This paper presents results of testing the coarse rapeseed oil additivated with different concentrations of ZnO (0.25%wt, 0.50%wt and 1%wt, with 14±5 nm in size), on a four-ball machine. The test parameters were load on main shaft of the machine: 100 N, 200 N and 300 N and the rotational speed 1000 rpm, 1400 rpm and 1800 rpm. For the tested range of ZnO concentration, the value of 1%wt does not improve the friction coefficient, but the wear rate of wear scar diameter was lower than that obtained with the neat rapeseed oil and the values are less sensitive with load and sliding speed for the more severe regimes. The additivation of rapeseed oil with ZnO is still efficient for the tested range of load and speed as compared to neat rapeseed oil. The authors formulated lubricants using as dispersant (2-methoxyphenol) in the ratio 1:1 to the additive. The technology is at scale laboratory and implies mechanical stirring and sonication. The tribological behavior was analysed based on obtained results, by mapping the friction coefficient, the wear rate of the wear scar diameter and the final temperature in the oil bath. For the additivated lubricants the following conclusions could be drawn. Friction coefficient tends to reach 0.1 only for low speed and high load (v = 0.38 m/s and F = 300 N), wear rate of wear scar diameter decreases with the increase of load, for each tested speed, probably because of a full fluid film generation. For F = 250…300 N, the map reveals a poor dependence on the additive concentration. The final temperature in the lubricant bath depends on speed, but for the same speed, it depends less on load, having a maximum value for 0.75% nano additive. These conclusions underlined the necessity of testing the new formulated lubricants because additive concentration and regime parameters could have synergic influences on the tribological parameters.

This paper presents results of testing the coarse rapeseed oil additivated with 1%wt hexagonal boron nitride (hBN). Tests are done on a four-ball machine from the laboratory LubriTest, at “Dunarea de Jos” University of Galati. Tests were done in mild regime (recommended for applications) and in severe regime. The mild test parameters were: load on the main shaft of the machine (100 N, 200 N and 300 N) and the sliding speed of 0.38 m/s, 0.53 m/s and 0.69 m/s, test duration 1 h. Severe test were run in step of 50 N till 900 N, each test being run for 1 minute at 0.53 m/s. The concentration of 1%wt hBN does not improve the friction coefficient, but it makes it stable for a larger domain of test parameters. The wear rate of wear scar diameter was lower than that obtained with the base oil, especially for high loads. Also, the paper presents the influence of the additive on the temperature of oil bath and the wear load curve of the neat oil and the additivated one. The additivation of rapeseed oil with hNB is still efficient for the tested ranges of load as compared to the rapeseed oil. The load-wear curve for the severe regime points out a sudden increase of wear scar diameter (WSD) for the rapeseed oil +1% hNB at 700 N, but the neat vegetal oil starts the increase of WSD at 550 N, followed by a greater slope, meaning the additive protect the rubbing surfaces under these high loads.

This paper presents the influence of hexagonal boron nitride (hBN) as additive in refined rapeseed oil in different mass concentration of 0.25%wt, 0.5%wt and 1%wt on the tribological parameters, obtained on a four-ball machine. The test parameters were load: 100 N, 200 N and 300 N and the rotational speed 1000 rpm, 1400 rpm and 1800 rpm, corresponding to the following sliding speed, 0.38 m/s, 0.53 m/s and 0.69 m/s, respectively. The average particle size of hBN is 14 nm. For the tested ranges of the parameters, the additivation of rapeseed oil with hBN does not improve the friction coefficient, but the wear rate of WSD seems to be less sensitive for the more severe regimes when the vegetal oil is additivated.

Particles of ZnO have 145 nm. The rapeseed oil was supplied by Expur SA Bucharest. For the tested ranges of the parameters, the additivation of rapeseed oil with ZnO does not improve the friction coefficient, but the wear rate of WSD seems to be less sensitive for the more severe regimes when the vegetal oil is additivated. The additivation of rapeseed oil with ZnO is still efficient for the tested ranges of load and speed as compared to the neat rapeseed oil, but there is visible that friction coefficient and analysed wear parameter are less influenced by the regime for the concentration of 1% ZnO in rapeseed oil.

This paper presents the influence of BN as additive in refined rapeseed oil in a mass concentration of 1%wt on the tribological parameters. Tests are done on a four-ball machine. The test parameters were load: 100 N...300 N and the the sliding speeds of 0.38 m/s, 0.53 m/s and 0.69 m/s, respectively. Particles of hexagonal BN have 500 ± 100 nm. The rapeseed oil was supplied by Expur SA Bucharest. For the tested ranges of the parameters, the additivation of rapeseed oil with BN does not improve the friction coefficient, but the wear rate of WSD seems to be less sensitive for the more severe regimes when the vegetal oil is additivated. The additivation of rapeseed oil with BN is still efficient for the tested ranges of load and speed as compared to the neat rapeseed oil, but there is visible that friction coefficient and analysed wear parameter are less influenced by the regime for the concentration of 1% BN in rapeseed oil.