Exploring Tribological Properties Of Carbon Films Indifferent Service Environments

Carbon films because of its high hardness, high wear resistance, low friction coefficient, high resistivity, high thermal conductivity, chemically inert, corrosion and other excellent performance has been widely used in special environments. But the tribological properties of carbon films affected by environmental factors. They are very different between special environment and ordinary conditions, and under different environmental performance requirements are also different. This paper explores the friction and wear properties under special condition and environment, such as space drilling, geophysical prospecting and spinnerets punching. The results showed that:(1)The friction behavior of HFCVD diamond film was evaluated in air and vacuum respectively at four different temperatures. Found in air, the friction coefficient curve is smooth, friction coefficient decreases at elevated temperature, and the wear mainly is related with debris and passivation layer; but in vacuum, the friction coefficient curve fluctuated remarkably, friction coefficient increased firstly at elevated temperature, then decreased at 650 oC, and the wear primarily is related with transition layer and surface cracks. The wear of diamond films is more severity in vacuum than in air and the film failed at lower temperatures. When the temperature was up to 650 oC, surface graphitization of diamond is to be detected both in air and vacuum, which help the reduction of friction coefficient.(2) Cr/Cr Nx/CryCz/Cr-DLC films were deposited onto Cr12Mo4 V substrates by mid-frequency dual-magnetron sputtering. At-140 V bia voltage, Cr-DLC films showed the best performance, include smooth surface, dense structure, high hardness, good adhesion strength and low friction and wear. The trend of tribological property with bia voltage change is similarly in air and seawater. But the friction coefficient and wear rate is higher in air than in seawater.(3) HFCVD diamond films were directly deposited on carbon steel punch needle are not complete. There are a large of non-diamond phase in films and the cabon black gather into particles on surface. Cabon steel punch needle tip may melt because the temperature is too high at general substrate temperature. Ti N transition layer was deposited between substrate and diamond film can effectively eliminate the adverse effects by direct coating. Diamond films were deposited with transition layer were uniform and full and no obvious defects. But the surface roughness of diamond is big. It can be reduced by increase the cabon source concentration or reduce the pressure.