Deposition Of Diamond-like Carbon On Inner Surface By Pulse Hollow Cathode Discharge

Diamond-like carbon (DLC) film has lots of excellent properties，such as highhardness，low friction coefficient，good chemical inertness，which makes it have greatprospect in the field of inner surface of metal tubes. By using a metal tube as a hollowcathode discharge electrode we can achieve DLC films directly on the inner wall ofthe tube, thereby forming a method that low cost. The properties of DLC filmsdeposited by DC-HCD are poor because low current and short deposition time. So thework of this paper is study the characteristics of pulse HCD and the DLC depositionon the inner surface of metal tube.Firstly, the characteristics of DC-HCD and P-HCD including the plasma images,the voltage-current curves and the optical emission spectrum (OES) were measured,and the affections of discharge conditions on the properties were studied. The particlenumber density ratio NCH/NArand the electron excitation temperature were calculated.The results show that the characteristics of DC-HCD and P-HCD are the sameroughly. The relative particle number density of CH is decrease when the DC voltageincreases. And the relative particle number density of CH increase firstly but thendecrease when the pulse voltage increase.Secondly, the DC-HCD has been used to deposit DLC films on the inner surfaceof stainless steel tube. The influences of the deposition parameter son the properties ofDLC films are systemically investigate. The results show that the content of sp3bonddecreases with the voltage supply and the deposition time. The CH4content should beappropriate.Finally, the P-HCD has been used to deposit DLC films on the inner surface ofstainless steel tube. The influences of the deposition parameters on the properties ofDLC films are systemically investigate. The results show that the discharge voltageand pulse frequency all affect the content of sp3bonds. The content of sp3bondincreases with the deposition time, so the film thickness and hardness are.