The main performance of DLC coating

The main performance of DLC coating

1. The hardness and elastic modulus of DLC films prepared by different deposition methods vary greatly. DLC films with hardness as high as or even higher than diamond can be prepared by magnetic filtering cathode arc method, and the hardness of DLC films prepared by cathode arc method can reach 50GPa Above, while the hardness of DLC film prepared by ion source combined with a non-equilibrium magnetron sputtering method is up to 21GPa, the composition of the film layer has a certain influence on the hardness of the film layer. DLC film has a high elastic modulus, which is lower than that of diamond (1100GPa), but obviously higher than that of general metal and ceramics b. The internal stress and binding strength of the film are two important factors that determine the stability and service life of the film and affect the performance of the film. DLC films with high internal stress and low binding strength are easy to produce cracks and folds or even fall off in the application. Therefore, the prepared DLC film is recommended to have moderate compressive stress and high bonding strength. Most studies show that the film/base bonding strength of DLC film deposited directly on the matrix is generally low, and the method of Ti/TiN/TiCN/TiC intermediate gradient transition layer is adopted to improve DLC The bonding strength between the film and the matrix is 44N-74N, and the overall thickness of the film conductance can reach 5 microns.

2.  Friction properties DLC film not only has excellent wear resistance but also has a very low friction coefficient, generally less than 0.2, which is an excellent surface wear resistance modified film The friction coefficient of DLC varies with the preparation process and the composition in the film, with a low friction coefficient up to 0.005. The doping of metal elements may reduce the friction coefficient, but the addition of H can improve the lubrication effect, and the environment also has a certain impact on the friction coefficient. However, in general, DLC film is different from traditional hard films (such as TiN mentioned above) TiC TiAlN, etc.) have obvious advantages in friction coefficient, the friction coefficient of these traditional hard films is above 0.4, so DLC film may replace these traditional hard films in many fields of tribology.

3. Thermal stability As DLC is a metastable material, poor thermal stability is limited An important factor for the application of DLC film is that the transition from SP3 bond to SP2 bond appears when annealing above 300 ℃. Therefore, a lot of work has been done to improve the thermal stability of DLC film. Research has found that the addition of Si can significantly improve the thermal stability of DLC film containing 20 AT %Si The transition from SP3 bond to SP2 bond occurs only when the film is annealed at 740 ℃. Similarly, the addition of metals (such as Ti W Cr) can also improve the thermal stability of DLC film. We are conducting research on this aspect.

4. Corrosion resistance Pure DLC film has excellent corrosion resistance, which is difficult to be eroded by all kinds of acids and alkalis and even aqua aqua aqua, but the corrosion resistance of DLC film doped with other elements is decreased, because the doped elements are eroded first, thus destroying the continuity of the film.

5. surface state The surface of DLC film is generally smooth and clean, which has no great influence on the surface finish of the substrate. However, with the increase in film thickness, the surface light will decrease. The surface finish of DLC film obtained by different deposition methods is also different, and the surface quality of DLC film deposited by ion source technology is obviously better than that of ARC ion plating DLC The film has good adhesion resistance, especially to non-ferrous metals (such as copper, aluminum, zinc, etc.), also has adhesion resistance to plastic, rubber, ceramics, etc

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