Multiscale frictional behaviors of sp 2 nanocrystallited carbon films with different ion irradiation densities
- PDF / 2,672,210 Bytes
- 13 Pages / 595.22 x 790.976 pts Page_size
- 34 Downloads / 163 Views
ISSN 2223-7690 CN 10-1237/TH
RESEARCH ARTICLE
Multiscale frictional behaviors of sp2 nanocrystallited carbon films with different ion irradiation densities Zelong HU, Xue FAN*, Cheng CHEN Institute of Nanosurface Science and Engineering, Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen 518060, China Received: 20 February 2020 / Revised: 28 March 2020 / Accepted: 02 April 2020
© The author(s) 2020. Abstract: sp2 nanocrystallited carbon films with large nanocrystallite sizes, smooth surfaces, and relative high hardness were prepared with different ion irradiation densities regulated with the substrate magnetic coil current in an electron cyclotron resonance plasma sputtering system. Their multiscale frictional behaviors were investigated with macro pin-on-disk tribo-tests and micro nanoscratch tests. The results revealed that, at an ion irradiation density of 16 mA/cm2, sp2 nanocrystallited carbon film exhibits the lowest friction coefficient and good wear resistant properties at both the macroscale and microscale. The film sliding against a Si3N4 ball under a contact pressure of 0.57 GPa exhibited a low friction coefficient of 0.09 and a long wear life at the macroscale. Furthermore, the film sliding against a diamond tip under a contact pressure of 4.9 GPa exhibited a stable low friction coefficient of 0.08 with a shallow scratch depth at the microscale. It is suggested that sp2 nanocrystallites affect the frictional behaviors in the cases described differently. At the macroscale, the contact interface via the small real contact area and the sp2 nanocrystallited transfer layer dominated the frictional behavior, while the sp2 nanocrystallited structure in the film with low shear strength and high plastic resistivity, as well as the smooth surface morphology, decided the steady low nanoscratch properties at the microscale. These findings expand multiscale tribological applications of sp2 nanocrystallited carbon films. Keywords: macro-tribology; micro-tribology; sp2 nanocrystallite; carbon film; ion irradiation density
1
Introduction
Carbon films show good tribological properties, for example, amorphous carbon has a low friction coefficient owing to sp2 carbon lubrication [1], and tetrahedral amorphous carbon has low wear owing to its high sp3 content [2]. Recently, nanocrystallited carbon films for tribo-applications have been intensively studied because adjustable nanostructures can strongly affect the overall behavior of the films [3–8]. Fullerenelike nanostructure can restrain dislocation migration and aid in stress relaxation to enhance the mechanical and tribological properties of carbon films [3–5]. * Corresponding author: Xue FAN, E-mail: [email protected]
Graphene nanocrystallite can reduce the friction coefficient [6] of carbon films owing to the low shear force between adjacent graphene layers [7] and increase their elastic recovery and hardness owing to the cross-linked structure between the g
Data Loading...
