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. 02, 1991
Filed:
Nov. 02, 1989
Myung H Oh, Seoul, KR;
Kyung J Lee, Seoul, KR;
In J Chung, Seoul, KR;
Nam Y Lee, Seoul, KR;
Myung S Kim, Seoul, KR;
Abstract
A method of producing a zinc oxide varistor for high voltage which is a voltage-current non-linear type of resistor including zinc oxide as the major ingredient and bismuth oxide or manganese dioxide as additives for use with a circuit protector and gapless arrester. The method of the invention includes sintering a zinc oxide composition lacking bismuth oxide at 1200.degree.-1350.degree. C. under conditions and for a period of time effective to form a primary sintered body, heat-treating a primary sintered body coated with an amount of metal oxide paste containing mostly bismuth oxide at a temperature of 1000.degree.-1200.degree. C. for a period of time effective to diffuse the metal oxide paste to the grain boundaries of the zinc oxide grains.