Analysis of the chemical composition of the PTFE transfer film produced by sliding against Q235 carbon steel

• Published in: Wear Vol. 320; pp. 87 - 93
• Main Authors: Zuo, Zhen, Yang, Yulin, Qi, Xiaowen, Su, Wenwen, Yang, Xiangchao
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.12.2014; Elsevier
• Subjects: Applied sciences; Barriers; Carbon steels; Chemical composition; Contact of materials. Friction. Wear; Density functional theory; Exact sciences and technology; Experimental measurement; Formations; Hydroxyl groups; Killed steels; Mathematical analysis; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Molecular dynamics; Polytetrafluoroethylene; Polytetrafluoroethylenes; Transfer film; X-ray photoelectron spectroscopy; Experimental measurement; Molecular dynamics; Density functional theory; Polytetrafluoroethylene; Transfer film; Chemical analysis; Sliding wear; Tribochemical reaction; Molecular dynamics method; Coatings; Energy barrier; Calcium nitride; Reaction mechanism; Density functional method; Carbon steel; Chemical composition
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2014.08.019

Polytetrafluoroethylene (PTFE) transfer films formed on the surface of Q235 carbon steel were studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), molecular dynamics (MD), and density functional theory (DFT) calculations. Changes in the chemical composition of the transfer film were analyzed using XPS measurements. Mechanisms of defluorination, chain scission, and formation of carbonyl and hydroxyl groups were elucidated using DFT transition state calculations. Of these four reactions, defluorination, which has an energy barrier of only 1.0kcal/mol, is most likely to occur. The formation of a carbonyl group, with an energy barrier of 23.1kcal/mol, can more easily take place than the chain scission, which has an energy barrier of 44.6kcal/mol, and is a precursor to the simplest path to the formation of a hydroxyl group. •Changes of the chemical component for PTFE transfer film are confirmed.•DFT calculation is of benefit for revealing the change of PTFE transfer film.•Defluorination of PTFE transfer film is mostly prone to take place.•Chain scission of PTFE transfer film is difficult to occur.•Based on carbonyl group formation, the hydroxyl group can be easily formed.