Metal Oxide Varistor: Zinc Oxide with 0.5 % Boric Oxide, Bismuth Oxide Paste Fired On (Masuyama 1972, Ex. 5)

A varistor with bismuth oxide fired on from a paste instead of mixed in: 99.5 % zinc oxide with 0.5 % boric oxide by moles, sintered at 1350 °C, coated with bismuth oxide paste and fired at 800 °C. The disc measured a C-value of 12 at 1 mA and a nonlinearity exponent n of 8.5. Source: T. Masuyama, M. Matsuoka and T. Nishi (Matsushita), US 3,663,458 (1972), Example 5. Unknown: how the aluminium is sprayed on, what the silver paint is, and how strong the epoxy solution of the paste is. The 10 g batch is our arithmetic. Picture: the patent's drawing.