Comparing hardness and wear data for tetrahedral amorphous carbon and hydrogenated amorphous carbon thin films

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Abstract

We compared nanoindentation and nanoscratch testing of 10 and 50 nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H). Raman spectroscopy shows the expected spectral features for the two carbon forms, however, luminescence from the ceramic substrate can alter the spectra. We find that hard ta-C films can blunt the diamond tip and hence use a tip area function re-calibration procedure after each indentation. This shows that, despite the correction, shallow depth hardness data is influenced by the tip geometry. Therefore, we also present a hardness slope ratio (sample/fused silica) protocol which is independent of tip geometry. The ta-C films are the hardest and the more wear resistant, i.e. for 50 nm thick ta-C films on Al2O3-TiC substrates; H (25 nm) = 51 GPa and the wear rate under a 37 GPa contact pressure is 1.8 x 10(-4) mm(3)/N in. Ramping load measurements of critical loads were complemented withscanning electron micrographs and energy dispersive X-ray (EDX) spot analysis of the wear regions. The comparison helped detect film delamination, particularly so for the thinner films. The ta-C films have higher critical loads than the a-C:H films. This finding contrasts with the large internal compressive stress usually associated with ta-C formation. In the present case, we believe that the filtered arc deposition at the floating potential provides sufficient energy for efficient atomic intermixing in the substrate but, appropriately, not enough to produce the large internal stress observed at higher energy.We note that the superior wear resistance of the ta-C films has more to do with their good adhesion to the substrate rather than their high hardness, as measured by the indenter tip. Finally, we find that a-C:H has better adhesion on silicon, whereas ta-C sticks better to theconducting ceramic substrate. (C) 2004 Elsevier B.V. All rights reserved.
LanguageEnglish
Pages509-522
JournalWEAR
Volume257
Issue number5-6
DOIs
Publication statusPublished - Sep 2004

Fingerprint

Carbon films
Amorphous carbon
hardness
Hardness
Wear of materials
Thin films
Amorphous films
carbon
thin films
Substrates
Residual stresses
Adhesion
adhesion
ceramics
Diamond
Geometry
Silicon
Nanoindentation
Fused silica
Compressive stress

Keywords

  • hardness
  • wear
  • amorphous carbon
  • critical load

Cite this

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abstract = "We compared nanoindentation and nanoscratch testing of 10 and 50 nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H). Raman spectroscopy shows the expected spectral features for the two carbon forms, however, luminescence from the ceramic substrate can alter the spectra. We find that hard ta-C films can blunt the diamond tip and hence use a tip area function re-calibration procedure after each indentation. This shows that, despite the correction, shallow depth hardness data is influenced by the tip geometry. Therefore, we also present a hardness slope ratio (sample/fused silica) protocol which is independent of tip geometry. The ta-C films are the hardest and the more wear resistant, i.e. for 50 nm thick ta-C films on Al2O3-TiC substrates; H (25 nm) = 51 GPa and the wear rate under a 37 GPa contact pressure is 1.8 x 10(-4) mm(3)/N in. Ramping load measurements of critical loads were complemented withscanning electron micrographs and energy dispersive X-ray (EDX) spot analysis of the wear regions. The comparison helped detect film delamination, particularly so for the thinner films. The ta-C films have higher critical loads than the a-C:H films. This finding contrasts with the large internal compressive stress usually associated with ta-C formation. In the present case, we believe that the filtered arc deposition at the floating potential provides sufficient energy for efficient atomic intermixing in the substrate but, appropriately, not enough to produce the large internal stress observed at higher energy.We note that the superior wear resistance of the ta-C films has more to do with their good adhesion to the substrate rather than their high hardness, as measured by the indenter tip. Finally, we find that a-C:H has better adhesion on silicon, whereas ta-C sticks better to theconducting ceramic substrate. (C) 2004 Elsevier B.V. All rights reserved.",
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Comparing hardness and wear data for tetrahedral amorphous carbon and hydrogenated amorphous carbon thin films. / Lemoine, P; Quinn, JP; Maguire, PD; McLaughlin, JAD.

In: WEAR, Vol. 257, No. 5-6, 09.2004, p. 509-522.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Comparing hardness and wear data for tetrahedral amorphous carbon and hydrogenated amorphous carbon thin films

AU - Lemoine, P

AU - Quinn, JP

AU - Maguire, PD

AU - McLaughlin, JAD

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N2 - We compared nanoindentation and nanoscratch testing of 10 and 50 nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H). Raman spectroscopy shows the expected spectral features for the two carbon forms, however, luminescence from the ceramic substrate can alter the spectra. We find that hard ta-C films can blunt the diamond tip and hence use a tip area function re-calibration procedure after each indentation. This shows that, despite the correction, shallow depth hardness data is influenced by the tip geometry. Therefore, we also present a hardness slope ratio (sample/fused silica) protocol which is independent of tip geometry. The ta-C films are the hardest and the more wear resistant, i.e. for 50 nm thick ta-C films on Al2O3-TiC substrates; H (25 nm) = 51 GPa and the wear rate under a 37 GPa contact pressure is 1.8 x 10(-4) mm(3)/N in. Ramping load measurements of critical loads were complemented withscanning electron micrographs and energy dispersive X-ray (EDX) spot analysis of the wear regions. The comparison helped detect film delamination, particularly so for the thinner films. The ta-C films have higher critical loads than the a-C:H films. This finding contrasts with the large internal compressive stress usually associated with ta-C formation. In the present case, we believe that the filtered arc deposition at the floating potential provides sufficient energy for efficient atomic intermixing in the substrate but, appropriately, not enough to produce the large internal stress observed at higher energy.We note that the superior wear resistance of the ta-C films has more to do with their good adhesion to the substrate rather than their high hardness, as measured by the indenter tip. Finally, we find that a-C:H has better adhesion on silicon, whereas ta-C sticks better to theconducting ceramic substrate. (C) 2004 Elsevier B.V. All rights reserved.

AB - We compared nanoindentation and nanoscratch testing of 10 and 50 nm thick tetrahedral amorphous carbon (ta-C) and hydrogenated amorphous carbon (a-C:H). Raman spectroscopy shows the expected spectral features for the two carbon forms, however, luminescence from the ceramic substrate can alter the spectra. We find that hard ta-C films can blunt the diamond tip and hence use a tip area function re-calibration procedure after each indentation. This shows that, despite the correction, shallow depth hardness data is influenced by the tip geometry. Therefore, we also present a hardness slope ratio (sample/fused silica) protocol which is independent of tip geometry. The ta-C films are the hardest and the more wear resistant, i.e. for 50 nm thick ta-C films on Al2O3-TiC substrates; H (25 nm) = 51 GPa and the wear rate under a 37 GPa contact pressure is 1.8 x 10(-4) mm(3)/N in. Ramping load measurements of critical loads were complemented withscanning electron micrographs and energy dispersive X-ray (EDX) spot analysis of the wear regions. The comparison helped detect film delamination, particularly so for the thinner films. The ta-C films have higher critical loads than the a-C:H films. This finding contrasts with the large internal compressive stress usually associated with ta-C formation. In the present case, we believe that the filtered arc deposition at the floating potential provides sufficient energy for efficient atomic intermixing in the substrate but, appropriately, not enough to produce the large internal stress observed at higher energy.We note that the superior wear resistance of the ta-C films has more to do with their good adhesion to the substrate rather than their high hardness, as measured by the indenter tip. Finally, we find that a-C:H has better adhesion on silicon, whereas ta-C sticks better to theconducting ceramic substrate. (C) 2004 Elsevier B.V. All rights reserved.

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KW - wear

KW - amorphous carbon

KW - critical load

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DO - 10.1002/j.wear.2004.01.010

M3 - Article

VL - 257

SP - 509

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