Diamond-like carbon films (DLC films), as new generation of optical thin film materials, have excellent optical, mechanical, electrical, thermal and acoustic properties. With the advantages of transparent infrared region, high hardness, high thermal conductivity, abrasion resistance, stable chemical properties, heat shock resistance and so on. It has good application prospects.
The DLC film is deposited by pulsed arc ion plating, which is a physical vapor deposition method. The plating method is simple. It does not need to add negative bias to the substrate and fill any gas in the vacuum chamber during the plating process. The plating process has good repeatability and is suitable for large batch industrial production. The DLC film layer coated by this method has high purity, good optical transparency; stable chemical properties and good wear resistance. It can be used as an excellent infrared film and protective film.
The diamond-like carbon films were coated by vacuum coating device imported from abroad. The device contains three ion sources: a gas ion source used to clean and heat the surface of the substrate; a continuous cathode multi-arc ion source with magnetic filtration, with a metal Ti cathode for the plating of the intermediate transition layer; the third ion source is a pulsed arc ion source with a graphite cathode and an arc pole. It is used for plating diamond like carbon film.
The principle and method of experiment
The pulsed arc ion source consists of a cathode, an anode, and an arcing electrode. The cathode is made of evaporated material and the ion source has a specially made anode. The vacuum arc discharge generated by the cathode of the ion source causes the cathode material to evaporate and ionize, forming a plasma, on the one hand, forms a coating on the substrate, and on the other hand, sustains an arc discharge. The electron emission mechanism of the cold cathode arc discharge is mainly the field electron emission, and the field emission needs to establish a strong electric field on the cathode surface. Therefore, only the potential difference between the cathode and anode of the ion source is not sufficient, so it is necessary to strike the arc. The device uses an arcing electrode, which generates a small current discharge and pre-ionization between the arcing electrodes, and then applies a not very high voltage between the two main electrodes of the cathode and the anode (generally between 40V and 400V). The gas and evaporation break down to form an arc.
During the work process, the vacuum chamber is evacuated to 2x10-3Pa, and the capacitors C1 and C2 are charged, giving the SCR an arcing signal. A small current discharge is generated between the arcing electrodes. There is a conductive layer between the anode and the cathode. The capacitor C1 discharges between the cathode and the anode. With the release of capacitor C1 energy storage, when the energy supplied by the capacitor is not enough to maintain discharge, the discharge will stop.