Atomic structure of an amorphous, hydrogenous carbon coating (a-C:H).
Amorphous, hydrogenous carbon coating (a-C:H): preparation of a fracture surface.
||This group is also commonly known as >diamond-like carbons< (DLC). This is due to the fact that some types of amorphous carbon films can have a very high diamond-like hardness of as much as 90 GPa (diamond itself is 100 GPa).
VDI guideline 2840 differentiates the following types of film:
Amorphous carbon films are used in particular for tribological applications. As well as offering a high degree of wear protection they exhibit - in contrast to many ceramic hard films (such as TiN) - a very low coefficient of friction with respect to many materials. With steel, coefficients of friction of less than 0.05 are possible. Very good non-stick properties can also be obtained.
- Hydrogen-free amorphous carbon films,
- Tetrahedral, hydrogen-free amorphous carbon films,
- Metal-containing, hydrogen-free amorphous carbon films,
- Hydrogenous amorphous carbon films,
- Tetrahedral, hydrogenous amorphous carbon film
- Metal-containing, hydrogenous amorphous carbon films,
- Modified hydrogenous amorphous carbon films,
Another useful property is a modulus of elasticity which in comparison to hardness is relatively low - this is a good precondition for high film adhesion.
Applications are found in the following fields:
Amorphous carbon films are deposited by the PVD or PA CVD methods or combinations of them.
- Wear protection - for example, for ball bearings
- Friction reduction - for example, for machine elements
- Non-stick function - for example, for forming tools
- Biological applications in medical technology.
A bibliography for further reading is provided here.