Skip to Main content Skip to Navigation
Theses

Transport de charges dans les alumines polycristallines - Application à l'optimisation de la rigidité diélectrique

Abstract : Dielectric breakdown constitutes an important limitation in the use of insulating materials under high-tension since it leads to the local fusion and the sublimation of material. The microstructure (average grain size, intergranular phase) has a great influence on the ability of material to resist this catastrophic phenomenon. Indeed, the interfaces between the various phases constitute potential sites of trapping for the charges. The optimization of the dielectric breakdown strength of a polycrystalline alumina sintered with a liquid phase passes necessarily through the control of the microstructural parameters. Thus, it is shown that by controlling the conditions of the process (rate of sintering aids, powder grain size and thermal cycle), it is possible to control the density (by the average grain size) but also the nature (by the crystallization or not of anorthite) of the grain boundaries. The study of the influence of these two parameters as well temperature on the properties of charge transport and storage was carried out by methods ICM and SEMME. The results, interpreted in light of the numerical simulation of the charge transport in bulk alumina sample during electron beam irradiation, allowed to highlight behaviors, and the corresponding microstructures, favourable to the dielectric breakdown resistance according to the considered temperature. Thus, at room temperature a high density of interfaces (low grain size and crystallized intergranular phase) makes it possible material to durably trap a great amount of charges, which leads to a high dielectric strength. On the other hand, at higher temperature, the presence of shallow traps (vitreous intergranular phase) supports the cherge diffusion and makes it possible to delay breakdown.
Complete list of metadata

Cited literature [96 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00012004
Contributor : Matthieu Touzin <>
Submitted on : Wednesday, March 22, 2006 - 11:42:03 AM
Last modification on : Wednesday, June 24, 2020 - 4:18:21 PM
Long-term archiving on: : Tuesday, June 15, 2010 - 4:32:41 PM

Identifiers

  • HAL Id : tel-00012004, version 1

Citation

Matthieu Touzin. Transport de charges dans les alumines polycristallines - Application à l'optimisation de la rigidité diélectrique. Matériaux. Ecole Nationale Supérieure des Mines de Saint-Etienne, 2005. Français. ⟨tel-00012004⟩

Share

Metrics

Record views

548

Files downloads

1321