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:
Apr. 18, 1978
Filed:
Jan. 07, 1977
Ronald L Andrus, Elmira, NY (US);
Richard F Reade, Corning, NY (US);
Corning Glass Works, Corning, NY (US);
Abstract
The instant invention is concerned with the preparation of iron-containing glasses having compositions within the R.sub.2 O-Al.sub.2 O.sub.3 -SiO.sub.2 field, wherein R.sub.2 O consists of Li.sub.2 O, Na.sub.2 O, and/or K.sub.2 O, which spontaneously develop thin surface layers containing hematite (alpha-Fe.sub.2 O.sub.3) crystals when exposed to relatively low temperature heat treatments, viz., at least about 675.degree. C. but less than about 950.degree. C., in an oxidizing environment. Described visually, the resulting surfaces exhibit a variety of appearances, ranging from mirror-like through lustrous metallic to dull-earthen. In all surface layers, the hematite crystals may subsequently be chemically reduced to magnetite (Fe.sub.3 O.sub.4) or metallic iron crystals. Permanent magnetization can then be induced by means of the application of a strong magnetic force. The magnetite-containing surfaces can also demonstrate semiconductivity. The metallic iron surface can be highly electrically conductive.