Glass element with high scratch tolerance

US9371248B2 · kind B2 · utility

Assignee

• Schott AG · DE

Inventors

• Oliver Hochrein · Mainz, DE
• Inge Burger · Wiesbaden, DE
• Irmgard Westenberger · Mainz, DE
• Jochen Alkemper · Klein-Winternheim, DE
• Gerd Rudas · Jugenheim, DE
• Katharina Alt · Mainz, DE
• Gordon Kissl · Heidesheim, DE
• Gunther Paulus · Mainz, DE

Key dates

• Filing date: Apr 10, 2014
• Grant date: Jun 21, 2016
• Expiry date: Apr 10, 2034

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03C21/002
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A glass element is provided that is made of a glass having SiO2, Al2O3, B2O3, and Na2O. The glass has a scratch tolerance that when scratches of 1 mm length are introduced using a Knoop diamond indenter which presses upon a surface of the glass with a force of 4 Newton and is displaced along the surface with a traverse speed of 0.4 mm/s, not more than 20% of the scratches have a noticeable width including visible chipping of more than 25 μm. In some embodiments, the glass, after chemical tempering, has sodium ions that are at least partially exchanged for potassium ions so that a compressive stress zone is provided at the surface of the glass. The compressive stress is at least 700 MPa and an exchange depth of alkali ions is at least 25 μm.