Study On Microstructure And Friction And Wear Property Of CrN/C Coating

In the precision mechanical transmission system, because the relative moving parts are almost zero-clearance assembly, it's hard to achieve the traditional manufacturing concept that relying on the formation of continuous oil film between the friction pairs to isolate the components to reduce wear. In order to solve this kind of relative motion precision mechanical foundation piece "friction reduction and longevity" problem, around 2-4 ?m thickness CrN/C coating of high thermal conductivity, low friction coefficient and high abrasion resistance was prepared on its surface, this suface treatment becoming an effective way. The micro structure,the friction and wear properties of the coatings were characterized by SEM,XRD, XEM, XPS,and micro-hardness, nano-indentation, scratches, friction and wear tester.The results showed that the C elements in CrN/C coatings were mainly in the form of sp2 bond, with the increasibg of the power density of C target, the content of sp2 bond decreased at first and the increased. The content of the sp3 bond increased at first and then decreased lightly.The working layer was the composite structure which composed by nano-crystalline in the nano-crystal inlay and nano-crystalline in amorphous substrate. The micro-hard ness of the CrN/C coating increased with the increase of the C target power density, reaching the maximum of 1125HV when the C target power was 39.0W/cm2. When the power density of C target was 29.5W/cm2, the friction coefficient of the coatings reached a minimum of 0.3, the specific wear rate of the coatings was minimal when the C target power density was 39.0W/cm2.With the gradual increase of the power density of Cr target, the content of sp2 bond in the coating decreased firstly and then increased, the content of the sp3 bond increased firstly and then decreased, and the nano-crystalline was increasing in the working layer, and the grain size of nano-crystalline was about 5nm.The micro-hard ness of the coatings decreased firstly and then increased, reaching a maximum of 1536HV at a Cr target power density of 0.4W/cm2.When the Cr target power density was 0.9W/cm2, the friction coefficient of the coatings reached a minimum of 0.2, and the wear rate also reached a minimum of 0.22×1016m3/Nm.With the increase of N2 flow rate, the content of sp2 bond in CrN/C coating decreased gradually, and the content of sp3 bond was increasing gradually. The crystallization degree of the coatings increased gradually,the number of nano-crystalline was gradually increasing,the grain size was about 3nm. The friction coefficient of the coating increased with the increase of N2 flow rate, when the N2 flow rate was Osccm, the friction coefficient of the coating reached the minimum value of 0.21. When the N2 flow rate was 8sccm, the specific wear rate of the coatings also reached the minimum value of 1.15×10-15 m3/Nm.