ZHOU Qiong, HUANG Biao, ZHANG Ergeng, ZHANG Zhifu

(Shanghai Engineering Research Center of Physical Vapor Deposition (PVD) Superhard Coating and Equipment,
Shanghai Institute of Technology, Shanghai 201418, China)

Abstract: Diamond-like carbon (DLC) coatings are widely used in aerospace, automotive parts and biomedical fields due to their high hardness, good wear resistance, low friction coefficient and good chemical inertia. However, the properties of DLC coating obtained from different types of carbon sources by different preparation technologies vary greatly. In this paper, the deposition mechanism of DLC coating prepared by using hydrocarbon and hydrogen free carbon and the reasons for performance difference between Hydrogen DLC coating and Hydrogen-free DLC coatings are reviewed. The differences in the DLC coating preparation technologies among physical vapor deposition, chemical vapor deposition and liquid phase method are described. The causes of high internal stress, insufficient bonding strength and poor thermal stability of DLC coatings and measures to solve them are summarized. On this basis, the mechanisms of reducing the internal stress of DLC coatings by doping with strong carbon elements (Ti), weak carbon elements (Al) and non-bonding elements (Cu), improving the bonding strength by designing functionally graded multilayers and improving the thermal stability of DLC coatings by element doping are analyzed. Additionally, it is suggested that the further research can be carried out on the mechanical properties of DLC films from basic theories and related technologies.
Key words: diamond-like carbon; preparation mechanisms; internal stress; bonding strength; thermal stability