Amorphous Carbon Films In Situ Formed From PTFE Transfer Layer in Solid Lubricated Cryogenic Turbopump Bearings

Very thin (<,100 nm) amorphous carbon films were grown on silicon substrates by unfiltered and filtered direct carbon ion beams. In situ surface modification was performed using C- energies in the range of 300–500 eV prior to the growth of the film. By lowering the energy of the C− beam to 150 eV, an amorphous carbon film was continuously grown after the surface modification. High-resolution electron microscopy showed that the film/substrate interface was damaged by 400 and 500 eV C− beams. The carbon composition profile at the interface investigated by electron energy-loss spectroscopy illustrated that the 500 eV C− beam generated a 30 nm thick carbon/silicon mixing layer at the interface. The damage and mixing layers were not observed at 300 eV modification. Wear testing found that strong adhesion occurred in samples modified at 400 and 500 eV. However, at 300 eV, modified samples exhibited delamination failure, which indicated inferior adhesion of the films. Surface roughness evolution of 30, 60, and 90 nm thick films was investigated by atomic force microscopy. The film surface roughness decrease as a function of film thickness was much faster when the films were grown by the filtered C− beam.

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The effect of substrate bias in amorphous carbon films prepared by magnetron sputtering and monitored by in-situ spectroscopic ellipsometry

Diamond and Related Materials ◽

10.1016/s0925-9635(97)00297-5 ◽

1998 ◽

Vol 7 (2-5) ◽

pp. 444-448 ◽

Cited By ~ 24

Author(s):

M. Gioti ◽

S. Logothetidis

Keyword(s):

Magnetron Sputtering ◽

Amorphous Carbon ◽

Spectroscopic Ellipsometry ◽

Carbon Films ◽

Substrate Bias ◽

Amorphous Carbon Films

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Contact Mechanisms of Transfer Layered Surface During Sliding Wear of Amorphous Carbon Film

Journal of Tribology ◽

10.1115/1.4004999 ◽

2011 ◽

Vol 133 (4) ◽

Cited By ~ 4

Author(s):

X. Fan ◽

D. F. Diao

Keyword(s):

Friction Coefficient ◽

Amorphous Carbon ◽

Sliding Wear ◽

Carbon Film ◽

Carbon Films ◽

Contact Stresses ◽

Transfer Layer ◽

Amorphous Carbon Film ◽

Amorphous Carbon Films ◽

Wear Life

The contact mechanisms of a transfer layered surface during sliding wear of a Si3N4 ball against the amorphous carbon film were investigated. In this study, amorphous carbon films were deposited by electron cyclotron resonance plasma sputtering technique. The dependence of friction coefficient and wear life of the films on transfer layer was tested with pin-on-disk tribometer. Wear tracks and the transfer layered surfaces at different friction coefficient stages were observed with scanning electron microscope and measured with energy dispersive spectrometer In order to clarify the contact mechanisms of a transfer layered surface, three contact models of initial high friction coefficient stage without transfer layer (state I), transfer layer forming stage with friction coefficient decreasing (state II), and transfer layered surface stable sliding stage with low friction coefficient (state III) were proposed, and the contact stresses (normal stress, shear stress, von Mises stress) of the three contact states were calculated by using finite element analysis. The results demonstrated that a transfer layer formed at the contact interface and gradually decreased the maximum contact stresses, which contributed to the long wear life of amorphous carbon films.

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