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Metal Oxide Varistor: Zinc Oxide with Bismuth, Manganese and Boric Oxides, 1350 °C (Masuyama 1972, Ex. 3)

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28. 10월 2026

Metal Oxide Varistor: Zinc Oxide with Bismuth, Manganese and Boric Oxides, 1350 °C (Masuyama 1972, Ex. 3)

Masuyama, Matsuoka and Nishi found that adding two more oxides to zinc oxide and bismuth oxide gives excellent non-linear properties. This is their Example 3 with manganese dioxide and boric oxide: 98.5 % zinc oxide and 0.5 % each of bismuth oxide, manganese dioxide and boric oxide by moles, sintered at 1350 °C. The disc measured a C-value of 101 at 1 mA and a nonlinearity exponent n of 22.2. Source: T. Masuyama, M. Matsuoka and T. Nishi (Matsushita), US 3,663,458 (1972), Example 3. 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.

고급

1 day

안내

Weigh 98.5 : 0.5 : 0.5 : 0.5 and wet-mill 5 hours

Mix zinc oxide, bismuth oxide, manganese dioxide and boric oxide 98.5 : 0.5 : 0.5 : 0.5 by moles. Ours, for 10 g: 9.626 g zinc oxide, 0.28 g bismuth oxide, 0.052 g manganese dioxide, 0.042 g boric oxide (our arithmetic). Mill wet for 5 hours, then dry. Unknown: the milling liquid.

이 단계의 재료:

산화아연 분말9.626 g

산화 비스무트0.28 g

이산화망가니즈 (연망가니즈석)0.052 g

산화 붕소0.042 g

필요한 도구:

접시 저울

철 볼 밀

건조 가마

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.

필요한 도구:

유압 프레스

원판 압축 금형

버니어 캘리퍼스

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).

필요한 도구:

머플로

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.

필요한 도구:

탄화규소 연마입자

버니어 캘리퍼스

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.

이 단계의 재료: