Dr. Keiji Nakayama, The President, Institute of Mesotechnology(IOM), Japan

Title: Triboelectromagnetic Phenomena in Combinations of Moving Tribomaterials against Stationary Ones

Abstract: Triboelectromagnetic phenomena embrace triboemission, post emission, triboplasma generation and tribocharging. The characteristics and mechanisms of triboelectromagnetic phenomena are presented in combinations of the moving tribomaterials against stationary ones.

In steel sliding against various metals such as Al, Ti, Mo, Fe and so on, no triboplasma was generated, but electrons were emitted. However, even in various metals and conductive amorphous carbon, as well as polymers of polyaceal and PTFE, triboplasma was generated when they slid against dielectric sapphire, since in this system tribocharging occurs.

In diamond sliding against various kinds of tribomaterials of metals of Al, Fe and Cu, semiconductors of SiC and glass, insulators of Si₃N₄ and Al₂O₃, nylon, PTFE and mica, the triboemission intensities of electrons, ions and photons increased with the electric resistivity to give the emission intensities in the orders of insulators > semiconductors > conductors, since tribocharge induced electric field to accelerate the emitted electrons for generating the triboplasma increases in this order.

Triboluminescence mechanisms were investigated in the tribo-systems of diamond sliding against single crystals of Al₂O₃, MgO and SiO₂. The triboluminescence in visible region were attributed to the photoluminescence (PL) and cathodoluminescence (CL) from the Cr3+ impurities in Al₂O₃, to the F⁺ and F centers, Fe³⁺ and Cr³⁺ impurities in MgO, and to the E, center, NBOHC, oxygen vacancy and impurities in SiO₂.

The triboplasma, which is cold plasma1), can be controlled by controlling the electric resistivity of the tribomaterials, the hydrogen content in DLC films and geometry of the tribomaterials2). It is anticipated that new advanced triboplasma technologies are developed using the triboplasma controlling technologies based on the materials science and engineering.

References: 1) K. Nakayama, et al: Trib. Lett. 66 (2018)10,
2) K. Nakayama: Jpn. J. Appl. Phys., 46 (2007) 6007.