Diamond Like Carbon coating has many commercial applications, including machine tools, aerospace parts, F1 engine parts, pharmaceutical implants, and of course, high end watches.
There are a few key characteristic of DLC, which has helped it to supplant the use of PVD as a cosmetic coating for fine timepieces:
It's Harder
DLC is an extremely hard coating. The following graph (from pvtechnology.it) shows the comparative surface hardness of various materials, using the Vickers of Hardness scale:
In terms of relative hardness, DLC, at 4000+ HV is:
- About 5X as hard as stainless steel
- About equal to sapphire
- About one-half as hard as diamond
- Significantly harder than other PVD coatings
It's Extremely Wear Resistant
Because of its durability, DLC is used as tribological coating for machine tools such as drill bits, saws, and dies. When used on a watch, DLC coatings provide superior durability and wear resistance.
It has a Lower Coefficient of Friction
DLC is quite slick. The following chart compares the coefficient of friction of DLC and other materials:
One of the primary uses of DLC is as a dry lubricant for pumps, machine parts, bearings, cams...even razor blades.
The low-friction attributes of DLC help to increase the durability of the coating when used on watches. Glancing blows against a hard surface, which may dig in and damage normal PVD coating, are more likely to simply slide over across the surface of a DLC coated case.
Simply stated, it's just more difficult to damage a DLC coating.
These characteristics, along with the beauty of DLC, have helped it to grow in popularity as a hard surface coating for fine watches.
Read more about the properties of DLC:
AZOM.com
WIKIPEDIA.org
PVTECHNOLOGY.it
