EFFECT OF X-IRRADIATION AND FRICTION ON THE PROPERTIES OF INSULATORS

The study of ceramics is tackled from the space-charge physics point o f view. The role of the polarization and relaxation mechanisms is demo nstrated for friction coefficient and wear, as well as for breakdown v oltage, therefore these characteristics depend on the permittivity. Th is approach is based on experiments performed with pure or X-irradiate d single crystal alumina (sapphire) or polycrystalline alumina. A new method (mirror method) is presented in which the possibility of creati ng trapped electrical charges in a given material is measured using th e electron beam of a scanning electron microscope X-ray irradiation ch anges permittivity, Young modulus and charging properties. These chang es can modify both the irradiated and the unirradiated areas. Friction , and consequently machining, create defects everywhere in the materia l i.e. inside as well as outside the contact or wear tracks.