Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Synergistic Effects of MoDTC and ZDTP on Frictional Behaviour of
  Tribofilms at the Nanometer Scale   The layered structure and the rheological properties of anti-wear films,
generated in a rolling/sliding contact from lubricants containing zinc
dialkyldithiophosphate (ZDTP) and/or molybdenum dialkyldithiocarbamate (MoDTC)
additives, have been studied by dynamic nanoindentation experiments coupled
with a simple modelling of the stiffness measurements. Local nano-friction
experiments were conducted with the same device in order to determine the
evolution of the friction coefficient as a function of the applied pressure for
the different lubricant formulations. For the MoDTC film, the applied pressure
in the friction test remains low (<0.5 GPa) and the apparent friction
coefficient is high ($\mu$ > 0.4). For the tribofilms containing MoDTC together
with ZDTP, which permits the applied pressure to increase up to a few GPa
through some accommodation process, a very low friction domain appears (0.01 <
$\mu$ < 0.05), located a few nanometers below the surface of the tribofilm.
This low friction coefficient is attributed to the presence of MoS2 planes
sliding over each other in a favourable configuration obtained when the
pressure is sufficiently high, which is made possible by the presence of ZDTP.

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The categories of this paper are: q-alg
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The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
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The categories of this paper are: q-bio
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The categories of this paper are: physics
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The categories of this paper are: stat
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: math
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat