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:
May. 03, 1977
Filed:
Nov. 13, 1975
Muneo Watanabe, Nishinomiya, JA;
Yamamura Glass Kabushiki Kaisha, Hyogo, JA;
Abstract
This invention relates to a chemical method of strengthening glass articles subjected to abrasion resistance treatment, which comprises (1) a first step of applying a metal oxide-forming compound to the surface of a heated glass article to form the corresponding metal oxide coating having a thickness of 50 to 130 Angstrom on the surface of the glass article, (2) a second step of causing to adhere, to the outer and inner surfaces of the glass article, a mixed solution of potassium chloride and potassium nitrate, having a potassium chloride to potassium nitrate ratio by weight of 85 to 45:15 to 55, or a mixed solution of potassium sulfate and potassium nitrate, having a potassium sulfate to potassium nitrate ratio by weight of 30 to 100:70 to 0, (3) a third step of holding the glass article at an elevated temperature below the strain point of the glass but as near the strain point as possible for a period of time sufficient to obtain a compressive stress layer having a depth of at least 10 microns and a compressive stress of at least 700 kg/cm.sup.2 and (4) a fourth step of cooling the glass article to room temperature and then washing the glass article to remove the mixture of the potassium salts remaining on the outer surface and inner surface of the glass article.