Dielectric properties of selected glass and glass-ceramics produced by plasma spraying

Abstract

Selected silicate materials were sprayed by plasma in the past and characterized from the standpint of their sprayability, chemical composition and crystallographic phases, structure and mechanical properties as well as thermal stability. Present work is concentrated on dielectric properties of these thick films. Synthetic mullite, mullite mixture with glass, and pure glass were produced using the water-stabilized plasma system (WSP ® ). The deposits were striped-out, ground and polished to produce planparallel plates, i.e. flat samples with a smooth surface. These samples serve in principle like monoblock capacitors. All of them were tested in the alternating electric field at low voltage to examine their capacity and loss tangent in the frequency range between 100 Hz and 1 MHz. Relative permittivity was calculated based on the measured capacity. It is shown that the relative permitivity and loss tangent of plasma-sprayed glass and glass-ceramics is similarly stable as for bulk polycrystalline dielectric materials of the same composition. The family of silicon oxide based ceramics and glass is often used in electrical industry, particularly as insulators. Sintered silicate materials exhibit extraordinary volume resistivity and small dielectric losses during a wide range electric