Properties and Classification of Diamond-Like Carbon Films

Abstract

Diamond-like carbon (DLC) films have been extensively applied in industries owing to their excellent characteristics such as high hardness. In particular, there is a growing demand for their use as protective films for mechanical parts owing to their excellent wear resistance and low friction coefficient. DLC films have been deposited by various methods and many deviate from the DLC regions present in the ternary diagrams proposed for sp3 covalent carbon, sp2 covalent carbon, and hydrogen. Consequently, redefining the DLC region on ternary diagrams using DLC coatings for mechanical and electrical components is urgently required. Therefore, we investigate the sp3 ratio, hydrogen content, and other properties of 74 types of amorphous carbon films and present the classification of amorphous carbon films, including DLC. We measured the sp3 ratios and hydrogen content using near-edge X-ray absorption fine structure and Rutherford backscattering-elastic recoil detection analysis under unified conditions. Amorphous carbon films were widely found with nonuniform distribution. The number of carbon atoms in the sp3 covalent carbon without bonding with hydrogen and the logarithm of the hydrogen content were inversely proportional. Further, we elucidated the DLC regions on the ternary diagram, classified the amorphous carbon films, and summarized the characteristics and applications of each type of DLC.

Electrical Conduction Properties of Hydrogenated Amorphous Carbon Films with Different Structures

“…As a result of this clarification, the a -C: H film with the optimum mechanical properties for use in a given environment has been applied to the surfaces of mechanical parts. [ 1 , 7 , 8 , 9 ]. Another notable feature of a -C:H films is that they have a wide range of physical properties resulting from their structural flexibility.…”

“…Another notable feature of a -C:H films is that they have a wide range of physical properties resulting from their structural flexibility. The sp 2 / sp 3 ratio and hydrogen content can be controlled in the range of 0.3–0.9 and 0.1–0.6, respectively [ 8 , 10 ]. These structural factors depend on the deposition condition [ 1 ].…”

“…Unlike silicon, carbon can form three types of covalent bonds because of its ability to form hybrid orbitals of sp , sp 2 and sp 3 . In a -C:H, there exist mainly sp 2 and sp 3 hybridized carbon simultaneously [ 8 , 19 ]. For sp 2 hybridized carbon, the 2 s orbital is mixed with two 2 p orbitals to form three equivalent sp 2 orbitals and one remaining p orbital.…”

Synthesis of Multilayered DLC Films with Wear Resistance and Antiseizure Properties

“…Diamond-like carbon (DLC) films are extensively utilized in various fields owing to their high hardness, low friction, chemical stability, and high wear resistance [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. The amorphous DLC films comprise sp 3 -bonded carbon of diamond with a tetrahedral 3D-network structure, sp 2 -bonded carbon of graphite with a hexagonal structure, and hydrogen [ 12 , 13 ].…”

DLC-Coated Ferroelectric Membranes as Vascular Patches: Physico-Chemical Properties and Biocompatibility

“…The following techniques are used for the deposition of DLC coatings on metal and ceramic implants: magnetron sputtering, ion beam deposition, vacuum-arc evaporation, pulsed laser deposition, mass selected ion beam deposition, and plasma-based ion implantation [ 20 , 21 ]. The listed methods of DLC coating fabrication require accelerating potential to the substrate, resulting in a significant rise in the substrate temperature, or they do not have a sufficient deposition rate.…”