Black DLC watch coating used by Wryst Sports Watches explained
Diamond-Like Carbon for sports watches exists in seven different forms of amorphous carbon materials that display some of the typical properties of diamond. They are usually applied as coatings to other materials that could benefit from some of those properties. All seven contain significant amounts of sp3 hybridized carbon atoms. The reason that there are different types is that even diamond can be found in two crystalline polytypes. The usual one has its carbon atoms arranged in a cubic lattice, while the very rare one (lonsdaleite) has a hexagonal lattice. By mixing these polytypes in various ways at the nanoscale level of structure, DLC coatings can be made that at the same time are amorphous, flexible, and yet purely sp3 bonded "diamond". The hardest, strongest, and slickest is such a mixture, known as tetrahedral amorphous carbon, or ta-C. For example, a coating of only 2 μm thickness of ta-C increases the resistance of common stainless steel against abrasive wear; changing its lifetime in such service from one week to 85 years. Such ta-C can be considered to be the "pure" form of DLC, since it consists only of sp3 bonded carbon atoms. Fillers such as hydrogen, graphitic sp2 carbon, and metals are used in the other 6 forms to reduce production expenses or to impart other desirable properties.The various forms of DLC can be applied to almost any material that is compatible with a vacuum environment.
What makes Wryst so different?
Today, not many watch brands use strong and resistant black coating for watch cases. Most of the ones that do, use a very vulnerable PVD coating (Physical vapor deposition) which hardly offers any resistance against wear and tear at all. Some Swiss Luxury watch brands such as Raymond Weil, Bell & Ross, Panerai and IWC use/used black PVD for coating the watch cases, when more High-end brands such as Audemars Piguet, Omega, Linde Verdelin & HYT exclusively use the benefits of the much harder DLC coating. In fact, 95 to 98% of black watches ever produced to date have a low grade PVD coating, and are therefore very vulnerable to scratches...
Originally, why was DLC invented?
The same internal stress that benefits the hardness of DLC materials makes it difficult to bond such coatings to the substrates to be protected. The internal stresses try to "pop" the DLC coatings off of the underlying samples. This challenging downside of extreme hardness is answered in several ways, depending upon the particular "art" of the production process. The most simple is to exploit the natural chemical bonding that happens in cases in which incident carbon ions supply the material to be impacted into sp3 bonded carbon atoms and the impacting energies that are compressing carbon volumes condensed earlier. In this case the first carbon ions will impact the surface of the item to be coated. If that item is made of a carbide-forming substance such as Ti or Fe in steel a layer of carbide will be formed that is later bonded to the DLC grown on top of it. Other methods of bonding include such strategies as depositing intermediate layers that have atomic spacings that grade from those of the substrate to those characteristic of sp3 bonded carbon. In 2006 there were as many successful recipes for bonding DLC coatings as there were sources of DLC.
Yes but, are Wryst watches really scratch resistant?
Here is the comment of one of our customer: " I have had a Wryst Airborne for a year and a half. Zero scratches on the coating or crystal". M. Petrose, Ohio USA