EVALUATING SEIZURE ON FOUR BALL TESTER FOR RAPESEED OIL

Abstract

This paper presents a tribological characterization in seizure regime for two lubricants (rapeseed oil and rapeseed oil additivated with 1%wt TiO2). Tests were done on a four-ball tester, in the load range at the tester shaft 500...900 N, in step of 50 N, for 60 seconds and with a rotational speed of 1400 rpm (equivalent to a sliding speed of 0.53 m/s). There were discussed the average value of friction coefficient, the wear scar diameter (WSD), the flash temperature parameter and several texture 3D parameters. Till 600 N, the influence of additivation is not obvious, the friction coefficient is lower for the neat oil, WSD is similar, but after this load, the slope for WSD is smaller for the additivated lubricant and for 900 N, this parameter is also smaller. Sa seems to be quite insensitive to the load increase, but other parameters, like St has a significant increase, meaning two processes: additive is pressed on the surface and developed high local peaks or/and the adhesive and abrasive wear is more intense. FTP is almost the same at 900 N, but the additive makes this parameter to evolve with a plateau with low slope, meaning the additivated lubricant has a better behavior under high loads.