mleku on Nostr: 2026-03-21 10:49 well, if i can get the CNC then i just need to find the ...

2026-03-21 10:49
well, if i can get the CNC then i just need to find the kiln/furnace. probably i can just build the mold form and then set and dry it and just need to find someone with a furnace. how hot does the ceramic cast with the iron oxide packed into it have to get to fuse to iron?

10:49 AM

Synthesized thermal requirements for iron oxide sintering process
Synthesized thermal requirements for iron oxide sintering process
Two different processes depending on what you're after.

If you want pure iron (reduced from oxide), you need a reducing atmosphere — hydrogen or carbon monoxide or mixed with charcoal. Surface iron oxides start reducing around 400°C, but the stable internal oxides need 600-1350°C to fully reduce.
Springer
Full sintering in hydrogen atmosphere at 1350°C gives complete reduction of all relevant oxides.
Taylor & Francis Online
That's serious but not insane — a good pottery kiln hits 1300°C on a normal firing cycle (cone 10 stoneware territory).

If you want a ferrite core (which is actually what you want for electromagnetic applications — ferrite has better magnetic properties for AC than pure iron because of higher resistivity and lower eddy current losses), the process is simpler. Ferrite sintering typically runs 1000-1250°C. Iron oxide pel
ResearchGate
lets heated at 1000 to 1250°C in a muffle furnace for 10-12 minutes at maximum temperature. That's within range of any ceramic kiln.

For your application, ferrite is probably better than pure iron anyway. Pure iron has low resistivity, which means eddy currents that fight your oscillating fields. Ferrite's high resistivity lets the alternating flux pass through without generating internal losses. That's why commercial transformer cores use ferrite and not solid iron.

The process: pack iron oxide (Fe2O3, common rust-red pigment, available in bulk from construction suppliers) into your ceramic mold, fire at 1200°C for a few hours in air. The oxide partially reduces and sinters into a solid ferromagnetic ceramic. If you want to push it further toward pure iron, pack charcoal powder mixed with the oxide and fire in a sealed container — the carbon scavenges the oxygen.

Any pottery kiln in the Osijek area that fires stoneware or porcelain hits 1200-1300°C routinely. You don't need an industrial furnace. You need a ceramicist with a big enough kiln and a willingness to fire something that isn't a coffee mug.