Surface treatment / Hard carbon coating
DLC coating
DLC coating is a surface treatment that deposits a thin film, typically a few micrometres thick, of amorphous diamond-like carbon, a material with near-diamond hardness and low friction. It offers excellent wear resistance, low friction and seizure resistance, and is widely used on sliding parts, molds and cutting tools.
How it works
"Why it works"DLC is an amorphous film that mixes diamond-type (sp3) and graphite-type (sp2) carbon bonds. Some types contain hydrogen (a-C:H) and some do not (such as ta-C), and their hardness and friction behaviour differ.
The film is deposited in vacuum by plasma CVD or by PVD (sputtering or arc evaporation). Process temperatures are generally a few hundred °C or less, so the hardness of hardened steel is largely preserved.
Because the film is only a few micrometres thick, dimensional change is small, but adhesion depends on the substrate and the pre-treatment. Combined treatments that use fine particle peening as a pre-treatment to improve adhesion are also offered.
Main effects
- Higher wear resistance
- Low friction (little adhesion to mating materials)
- Seizure and build-up resistance (reduces aluminum build-up on tools and dies)
- Better mold release
- Chemically stable; helps with corrosion resistance
Definitions
- DLC (diamond-like carbon)
- An amorphous hard carbon film with mixed sp3 and sp2 bonds. Its classification and designations are defined in ISO 20523.
- a-C:H / ta-C
- a-C:H is hydrogenated amorphous carbon; ta-C is hydrogen-free with a high share of sp3 bonds. ta-C is generally harder.
- Plasma CVD
- A deposition method that decomposes a source gas in plasma and deposits a film on the substrate. Hydrocarbon gases are used for DLC.
Applications
"Where it is used"| Field | Examples |
|---|---|
| Automotive | Piston rings, cam followers, valve lifters and other sliding parts |
| Cutting tools | Preventing build-up on tools for aluminum and non-ferrous metals |
| Molds and dies | Better release and wear resistance on plastic molds and press dies |
| Food and medical | FDA-certified DLC for food-contact use (published by a listed company) |
Typical process conditions
"Under what conditions"These are general guides. Actual conditions are set by the supplier for each part, material and specification.
| Item | Typical |
|---|---|
| Film thickness | Generally 1 to a few μm |
| Hardness | Varies widely by type |
| Friction coefficient | Around 0.1 against steel, unlubricated, as a typical guide |
| Process temperature | Generally a few hundred °C or less |
| Materials | Steel, cemented carbide, stainless steel; aluminum alloys need pre-treatment or an interlayer for adhesion |
| Pre-treatment | Cleaning, lapping, fine particle peening, etc. |
FAQ
"Direct answers"How thick is a DLC coating?
Generally 1 to a few micrometres. As a thin film it changes dimensions very little, so it is easy to apply to precision parts.
Can DLC be applied to aluminum parts?
Aluminum is too soft to support a hard film well, which makes adhesion difficult, but some suppliers handle it with combined treatments that add a pre-treatment or interlayer.
How does DLC differ from other PVD coatings such as TiN?
Nitride films such as TiN and CrN excel in hardness and heat resistance. DLC has a lower friction coefficient and rarely adheres to mating materials, which suits sliding parts and machining of non-ferrous metals.
Can I order a single prototype?
It depends on the supplier. See the minimum lot column in the comparison table below for each company's published information.
Which companies in Japan offer DLC coating?
Among the companies listed on FactoryMatch, Fuji WPC Co., Ltd., Surf Technology Co., Ltd. offer DLC coating (based on each company's published information). See the supplier comparison table for minimum lots and overseas support.
Suppliers
"Who to ask"Based on the listed companies' published information.
| Company | Location | Relevant technology | Minimum lot | Overseas support |
|---|---|---|---|---|
| Fuji WPC Co., Ltd. | Sagamihara, Kanagawa | DLC coating, Super DLC coating | From 1 pc | English inquiry OK, 2005: established the US subsidiary WPC Treatment Co., Inc in Los Angeles |
| Surf Technology Co., Ltd. | Sagamihara, Kanagawa | DLC-F&D® coating (FDA certified) | — | English inquiry OK |