Effect of sealing temperature on the sealing edge performance of vacuum glazing

• The microstructure and phase composition of sealing edges were analyzed.
• The cause of pores in the sealing edge of vacuum glazing was explored.
• The impacts of temperature and solder grain size were experimented.
• Influence of hardness and residual stress of the sealing layer was discussed.

Because inadequate control of the temperature of vacuum glazing may cause changes in form, stress, microstructure, or performance and thereby affect its lifetime, vacuum welding has been adopted to seal the vacuum glazing from the side, and experiments using different sealing temperatures have been executed. The impact of different sealing temperatures on the microstructure of the sealing layer was analyzed to evaluate the combination of material science features on the interface and to reveal the influence of the sealing temperature on the hardness and residual stress of the sealing layer. The results show that a sufficiently high sealing temperature will drive the sealing layer to transform from a hybrid structure to the liquid phase, accelerate the element migration, eliminate pores, stabilize and compact the structure and improve the sealing performance of the vacuum glazing. As the sealing temperature increases, the residual stress and hardness substantially increase. However, when the sealing temperature reaches 460 °C, the residual stress and hardness begin to plateau, and when the sealing temperature reaches 470 °C, no further change can be detected. Therefore, a sufficiently high sealing temperature is beneficial to the bonding of glass and sealing solder and can promote the sealing performance of the vacuum glazing.