DLC High-Tech Coating

DLC HIGH-TECH COATING

The coating that today offers the greatest potential for a variety of applications is DLC, an acronym for DIAMOND LIKE CARBON.

DLC is a meta-stable coating consisting of Carbon (C) which is present in two different allotropic forms: sp2 (Graphite) and sp3 (Diamond).

GALVANOTECHNIK has its own know-how for the completely independent management of all the phases of the process with which it develops cycles dedicated to the specific needs of the various applications.

TYPES OF DLC

  • a-C (Amorphous graphite)
  • ta-C Amorphous Tetrahedral C Layer)
  • a-C:Me (Layer of amorphous C doped with Metal such as Ti,Ce,W…)
  • a-C:H (Hydrogenated amorphous C layer)
  • ta-C:H (Hydrogenated amorphous tetrahedral C layer)
  • a-C:H:Me (Hydrogenated amorphous C layer doped with Metal)

CHARACTERISTICS OF THE DLC:

Being acquainted with the characteristics of DLC coating enables you to appreciate its extraordinary versatility of use:

  • The thickness of the layer can vary from 0.5 to 15 microns, maintaining a highly compact structure (Figure 2-3).
  • The application of the DLC must always and only be carried out on finished products.
  • The deposition temperature is between 100°C and 250°C.
  • The hardness of the various types of DLC can vary from 1.900Hv to 4.000Hv depending on the content of sp3 and this allows tackling the most complicated abrasion wear phenomena.
  • The internal stresses are of a compressive nature and can be estimated at 0.5-15 GPa.
  • The coefficient of friction measured against 100Cr6 is very low (0.05-0.06) depending on the amorphous structure of the carbon.
  • The low coefficient of friction makes it possible to curb the forces involved in the system avoiding any dissipation of energy in heat.
  • Resistance to corrosion against chemical agents is linked to the compactness of the coating and its chemical inertia (it resists in salt spray for over 1500 hours or 40 hours in hydrofluoric acid). This characteristic enables it to be used in harsh environments from the corrosive point of view and even in contact with biological fluids.
  • Sensitivity to high temperatures limits its use within 400°C. The thermal instability of DLC is associated with low hydrogen content.
  • DLC is an electrical insulator (102-1016 cm-1), showing a refractive index n= 1.8-2.4 E thermal conductivity of around 0.5W/m cm.

DLC APPLICATIONS

In the light of the many experiences acquired, the applications where DLC coating has been most successful are listed below:

  • Automotive and Racing: gears, valves, rocker arms, stems, camshafts, cups, pistons, pins, injection pins.
  • Automatic machines: food, textile, packaging, printing.
  • Mechanical parts in general: hard disks, ball valves, weapons, knives, parts for compressors, razor blades.
  • Tools: moulds for plastic materials.
  • Fashion: watches, jewellery, bracelets, piercings.