Patent ID: 6151916
Filing Date: 2000-11-28
Classification: C03C,G02B

Abstract:
A method for the manufacture of glass ferrules comprising the steps ofa. drawing a glass tube from a glass preform, said preform having a hollow cylindrical bore extending essentially throughout the length of the preform, said cylindrical bore and said cylindrical glass preform being essentially concentric,b. cutting the drawn tube into sections to form individual glass ferrule bodies,c. subjecting said glass ferrule bodies to an ion exchange process by treating them in a molten alkali metal bath,the improvement characterized in that the glass ferrule bodies have a composition comprising silicon oxide, alkali metal oxide, lead oxide and aluminum oxide in the following weight %:alkali metal oxide (as A.sub.2 O): 9-17 wt %aluminum oxide (as Al.sub.2 O.sub.3) 9-18 wt %lead oxide (as PbO) 1-35 wt %silicon oxide (as SiO.sub.2): remainderwhere A is selected from the group consisting of Li, Na and K and A.sub.2 O comprises at least 9 wt % of Na.sub.2 O.