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Title: Influence of the chemical surface structure on the nanoscale friction in plasma nitrided and post-oxidized ferrous alloy

Friction is a ubiquitous phenomenon in everyday activities spanning from vehicles where efficient brakes are mandatory up to mechanical devices where its minimum effects are pursued for energy efficiency issues. Recently, theoretical models succeed correlating the friction behavior with energy transference via phonons between sliding surfaces. Therefore, considering that the energy losses by friction are prompted through phonons, the chemical surface structure between sliding surfaces is very important to determine the friction phenomenon. In this work, we address the issue of friction between a conical diamond tip sliding on different functionalized flat steel surfaces by focusing the influence of the chemical bonds in the outermost layers on the sliding resistance. This geometry allows probing the coupling of the sharp tip with terminator species on the top and underneath material surface at in-depth friction measurements from 20 to 200 nm. Experimentally, the friction coefficient decreases when nitrogen atoms are substituted for oxygen in the iron network. This effect is interpreted as due to energy losses through phonons whilst lower vibrational frequency excitation modes imply lower friction coefficients and a more accurate adjustment is obtained when a theoretical model with longitudinal adsorbate vibration is used.
Authors:
; ; ; ; ;  [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [2]
  1. Centro de Ciências Exatas e Tecnologia, Universidade de Caxias do Sul, Caxias do Sul-RS 95070-560 (Brazil)
  2. (Brazil)
  3. Instituto de Física 'Gleb Wataghin', Universidade Estadual de Campinas, Campinas-SP 13081-970 (Brazil)
Publication Date:
OSTI Identifier:
22303498
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ATOMS; CHEMICAL BONDS; COUPLING; DIAMONDS; ENERGY EFFICIENCY; ENERGY LOSSES; EQUIPMENT; EXCITATION; FOCUSING; FRICTION; IRON; LAYERS; NANOSTRUCTURES; NITROGEN; OXYGEN; PHONONS; PLASMA; STEELS; SURFACES