Page 27 - Curriculum Visions Dynamic Book

Solder glasses
A variety of lead glasses are important as low-melting sealing and solder glasses. A solder glass is a piece of glass used to join two pieces of glass together. This may be important, for example, in joining two intricate shapes or when sealing glasses to metals, as in the manufacture of television tubes.
For these purposes a low softening point glass is needed so that the solder glass can be softened and used at temperatures well below the softening points of the two pieces of glass that are to be joined. This glass will soften at about 630°C. A typical sealing glass contains about 23% lead oxide by weight. (Glass used for fine lead crystal contains about 30% lead oxide by weight.)
bond: chemical bonding is either a
transfer or sharing of electrons by two
or more atoms. There are a number of types of chemical bond, some very strong (such as covalent bonds), others weak
(such as hydrogen bonds).
oxide: a compound that includes oxygen and one other element.
refractive index: the property of a transparent material that controls the angle at which total internal reflection will occur. The greater the refractive index, the more reflective the material will be.
viscous: slow moving, syrupy. A liquid that has a low viscosity is said to be mobile.
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