As can be seen from Fig. 5, the friction force of a diamond/ta-C interface is lower than that of a ta-C/ta-C interface. This is because carbon atoms in the diamond film are in a saturated state, which decreases the possibility of additional bond formation at the two contact surfaces, and consequently decreases the adhesion force during sliding resulting in low friction. It also can be seen that the friction curve of diamond/ta-C system fluctuates and shows a perfect stick-slip periodical frictional behavior. The XMD8-92 of sliding distance is about 4 Å, which is very close to the lattice constant of diamond of 3.57 Å. This indicates megaspore mother cell the periodical atomic structure of materials affects the stick-slip process during sliding. More information can be obtained from the profile snapshots of the diamond and the DLC films shown in Fig. 6. The MD conditions for the diamond sample, e.g., size, layers and temperature are exactly the same as the previous blocks of DLC films. The friction force of stick-slip behavior of DLC/DLC is more irregular than that of diamond/DLC because of no periodic structure at the interface; however, the influence of adhesion on the friction force cannot be completely eliminated during sliding.