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Barium Ferrite Disc Magnet: 0.5 mol BaCO3 to 3.5 mol Iron Oxide, 10 Minutes at 1330 °C (Went, Philips 1956, Ex. 4)
Omegatron (Wikimedia Commons) · CC BY-SA 3.0
Charlie

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Charlie

28. October 2026DE
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Barium Ferrite Disc Magnet: 0.5 mol BaCO3 to 3.5 mol Iron Oxide, 10 Minutes at 1330 °C (Went, Philips 1956, Ex. 4)

A barium ferrite with much more iron oxide: 0.5 mol barium carbonate to 3.5 mol, milled 15.5 hours, bound, formed and sintered 10 minutes at 1330 °C. Went's rod held 2,040 gauss with a coercive force of 2,380 oersted. Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 4. They sintered rods; discs and the magnetising are ours. Picture: ferrite magnets, Omegatron, Wikimedia Commons, CC BY-SA 3.0.
Advanced
2 days

Instructions

1

Weigh barium carbonate and iron oxide

Weigh 99.2 g barium carbonate (0.5 mol) and 564.8 g ferric oxide (3.5 mol). Barium carbonate is poisonous if swallowed: gloves and a dust respirator.

Materials for this step:

Barium Carbonate (Witherite)Barium Carbonate (Witherite)99.2 g
Ferric OxideFerric Oxide564.8 g

Tools needed:

Balance ScaleBalance Scale
Rubber GlovesRubber Gloves
P100 RespiratorP100 Respirator
2

Mill with alcohol 15.5 hours, dry and sieve

Grind the mixture with alcohol in a ball mill for 15.5 hours, then dry it and sieve it.

Tools needed:

Iron Ball MillIron Ball Mill
Ethanol - Lab Grade, 95%Ethanol - Lab Grade, 95%
Drying OvenDrying Oven
SieveSieve
3

Knead with a binder and form

Mix 300 g of the powder with a binder such as polyvinyl alcohol (Went names it or nitrocellulose) into a kneadable mass. The patent extrudes rods about 3 mm across; ours: press discs at 1.5 tonnes per cm², as in its other examples. Dry them in air for about 24 hours.

Tools needed:

Polyvinyl Alcohol PowderPolyvinyl Alcohol Powder
Hydraulic PressHydraulic Press
Disc Pressing DieDisc Pressing Die
Drying OvenDrying Oven
4

Sinter in air at 1330 °C for 10 minutes

Sinter the pieces in air at 1330 °C for 10 minutes. The patent gives no zone length or speed for this example.

Tools needed:

Tube FurnaceTube Furnace
Heat-Resistant GlovesHeat-Resistant Gloves
5

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.

Tools needed:

ElectromagnetElectromagnet
CompassCompass

Materials

2

Tools Required

14

This blueprint makes

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Disc Magnet

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Barium Ferrite Disc Magnet: Barium Carbonate and Iron Oxide Sintered (Went, Philips 1956)

Barium Ferrite Disc Magnet: Barium Carbonate and Iron Oxide Sintered (Went, Philips 1956)

by CharlieDE

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