Growth feature of PTFE coatings on rubber substrate by low-energy electron beam dispersion

Abstract

Polytetrafluoroethylene (PTFE) coatings were prepared on Si and acrylonitrile-butadiene rubber substrates by lowenergy electron beam dispersion. The effects of substrate nature, distance of target to substrate (d ts ) and coatings thickness on the surface morphology, structure, and tribological properties of the coatings were investigated. The results showed that substrate nature affects the shape and size distribution of surface conglomerations of PTFE coatings due to the interaction process of active dispersion particles with underlying polymer layer. Surface energy of PTFE coatings decreases first with the coatings thickness increases to 1.25 μm and then slowly increases with the thickness. Structure defects (pore, interstice, and so on) in the coatings increase with the thickness increases but reduce significantly with the d ts increases. PTFE coating prepared at the d ts of 20 cm had a higher intensity of the amorphous absorption bands. Friction experiment indicated that the destroyed area of the coatings in the friction region decreases with increases the coatings thickness but increases with the d ts . The rubber modified by PTFE coatings with spherical structure possesses a higher stability in the friction process and a lower coefficient of friction.

Structure and tribological properties of Cu-PU-PTFE composite coatings prepared by low-energy electron beam dispersion with glow discharge

“…The relative intensity ratios of characteristic peak of Cu–PTFE coatings are summarized in Table . The intensities of the bands at 516 and 638 cm −1 of Cu–PTFE composite coating are lower than for PTFE coating, indicating that Cu doping weakens the crystallinity and ordering degree of PTFE coatings. This may be because of the interaction of Cu with PTFE in the process of electron beam dispersion, that is, Cu particles as the nucleation centers enter into the polymer phase and change the molecular structure of PTFE.…”

“…Figure shows the SEM images of surface and cross section of PU–PTFE composite coatings without and with glow discharge treatment. Different from PTFE coating, the growth process of PU single coatings includes the melting of PU target and the agglomeration of droplet phase, which is described in detail in the previous work . The large size of protuberance structure on substrate surface and the droplets size of smaller than 0.1 µm are observed from Fig.…”

“…However the facts show that poor adhesion strength and low wear resistance of PTFE coatings to rubber substrate cause the coating peeling off in the application process. Although the working life of the products can be extended by increasing the coating thickness to some extent, the wear resistance also decreases with the thickness because of the increase in the internal stress of coatings . Evidently increasing coating thickness is an unadvisable and unsatisfactory method.…”

Modification of Cu‐PE‐PTFE composite coatings on rubber surface by low‐energy electron beam dispersion with glow discharge

“…It can be from Fig. a observed that PE‐PTFE composite coating is considerably different from the morphological feature of PE and PTFE single coatings that reported in the previous work . There is no distinct columnar structure like the PTFE coating from cross‐sections morphology, whereas forms spherical aggregations.…”

“…Insufficient knowledge of polymeric materials tribology results from the complex multiphase structures of polymers, which make evaluation of their tribological behavior relatively difficult . With respect to the coating materials, fluoroligomeric coatings have been used to modify rubber products changing the surface morphology, and moreover improving the hydrophobic and tribological properties, e.g., polytetrafluoroethylene (PTFE) . The enhancement of protective properties is due not only to the barrier effect, but also to the obstruction effect of structural aggregations of the coatings on the process of liquid extension on the surface of modified rubber.…”