Description
Diamond-Like Carbon Coating (DLC) is the ultimate performance coating, offering a wear-resistant chemical barrier for metal, ceramic, glass, and plastic, normally deposited at temperatures below 150°C.
DLC is ultra resistant to abrasive and adhesive wear, rendering it suitable for use in both rolling and sliding applications that experience extreme contact pressure. Unlike graphite, DLC provides high lubricity at both ambient atmosphere and at vacuum.
We offer three specialized DLC processes: Advanced Auto Pro (AAP), Advanced Mold Pro (AMP) and Advanced Combo Pro (ACP).
Technology
DLC films are amorphous and consist of a mixture of sp2 (graphite) & sp3 (diamond) phases. The film properties are strongly dependent on the flux characteristics of the chosen deposition process (PVD sputter or evaporation and PACVD), metal and hydrogen content within the film, sp2:sp3 ratio, substrate bias voltage, ion energy and density, as well as substrate temperatures.
Properties
- Wear and abrasion resistance
- Low friction
- High hardness
- Anti-reflective coating
- Corrosion resistance
- Gas barrier
- Precision control of thickness
- Optical properties
- “Line of sight” process – part rotation is required and does not coat internal diameters
Typical Parameters
| Crystallinity | Amorphorous |
| Micro-hardness | 20 – 30 GPa |
| Coefficient of Friction Against Steel (dry) | 0.05 – 0.1 |
| Coating Thickness | 1 – 2 µ |
| Maximum Working Temperature | 300°C (570F) |
| Maximum Coating Temperature | 150°C – 180°C (350F) |
| Thermal Conductivity | 100 – 150 (W/(m·K)) |
| Coating Method | PACVD |
Our DLC Processes
ADVANCED AUTO PRO (AAP)
A DLC process which helps automotive designers achieve the EU6 emission limit and ensures component reliability with a surface solution that combines reduced friction and excellent wear protection.
Designed for highly stressed components, AAP is characterized by its extremely smooth surface and self-lubricating properties. Even in low lubrication conditions, the coating decreased the coefficient of friction significantly, performing as well as in well-lubricated conditions.
Properties
- Excellent abrasive and adhesive wear protection in tribological systems
- Low friction
- Ensures optimal function in lubrication deprived conditions
- Increases lifecycle
- Contributes towards lowering emissions
Applications
- Pistons, rings and pins
- Finger followers
- Tappets
- Injection components
ADVANCED MOLD PRO (AMP)
This Plasma-Assisted Chemical Vapour Deposition (PACVD) process activates chemical reactions through plasma excitation and ionization. It has been designed with the engineering, automotive, plastics processing, and semiconductor industries in mind. To guarantee best quality and performance, AMP coating is applied in a clean environment at a temperature range of 180°C – 220°C.
Properties
- Low surface energy
- Low micro porosity
- High hardness
- Low friction
- Biocompatible
- Excellent adhesion
- Can be tailored with respect to electrical conductivity and hydrophobic and hydrophilic behaviour
Applications
- Components for the automotive, engineering, and semiconductor industries
- Moving and form-giving mold components
- Caps and closures
- Ejector pins and bushings
- Blow mold and forms for PET cores and bottles
ADVANCED COMBO PRO (ACP)
This process is deposited by a combination of PVD and PACVD. It has been designed with racing and high performance engine applications in mind. The ACP coating is applied at a temperature range of 180°C – 350 °C.
Properties
- Enhances performance
- Reduces friction
- Reduces wear and extends part life
- Greater performance and reliability
- Protects both coated component and uncoated counterpart
Applications
- Piston rings
- Valve train components
- Oil pump shafts
Applications
Due to their unique combination of properties, DLC coatings are extremely effective in many other tribological and wear applications, such as:
- Mold and mold components
- Engines of modern super-sport motorcycles
- Formula 1 race cars
- NASCAR vehicles
- Magnetic storage media like hard disk platters and hard-disk read heads
- Diesel injection pumps
- Dry shaping of difficult exposed surfaces of wood and aluminum
- Human heart pump implants
- Electrical insulator of copper devices for chip cooling
- Encapsulants for photovoltaic solar cells
- Laser barcode scanner windows in supermarkets
- Textile industry parts, etc.
Questions & Answers
- most common defects are due to adhesion to the base metal and high residual stress deposit.
- DLC is a very stress deposit and when applied in a thick layer; one way to avoid the stress is to dope it with other metals.
What is DLC coating?
DLC coatings are a family of coatings made up primarily of carbon chains in an amorphous structure with sp2 bond (hexagonal known as graphite) and sp3 bond (cubical known as diamond). They are recognized for outstanding mechanical properties and tribological performance.
There are many different types of DLC coatings, some hydrogen free, (a-C) some hydrogenated (a-C:H)
At CMC most of the DLC we do is hydrogenated; some of our process is applied in a multi-layer (gradient hardness layers).
The DLC coatings we do are deposited by PACVD method.
What is the typical coefficient of thickness of DLC?
DLC coatings have a very low coefficient of thickness values. In a dry ball-on-disc (BOD) test the friction values are in the range of 0.1 and in some cases as low as 0.05.
What are the applications of DLC?
Although DLC coatings are more that 40 years old, they now became very popular for many applications.
They have provided good results for automotive products, cutting tools, mold, stamping, optical products, biomedical, filters, meshes, audio devices, medical products, nuclear products, among many others.
How much thickness does the DLC add?
DLC coatings are usually 1-4 microns thick. A very thin layer gives a great performance both wear and corrosion protection.
What are the most common problems after DLC coating?
What is the maximum working temperature for DLC coated components?
The oxidation temperature for DLC is low (300C); the application that requires a higher temperature that this will not be a good fit for DLC coatings.
On which substrates can you apply DLC coating?
DLC can coat most conductive metals. Substrate hardness and surface finish influence the durability of the coating (the more polished the surface, the better the durability).
At CMC we can successfully apply DLC on copper and copper alloys, steel and steel alloys, aluminum, or nickel and chrome plated parts.
What is the typical DLC coating temperature?
Typical DLC coating temperatures range from 100-250 C. Our DLC coating machines run in the 150-200 C range. Above those temperatures, the DLC coating may not form properly. The DLC coating thickness required to achieve opaque finishes makes maintaining part temperatures <125C challenging.
Are there limitations on geometry in DLC coating?
DLC coating is excellent at coating exterior product surfaces, and some internal dimensions can be coated. But DLC has limitations, as the PVD coating, being “ line of sight” type of coatings, can’t be used to coat deep recesses like the inside of tubes.