TECHNICAL SUPPORT

TECHNICAL SUPPORT

Sealing of glass and metal

SEALThe most common glass-to-metal seals are electrode leads and pipe-like glass-to-metal seals.This kind of sealing is divided into matched sealing and unmatched sealing.Matching sealing refers to the sealing between glass and metal with similar coefficient of expansion.Mismatched sealing refers to the sealing between glass and metal with a large difference in expansion coefficient.The internal stress at the sealing is large.In order to eliminate the internal stress caused by a large difference in expansion coefficient between glass and metal,thin wall metal pipe with good ductility is generally used to seal with glass to eliminate the internal stress by plastic deformation of metal.

 

As shown in the figure is a mismatched sealing form of metal tube and glass tube.The metal pipe wall gradually thins at the sealing to facilitate deformation,and the thinning area is about twice the length of the sealing area.This kind of sealing is generally divided into three types:outer sealing(glass is only fused on the outside of the metal tube wall),inner sealing(glass is only fused on the inside of the metal tube wall)and bilateral sealing(glass is only fused on the inside of the metal tube wall).When double sealing,the inside glass sealing length should be twice as long as the outside.Not withstand such sealing temperature rise and fall repeatedly,such as copper and glass sealing,if the temperature swing is at room temperature to 400℃,can only use hundreds of times.