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Metal Oxide Varistor: Zinc Oxide, 0.5 % Bismuth Oxide, 0.5 % Boric Oxide, 1350 °C (Masuyama 1972, Ex. 2)

أنشأه

28. أكتوبر 2026

Metal Oxide Varistor: Zinc Oxide, 0.5 % Bismuth Oxide, 0.5 % Boric Oxide, 1350 °C (Masuyama 1972, Ex. 2)

Masuyama, Matsuoka and Nishi found that adding a second oxide to zinc oxide and bismuth oxide changes the varistor a great deal. This is their Example 2 with boric oxide: 99 % zinc oxide, 0.5 % bismuth oxide and 0.5 % boric oxide by moles, sintered at 1350 °C. The disc measured a C-value of 6.5 at 1 mA and a nonlinearity exponent n of 5.7. Source: T. Masuyama, M. Matsuoka and T. Nishi (Matsushita), US 3,663,458 (1972), Example 2. Unknown: what the silver paint 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

1 day

التعليمات

Weigh 99 : 0.5 : 0.5 and wet-mill 5 hours

Mix zinc oxide, bismuth oxide and boric oxide 99 : 0.5 : 0.5 by moles. Ours, for 10 g: 9.678 g zinc oxide, 0.28 g bismuth oxide, 0.042 g boric oxide (our arithmetic). Mill wet for 5 hours, then dry. Unknown: the milling liquid.

المواد لهذه الخطوة:

مسحوق أكسيد الزنك9.678 غ

أكسيد البزموت0.28 غ

أكسيد البوريك0.042 غ

الأدوات المطلوبة:

ميزان ذو كفّتين

مطحنة كرات حديدية

فرن تجفيف

Press discs 13 mm by 2.5 mm

Press the powder in a mould into 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

Sinter the discs in air for 1 hour at 1350 °C, then let them cool in the furnace to room temperature (about 15-30 °C).

الأدوات المطلوبة:

فرن مفل

Lap to 10 mm by 1.5 mm

Lap both faces with 600-mesh silicon carbide. The finished disc is 10 mm across and 1.5 mm thick.

الأدوات المطلوبة:

حبيبات كربيد السيليكون

قدمة ورنية

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. 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: