Coatings

DLC (diamond like carbon) coatings are a family of coatings with properties and underlayers that can be adjusted to provide the optimum performance for an application. Within the DLC family of coatings, the coating hardness and can vary tremendously depending on the region of the phase diagram the coatings fall in to. The ratio of SP² to SP³ bonding and hydrogen content can vary in the film depending on the process used to deposit the DLC coating and the process parameters. The phase diagram to the right shows the various groups or regions for DLC coatings and the possibilities that are available. Films with higher SP² bonding or graphitic content will exhibit lower film hardness and tend to provide lower abrasion-resistance. Films with a very high SP³ bonding content will tend to be very hard with a high level of abrasion-resistance but will be brittle and less ductile. Films with very high SP³ content and no hydrogen are tetrahedral DLC (ta-C) coatings exhibiting a very high surface hardness of up to 5000 Hv but offer low ductility.

All DLC coatings will have multiple bonds and varying hydrogen content within the coating. Depositing a film that combines the proper amount of hydrogen as well as the proper ratio of SP² to SP³ bonding and the best underlayer for the application is key to providing customers with low friction, a high level of wear-resistance, ductility and proper adhesion and load carrying capability. NCT works with customers to understand the wear modes and operating conditions of your component to select the best DLC coating for your application.