The aim of this study was to evaluate and compare the effect of the material type and the morphology of well-known solid lubricant nanoparticles on the tribological properties of poly ether ether ketone (PEEK) composites. Different nanoparticles were added to the PEEK matrix: WS2 fullerene like, WS2 needle-like, carbon nanotubes and graphene nanopowder. The results of dry-sliding tribological tests show that the material and the morphology of the nanoparticles have a crucial effect on both the wear and the coefficient of friction, primarily by affecting their macroscopic hardness, as well as the thickness and the surface coverage of their transfer films. The WS₂ based nanoparticles outperformed the carbon-based nanoparticles in terms of wear performance; compared to PEEK, WS2F improved the wear rate by 10 % and the WS2N by 60 %.
COBISS.SI-ID: 13905691
The addition of different concentrations (2–10 wt.%) of molybdenum disulphide (MoS₂) to a poly ether ether ketone (PEEK) matrix has been studied in terms of the thermal, mechanical and tribological properties of the materials. The results of dry-sliding tribological tests, DSC and SEM-EDS analyses show that the concentration of MoS₂ influences the tribological, mechanical and thermal properties. With the highest concentration of MoS₂ (10 wt.%), the coefficient of friction was reduced by as much as 25 %, while the maximum reduction in the wear rate was ~20 %, which required 5 wt.% of MoS₂. The most important parameter when it comes to achieving an improved tribological behaviour was found to be the combination of a high hardness and a sufficient quantity of transfer film being formed.
In this paper the influence of processing temperature on PEEK was investigated in terms of material and tribological properties. PEEK samples were produced at temperatures below (300 °C), around (350 °C) and above (400 °C) melting point of PEEK and were compared to the commercially available PEEK material. The results of dry-sliding tribological tests, hardness measurements and XRD analysis show, that the processing temperature importantly influences the material properties (i.e. hardness and crystallinity) that is later on expressed also in the tribological behaviour. Samples that were produced at 350 °C and 400 °C showed ~60 % higher hardness (compared to 300 °C and commercial material) and a ~20 % lower coefficient of friction, but also a two order of magnitude higher wear rate. On the other hand, the sample produced at 300 °C showed in all respects (hardness, friction, wear) properties very similar to those measured for commercial PEEK.
Aqueous electrophoretic deposition (EPD) is a colloidal processing technique, which enables fast formation of bulk deposits. The addition of suitable surfactant would enable dispersion, and due to their effect on electrokinetic properties, also the deposition of hydrophobic particles of polyether ether ketone (PEEK). The electrophoretic properties and the conductivities of suspensions were analysed as a function of the addition of surfactants or the pH, and related to the properties of the as-prepared bulk deposits. A more in-depth understanding of the deposition process was achieved by monitoring the suspensions’ properties (pH, ζ and conductivity) before and after the deposition and observation of the deposits’ properties. We have shown that by using a concentrated suspension of PEEK (50 wt. %) with the addition of DBSA at pH)4, thick deposits () 15 mm) were formed at moderate voltages (10-30 Vcm-1) in one minute. Although the PEEK polymer is hydrophobic by nature, aqueous EPD was shown to be an effective technique for shaping bulk parts. During the deposition, unusual current increase was observed and was attributed to an increase in the conductivity due to the migration of ions and electrochemical reactions at the electrodes.