AVS 60th International Symposium and Exhibition
    Tribology Focus Topic Tuesday Sessions
       Session TR-TuP

Paper TR-TuP1
Study of Charge Separation and Relaxation during Friction between Metal and Plastics in a Vacuum and in Air

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

Session: Tribology Poster Session
Presenter: T. Miura, National Institute of Occupational Safety and Health, Japan
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Electric charges generated by friction, i.e., triboelectricity, between industrial materials induce incendiary electrostatic discharges, such as a spark. In fact, many industrial accidents involving explosions and fires occur due to the electrostatic discharges. In this study, we focus on the elemental processes, e.g., charge separation and relaxation, during friction between metal and plastics. Measurement of the charge separation in a vacuum makes it clear that the real amount of triboelectrification between solid materials because of suppression of charge relaxation through gas discharge in a micro-gap interface of them. In air, we can obtain the relaxation efficiency for the initial charge separation.

The experimental equipment was constructed on the basis of pin-on-disk technique in a vacuum chamber. The pin was made of metal and the disk was made of plastic material. Amount of the separated electric charges between them during sliding friction was measured with an electrometer by connecting to the metal sample.

Experiment with a stainless steel pin and a poly-ethylene terephthalate (PET) disk was performed. The charge density on the rubbed surface of PET was calculated to be about -5x10-4 C/m2 from the generated charges and the width of the friction track. In air, the charge accumulation was, however, one order of magnitude less than the value measured in a vacuum. This should be caused by the charge relaxation as a result of the micro-gap discharge [1].

[1] T. Miura and I. Arakawa, IEEE Transactions on Dielectric and Electrical Insulation, 14, 560-565 (2007).