Diamond-like carbon (DLC) is a class of amorphous carbon material that displays some of the typical properties of diamond. DLC is usually applied as coatings to other materials that could benefit from some of those properties.
DLC coatings are often used to prevent wear due to their excellent tribological properties. DLC is very resistant to abrasive and adhesive wear making it suitable for use in applications that experience extreme contact pressure, both in rolling and sliding contact. DLC is often used to prevent wear on razor blades and metal cutting tools, including lathe inserts and milling cutters. DLC is used inbearings, cams, cam followers, and shafts in the automobile industry. The coatings reduce wear during the 'break-in' period, where drive train components may be starved for lubrication.
DLCs may also be used in chameleon coatings that are designed to prevent wear during launch, orbit, and re-entry of land-launched space vehicles. DLC provides lubricity at ambient atmosphere and at vacuum, unlike graphite which requires moisture to be lubricious.
Despite the favorable tribological properties of DLC it must be used with caution on ferrous metals. If it is used at higher temperatures, the substrate or counter face may carburize, which could lead to loss of function due to a change in hardness. This phenomenon prevents the use of DLC coated machine tool on steel.
Applications of DLC typically utilize the ability of the material to reduce abrasive wear. Tooling components, such as endmills, drill bits, dies and molds often use DLC in this manner. DLC is also used in the engines of modern supersport motorcycles, Formula 1 racecars, NASCAR vehicles, and as a coating on hard-disk platters and hard-disk read heads to protect against head crashes. Virtually all of the multi-bladed razors used for wet shaving have the edges coated with hydrogen-free DLC to reduce friction, preventing abrasion of sensitive skin. It is also being used as a coating by some weapon manufacturers/custom gunsmiths. Some forms have been certified in the EU for food service and find extensive uses in the high-speed actions involved in processing novelty foods such as "chips" and in guiding material flows in packaging foodstuffs with plastic wraps. DLC coats the cutting edges of tools for the high-speed, dry shaping of difficult exposed surfaces of wood and aluminium, for example on automobile dashboards.
Medical applications: The wear, friction, and electrical properties of DLC make it an appealing material for medical applications. Fortunately, DLC has proved to have excellent bio-compatibility as well. This has enabled many medical procedures, such as Percutaneous coronary intervention employing brachytherapy to benefit from the unique electrical properties of DLC. At low voltages and low temperatures electrodes coated with DLC can emit enough electrons to be arranged into disposable, micro-X-ray tubes as small as the radioactive seeds that are introduced into arteries or tumors in conventional brachytherapy. The same dose of prescribed radiation can be appliedfrom the inside, out with the additional possibility to switch on and off the radiation in the prescribed pattern for the X-rays being used. DLC has proved to be an excellent coating to prolong the life of and reduce complications with replacement hip joints and artificial knees. It also has been successfully applied to coronary artery stents, reducing the incidence of thrombosis. The implantable human heart pump can be considered the ultimate biomedical application where DLC coating is used on blood contacting surfaces of the key components of the device.
The Space Black stainless steel Apple Watch is coated with diamond-like carbon.