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Barium Ferrite Disc Magnet from Natural Magnetite, Presintered at 900 °C (Went, Philips 1956, Ex. 36, Procedure 1)
A barium ferrite magnet made from natural magnetite instead of ferric oxide: barium carbonate and magnetite ground 18 hours, presintered 3 hours at 900 °C, ground again 18 hours, pressed and sintered 2 hours at 1200 °C. Went's rod held 1,450 gauss with a coercive force of 2,425 oersted.
Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 36. They sintered rods; discs and the magnetising are ours. Picture: ferrite magnets, Omegatron, Wikimedia Commons, CC BY-SA 3.0.
Ilọsíwájú
2 days
Ìlànà
1
1
Weigh barium carbonate and magnetite
Weigh barium carbonate and magnetite
Weigh 9.9 g barium carbonate (0.05 mol) and 46.9 g natural magnetite, Fe3O4 (0.20 mol). Barium carbonate is poisonous if swallowed: gloves and a dust respirator.
Àwọn ohun èlò fún ìgbésẹ̀ yìí:
Barium carbonate (witherite)9.9 g
Magnetite46.9 gÀwọn irinṣẹ́ tí a nílò:
Òǹwọ̀n ìdọ́gba
Ìbọ̀wọ́ rọ́bà
Ẹ̀rọ Ìmí P1002
2
Grind 18 hours in a ball mill
Grind 18 hours in a ball mill
Grind the mixture in a ball mill for 18 hours. The patent does not say whether wet or dry.
Àwọn irinṣẹ́ tí a nílò:
Ẹ̀rọ Lílọ Bọ́ọ̀lù Irin
Ẹ̀rọ Ìmí P1003
3
Presinter at 900 °C for 3 hours
Presinter at 900 °C for 3 hours
Fire the ground mixture at 900 °C for three hours and let it cool.
Àwọn irinṣẹ́ tí a nílò:
Ààrò muffle
Ìkòkò ìyọ́ pẹ̀lú ìdérí (porcelain)
Ẹmú Ìkòkò Ìyọ́
Ìbọ̀wọ́ Tí Ń Fara Da Ooru4
4
Grind 18 hours in a ball mill
Grind 18 hours in a ball mill
Grind it again in a ball mill for 18 hours. The patent does not say whether wet or dry.
Àwọn irinṣẹ́ tí a nílò:
Ẹ̀rọ Lílọ Bọ́ọ̀lù Irin
Ẹ̀rọ Ìmí P1005
5
Press at 1.5 t/cm²
Press at 1.5 t/cm²
Press at 1.5 tonnes per cm² (ours: discs instead of a rod).
Àwọn irinṣẹ́ tí a nílò:
Ẹ̀rọ ìtẹ̀ háídírọ́líìkì
Mọ́ọ̀dù títẹ díìsì6
6
Sinter at 1200 °C for 2 hours
Sinter at 1200 °C for 2 hours
Sinter at 1200 °C for 2 hours. The patent gives no atmosphere for this example. Went's rod: 1,450 gauss, 2,425 oersted.
Àwọn irinṣẹ́ tí a nílò:
Ààrò muffle
Ẹmú Ìkòkò Ìyọ́
Ìbọ̀wọ́ Tí Ń Fara Da Ooru7
7
Magnetise the discs
Magnetise the discs
The patent gives no magnetising method. Ours: lay a disc with its faces against the poles of a strong electromagnet, switch the current on, then off. Find which face is north with a compass.
Àwọn irinṣẹ́ tí a nílò:
Òòfà iná-mànàmáná
Kọ́mpasiÀwọn irinṣẹ́ tó nílò
12- Àyè
- Àyè
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