Researches on Tie Rod Ends Lubricated by Grease with TiO₂ and ZrO₂ Nanoparticles

Abstract

Abstract. The nanoparticles of some materials can be used successfully to improve tribological properties through decreasing both wear and friction borne out of contact between the contact surfaces of elements in different devices, particularly vehicles. Nanoparticles of TiO2 and ZrO2 were chosen as additives to the lithium grease lubricating the contact surfaces in tie rod ends. The object of study was the steel ball -the component of the tie rod end -mating with the polymer insert and lubricated with the pure lithium grease or containing the addition of pure TiO2, pure ZrO2 nanoparticles, with a 1%wt. Studies on friction were carried out using the tester allowing cyclical rotational motion and different loading of contact. Wear was investigated by driving a car, whose tie rod ends were analysed, on a fixed 'eight'-shape track and with a fixed velocity pattern. The aim of the study was to obtain the values and waveforms of friction moment and wear versus cycles, loading and composition of lubricating grease. The waveforms of friction coefficient were obtained using the FEM model of the analysed contact zone. Based on the obtained waveforms, recommendations for the composition of additives for lithium grease were made.

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

“…The preliminary analysis of the nanopowder market, particularly in Poland, has shown that zirconia nanopowders are available on the market and are relatively cheap. The number of available publications on the use of ZrO 2 nanoparticles as an additive to lubricants is not great; nevertheless, the results of preliminary studies carried out by Wozniak et al [61] pointed such nanoparticles as a candidate improving the tribological properties of some lubricants. It has been noted that the problem of agglomeration may also occur during preparation of nanolubricants with zirconia nanoparticles.…”

“…Wozniak et al [61] studied lithium grease with the TiO 2 and ZrO 2 nanoparticles lubricating the mating surfaces in tie rod ends. The steel ball-polymer insert contact zone was lubricated with the pure lithium grease or containing 1 wt.% of TiO 2 or ZrO 2 nanoparticles.…”

“…The ball mates with the polyethylene counterpart of 30 mm inner diameter and fixed in the steel ring. The contact zone was loaded with a constant force and lubricated with lithium grease without or with 1 wt.% amount of ZrO 2 nanoparticles of a size 10-20 nm (for details see Reference [61]). The lithium grease was mixed with the ZrO 2 nanoparticles by the High-Speed Planetary Mixer THINKY SR-5000 [156] followed by treatment with GT Sonic VGT-800 Ultrasonic Cleaner for approximately 120 s in order to avoid agglomeration or the structural break of the nanoparticles.…”

“…The friction in the steel ball/polymer insert contact zone lubricated by the lithium grease without or with ZrO 2 nanoparticles was studied with the use of a tribotester [61]. The tribotester allowed obtaining values of the spinning friction torque in the contact zone between ball and its counterpart.…”

“…Measurements were performed under constant rotating speed of 36 rpm of the ball and under constant load in the contact zone that was increased stepwise from 7.2 to 27.2 N. The COF values were calculated using measured values of the friction torque, diameter of contact zone, and an average contact pressure in the contact zone between the ball and its counterpart. The average contact pressure and diameter of the contact zone were estimated using the FEM model of such a zone [61]. The values of the contact pressure did not exceed 38 MPa.…”