Glass-forming tools and methods

摘要

Refractory glass-forming tools, including glass-forming molds incorporating protective metal nitride surface coatings, with optional alumina barrier layers disposed between the mold bodies and coating for high-temperature nitride coating stability, offering particular advantages for the manufacture by direct molding of optically finished glass products such as information display cover glasses from refractory alkali aluminosilicate glasses at molding temperatures up to and above 800° C.

主权项

1. A method for making a glass article having an optical surface finish, the method comprising shaping a charge of a softened silicate glass into a glass article using a mold,
wherein the silicate glass is an aluminosilicate glass having an alkali metal oxide content in excess of 5 weight percent, and wherein the mold comprises: a metallic molding surface; a refractory metal nitride surface coating disposed on at least a portion of the metallic molding surface resistant to alkali corrosion and oxidation damage up to a temperature of at least 800° C.; a diffusion barrier layer comprising amorphous aluminum oxide disposed on the metallic molding surface and between the metallic molding surface and the refractory metal nitride surface coating; and a metal oxynitride transition layer disposed between the diffusion barrier layer and the refractory metal nitride surface coating, wherein the metallic molding surface consists predominantly of a metal selected from the group consisting essentially of a metal selected from the group consisting of iron, nickel, chromium, and mixtures and alloys thereof, and wherein the refractory metal nitride surface coating consists essentially of titanium nitride, titanium aluminum nitride, or combinations thereof.