ABSTRACT Electrostatic discharge (ESD) influences a lot in the industries of petrochemistry, semiconductor, and electronics. ESD is one of the reasons for the deterioration of the lubricant in the lubrication system. In this study, to understand the performance of the frictional electrification of the lubricant, the circumrotating frictional electrification tester with the measurement systems is employed to investigate the friction electrification under the dry and lubricated conditions. The materials of the specimens are made of Fe and PTFE, and the paraffin base oil is used as the lubricant. Furthermore, the effects of the load, the sliding speed, and the sliding distance on the friction electrification are investigated. Results show that the electrification voltage and the surface voltage in the lubricated condition is much lower than in the dry condition for the pair of Fe/PTFE. Because the capacitance effect is almost disappears in the lubricated condition for the pair of Fe/PTFE. When two conductors become a capacitor by inserting an insulator, such as Fe/PTFE in the dry condition, the surface voltage is about 3~4 times higher than in the lubricated condition, and the frictional voltage is about 10 times higher than in the lubricated condition because of the isolator capacitance. Moreover, the oil, the PTFE and the Fe have different polarities. The surface voltage of PTFE and output voltages of Fe are negative, and surface voltage of oil are positive. The normal load, the sliding speed, and the sliding distance also affect the surface voltage of PTFE and output voltage of Fe. Among them, the load is the most significant parameter for surface voltage of PTFE, the sliding speed is the most significant parameter for output voltage of Fe.

ABSTRACT Electrostatic discharge (ESD) influences a lot in the industries of petrochemistry, semiconductor, and electronics. ESD is one of the reasons for the deterioration of the lubricant in the lubrication system. In this study, to understand the performance of the frictional electrification of the lubricant, the reciprocating frictional electrification tester with the measurement systems is employed to investigate the friction electrification under the dry and lubricated conditions. The materials of the specimens are made of Fe and PTFE, and the paraffin base oil is used as the lubricant. Furthermore, the effects of the load, the sliding speed, and the duration of the friction on the friction electrification are investigated. Results show that the electrification voltage in the lubricated condition is much higher than that in the dry condition for the all-material pairs, but the surface voltage is reverse. The measured voltage is lower for the pair of Fe/PTFE and PTFE/Fe because the capacitance effect of the isolator disappears. When two conductors become a capacitor by inserting an insulator, such as Fe/PTFE-Fe, the frictional voltage is about 2~3 times higher than the other pairs because of the isolator capacitance. Moreover, the rotational speed, the normal load, and the duration also affect the output voltage. Among them, the rotational speed is the most significant parameter. At a certain normal load, the oil and the iron have different polarities, and their voltages increase with increasing rotational speed for Fe/Fe pair. In the polarity study; the tribo-electrification mechanism is proposed for Fe/PTFE, PTFE/Fe and Fe/PTFE-Fe pairs. The output voltages are negative at the lower and the upper specimens for Fe/PTFE and PTFE/Fe pairs, but negative and positive for Fe/PTFE-Fe pairs, respectively. After the surfaces of Fe and PTFE slide together, since the high residual negative voltage appears on PTFE, which causes the separation of induced charge on Fe, the surface residual voltage of PTFE dominates the polarity of output voltage. At Fe/PTFE-Fe pair, the polarity at the upper specimen of Fe is negative. However, the polarity at the lower specimen of Fe is positive, because the lower specimen is also influenced by the surface residual voltage of PTFE.