Glass solder

Glass solder is a glass with a particularly low softening temperature (e.g. 400 ° C) that is used for thermal bonding or sealing of objects made of glass. The main components are boron and lead oxide . The process is similar to soldering with metals ; here, too, good adhesion to the components to be soldered is achieved through dissolving processes . However, since they are non-metals, glass solders belong to the group of adhesives .

Depending on the type, glass solder is processed at a temperature between 350 ° C and 700 ° C (typically: 500 ° C), with a viscosity of η = 10 ⁴ -10 ⁶ dPa · s. Since glass has a typical softening temperature of 600 ° C, it is still solid at this temperature, while the glass solder is already liquid.

Applications

Glass solder is used in the manufacture of electron tubes to connect the bulb and base. The low processing temperature largely prevents an undesirable reaction of the inner parts of the tube with the room air.

Glass solder is also used in the manufacture of the control grid for tension grid tubes .

Individual evidence

1. ↑ Schott technical glasses, physical and chemical properties (PDF file) , Chapter 8 “Glass solders”.

literature

• Werner Espe: Materials science of high vacuum technology . 2: Silicate materials. VEB Deutscher Verlag der Wissenschaften, Berlin 1960.