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Metal Oxide Varistor: Zinc Oxide with 0.2 % Manganese Dioxide, Bismuth Oxide Paste Fired On (Masuyama 1972, Ex. 5)

أنشأه

28. أكتوبر 2026

Metal Oxide Varistor: Zinc Oxide with 0.2 % Manganese Dioxide, Bismuth Oxide Paste Fired On (Masuyama 1972, Ex. 5)

A varistor with bismuth oxide fired on from a paste instead of mixed in: 99.8 % zinc oxide with 0.2 % manganese dioxide by moles, sintered at 1350 °C, coated with bismuth oxide paste and fired at 800 °C. The disc measured a C-value of 114 at 1 mA and a nonlinearity exponent n of 15.3. Source: T. Masuyama, M. Matsuoka and T. Nishi (Matsushita), US 3,663,458 (1972), Example 5. Unknown: what the silver paint is, and how strong the epoxy solution of the paste is. The spraying is ours, after US Army Corps of Engineers EM 1110-2-3401 (1999). The 10 g batch is our arithmetic. Picture: the patent's drawing.

متقدم

2 days

التعليمات

Weigh 99.8 : 0.2 and wet-mill 5 hours

Mix zinc oxide and manganese dioxide 99.8 : 0.2 by moles. Ours, for 10 g: 9.979 g zinc oxide and 0.021 g manganese dioxide (our arithmetic). Mill wet for 5 hours, then dry, as in Example 1. Unknown: the milling liquid.

المواد لهذه الخطوة:

مسحوق أكسيد الزنك9.979 غ

ثاني أكسيد المنغنيز (بيرولوسيت)0.021 غ

الأدوات المطلوبة:

ميزان ذو كفّتين

مطحنة كرات حديدية

فرن تجفيف

Press discs 13 mm by 2.5 mm

Press discs 13 mm across and 2.5 mm thick at 340 kg/cm², as in Example 1.

الأدوات المطلوبة:

مكبس هيدروليكي

قالب كبس الأقراص

قدمة ورنية

Sinter 1 hour at 1350 °C and furnace-cool

As in Example 2: sinter in air at 1350 °C for 1 hour and let the discs cool in the furnace.

الأدوات المطلوبة:

فرن مفل

Lap both faces

Lap both faces with silicon carbide abrasive. Example 5 gives no thickness.

الأدوات المطلوبة:

حبيبات كربيد السيليكون

قدمة ورنية

Coat with bismuth oxide paste and fire at 800 °C

Coat both lapped faces with a paste of 50 % by weight bismuth oxide in a solution of epoxy resin in butyl alcohol, and fire it in air at 800 °C for 30 minutes. The bismuth oxide diffuses into the zinc oxide. Not given: how much paste, or the strength of the epoxy solution.

المواد لهذه الخطوة:

أكسيد البزموت1 as required

الأدوات المطلوبة:

راتنج إيبوكسي

ن-بيوتانول

فرن مفل

Spray aluminium electrodes and attach leads

Spray a metallised film of aluminium on both faces. Attach a lead wire to each with conductive silver paint, as in Example 1. Ours, after US Army Corps of Engineers EM 1110-2-3401 (1999): wire-arc spray the aluminium from two 3.2 mm wires melted by an 18-40 V DC arc and atomised by compressed air, 15-20 cm from the disc and never at less than 45°, in at least two coats at right angles of 50-75 µm each. Unknown: the paint.

المواد لهذه الخطوة: