【作者】 吕金龙；

【导师】 耿洪滨；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2007， 硕士

【摘要】 本文利用空间环境地面模拟设备和Co-60γ辐照装置,研究了热循环和辐照对陶瓷封装电容器电容量和损耗角正切值的影响规律。利用扫描电镜观察了陶瓷封装电容器结构和失效形式,并利用能谱仪对金属电极、陶瓷电介质等进行了成分分析。建立了陶瓷封装电容器横截面二维有限元模型,分析了陶瓷封装电容器电极和电介质层的热应力分布规律。实验结果表明,在热循环过程中,随着温度的升高,陶瓷封装电容器的电容量变化率存在一个峰值,电容量变化率与温度呈Lorentz峰值函数的变化关系;随着温度的升高,其损耗角正切值是单调递减的。随着循环次数(循环时间)的增加,电容器的电容量是减小的,瓷片电容器的电容量变化率与循环次数满足抛物线函数变化关系;其损耗角正切值是单调递增的,损耗角正切值与循环次数满足线性的函数关系。在热循环过程中,金属电极发生氧化,引起电容量减小;电容器内部电介质和金属电极之间的热错配应力对其结构造成损伤,当这种损伤累积到一定程度,就表现为电介质和电极层间开裂,导致电容体失效。在热循环的上下限温度,靠近陶瓷电介质和金属电极界面位置附近存在等效应力极大值,这与试验中观察到电容器的失效形式相对应。经过rad、rad和rad三种递增剂量Co-60γ辐照后,陶瓷封装电容器的电容量递减,损耗角正切值D是递增的。5.36×1055.05×1061.26×107更多还原

【Abstract】 Effects of thermal cycling and irradiations on the property degradation of the ceramic encapsulation capacitor were investigated by space environment simulators for thermal cycling and Co-60γirradiation. The structure and invalidation pattern of the ceramic encapsulation capacitor were analyzed by means of scanning electron microscopy. The composition of metal electrode and ceramic medium layer was studied by the energy spectrometer. The planar finite element mode for the cross section of the ceramic encapsulation capacitor was set up. The thermal stress distribution for the structure layers was analyzed.The experimental results show that the change ratio of capacity presents a peak value with increasing temperature in heating stage of thermal cycling. There is a relationship of Lorentz between the change rate of the capacity and temperature. The tangent angle of wastage decreases in heating stage of thermal cycling. The capacity decreases with increasing the cycles, and there is a relationship of parabola between the change rate of capacity and cycles. The tangent angle of wastage increases with increasing the cycles. There is a relationship of liner between the tangent angle of wastage and cycles.During thermal cycling, the metal electrodes are oxidated that results in the decreasing in the value of capacity. The thermal mismatch stresses between the metal electrode and ceramic medium generate damage to the structure of capacitor. When the damage was accumulated to a certainty extent, the structural fracture of the layers will occur and result in the invalidation of capacitor.The maximal equivalent stress existed in the segment near the interface between metal electrode and ceramic medium at up and down limit temperature during thermal cycling, which was corresponding with the invalidation pattern of capacitorThe capacity of ceramic encapsulation capacitor decreases and the tangent angle of wastage increases after Co-60γradiation in three dosages of 5×105rad、5×106rad and 1×107rad.更多还原