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Barium-Calcium Ferrite Disc Magnet: 0.09 mol BaCO3 and 0.01 mol CaCO3 (Went, Philips 1956, Ex. 19)
A ceramic magnet with a tenth of the barium replaced by calcium: 0.09 mol barium carbonate and 0.01 mol calcium carbonate to 0.6 mol iron oxide, made as in Example 18: milled, presintered at 1000 °C, milled again, formed and passed through a 1330 °C furnace in 10 minutes. Went's rod held 1,705 gauss with a coercive force of 1,110 oersted.
Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 19. 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
1
Weigh barium carbonate, chalk and iron oxide
Weigh barium carbonate, chalk and iron oxide
Weigh 17.76 g barium carbonate (0.09 mol), 1.001 g calcium carbonate (0.01 mol) and 95.55 g ferric oxide (0.6 mol). Barium carbonate is poisonous if swallowed: gloves and a dust respirator.
Materials for this step:
Barium Carbonate (Witherite)17.76 g
Calcium Carbonate - Whiting1.001 g
Ferric Oxide95.55 gTools needed:
Balance Scale
Rubber Gloves
P100 Respirator2
2
Mill with alcohol 4 hours, dry at 150 °C
Mill with alcohol 4 hours, dry at 150 °C
Grind with alcohol in a ball mill for 4 hours and dry in air at 150 °C.
Tools needed:
Iron Ball Mill
Ethanol - Lab Grade, 95%
Drying Oven3
3
Presinter in air at 1000 °C for 2 hours
Presinter in air at 1000 °C for 2 hours
Fire in air at 1000 °C for 2 hours.
Tools needed:
Muffle Furnace
Crucible with Lid (Porcelain)
Crucible Tongs
Heat-Resistant Gloves4
4
Mill again 4 hours, dry, form
Mill again 4 hours, dry, form
Grind again with alcohol for 4 hours and dry. Example 19 extrudes a rod; ours: press discs at 1.5 tonnes per cm², as Example 18 moulds its rod.
Tools needed:
Iron Ball Mill
Ethanol - Lab Grade, 95%
Drying Oven
Hydraulic Press
Disc Pressing Die5
5
Pass through a 1330 °C zone in 10 minutes
Pass through a 1330 °C zone in 10 minutes
Sinter at 1330 °C by passing the pieces through a 10 cm hot zone at 10 mm per minute: 10 minutes in the heat.
Tools needed:
Tube Furnace
Heat-Resistant Gloves6
6
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.
Tools needed:
Electromagnet
CompassMaterials
3- 17.76 gPlaceholder
- 1.001 gPlaceholder
- 95.55 gPlaceholder
Tools Required
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