Annealing and firing in wet hydrogen are widely used steps in the processing alumina.ceramic insulators that may affect their dielectric breakdown strengths (DBS). In this study, the effects of annealing (at 1300 °C for 7 h) and firing in wet hydrogen on the DBS of alumina ceramics (all sintered at 1650 °C) were studied, and the underlying mechanisms were analyzed by material characterizations. Annealing reduced the DBS of the 95% alumina ceramics due to the inter-granular phase crystallization, and the reduction in the DBS could be correlated to the reduction in mechanical strength. In contrast, annealing improved the DBS of the 99% alumina ceramic without intergranular phase transformation. Firing in wet hydrogen at 1500 °C caused the DBS increment, which can be ascribed to the reduction in the concentrations of point defects and electrical carriers.

中文翻译：

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湿氢退火和烧成对氧化铝陶瓷介电击穿强度的影响

在湿氢中进行退火和焙烧是氧化铝/陶瓷绝缘子加工中广泛使用的步骤，可能会影响其介电击穿强度（DBS）。在这项研究中，研究了退火（在1300°C下进行7 h）和在湿氢中烧成对氧化铝陶瓷（均在1650°C下烧结）的DBS的影响，并通过材料表征分析了其潜在机理。退火会由于晶间相结晶而降低95％氧化铝陶瓷的DBS，而DBS的降低可能与机械强度的降低有关。相反，退火改善了99％氧化铝陶瓷的DBS，而没有晶间相变。在1500°C的氢气中燃烧会导致DBS增量，