摘要
Abstract
In actual traveling-wave tube (TWT) production,ceramic energy transmission windows appear concentrated air leakage under repeated thermal shock.The main phenomenon is that the ceramic windows could not withstand the thermal shock,air escapes from the copper weld between the molybdenum rod and the ceramic window,and the ceramic cracks.Checking the surface of cracked ceramic wafers,plenty of bright molten glass phases are found.They have big grain size and seem to be over-fired.In this research,a thermal shock experiment is carried out.Two different Al2O3 ceramic wafers made in actual production are tested after being assembled into the ceramic energy transmission windows.In the experiment,the section plane analysis of the two ceramic wafers is done with SEM,and the effect of different grain size on sealing strength and ceramic strength is compared.The results show that ceramics with bigger grain size and being over-fired have weaker thermal shock resistance and lower ceramic strength,and so ceramics near needle sealing joints are more likely to have micro-cracks and get cracked because of concentrated thermal stress,which decrease the reliability of ceramic energy transmission windows.关键词
氧化铝陶瓷/晶粒度/热冲击Key words
Al2O3 Ceramic/Grain size/Thermal shock
