Properties & application possibilities:
- Smooth surface
- High mechanical hardness
- Chemical resistance
- Low coefficient of friction between a tool and a workpiece
- Non-reflective surface
- Suitability for biocompatible products
Categories of
DLC coatings:
- a-C = hydrogen-free amorphous carbon
- ta-C = tetrahedrally bound hydrogen-free amorphous carbon
- a-C:Me = metal-doped hydrogen-free amorphous carbon
(Me = Ti) - a-C:H = amorphous carbon with hydrogen
- ta-C:H = tetrahedrally bound amorphous carbon with hydrogen
- a-C:H:X = non-metal-doped amorphous carbon with hydrogen
- a-C:H:Si = Si-doped amorphous carbon with hydrogen
- a-C:H:Me = metal-doped amorphous carbon with hydrogen
(Me = W, Ti)
Comparison of the most important properties of DLC coatings
DLC1 (CBC)
DLC2
DLC3
Composition
a-C:H:Me
a-C:H:Si
ta-C + a-C (up to 50% ta-C)
Process
ARC in C2H2 atmosphere
PECVD
SPUTTERING
Coating architecture
As top layer
As stand alone or as top layer
As stand alone
Doping
Ti or Cr
Si
None
Coating thickness [µm]
x < 1
x < 4
x < 1.5
Young’s modulus [GPa]
200
250
500
Hardness [GPa]
< 20
> 25
Up to 50
Roughness
Ra ~ 0.1 µm
Rz ~ coating thicknessRa ~ 0.03 µm
Rz ~ coating thicknessRa ~ 0.02 µm
Rz ~ coating thicknessCoefficient of friction to steel
µ ~ 0.15
µ ~ 0.1
µ ~ 0.1
Temperature resistance [°C]
< 400
< 450
< 450
Coating temperature [°C]
< 400
< 180
< 180
Example coating
cVIc
CROMVIc2
CROMVIc3
Main application
Improvement of the run-in process of a tool,
lubrication by forming of transfer filmsFriction reduction for machine components, molds & dies
Cutting of light metals, composites & graphite