The "diamond-like" term reflects that the film (coating) contains some portion of sp3 (diamond) and sp2 (carbon) bonding. This bonding has mechanical properties different from those of a diamond. Diamond-like carbon (DLC) is an amorphous carbon material that displays some of the typical properties of a diamond. It is a thin film coating deposited on other materials to impart essential properties of diamond, such as hardness, chemical resistance, and scratch resistance, and to provide surface lubrication to minimize friction, among others. DLC coatings have high thermal and electrical conductivity, making them ideal for use in medical devices, microelectronics, and automotive components. Protective coatings on displays, flexible semiconductors, and sensors are coated with DLC to increase the durability of the product and increase the overall product life.
DLC coating is deposited on any material by the "plasma-enhanced chemical vapor deposition (PE-CVD)" process. Polymers are often known to have low melting points and are therefore coated with DLC in order to improve their melting points and surface hardness. Polymers like PET (Polyethylene Terephthalate) are one of the major products coated with DLC in order to impart strength and have an extended product life. The structure and mechanical properties of DLC are based on the method of deposition and incorporation of additional elements like hydrogen, nitrogen, silicone, and other metal dopants. These additional elements control the hardness of the resultant film, the level of residual stress, and the tri-biological properties. The DLC coatings are chemically inert and can be used for a number of materials like aluminum-silicon alloys, powder metallurgy, cylinders, pistons, balls, gates, actuators, crankshafts, ball bearings, rotors, and impellers, amongst many others.
The limited coating thickness of DLC (5 m and below) is a major impediment to its use. Since the film itself is under the influence of residual stresses, de-lamination failure can occur in cases of high film stress. A lower temperature, which degrades the DLC to graphite, is another factor restraining the growth. The properties of graphite are not similar to those of diamond, and hence the coating may not be worthy enough to impart desired properties. In recent years, there has been an increased focus on applying DLC films to mass-produced mechanical components, including medical components. This is one of the major factors that is expected to propel the market growth for DLC coatings and their applications.
Diamond-like Carbon (DLC) is classified as Hydrogen Free DLC (a-C), Hydrogenated DLC (a-C: H), Tetrahedral Amorphous Carbon DLC (ta-C: H), and Others (Silicon DLC, Metal DLC, and so on). The DLC market by product type is driven by the ta-C segment due to the fact that it is the purest form of DLC as it contains only sp3-bonded atoms. It has major applications in metal coatings. Based on the application, the market is segmented into medical products, thermal applications, packaging products, automotive products, and others (metal forming, tools & tackles, mechanical seals, etc.). Automotive applications led the market in 2017 due to DLC's high wear resistance, friction resistance, and non-stick properties. It is considered an ideal surfacing solution for automotive and other stressed components and tools.
In terms of demand and consumption, Asia Pacific was the largest market for diamond-like carbon (DLC) in 2017, closely followed by Europe and North America. As of 2017, China was the largest market for DLC since, for the same year, it was the leading automotive manufacturing hub in the world. Other BRICS countries like India, with their ongoing "Make in India" program, are expected to boost the manufacturing sector, especially automotive and electronics. The Asia Pacific region is projected to be the largest market for medical, electrical, and automotive components for the forecast period.
The global diamond-like carbon (DLC) market is segmented as below:
