(higher % amorphous region) exhibited improved fatigue performance, suggesting that cracks preferentially travel through the amorphous region of PFA 6. Transmission IR spectra of PFA wear debris revealed the presence of free carboxylic acid endgroups that were not present in the bulk PFA surface. The presence of free carboxylic acids is due to the breaking of C-C bonds in the PFA backbone reacting with environment constituents. The formation of free-carboxylic acids endgroups is a critical intermediate step of the tribochemical reaction necessary to form robust transfer films and running films proposed for PTFE-alumina composites 7.
Figure 1 – Effects of sliding on unfilled PFA against a stainless steel substrate
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