Ferrite Toroid Core: Copper-Zinc Ferrite Sintered at 1150 °C (Snoek 1948, Ex. I)

A soft ferrite ring core for coils and transformers: copper, zinc and iron oxides with a little brownstone, pressed into a ring and sintered at 1150 °C in oxygen. Snoek's ring had an initial permeability of 175. Source: J. L. Snoek, US 2,452,530 (Philips, 1948), Example I and its table. The violet iron oxide has its own blueprint (precipitated hematite calcined at 1000-1100 °C, after Nurdini et al. 2022); Snoek does not say how his was made. Picture: the patent's Fig. 4, the ring core.

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Weigh 20 : 30 : 50 mol % and 1 % brownstone

Mix 20 mol % pure copper oxide, 30 mol % pure zinc oxide and 50 mol % pure violet iron oxide, and add 1 % by weight of brownstone (manganese dioxide). Ours, by weight: 13.24 g copper oxide, 20.32 g zinc oxide and 66.44 g iron oxide per 100 g, plus 1 g brownstone. Snoek does not say what makes it 'violet'; violet iron oxide has its own blueprint.

このステップの材料:

酸化銅13.24 g

酸化亜鉛粉末20.32 g

紫色酸化鉄66.44 g

二酸化マンガン（軟マンガン鉱）1 g

必要な工具:

天秤ばかり

防じんマスク

Grind half an hour in an iron ball mill

Grind the mixture for half an hour in a mill with iron balls.

必要な工具:

鉄製ボールミル

防じんマスク

Press a ring at 4 tons per cm²

Press the powder at 4 tons per square centimetre into a ring 3 cm across with a 4 × 4 mm cross-section.

必要な工具:

油圧プレス

リング成形ダイス

防じんマスク

Sinter at 1150 °C in oxygen, cool 5–10 °C a minute

Sinter the ring at 1150 °C in a current of oxygen. Example I heats for 1 hour and cools in the oxygen at 5 to 10 °C per minute. Snoek's ring had an initial permeability of 175, measured at room temperature at 2 kHz.

必要な工具: