Electron microscopic evidence for a tribologically induced phase transformation as the origin of wear in diamond

Journal Article · Fri Feb 14 00:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4865742· OSTI ID:22278062

Zhang, Xinyi; Schneider, Reinhard; Müller, Erich; Gerthsen, Dagmar ^[1]; Mee, Manuel; Meier, Sven ^[2]; Gumbsch, Peter ^[2]

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1. Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), Engesserstr. 7, D-76131 Karlsruhe (Germany)
2. Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstr. 11, D-79108 Freiburg (Germany)

Tribological testing of a coarse-grained diamond layer, deposited by plasma-enhanced chemical vapor deposition, was performed on a ring-on-ring tribometer with a diamond counterpart. The origin of the wear of diamond and of the low friction coefficient of 0.15 was studied by analyzing the microstructure of worn and unworn regions by transmission and scanning electron microscopy. In the worn regions, the formation of an amorphous carbon layer with a thickness below 100 nm is observed. Electron energy loss spectroscopy of the C-K ionization edge reveals the transition from sp{sup 3}-hybridized C-atoms in crystalline diamond to a high fraction of sp{sup 2}-hybridized C-atoms in the tribo-induced amorphous C-layer within a transition region of less than 5 nm thickness. The mechanically induced phase transformation from diamond to the amorphous phase is found to be highly anisotropic which is clearly seen at a grain boundary, where the thickness of the amorphous layer above the two differently oriented grains abruptly changes.

• OSTI ID: 22278062
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
AMORPHOUS STATE
ANISOTROPY
CHEMICAL VAPOR DEPOSITION
DIAMONDS
ENERGY-LOSS SPECTROSCOPY
FRICTION FACTOR
GRAIN BOUNDARIES
LAYERS
MATERIALS TESTING
PHASE TRANSFORMATIONS
SCANNING ELECTRON MICROSCOPY
THICKNESS
TRIBOLOGY
WEAR