Effects of individual and sequential irradiation with atomic oxygen and protons on the surface structure and tribological performance of polyetheretherketone in a simulated space environment

Abstract

The changes in the surface structure and the tribological performance of polyetheretherketone (PEEK) induced by individual and sequential irradiations with atomic oxygen (AO) and protons (Prs) were investigated in a space environment simulation facility. The experimental results showed that Pr irradiation induced the surface carbonization of PEEK which induced the greatest degree of decrease in the surface roughness from 29.61 nm to 16.15 nm, surface energy from 49.16 mJ m À2 to 46.96 mJ m À2 , friction coefficient from 0.28 to 0.08 and wear rate from 10.28 Â 10 À5 mm 3 N À1 m À1 to 5.45 Â 10 À5 mm 3 N À1 m À1 . The AO irradiation induced the surface oxidation of PEEK, and then increased the surface roughness from 29.61 nm to 58.77 nm, surface energy from 49.16 mJ m À2 to 73.75 mJ m À2 , friction coefficient from 0.28 to 0.35 and wear rate from 10.28 Â 10 À5 mm 3 N À1 m À1 to 18.22 Â 10 À5 mm 3 N À1 m À1 . The surface structural variations and tribological performance of PEEK induced by the sequential Pr-AO and AO-Pr irradiations were respectively similar to the results of the individual AO and Pr irradiations, and the final form of irradiation has a bigger effect on the changes in the surface structure and tribological performance during the sequential irradiation tests. The erosion stacking effect of the sequential irradiations was observed, and the AO-Pr irradiations caused the biggest changes in infrared spectra and the surface composition of C and O elements in X-ray photoelectron spectroscopy. The Pr-AO irradiations gave the biggest increment in the surface energy from 49.16 mJ m À2 to 74.03 mJ m À2 and wear rate from 10.28 Â 10 À5 mm 3 N À1 m À1 to 24.07 Â 10 À5 mm 3 N À1 m À1 .

Ultralow Friction and Wear of Polymer Composites under Extreme Unlubricated Sliding Conditions

“…Structure and property of the tribofilm formed on the steel counterface play an important role in the tribological performance of polymer composites . As seen from Figure a, energy‐dispersive X‐ray spectroscopy (EDS) analysis demonstrates that a C‐based tribofilm (indicated by red arrows) is formed on the steel surface when sliding against PI/SCF/Gr at 1 MPa m s ‐1 .…”

“…Both PEEK and PI are temperature‐resistant polymers . Thermogravimetric analysis (TGA) curves of the both polymers are given in Figure .…”

“…PI‐based wear particles and iron oxide fill the roughness grooves as indicated by EDS (Figure a2). Consistent with our previous studies on epoxy hybrid nanocomposites, silica nanoparticles were released from the polymer matrix in the wear particles and thereafter abraded the iron oxide layer on the steel surface . Finally, the nanoparticles, abraded iron oxide and remnant polymer were tribo‐sintered into a tribofilm with a complex structure.…”

“…The PI and PEEK composites were prepared by means of hot‐press molding following the procedure given in refs. and . The designations and chemical compositions of these composites were listed in Table 1 .…”

Assessment of high performanceSAPO‐34/S‐PEEKcomposite coatings for adsorption heat pumps

“…Afterward, the peak at 1305 cm −1 can be ascribed to the bending motion of CC (O)C; the couple of peaks at 1276 and 1186 cm −1 , due to COC asymmetric stretching of aryl ether group, are also identified 34 . Peaks at 1151 and 1096 cm −1 are correlated to the deformation bands of aromatic hydrogen in‐plane; the peaks at 924 and 832 cm −1 are related to the diphenyl ketone band and out of plane bending modes of the aromatic hydrogen, respectively 35 …”