Claims
- 1. A method for manufacturing a zinc oxide varistor disk having a glass collar around the periphery thereof which comprises the steps of providing a zinc oxide varistor disk, applying as a passivating coating to the periphery of said disk a coating composition comprising a mixture of 64-74 parts by weight of a glass powder, 22-35 parts by weight of water, and 0.5-2 parts by weight of an additive comprising fumed silica, clay and urea, and then curing.
- 2. A method as defined in claim 1 wherein said glass powder comprises a mixture of from about 35% to about 45% of Bi.sub.2 O.sub.3, from about 25% to about 35% by weight of ZnO, and from about 25% to about 35% by weight of B.sub.2 O.sub.3.
- 3. A method as defined in claim 1 wherein said glass powder comprises a mixture of from about 35% to about 45% by weight of Bi.sub.2 O.sub.3, from about 22.5% to about 30% by weight of ZnO, from about 22.5% to about 30% by weight of B.sub.2 O.sub.3, and from about 5% to about 10% by weight of V.sub.2 O.sub.5.
- 4. A method as defined in claim 1 wherein the approximate weight ratio of fumed silica:clay:urea is 2:1:1.
- 5. A method as defined in claim 2 wherein the approximate weight ratio of fumed silica:clay:urea is 2:1:1.
- 6. A method as defined in claim 3 wherein the approximate weight ratio of fumed silica:clay:urea is 2:1:1.
- 7. A method as defined in claim 1 wherein said water is deionized water.
- 8. A method as defined in claim 1 wherein the particle size of said glass powder is below 45 .mu.m.
Parent Case Info
This is a division of application Ser. No. 08/209,919 filed Mar. 14, 1994.
US Referenced Citations (6)
Non-Patent Literature Citations (2)
Entry |
Abstract of Japanese Patent 58-74539 dated May 6, 1983. |
Abstract of Japanese Patent 53-78048 dated Jul. 11, 1978. |
Divisions (1)
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Number |
Date |
Country |
Parent |
209919 |
Mar 1994 |
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