
Diamond-like carbon (DLC) coating is a thin-film material that combines some of the desirable properties of diamond and graphite. It is widely used across industries to enhance the performance, durability, and efficiency of various components. This article provides a detailed overview of DLC coating, including its composition, properties, applications, and benefits.
What is DLC Coating?
DLC coating is a type of carbon-based coating that exhibits characteristics similar to natural diamond, such as high hardness and low friction. The term “diamond-like” originates from its structure, which includes both diamond-like (sp3) and graphite-like (sp2) carbon bonds.
DLC coatings can be deposited as amorphous (non-crystalline) layers using techniques such as Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD). These coatings are typically applied to a variety of substrates, including metals, plastics, and ceramics, depending on the application.
Advantages:
- Significant improvement in surface hardness and durability
- Reduction in friction and wear
- Enhanced resistance to corrosion and oxidation
- Customizable properties through doping and deposition methods
- Biocompatibility for medical uses
While DLC coatings offer numerous advantages, they also have some limitations:
- High initial cost of deposition equipment
- Limited coating thickness (typically <5 micrometers)
- Sensitivity to substrate material compatibility
Types of DLC Coating
There are several types of DLC coatings, categorized based on their bonding structure and deposition process. The most common types include:
- Hydrogenated DLC (a-C:H): Contains hydrogen atoms in its structure, offering lower internal stress and better adhesion to certain substrates.
- Hydrogen-Free DLC (a-C): Highly dense and harder than hydrogenated DLC, it is suitable for extreme wear and high-temperature applications.
- Tetrahedral Amorphous Carbon (ta-C): Known for its high sp3 bond content, this is the hardest type of DLC coating and provides excellent wear resistance.
- Doped DLC Coatings: Incorporating elements such as silicon (Si), oxygen (O), or metals (e.g., tungsten, chromium) improves specific properties, such as thermal stability or electrical conductivity.
DLC Coating Processes
Diamond-Like Carbon (DLC) coatings are applied using several deposition methods, each offering unique advantages:
Physical Vapor Deposition (PVD)
PVD is a vacuum-based process where solid carbon is vaporized and condensed onto a substrate, forming a thin film. Techniques such as sputtering and arc evaporation are commonly used in this method.
Chemical Vapor Deposition (CVD)
CVD involves introducing hydrocarbon gases into a reaction chamber, where they decompose at elevated temperatures to deposit a carbon-based film on the substrate. Plasma-enhanced CVD (PECVD) utilizes plasma to enhance chemical reactions, allowing for lower deposition temperatures and improved film properties.
Plasma-Assisted Deposition
Plasma-assisted methods, such as Plasma-Assisted Chemical Vapor Deposition (PACVD), use plasma to enhance the deposition process. In PACVD, a precursor gas is introduced into a plasma environment, where it is ionized and decomposed. The resulting carbon species then deposit onto the substrate, forming a DLC coating. This technique is effective for coating complex shapes and achieving films with tailored properties.

DLC Finishing Properties
Diamond-Like Carbon (DLC) coatings are renowned for their exceptional surface finishing properties, which significantly enhance the performance and durability of various components. Key finishing properties of DLC coatings include:
Surface Smoothness and Uniformity
DLC coatings are characterized by their extremely smooth and uniform surfaces. This smoothness reduces friction and wear, making them ideal for applications requiring precise and consistent surface finishes.
Low Friction Coefficient
The low friction coefficient of DLC coatings minimizes energy loss due to friction, enhancing the efficiency of mechanical systems. This property is particularly beneficial in applications involving sliding or rolling movements.
Hardness and Wear Resistance
DLC coatings exhibit high hardness, with Vickers hardness values ranging from 2500 to 4500 HV. This hardness provides excellent wear resistance, extending the lifespan of components subjected to mechanical stress.
Corrosion Resistance
DLC coatings offer superior corrosion resistance, protecting substrates from chemical degradation and extending the service life of components in corrosive environments.
Aesthetic Appeal
The uniform and smooth finish of DLC coatings also enhances the aesthetic appeal of components, making them suitable for consumer products where appearance is important.
Applications of DLC Coatings
The unique combination of properties makes DLC coatings suitable for various applications:
- Automotive Industry: DLC coatings are commonly applied to engine components, such as pistons, camshafts, and valve lifters, to reduce wear, friction, and improve fuel efficiency.
- Aerospace: In aerospace, DLC coatings are used on turbine blades, bearings, and other high-stress components to extend their lifespan and improve performance in high-temperature environments.
- Medical Devices: Due to their biocompatibility, DLC coatings are used in medical devices like joint implants, catheters, and surgical tools, offering both improved durability and reduced friction when in contact with tissues.
- Cutting Tools and Machinery: DLC coatings are applied to cutting tools, dies, and molds to reduce friction, enhance tool life, and improve machining performance. This is particularly beneficial in industries like metalworking and plastics molding.
- Electronics: DLC coatings are used in semiconductor devices and in electronics manufacturing to reduce wear and enhance the performance of components like magnetic storage devices and connectors.
DLC Coating Options:
Coating | Composition | Key Features |
---|---|---|
CeraTough®-0601 | a-C:H (Hydrogenated DLC) | High hardness, wear resistance, low friction |
CeraTough®-0602 | ta-C (Tetrahedral DLC) | Extremely hard, wear-resistant |
CeraTough®-0603 | a-C:H:Si (Si-doped DLC) | Enhanced wear resistance, thermal stability |
CeraTough®-0604 | a-C:H:W (Tungsten-doped DLC) | Increased wear resistance, high load-bearing capacity |
CeraTough®-0605 | a-C:H:WC (WC-doped DLC) | Superior hardness, toughness, wear resistance |
CeraTough®-0606 | a-C:H:Cr (Chromium-doped DLC) | Corrosion resistance, enhanced hardness |
CeraTough®-0611 | a-C:H+CrN (DLC + Chromium Nitride) | Wear and corrosion resistance |
CeraTough®-0701 | a-C:H:Si (Thin DLC) | Precision, thin coating, wear resistance |
CeraTough®-0702 | a-C:H:Si (Thick DLC) | Enhanced durability, thicker coating |
CeraTough®-0710 | a-C:H:Si (Rainbow DLC) | Aesthetic finish, silicon-doped for high performance |
CeraTough®-D-F | a-C:H:Si (Food-safe DLC) | Approved for food contact, wear resistance |
Conclusion
DLC coatings offer a powerful solution for enhancing the performance of a wide variety of industrial components. With their exceptional hardness, wear resistance, low friction, and corrosion resistance, DLC coatings are well-suited for high-performance applications across industries like automotive, aerospace, medical, and manufacturing. However, careful consideration of factors such as cost, brittleness, and adhesion is necessary to maximize the benefits of DLC coatings in each specific application.

This article was written by engineers from the BOYI team. Fuquan Chen is a professional engineer and technical expert with 20 years of experience in rapid prototyping, mold manufacturing, and plastic injection molding.