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This content will become publicly available on June 16, 2017

Title: Temperature-Dependent Friction and Wear Behavior of PTFE and MoS2

We present an investigation of the temperature-dependent friction behavior of PTFE, MoS2, and PTFE-on- MoS2. Friction behavior was measured while continuously varying contact temperature in the range -150 to 175°C while sliding in dry nitrogen, as well as for self-mated PTFE immersed in liquid nitrogen. These results contrast with previous reports of monotonic inverse temperature dependent friction behavior, as well as reported high-friction transitions and plateaus at temperatures below about -20°C that were not observed, providing new insights about the molecular mechanisms of macro-scale friction. The temperature-dependent friction behavior characteristic of self-mated PTFE was found also on the PTFE-on-MoS2 sliding contact, suggesting that PTFE friction was defined by sub-surface deformation mechanisms and internal friction even when sliding against a lamellar lubricant with extremely low friction coefficient (μ ~ 0.02). The various relaxation temperatures of PTFE were found in the temperature-dependent friction behavior, showing excellent agreement with reported values acquired using torsional techniques measuring internal friction. Additionally, hysteresis in friction behavior suggests an increase in near-surface crystallinity at upon exceeding the high temperature relaxation, Tα~ 116°C.
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [2] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Science and Engineering Center
  2. Univ. of Florida, Gainesville, FL (United States). Dept. of Mechanical and Aerospace Engineering
Publication Date:
OSTI Identifier:
1285954
Report Number(s):
SAND2016--7052J
Journal ID: ISSN 1023-8883; PII: 702
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Tribology Letters
Additional Journal Information:
Journal Volume: 63; Journal Issue: 2; Journal ID: ISSN 1023-8883
Publisher:
Springer
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE Cryogenic; Temperature; disulfide; MoS2; Solid lubrication; ; Friction; Friction mechanisms; Wear; PTFE; Molybdenum