Fabrication method for high voltage zinc oxide varistor
US5004573A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 2, 1989 |
| Grant date | Apr 2, 1991 |
| Priority date | — |
| Expiry date | Nov 2, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01C7/112
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.