Process for the chemical preparation of high-field ZnO varistors
US4681717A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 19, 1986 |
| Grant date | Jul 21, 1987 |
| Priority date | — |
| Expiry date | Feb 19, 2006 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/453
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Chemical preparation techniques involving co-precipitation of metals are used to provide micro-structural characteristics necessary in order to produce ZnO varistors and their precursors for high field applications. The varistors produced have homogeneous and/or uniform dopant distributions and a submicron average grain size with a narrow size distribution. Precursor powders are prepared via chemical precipitation techniques and varistors made by sintering uniaxially and/or isostatically pressed pellets. Using these methods, varistors were made which were suitable for high-power applications, having values of breakdown field, E.sub.B, in the 10-100 kV/cm range, .alpha.>30 and densities in the range of 65-99% of theoretical, depending on both composition and sintering temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.