Environmental dependence of ultra-low wear behavior of polytetrafluoroethylene (PTFE) and alumina composites suggests tribochemical mechanisms

Krick, Brandon A.; Ewin, Jeffrey J.; Blackman, Gregory S.; Junk, Christopher P.; Sawyer, W. Gregory

doi:10.1016/j.triboint.2012.02.015

Cited by 146 publications

(142 citation statements)

References 30 publications

Supporting

Mentioning

127

Contrasting

Order By: Relevance

“…However, since the tribo-film consisted of a significant amount of iron from the counter-surface, this tribo-film increased friction in the system. Alumina particles added to PTFE showed a consistently decreasing wear rate as RH increased from under 1% to near 90% RH [204]. Figure 11 shows the relationship between wear and humidity for the control and composite surfaces.…”

Section: Environmental Effect On Friction and Wear Of Polymeric Matermentioning

confidence: 99%

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

et al. 2015

View full text Add to dashboard Cite

Tribology involves not only two-body contacts of two solid materials-a substrate and a counter-surface; it often involves three-body contacts whether the third body is intentionally introduced or inevitably added during the sliding or rubbing. The intentionally added third body could be lubricant oil or engineered nanomaterial used to mitigate the friction and wear of the sliding contact. The inevitably added third body could be wear debris created from the substrate or the counter surface during sliding. Even in the absence of any solid third-body between the sliding surfaces, molecular adsorption of water or organic vapors from the surrounding environment can dramatically alter the friction and wear behavior of solid surfaces tested in the absence of lubricant oils. This review article covers the last case: the effects of molecular adsorption on sliding solid surfaces both inevitably occurring due to the ambient test and intentionally introduced as a solution for engineering problems. We will review how adsorbed molecules can change the course of wear and friction, as well as the mechanical and chemical behavior, of a wide range of materials under sliding conditions.

show abstract

Section: Environmental Effect On Friction and Wear Of Polymeric Matermentioning

confidence: 99%

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Obviously such additives should be selected which bear the same functional groups evolved according to above schemes, which may enter in reaction with them, or which have possible ligands for the supposed complex formation. The latter aspect seems to be confirmed by the ultralow wear results measured for PTFE with alumina and silicate type nanofillers [6][7][12][13][14][15]. Suitable functional groups for complexing can be produced, however, also on carbonaceous nanofillers, such as CNT and graphene derivatives.…”

Section: Introductionmentioning

confidence: 72%

“Ultralow” sliding wear polytetrafluoro ethylene nanocomposites with functionalized graphene

Padenko

Rooyen

Wetzel

et al. 2016

Journal of Reinforced Plastics and Composites

View full text Add to dashboard Cite

Abstract:The dry friction and sliding wear behavior of sintered PTFE containing various amounts of functionalized graphene (GR) were studied in this work. GR was incorporated in 0, 0.25, 0.75, 1, 2 and 4 vol%, respectively. Sliding wear tests were performed in ring(metal)-on-plate(PTFE) (ROP) test rig under ambient temperature setting 1 m/s sliding speed and 1 MPa contact pressure. The dynamic coefficient of friction (COF) and specific wear rate (ws) data were determined. Very low COFs (0.12-0.14) were measured for PTFE containing 2 or 4 vol% GR which was attributed to the formation of a tribofilm on the countersurface. ws went through a maximum (peaked at doubling that of the unmodified PTFE at about 0.75 vol% GR) as a function of GR content. Ultralow ws data in the range of 10 -6 mm 3 /(N.m) were measured for the PTFE nanocomposites with 2 and 4 vol% GR. This was reasoned by the formation of a robust tribofilm, the development of which was followed by scanning electron microscopy (SEM) by inspecting the worn surface of PTFE nanocomposites and that of the steel ring of the ROP test rig. Fourier transform infrared spectroscopic results confirmed the formation of carboxyl groups in the tribofilm. They were 2 supposed to react with the functional groups of GR and to create complexes with the metal countersurface ensuring the tribofilm with high adhesion and cohesion strengths.

show abstract

“…Unfortunately, the XPS observation provided no direct insight into what the tribochemical species was or why it formed. Krick et al [23] and Pitenis et al [25] both found the removal of environmental moisture caused increased wear rates (from K~10´7 to K~10´5 mm 3 /Nm), reduced transfer film quality, severe counterface abrasion, and loss of transfer film discoloration. The remarkable effects of water removal alone strongly suggested a wear reduction mechanism of tribochemical origins.…”

Section: Chemistry Of the Transfer Filmmentioning

confidence: 99%

“…In addition to producing thinner and more uniform transfer films, low-wear alumina-PTFE transfer films are obviously discolored [13,18,20,[23][24][25][26][27]29,31,32,[37][38][39], which suggests chemical reactions had taken place and possibly enhanced adhesion of the transfer film. In 2013, Ye and Burris used optical microscopy to determine the degree to which transfer films persist during sliding [20].…”

Section: The Effects Of Filler Characteristics On Transfer Films and mentioning

confidence: 99%

A Review of Transfer Films and Their Role in Ultra-Low-Wear Sliding of Polymers

Burris

Xie

2016

Lubricants

View full text Add to dashboard Cite

Abstract:In dry sliding conditions, polytetrafluoroethylene (PTFE) composites can form thin, uniform, and protective transfer films on hard, metallic counterfaces that may play a significant role in friction and wear control. Qualitative characterizations of transfer film morphology, composition, and adhesion to the counterface suggest they are all good predictors of friction and, particularly, wear performance. However, a lack of quantitative transfer film characterization methods and uncertainty regarding specific mechanisms of friction and wear control make definitive conclusions about causal relationships between transfer film and tribological properties difficult. This paper reviews the state of the art in the solid lubricant transfer film literature and highlights recent advances in quantitative characterization thereof.

show abstract

Environmental dependence of ultra-low wear behavior of polytetrafluoroethylene (PTFE) and alumina composites suggests tribochemical mechanisms

Cited by 146 publications

References 30 publications

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

“Ultralow” sliding wear polytetrafluoro ethylene nanocomposites with functionalized graphene

A Review of Transfer Films and Their Role in Ultra-Low-Wear Sliding of Polymers

Contact Info

Product

Resources

About