Process for the treatment of glass by metal migration

Claim 2

A process for the treatment of glass for the purpose of varying properties of the glass, comprising the steps of applying a vapor-coating of at least one metal onto the surface of said glass and thereafter heating said metal coating and said glass substrate, in the absence of oxygen, to a temperature sufficient to cause said metal to migrate from the surface of said glass into said glass without any residue remaining on the surface of said glass.

Claim 3

The process of claim 1, comprising applying a thin coating of said metal onto the surface of said glass.

Claim 4

The process of claim 1, wherein said metal has a melting point of between 29° and 850° C and a vaporization point between 670° and 1527° C under normal pressure.

Claim 5

The process of claim 3, wherein said metal is an alkaline earth metal, an alkali metal, lead, cadmium, zinc, tellurium or mixtures thereof.

Claim 6

The process of claim 4, wherein said alkali metal is cesium, rubidium, lithium, sodium or potassium.

Claim 7

The process of claim 4, wherein said alkaline earth metal is magnesium, calcium, barium or strontium.

Claim 8

The process of claim 4, wherein said metal is lead, cadmium, zinc or tellurium.

Claim 9

The process of claim 1, wherein said metal has a difference of at least 390° C between the vaporization temperature and melting temperature of said metal.

Claim 10

The process of claim 8, wherein said metal has a vaporization temperature up to 1530° C.

Claim 11

The process of claim 1, wherein said glass contains from 40 to 100 weight percent SiO 2 .

Claim 12

The process of claim 10, wherein said glass has the following composition: ______________________________________ Weight Percent ______________________________________ SiO.sub.2 40-100 B.sub.2 O.sub.3 0-30 P.sub.2 O.sub.5 0-11 Al.sub.2 O.sub.3 0-25 ZrO.sub.2 0-6 La.sub.2 O.sub.3 0-12 MgO 0-15 CaO 0-21 SrO 0-8 BaO 0-26 ZnO 0-20 PbO 0-50 TiO.sub.2 0-20 Li.sub.2 O 0-15 Na.sub.2 O 0-30 K.sub.2 O 0-35 ______________________________________

Claim 13

The process of claim 1, comprising heating said metal coating at a temperature between 260° and 1850° C and for a time between 1 minute and 136 hours in the absence of oxygen.

Claim 14

The process of claim 1, comprising applying a coating of said metal onto said glass by condensing said metal from the vapor phase.

Claim 15

The process of claim 1 further comprising the step of shaping said glass into a desired form.

Claim 16

The process of claim 14, wherein said glass is shaped by lowering movement at elevated temperature, by pulling said glass into rods and tubes, by pressing, rolling, collapsing or by glass-blowing.

Claim 17

The process of claim 1, wherein said glass is in the form of a rod having plane surfaces and further comprising the steps of sawing said rod into discs, and polishing said discs thereby forming a lens.