Study On Tribological Properties Of Diamond-like Carbon And Si Incorporated Diamond-like Carbon Ultra-thin Films

There has been a wide range of applications of diamond-like carbon (DLC) films, in the field of optical, electronic, biomedical and tribological engineering for their outstanding properties. In certain applications, there is a need for ultra-thin coatings to improve friction and wear performance. Two primary examples include overcoats for heads and magnetic media in hard disk and tape drive systems and [3-6] the recently emerging field of Micro Electro Mechanical Systems (MEMS). [7, 8] In both these cases, coatings of thicknesses ranging from 100 nm down to 10 nm are being employed.In our work, a radio frequency inductively coupled plasma (ICP) source and ion beam sputtering source were used to deposit the Diamond-like carbon (DLC) ultra-thin films and Si incorporated Diamond-like carbon (Si- DLC) ultra-thin films. We studied the tribological properties of the DLC and the Si- DLC films.The thesis mainly includes three parts:Part One: Effects of negative bias on the structure and properties of DLC ultra-thin films.Diamond-like carbon ultra-thin films were prepared by ion beam sputtering deposition and the effects of the bias on the properties of the films were studied. The surface topography and microstructure of the films were measured by AFM and visible Raman spectroscopy. The friction and wear behavior of the DLC films sliding against stainless steel was examined on UTM-2. The results show that DLC films prepared by ion beam sputtering deposition have good friction-reducing and wear resistant. With the negative bias increased, the COF decreased first and then increased. DLC film deposited under negative bias of -150 V was superior to others.Part Two: The effect of negative bias on the properties of DLC ultra-thin films by inductively coupled plasma assisted chemical vapor deposition.Diamond-like carbon ultra-thin films were prepared from C2H2 by inductively coupled plasma (ICP) assisted CVD and the effects of the bias on the properties of the films were studied. The surface topography and microstructure of the films were measured by AFM and visible Raman spectroscopy. The friction and wear behavior of the DLC films were examined on UTM-2. The results show that DLC films prepared by ICP assisted CVD method have good friction-reducing and wear resistant behavior. The films deposited in the low-bias voltage regime (-100V) showed the best behavior as a whole.Part Three: Study on the structure and the tribological properties of Si incorporated Diamond-like carbon ultra-thin films.The tribological properties and the structure of Si incorporated into Diamond-like carbon ultra-thin films were studied. The films were deposited from C2H2 by inductively coupled plasma (ICP) assisted CVD with simultaneous sputtering of Si. The Si concentration in the film could be controlled by changing the energy of the ion beam sputtering source. It was observed that the tribological properties of the Si-DLC ultra-thin films were not very well when the Si concentration was less than 1.63 %. and more than 8.25%. The good tribological properties observed when the Si concentration was approximately 4% are due to the formation of a large amount of SiC phase in the deposited film.