Dry Friction And Wear Performance Of Graphite-like Carbon Films On Different Substrate

Because of the high-hardness,low-friction coefficients,low-specific wear rates,high-bearing capacity and other excellent performances,much attentions had been paid to the Graphite-Like-Carbon?GLC?film.GLC has been widely used in cutting tools,anti-friction wear-resisting materials,etc.However,almost all GLC films are fabricated on the high speed steel which hardness is higher,the fabrication and the study about dry friction and wear performance on the lower hardness substrate such as copper is pretty rare.National literature about Diamond-Like-Carbon?DLC?on copper are more,but the preparation of GLC films on the copper can be seen hardly.When the GLC films are fabricated on the soft substrate,whether the pit method or the scratch test can be used for testing the adhesion is worth exploring.In this dissertation,GLC films were prepared on high speed steel and copper alloy by unbalanced magnetron sputtering ion plating technology combined with under layer,gradient layer and work layer.Different metalcontent was doped to the films through adjusting the Ti target current when sputtering the work layer.The surface and section morphology,chemical composition were analyzed by scanning electron microscope,atomic force microscope,energy spectrum.The carbon bond structure was tested by Raman spectroscopy,X-ray photo-electron spectrometer.The electrical conductivity was tested by surface resistance instrument.The hardness and elastic modulus were tested through nano indentation.Through the friction and wear testing machine,the white light interferometer,optical microscopy,dry friction and wear properties of GLC films on different substrates were studied.The investigative results indicated that:1.At different Ti target current,the films surfaces presented the island growth model,the surface roughness increased first and then decreased.The cross section had cracks or other defects.With the increase of the Ti target current,the quality percentage of Ti element and the deposition rate increased gradually,tending the cross section to be columnar.2.With the increase of the Ti target current,the ration of the sp2 bond tested by Raman and XPS increased first and then decreased,reaching a maximum at0.8 A.Four point probe test showed that film had good electric conductivity.3.With the increase of the Ti target current,the ration of the sp3 bond decreased first and then increased,the hardness and elastic modulus reduced and then raised.The ratio of H/E and H3/E2 decreased which meant the elastic deformation property and the wear-resistant property decreased at the same time.4.The Rockwell pit method showed that the adherence of carbon films on high speed steel increased first and then decreased,reaching a maximum at 0.8A about HF3.When dry friction load was 20 N,the prepared carbon films could reduce the dry friction coefficient compared to raw high speed steel,acquiring a minimum friction coefficient of 0.10 at 0.8 A and a minimum wear rate of5.21×10^-16 m³/N·m at 0.2 A.With the protection of transfer films,the wear rate of grinding ball was extremely low.The GLC films turned the mechanism of adhesive,oxidative wear to be abrasive wear when the substrate changed from raw high speed steel to GLC films.5.The Vickers pit method was suitable for testing soft substrate hard film,and the tested results indicated that the adhesion of GLC films on the copper alloy had been reduced due to the carbon's diffusion to the copper.6.When the load was 10 N,GLC films on copper alloy could reduce the dry friction coefficient with grinding ball,achieving minimum friction coefficient of0.14 and wear rate of 2.89×10^-16 m³/N·m at 0.2 A.With the protection of transfer films,the wear rate of grinding ball was extremely low.The GLC films turned the mechanism of adhesive,oxidative wear to be abrasive wear when substrate changed from copper alloy to GLC films.7.With the load increased,the friction coefficient decreased first and then increased when the substrate was copper alloy and the Ti target was 0.2 A,acquiring the minimum friction coefficient at 20 N.The wear rate of films increased and the wear rate of grinding ball reduced and then raised.