Preparation And Design On Deposition System Of DLC Films With Micro-crater-like Structures

Diamond-like carbon films with micro-crater-like structures were successfully deposited on the carbon steel substrates by an RF-DCCVD dual power chemical vapor deposition system which was home designed. The adhesive strength between DLC films and carbon steel substrates was enhance, which could provide a reliable method for solving the wear problem of compressors.An RF-DCCVD dual power chemical vapor deposition system using a molecular pump as the main pump and a rotary vane pump as the backing pump was designed. The system can achieve limiting vacuum of5×10-4Pa in the vacuum chamber whose volume is6.28×10-3m3and provide the high vacuum needed for experimental deposition equipments whose magnitude is50mm. The deposition system is equipped with complete gas supply system and testing system, whose power supply system adopts a dual power combinated of DC power and RF power.The anode of RF-DCCVD equipment is a composite anode, and the auxiliary anode with zigzag is used to produce cutting-edge discharge. In order to improve the adhesive strength at the interface, an intermediate layer of a-Si:H:C with non-continuous surface was deposited between the films and SAE1060carbon steel substrates, then DLC films with micro-crater-like structures were formed. The experimental evaluations of the friction properties were carried out with a “Ball-on-Disk” wear testing machine; The effect of electrode spacing S-T on the density of the micro-crater-like on the surface of the films was studied; The structure and composition were determined by a Raman spectrometer.The experimental results indicate that the micro-crater-like density on the surface of DLC films decreases with an increase in the electrode spacing (S-T) under the same voltage. The best electrode spacing is40～60mm; in this interval there is a relatively moderate micro-crater-like density, leading to a relatively strong adhesive strength at the interface and little effect on the friction characteristics. For instance, when S-T=50mm or so, there is a maximum in the failure lifetime, which reaches approximately1.3million cycles as applying the load P=3N, an increase of300,000cycles over films with a smooth surface. In conclusion, the micro-crater-like discontinuous structures effectively reduce the residual compressive stress within films, and the failure life of DLC films deposited on SAE1060substrates is effectively prolonged.