DLC coating

Super-hard DLC coatings are increasingly gaining importance, thanks to their unique and exceptional wear-, friction- and corrosion-reducing properties.

Specifications

Hardness	2000-6000 kg/mm²
Friction coefficient	0,02 (vacuum) -0.7 (air)
Density	2-2,8 g/cm³
Resistivity	10 6 - 10 16 Ohm/cm
Index of refraction	1,8-2,4
Infrared transparency	2-20 µm
Thermal conductivity	1100 W/mK
Surface quality	Dependent on the preparation Ra<0.05
Chemical resistance	Acids, bases, organic compounds
Thermal resistance	Up to about 600°C
Biocompatibility	Yes
Coat thickness	Adjustable 1-5 µm
Color	Anthracite black

Examples of use

All metals and semiconductors that form stable carbide compounds, e.g. aluminum, iron, titanium, molybdenum, tungsten, chromium, silicon, germanium; glass, ceramics and titanium nitride are also well suited. Good adhesive coatings are also possible on plastics such as polyolephine and silicone-based plastic materials.

Materials that can be coated

Rhenotherm DLC coatings can be used where great hardness, low wear and low friction are required: thread guides, friction bearings, cylinder liners , guide rails, valve guides, valve seats, forming dies, reeds, orthopedic pins and plates, implants, audio and video heads, hard discs, glasses, IR optics.

: Duolayer, a-C:H - coatings

: Multilayer, a-C:H - coatings

Rhenotherm GmbH was a member of an expert committee on CVD diamond tools, where it was actively involved in formulating a guideline for the Verein Deutscher Ingenieure [Association of German Engineers], VDI 2840.

NEW: Hard-coat processes in thin-film coating technology

(coatings from 0.5 – 5 µm)

A diamond-like carbon coating refined by Rhenotherm that is applied using the plasma polymerization process.

: Transition to the dark hard-coating film

Process:

CVD process (plasma-enhanced chemical vapor deposition)

During this process, the coating is deposited directly from an argon/methane plasma. Due to the use of a bipolar pulsed plasma generator, nearly all types of substrates can be coated. In addition, this process provides a possibility for the development of adhesion promoter layers, although within several restrictions.

However, the interest in such hard-coating films isn’t just predicated on corrosion prevention.

In fact, one of the most surprising realizations of materials science is that the quality of a tool is influenced significantly by its surface condition and less so by the base material. As a result, coated materials offer the potential for much longer service life spans and may be used to replace hardened and tempered raw materials with less hard, but coated materials (e.g. ductile tool steel with DLC coatings replaces brittle carbides).

Due to their exceptional characteristics, diamond coatings or diamond-like coatings should certainly be considered among the hard-coating films of the future.

Their properties determining corrosion and wear are very similar to those of diamonds.

The DLC coatings can be deposited from a carbon plasma on nearly all metals and metal alloys (steel, bronze etc.), carbides and light metals (aluminum, magnesium etc.), but also on nonmetals (silicon, glass, ceramics, plastics etc.), with excellent bonding strength. The biggest advantage of this process is that different process parameters such as processing time influence the characteristics of the DLC coatings. Coating thickness, resistivity, hydrogen content and the like can thus be largely adapted to specific specifications.