High performance polymers, such as poly-ether-ether-ketone, are frequently used as a replacement for machined metals in a variety of applications. Compared to other polymer materials, PEEK has shown promising tribological properties; however, when using PEEK in harsh conditions, such as dry sliding contacts, further improvement of its tribological properties is still needed. In order to do that, different concentrations of molybdenum disulphide (MoS₂) particles (2 10 wt.%) were dispersed into PEEK matrix and compared to a pure PEEK sample. Tribological tests were performed by reciprocating sliding in dry conditions with steel pin as a counter-material. Observations of steady state friction, wear performance, hardness and transfer film formation were made. Results show that MoS₂ particles improve friction and wear behaviour of a material up to 25 %.
B.01 Organiser of a scientific meeting
COBISS.SI-ID: 13688347Polymer materials are getting ever more attention in various applications due to their low weight, low cost, suitability for mass production, and several other beneficial specific properties, often also tribological. During tribological research real-scale studies or model contact-based studies can be selected. Each of them has some positive and some negative sides. However, for contact-based studies, which are more common, several restrictions holds for polymers, which are valid due to polymer low thermal resistance and mechanical strength, at least compared to conventional metals. Namely, the contact loads and temperatures have relatively narrow window of appropriateness to lead to relevant results, suitable for transfer into real application. Therefore, in order to be able to perform the experiments under these conditions, real contact area and real contact temperatures should be known and controlled. This paper presents some of the above discussed specifics and discusses possible ways how to overcome them, primarily addressing necessary future research directions to better control polymer tribology research.
B.04 Guest lecture
COBISS.SI-ID: 13690139In this study, coefficient of friction, wear rate and wear mechanisms of PEEK/MoS composites are presented in a relationship to MoS particles concentration (0–10 wt.%) and processing temperature (300–350 °C). Tribological tests were performed by reciprocating sliding in dry conditions with steel pin as a countermaterial. Results show that processing temperature and concentration have a considerable influence on tribological and mechanical properties.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 13532955Although polyetherether ketone (PEEK) polymer is hydrophobic by nature, aqueous electrophoretic deposition can be employed as efficient technique for shaping bulk parts and coatings. In this paper, the development of the suspension, processing parameters and the properties of the PEEK deposits are described. The mechanisms that took place to form a deposit are suggested and discussed. Aqueous PEEK suspension with high surface charge and low conductivity was successfully prepared by addition of dodecylbenzene sulphonic acid (DBSA) and NaOH to adjust pH. The nonpolar DBSion attached to the hydrophobic surface of PEEK resulting in hydrophilisation of the PEEK particles as well as in highly negative surface charge favourable for EPD process. During the deposition, the DBSappear to remain attached at the particles in the deposit. H+ ions produced at depositing electrode through the decomposition of water replaced Na+ ions, which migrate toward the negative electrode where after reduction to Na0 and reaction with water increase the pH of the remaining suspension. The aqueous electrophoretic deposition from suspensions with 50 wt.% of solids loading was rather fast and resulted in large homogeneous PEEK deposits with density of up to 557% TD. The deposit resistance is greatly affected by the behaviour, amount and concentration of the ions within the interparticle electrolyte within the deposit.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 28042791PEEK properties are contributed to its semicrystalline structure that is developed during processing. In this work, we have produced PEEK samples with variation of compression moulding where compression was separated from a heating part. This enabled us to use different processing temperatures, even those under a melting point of PEEK (300–400 °C). Produced samples were tested in a reciprocating sliding regime in a dry sliding contact and evaluated in terms of friction, wear, hardness and transfer film formation. The results show that processing temperature has a great influence on wear performance and hardness of a material. Hardness was increased by higher processing temperature but, on the other hand, wear resistance was better at lower processing temperatures. Temperature influence was also seen in transfer film formation and in the appearance of worn surfaces.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 13691163