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Strontium-Calcium Ferrite Disc Magnet: 0.08 mol SrCO3 and 0.02 mol CaCO3, 1280 °C (Went, Philips 1956, Ex. 23)
A strontium ferrite with a fifth of the strontium replaced by calcium: 0.08 mol strontium carbonate and 0.02 mol calcium carbonate to 0.6 mol iron oxide, ground, dried, formed and passed through a 1280 °C furnace in 10 minutes. Went's rod held 2,320 gauss with a coercive force of 1,395 oersted.
Source: J. J. Went, G. W. van Oosterhout and E. W. Gorter (Philips), US 2,762,777 (1956), Example 23. 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 the carbonates and iron oxide
Weigh the carbonates and iron oxide
Weigh 11.81 g strontium carbonate (0.08 mol), 2.002 g calcium carbonate (0.02 mol), 95.55 g ferric oxide (0.6 mol).
Materials for this step:
Strontium Carbonate11.81 g
Calcium Carbonate - Whiting2.002 g
Ferric Oxide95.55 gTools needed:
Balance Scale
P100 Respirator2
2
Mill with alcohol 4 hours, dry
Mill with alcohol 4 hours, dry
As in Examples 18 to 21: grind the mixture with alcohol in a ball mill for 4 hours, then dry it.
Tools needed:
Iron Ball Mill
Ethanol - Lab Grade, 95%
Drying Oven3
3
Press at 1.5 t/cm²
Press at 1.5 t/cm²
Example 23 does not say whether the 1000 °C presinter of Examples 18 to 21 is used. Press the dry powder at 1.5 tonnes per cm² (ours: discs instead of a rod).
Tools needed:
Hydraulic Press
Disc Pressing Die4
4
Pass through a 1280 °C zone in 10 minutes
Pass through a 1280 °C zone in 10 minutes
Sinter at 1280 °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 Gloves5
5
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- 11.81 gPlaceholder
- 2.002 gPlaceholder
- 95.55 gPlaceholder
Tools Required
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