US 5,780,371 A · Reinforced glass substrate

Abstract

The invention relates to glass substrates intended for use as a support in data storage units, reinforced by surface ion exchanges and whose matrix comprises the constituents given hereinafter in the following weight proportions: ______________________________________ SiO.sub.2 45-65% Al.sub.2 O.sub.3 0-20% B.sub.2 O.sub.3 0-5% Na.sub.2 O 4-12% K.sub.2 O 3.5-12% MgO 0-8% CaO 0-13% ZrO.sub.2 0-20% ______________________________________ the sum of the oxides SiO.sub.2, Al.sub.2 O.sub.3 and ZrO.sub.2 remaining equal to or below 70%, said composition optionally incorporating the oxides BaO and/or SrO in proportions 11%.ltoreq.MgO+CaO+BaO+SrO.ltoreq.24% and the alkaline oxides are introduced in the following weight percentages 0.22%.ltoreq.Na.sub.2 O/Na.sub.2 O+K.sub.2 O.ltoreq.0.60.

Claims19

Dependent claims

A glass substrate, obtained by (1) forming a base glass having a composition comprising the following constituents in the weight percentages given below:

______________________________________ SiO.sub.2 45-65% Al.sub.2 O.sub.3 0-20% B.sub.2 O.sub.3 0-5% Na.sub.2 O 4-12% K.sub.2 O 3.5-12% MgO 0-8% CaO 0-13% ZrO.sub.2 0-20% ______________________________________
wherein the sum of SiO.sub.2, Al.sub.2 O.sub.3 and ZrO.sub.2 is less than or equal to 70% by weight, wherein 0.22.ltoreq.Na.sub.2 O/(Na.sub.2 O+K.sub.2 O).ltoreq.0.60, wherein BaO, SrO, or a mixture thereof are optionally present, and wherein 11 % wt. %.ltoreq.MgO+CaO+BaO+SrO.ltoreq.24 wt. %, (2) polishing said base glass to form a polished base glass, and (3) reinforcing said polished base glass by a surface ion exchange.

Dependencies are inferred from the claim text.

Reinforced glass substrate

Life of this patent

Reinforced glass substrate

Life of this patent

Abstract

Claims19