真空平板玻璃封边气孔成因研究

Mechanism for Porosity Formation in Sealing Vacuum Plate Edges by Glazing

针对真空平板玻璃封边封接层中易出现气孔缺陷的问题,采用真空熔接法侧边封接真空平板玻璃,利用EBSD、EDS方法分析了真空平板玻璃封接层的显微组织结构与物相组成,探究了真空平板玻璃封边气孔的形成原因,并对真空平板玻璃进行了不同封接焊料粒径在不同封接温度的试验研究,分析了真空平板玻璃封边气孔率的影响因素。研究结果表明,真空平板玻璃封接层外侧为呈一定厚度且连续分布的层状界面反应润湿层,内部为熔融层,在熔融层存在大量的气孔,润湿层未出现明显的气孔,气孔均为相互不连通的孤立气孔,主要位于颗粒的交界处,主要是由焊料颗粒间的残留空气引起的。随着封接温度的升高与封接焊料粒度的减小,结构变得致密平整,气孔数量减少,只要通过合理选择封接温度与封接焊料粒度,可以避免或减少气孔缺陷。

The formation of pores in sealing the vacuum plate edges by glazing. The impact of the glazing conditions, including but not limited to the glazing temperature,molar ratio and average size of the sealing solder,on the microstmctures, phase structures, contents and porosity at the sealed edges was investigated with scanning electron microscopy, energy dispersive spectroscopy and electron backscattered diffraction. The results show that the glazing temperature and average powder size of solder strongly affect the porosity. To be specific, as the glazing temperature increased and the average solder grain-size decrease, both the number and size of pores decreased, and the sealed edges became increasingly smooth, uniform and compact. The gases adsorbed by powder surfaces and/or trapped in the spaces enclosed by grain boundaries account for the formation of pores in glazing. We suggest that the optimized size of solder powder and glazing temperature may significantly reduce or eliminate the pores formed in glazing the vacuum-plate edges.