Effect of micrometer sized ceramic particles on the tribological properties of Polytetrafluoroethylene based composites

Abstract

Polytetrafluoroethylene (PTFE) is a self-lubricating matrix material with low friction coefficient and corrosion resistance but high wear rate. Ceramic particle fillers could effectively improve the tribological properties of PTFE-based composites, reduce its wear rate. However, there has been much debate about anti-wear mechanisms for particle fillers, which mainly focus on wear resistance micromechanism and mechanochemistry approach. In this paper, four kinds of PTFE-based composites filled with micrometer-sized ceramic particles (SiC, Si 3 N 4 , SiO 2 and h-BN) were prepared and tested to explore their tribology properties using a pin-on-disk tribometer. The filler proportions ranged from 5 to 20 wt% in 5 wt% increments were added. The worn surfaces of the composites and transfer films attached on the steel disk were examined by Scanning electron microscopy (SEM), energydispersive x-ray spectroscopy (EDS), Fourier-transform infrared (FTIR) and 3D topographies. Ultralow wear was observed on the PTFE/SiO 2 and PTFE/Si 3 N 4 composites in wear tests, which was attributed to tribochemistry. There were protection films formed on the worn surface, which hindered further transfer of the composites. Meanwhile, adhesion of the transfer film was enhanced by metalchelate salts of perfluorinated carboxylic acids formed by tribo-chemical reactions. The wear rate of PTFE decreased by three orders of magnitude (from 6.25 * 10 −4 to 2.21 * 10 −7 mm 3 /(Nm)) after addition of 20 wt% SiO 2 particles. No chemical reaction was observed on the worn surface of PTFE/ SiC and PTFE/h-BN composites.

Enhanced mechanical and tribological properties of polymer nanocomposites by improving interfacial properties by hexagonal boron nitride nanosheets: Molecular dynamics simulations

“…In the present study, the trajectory data from the last 200 ps were used to calculate the average friction coefficient and analyze the evolution of microstructure. The average friction coefficients of the Gr/PTFE and h‐BN/PTFE composites are calculated to be 0.106 and 0.097, respectively, which are in good agreement with the experimental friction study results 9,38,39 . This result demonstrates that an obvious decrease of 8.49% in the friction coefficient of the nanocomposites can be obtained by the incorporation of h‐BN nanosheets than by that of Gr nanosheets.…”

Effect of homologous molecular crosslinking on the tribological properties of PTFE composites

“…It can be speculated that MP1100 composite material containing COOH polar groups is easy to have a frictional chemical reaction with Fe and Cr elements in duplex stainless steel to generate carboxylic acid metal-chelate salt, which contributes to the bonding between transfer film and discs and leads to ultra-low wear, which also a conclusion of previous studies. 37,64,65 With an increase in MP1100 in the composite, more oxygen and carbon elements remain on the surface of the duplex stainless steel due to chemical reactions. When MP1100 is 32 wt%, the agglomerated MP1100 particles reduce the contact area with the duplex stainless steel during friction, reducing the intensity of the tribochemical reaction, thus reducing the content of oxygen and carbon content on the surface of the duplex stainless steel.…”

Impact of recovered silicon particles incorporation on tribo-characteristics of a poly ether ether ketone polymer composite

“…The formation of a thin and uniform tribofilm, which is essential for improving the lubricating ability of the tribo system, is attributed to these enhanced anti-wear characteristics. 26,45,46 Furthermore, the tribofilm sustaining the steel surface continues until the composite silicon particle percentage reaches 10%. 47 Friction and wear mechanisms at low load conditions (30 N-m/s).…”

“…The directly contacted silicon particles as well as those present in the wear particles on the sliding surface helped to reduce the degradation of the polymer matrix during friction. 26 After that, some of the silicon particles can be retained, and then they are tribo-sintered into a more compact piece as a tribo layer over the steel disc. The tribo film over the counter surface reduces the contact between the steel counter disc and the PEEK/ silicon composite, lowering wear and friction.…”

“…These siliconbased fillers enhanced the tribolayer formation over the steel disc, resulting in anti-friction and anti-wear properties. [26][27][28] The superlubricity effect can be obtained by adding highpurity Si filler to substrates that tend to form CSi:H transfer film, which helps lower the COF and wear rate. 29 Silicon can be obtained from various sources and is used in various applications like electronic devices, solar panels, etc.…”