DLC coatings can be deposited using a number of different techniques. These techniques can generally be divided in two categories: chemical vapour deposition (CVD) and physical vapour deposition (PVD). In general, a carbonaceous precursor and an energy source are required. The carbon source may be an ionized carbon-containing gas or a solid carbon target that can be activated by, for example, thermal evaporation, ion sputtering or laser ablation. Most of the processes upon which DLC deposition is based are physical in nature, as the sp3 bonds are produced by the impact of carbon (or hydrocarbon) ions on the growing film.

The physical processes that have been proposed to deposit DLC thin films include direct ion beam (IB) and ion beam assisted deposition (IBAD), filtered cathodic vacuum arc (FCVA), DC and RF sputtering, pulsed laser deposition (PLD), and plasma immersion ion implantation (PIII). Other techniques involving chemical processes include plasma enhanced chemical vapour deposition (PECVD) and electron cyclotron resonance plasma chemical vapour deposition (ECR-CVD).

You can increase the dep. rate if you deposit in PECVD equipment. Though u have to go with high power pressure regime to reduce the deposition time for 10 micron thick film.

Hello Ruslan.

I would like to clarify. What is meant by DLC (Diamond Londeylite ...)? This is generally mixture of carbon allotropic phases. If we are talking about a mixture of phases (as I understand it), what phase (mostly) do you mean?

B.R.

Konstantin.

Sorry for confusion. DLC stays for Diamond-like Carbon coating, which is deposited from a pure graphite target.

It depends on the area to coat. Smaller surfaces in the range of some cm² may be also coated by PLD (Pulse Laser Deposition with a stationary plume) with a rate of up to 10 - 20 µm/h.

Hello Ruslan.

If carbon is evaporated from surface a carbon target in form of ions and radicals, then it is deposited on (metallic?) Surface and thus obtain DLC. Right?

In this case, after evaporation, carbon or argon-carbon plasma will transport ionic and carbon radicals to deposition surface.

Depending from energy of ions and their concentration, in unit of volume, allotropic modifications of carbon will be deposited on surface. To obtain a predominantly crystalline diamond, it is necessary to set such energy and concentration of carbon ions at which the quantity of crystalline diamond will be maximum.

Do I correctly understood that you apply?

B.R.

Konstantin

Dear Konstantin,

It is correct, except that DLC is typically amorphous.

We tried different pressure levels and argon flow rates, but the voltage is always unstable (jumps from 200 to 500 V) and the deposition rate is extremely small. Perhaps it is something wrong with our magnetron. Anyway, magnetron sputtering seems to be impractical for 10 micron coatings. Can Arc-PVD do 10 micron of brittle coating on metallic/ceramic free form surface ?

Hello Ruslan.

In theory, the rate of carbon coating in 1μM/min is quite achievable when using graphite cathode as target for ARC-PVD at continuous operation mode. Composition and quality of coating deposited by this method will probably have to work out.

Few separate trial experiments were carried out with this method of deposited (DLC) coatings, but I do not know how to mass production.

B.R.

Konstantin.

The higher thickness of the DLC coating would induce residual stress and make the coated layer very brittle. Typically the thickness blow 2 micrometer is recommended. You can use PECVD technique however the structure of the coating would be ta-C:H.

Here is the article you may have interest in:

"Omid Sharifahmadian, Farzad Mahboubi, Sepehr Yazdani,

Comparison between corrosion behaviour of DLC and N-DLC coatings deposited by DC-pulsed PACVD technique"