Effect of Low-Friction Composite Polymer Coatings Fabricated by Electrophoretic Deposition and Heat Treatment on the Ti-6Al-4V Titanium Alloy’s Tribological Properties

Abstract

In this work, polytetrafluoroethylene/polyetheretherketone (PTFE/PEEK 708) coatings were fabricated by electrophoretic deposition (EPD) and heat treatment to improve the tribological properties of the Ti-6Al-4V alloy. A stable suspension containing chitosan polyelectrolyte allowed the co-deposition of both polymer types. The effect of soaking temperature and cooling rate on the coating microstructure was determined. The homogeneous coatings were obtained by heating at 450°C and cooling with a furnace or in water. The crystalline PTFE separate particles and their agglomerates were homogeneously distributed in a PEEK matrix. Interestingly, the PEEK structure was amorphous regardless of the cooling rate after heating. This new phenomenon is associated with the fluorination process. The coatings exhibited moderate scratch resistance but significantly decreased the coefficient of friction (COF) and enhanced the wear resistance of the alloy during the dry friction process in sliding contact with an Al 2 O 3 ball. The COF of the PTFE/PEEK 708 coating equaled 0.10 at room temperature (RT) and was lower than that of the alloy and pure PEEK 708 coating investigated in the same conditions, which reached 0.70 and 0.27, respectively. The wear rate of the coated alloy at RT was lower than that of the uncoated and PEEK 708 coated alloy, around 1900 and 10 times, respectively. Both the COF and wear increased slightly during friction at 150°C. The coating was not effective in improving the alloy's tribological properties during friction at 260°C.

Microstructure and Selected Properties of Advanced Biomedical n-HA/ZnS/Sulfonated PEEK Coatings Fabricated on Zirconium Alloy by Duplex Treatment

“…Fiołek et al [ 50 ] also showed that the addition of chitosan polyelectrolyte allowed for the co-deposition of different polymer particles, such as PEEK and PTFE, by changing their charge from negative to positive and via the steric stabilization of the suspension. The mechanism of interaction, as a result of which PEEK acquires a positive charge in the presence of chitosan, has been studied and described by Luo and Zhitomirsky [ 51 ].…”

Excellent Lubricity of PVA/PEG/CS Composite on Ceramic Surface and Stainless Steel Friction Pair

“…Chitosan has more oxygen‐containing functional groups. [ 58 ] When low‐quality chitosan was added, PVA played a crosslinking role, [ 49 ] so that the three materials could better form intermolecular hydrogen bonds and intramolecular hydrogen bonds through the hydrogen bond effect to better form a 3D network structure. [ 59 ] This network structure can better isolate the direct contact of friction pairs, and it can carry more load, so the friction coefficient decreased in the tribological test.…”

Evaluation of tribological and biological properties of TaB2/PEEK composite coatings prepared by electrodeposition

“…Particle filling is a typical method for improving the tribological characteristics of PEEK. The tribological characteristics of PEEK can be improved by filling it with nanoparticles such as titanium dioxide (TiO 2 ), 15 graphite(C), 16 and alumina (Al 2 O 3 ) 17 . Unfortunately, these particles did not significantly improve the biological properties of PEEK.…”