TRIBOEMISSION OF CHARGED-PARTICLES AND PHOTONS FROM WEARING CERAMIC SURFACES IN VARIOUS GASES

Triboemission of charged particles and photons from Si3N4, Al2O3, ZrO2, and glass was investigated under He, Ar, N2, O2, dry air, and wet air atmospheres using a specially-developed triboemission measuring system for charged particles and photons. The results demonstrated that charged particles and photons were emitted simultaneously from wearing contact. Negatively charged particles were detected more intensively than positively charged particles from all ceramic materials and glass in every gas atmosphere tested. The charge intensity ratios of negative and positive particles were almost equivalent to mobility ratios of negative ions to positive ions. The emission intensities of both negative and positive particles decreased linearly with higher Vickers hardness, depended on gas, and linearly increased with an increase in the ionization coefficient. It was concluded that the triboemission of charged particles and photons from insulating ceramics originated from gas discharge through dielectric breakdown of the ambient gas.