The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 28, 2003
Filed:
Dec. 18, 2001
Terry Lee Jensen, Rochester, MN (US);
John William Marier, Byron, MN (US);
Rick Allan Sprague, San Jose, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method of adjusting the pH of a strengthening melt for use in strengthening glass substrates, e.g., glass disk substrates for use in data storage devices. A non-particle-forming acid is added to the strengthening melt to lower the pH of the strengthening melt to ≦8. The acid is added while the strengthening melt is in a molten state and selected to avoid particle formation. Nitric acid, for example, is non-particle-forming with respect to nitrate based strengthening melts such as potassium nitrate and/or sodium nitrate. A base, e.g., sodium hydroxide, may be added if the pH of the strengthening melt falls below 5. Strengthening melts are subject to pH shift that can cause glass substrates strengthened therein to etch, creating pits on the substrate surface. Glass disk substrates treated in the pH adjusted strengthening melt are essentially free from such pits, as well as contamination caused by particle formation.