Fe16N2 in the rotor. Fe4N in the stator.
Iron and nitrogen – the fourth and second most abundant elements in the Earth's crust and atmosphere – arranged into two crystal structures that together outperform every rare-earth-based generator material on the market. This page is the technical brief.
What we're actually swapping out.
The base generator is Bill Mercer's patented split-rotor multiphase architecture – a machine that separates the rotor into segmented sections carrying the permanent-magnet flux and links them through a carbon-fiber compression sleeve. In the legacy configuration, the rotor magnets are neodymium-iron-boron (NdFeB) and the stator laminations are grain-oriented silicon steel.
Our substitution replaces two things and only two things:
- Rotor magnets: NdFeB → α''-Fe16N2.
- Stator core: laminated silicon steel → sintered γ'-Fe4N.
Everything else – the winding topology, the bearing geometry, the inverter frame, the cooling loop – carries over from the underlying patent unchanged. This is why we can move fast: the mechanical package is already engineered.
The two components. Nothing else.
Every design gain flows from the two component swaps. Fewer moving parts, fewer new tolerances, fewer supply-chain unknowns. The machine that Bill's patent describes still spins; it just doesn't need a Chinese-refined magnet to do it.
What carries over
Segmented rotor + carbon-fiber compression sleeve. Multiphase winding topology. Bearing geometry. Cooling loop. Inverter frame. Every one is unchanged from the reference architecture.
12 components between iron ore and the megawatt
Baseline vs upgrade — side by side
The Joe Shepard split-rotor multiphase generator is a proven mechanical architecture — three-phase output, segmented rotor, carbon-fiber sleeve. We keep every one of those decisions. The upgrade is purely in the magnetics.
NdFeB rotor + Si-steel laminated stator
- Rotor magnet NdFeB
- Stator core Si-steel 0.35 mm laminated
- Msat 1.6 T
- (BH)max 35 – 52 MGOe
- Curie 315 °C
- Coercivity Hci 12 kOe and up
- Supply ~95% China
Fe16N2 rotor + Fe4N sintered stator
- Rotor magnet Fe16N2
- Stator core Fe4N sintered
- Msat ~2.4 T
- (BH)max ~10 MGOe (bulk, today)
- Curie ~540 °C
- Coercivity Hci 1 – 2 kOe
- Supply Fe + N (domestic)
Why the machine, not the magnet.
Saturation magnetization – the one place the material wins outright
Fe16N2 has a saturation magnetization of approximately 2.4 T. Sintered NdFeB is around 1.6 T. Saturation sets the ceiling on how much flux the material can carry; it does not by itself set how much flux reaches the air gap, which is a function of the magnet's energy product and of the rotor geometry that routes it.
Energy product (BH)max – where the material loses, and what we do about it
A perfectly ordered, perfectly aligned Fe16N2 single crystal has a calculated energy product of roughly 135 MGOe, about two and a half times the best sintered NdFeB. No one has made that material. Bulk anisotropic iron-nitride magnet from pilot production delivers on the order of 10 MGOe, with supplier roadmaps pointing at 36; sintered NdFeB is 35 to 52 today.
So the machine is designed to 10 MGOe, and to the 1 to 2 kOe coercivity that comes with it. Two magnets per pole feed one narrower pole piece, which concentrates their flux so the air-gap flux density exceeds the magnet's own remanence, and the magnets sit buried behind those pole pieces between flux barriers, where the armature's demagnetizing field cannot reach them under fault. That is the invention: a rotor that makes a weak, cheap, rare-earth-free magnet sufficient. Quoting 135 as though it were our magnet gets the physics wrong in our own favour, which is the one direction that costs you the room.
Curie temperature – the failure mode under heat
Fe16N2 has a Curie temperature of approximately 540 °C against 315 °C for NdFeB, and it reaches that without dysprosium or terbium doping. The nearer constraint is a different one: α″-Fe16N2 is metastable and decomposes toward Fe4N and α-Fe above roughly 200 °C, so processing and service temperature are bounded by phase stability well before Curie.
Fe4N stator – the same plant, a different nitriding potential
Where the layered composite core is not available or its cost is not justified, the stator core is γ′-Fe4N: soft, approximately 1.9 T saturation, higher than silicon steel, and containing no rare earth. Its real advantage is industrial rather than magnetic. It is produced by the same nitriding plant as the rotor magnet, at a different nitriding potential, so one process line feeds both halves of the magnetic circuit.
Mechanical – the segmented rotor
The rotor is segmented and wrapped in a carbon-fiber compression sleeve so every segment stays in compression rather than carrying centrifugal load in tension, which is the loading a sintered magnet is worst at. The high-speed worked example in the application runs at 12,000 rpm on a 29.8 mm air-gap diameter.
| Metric | Fe16N2 (ours) | NdFeB (legacy) |
|---|---|---|
| Msat | ~2.4 T | ~1.6 T |
| (BH)max, bulk material today | ~10 MGOe | 35 – 52 MGOe |
| Curie temperature | ~540 °C | ~315 °C |
| Intrinsic coercivity Hci | 1 – 2 kOe | 12 kOe and up |
| Stator core Msat | ~1.9 T (Fe4N) | ~2.0 T (Si steel) |
| Feedstock supply | Iron ore + N (domestic) | Nd (~95% China) |
Iron and nitrogen. Both domestic. Both abundant.
Iron is the fourth most abundant element in the Earth's crust and the U.S. has significant proven reserves. Nitrogen is 78% of the atmosphere. Extraction is 70–90% cleaner than neodymium refining on greenhouse gases, water consumption, and chemical waste. And every stage – ore, powder, sintering, magnetization, assembly – can happen inside the United States.
We're sourcing Fe16N2 powder from Niron Magnetics (the commercial pioneer of the material) and qualifying two alternate suppliers in parallel so the supply chain isn't single-vendor at any point.
Open research threads
- Ternary alloy tuning (Co / Mo / W ratios) to push (BH)max further
- Second-source Fe16N2 powder qualification
- Fe-N electrode candidate screening for graphene & Na-ion-graphene cells
- Super-capacitor pilot cell chemistry
Filed as a provisional. Owned by Business Development LLC.
The Fe16N2 rotor + Fe4N stator substitution on the split-rotor multiphase generator is being filed as a U.S. provisional patent, joining the ROSE-001, SonicBrief, XODIAK, Okari GX, and UQCTA provisional cluster held by Bill's operating entity, Business Development LLC.
Filing establishes a priority date and unlocks the "patent pending" designation for institutional conversations, government-contract submissions, and pilot RFPs.