR-FTIR analysis revealed that F was present in the amorphous matrix mainly as C-F and C-F2 groups. Based on Raman spectroscopy results, it was determined that F made the DLC films more graphitic. Additionally, it was shown that adding F into the DLC coating resulted in weaker mechanical properties and the F-DLC coating exhibited lower stress than DLC films. These effects were attributed to the replacement of strong C = C by feebler C-F bonds in the F-DLC films. F-doping decreased the hardness of the DLC from 11.5 to 8.8 GPa. In addition, with F addition, the compressive stress of the DLC sample decreased from 1 to 0.7 GPa.

Abstract
1. Introduction
2. Materials and Methods
3. Results and Discussions
4. Conclusion
References

• Sayed Mohammad Adel Aghili(Department of Materials Science and Engineering, Marvdasht Branch, Islamic Azad University)
• Raheleh Memarzadeh(Department of Materials Science and Engineering, Marvdasht Branch, Islamic Azad University) Corresponding author
• Reza Bazargan Lari(Department of Materials Science and Engineering, Marvdasht Branch, Islamic Azad University) Corresponding author
• Akbar Eshaghi(Department of Materials Engineering, Malek Ashtar University of Technology)