Glass to glass sealing

      The sealing between glass and glass is usually carried out by sintering and melting in a mixed flame of coal gas or natural gas and oxygen. In order to ensure reliable sealing, the coefficient of thermal expansion between the sealing glasses must be very similar, otherwise the glass will break due to the internal stress generated during the sealing.

     Experience has proved that if the difference in the coefficient of linear expansion is not greater than 7×10-7/℃, the internal stress generated at the weld will not cause explosion. If the expansion coefficient is too large, an intermediate glass with an expansion coefficient between the two should be used for transitional sealing. It is best to use annealing process to eliminate internal stress in the sealed place, otherwise the sealed place will easily cause cracks.

       The thermal stability of glass is poor, and attention should be paid to the temperature of the flame acting on the glass when sealing, because rapid temperature changes can also cause glass to burst.