## Electrode area dependence of dielectric breakdown strength

- Dielectric breakdown of ceramics is widely believed to originate from microstructural defects. Still, there is no commonly accepted model for the origin and process of dielectric failure that covers all observed phenomena and dependencies. In analogy to mechanical strength, the Weibull distribution is commonly used to evaluate dielectric strength data. This works well for a given group of specimens with constant geometry. But unlike mechanical strength, dielectric strength scales with the inverse square root of sample thickness. This cannot be explained by the classic Weibull concept. The Griffith type energy release rate model of dielectric breakdown proposed by Schneider is based on space charge injection and conducting filaments from the sample surface. This model incorporates the distinct thickness dependence and the pronounced influence of surface defects. Based on this model and the classic Weibull probability of failure, Schneider’s group theoretically derived a probability ofDielectric breakdown of ceramics is widely believed to originate from microstructural defects. Still, there is no commonly accepted model for the origin and process of dielectric failure that covers all observed phenomena and dependencies. In analogy to mechanical strength, the Weibull distribution is commonly used to evaluate dielectric strength data. This works well for a given group of specimens with constant geometry. But unlike mechanical strength, dielectric strength scales with the inverse square root of sample thickness. This cannot be explained by the classic Weibull concept. The Griffith type energy release rate model of dielectric breakdown proposed by Schneider is based on space charge injection and conducting filaments from the sample surface. This model incorporates the distinct thickness dependence and the pronounced influence of surface defects. Based on this model and the classic Weibull probability of failure, Schneider’s group theoretically derived a probability of breakdown that predicts an increase of failure probability with increasing electrode area. In our study we tested this model with dielectric strength data measured on dense alumina samples using different electrode areas. Weibull modulus and characteristic dielectric strength (scale parameter) were determined for a set of measurements using small electrodes. These values were used to calculate the failure probability under large electrodes according to the model. The calculated data excellently fits the measured values. Thus, our experiments substantiate the assumptions made in the breakdown model and the significance of surface defects for dielectric failure.…

Autoren/innen: | Björn Mieller |
---|---|

Dokumenttyp: | Vortrag |

Veröffentlichungsform: | Präsentation |

Sprache: | Englisch |

Jahr der Erstveröffentlichung: | 2019 |

Organisationseinheit der BAM: | 5 Werkstofftechnik |

5 Werkstofftechnik / 5.5 Technische Keramik | |

DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten |

Freie Schlagwörter: | Breakdown strength; Ceramics; Dielectric strength |

Themenfelder/Aktivitätsfelder der BAM: | Material |

Material / Materialien und Stoffe | |

Veranstaltung: | 94. DKG Jahrestagung |

Veranstaltungsort: | Leoben, Austria |

Beginndatum der Veranstaltung: | 05.05.2019 |

Enddatum der Veranstaltung: | 08.05.2019 |

Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |

Datum der Freischaltung: | 20.05.2019 |

Referierte Publikation: | Nein |