Nickel Mesh, Titanium Mesh, Nickel Foam and Porous Titanium Plate
Felt gets the attention, but most stacks are assembled from a family of porous metal forms — and choosing the wrong form is as expensive as choosing the wrong metal. This guide lines up four of them: woven nickel mesh, titanium mesh, nickel foam and sintered porous titanium plate.
Four structures, four jobs
| Material | Structure | Porosity scale | Strength | Cost | Where it wins |
|---|---|---|---|---|---|
| Nickel mesh (N4/N6 woven) | 2D woven wire, 20–400 mesh | Open area by mesh count | High tensile, shape-stable | Low | Current collector, electrode frame, reinforcement inside composite felt |
| Titanium mesh | 2D woven/expanded | Open area by mesh count | High tensile | Medium-high | PEM current collection and support where acid forbids nickel (Pt-coated) |
| Nickel foam | 3D open-cell skeleton | ~95%+ porosity, 100–500 μm cells | Low; compressible | Low-medium | Catalyst-loading electrode bodies in alkaline stacks; flow smoothing |
| Porous titanium plate (sintered powder) | Rigid sintered powder body | 25–50% porosity, 5–100 μm rating | Rigid, flat, no fibre shedding | Highest | PEM/AEM PTL and gas-distribution plates with fine pores and zero-gap geometry |
The 2D vs 3D distinction is the whole game
A mesh conducts current beautifully along its wires, but it touches the layer beneath it only where wires cross — a sparse set of contact points. A sintered fiber felt touches everywhere at once, which is why felts deliver lower and more uniform areal resistance under compression. Foam goes further: a 3D skeleton with over 95% porosity that soaks up catalyst slurry and distributes gas, but whose thin pore walls fold under sustained compression.
Rigid porous plates sit at the opposite pole: sintered from titanium powder, they offer fine, tightly controlled pores (5–100 μm), a flat surface that seals against gaskets, and zero fiber shedding — at the highest cost per unit area and with no compliance to absorb flatness errors.
Substitution matrix — where one form replaces another
| Position | First choice | Workable alternative | Poor choice |
|---|---|---|---|
| ALK/AEM current collector | Ni mesh | Ni felt (thin) | Porous Ti plate (cost, no benefit) |
| ALK electrode body | Ni foam or Ni felt + catalyst coating | Mesh-reinforced Ni felt for large area | Bare Ti mesh (corrosion margin unnecessary, cost up) |
| PEM anode PTL | Ti felt or porous Ti plate | Pt-coated Ti mesh (economy designs) | Any nickel form (acid) |
| PEM/AEM gas distribution plate | Porous Ti plate (fine pores, flat) | Machined + coated Ti plate | Compressible materials (sealing needs rigidity) |
| Large-area AEM electrode | Mesh-reinforced Ni felt | Thicker single Ni felt | Ni foam alone (sags, crushes) |
Three misuses that show up in failed trials
- Mesh asked to do a felt’s job. Used directly as a high-current-density PTL, a single mesh layer under-compresses locally; gas pockets form where no wire touches. Multi-layer sintered mesh partly fixes this — see multi-layer sintered mesh — but a felt still distributes contact more uniformly.
- Foam crushed at assembly. A zero-gap design specified 1.5 MPa on a 1 mm foam: the skeleton densified, porosity fell, and mass transport collapsed. Foam wants moderate compression or a reinforced composite.
- Plate specified where compliance was needed. A porous Ti plate cannot absorb a warped bipolar plate; flatness tolerances of the mating surfaces decide whether it works at all.
For the chemistry-driven choice between nickel and titanium substrates, read nickel felt vs titanium felt; for the layer-by-layer context, see electrolyzer stack structure.
Frequently asked
What is the difference between nickel mesh and nickel felt?
Mesh is 2D: strong, cheap, current flows along wires, contact happens only at crossings. Felt is 3D: distributed contact, higher usable porosity, better gas handling under compression. Mesh reinforces and collects; felt transports and diffuses.
When is porous titanium plate better than titanium felt?
When the design needs fine controlled pores, a flat rigid sealing surface or an integrated gas-distribution function, and can guarantee flatness of the mating parts. Felt wins where compliance and uniform compression matter.
Is nickel foam a good PTL?
For alkaline electrode bodies with moderate compression, yes. At high compression the pore walls collapse; mesh-reinforced nickel felt is the more durable form.
Do titanium meshes need platinum coating?
In acidic electrolyzer service, yes — uncoated titanium passivates and contact resistance rises. The same logic applies as for titanium felt.
Need a material quote for your stack?
AIFILTECH sinter-manufactures the porous metal layers that go between the bipolar plate and the catalyst: titanium fiber felt (with optional Pt coating 0.2–0.5 μm), porous titanium plates, nickel fiber felt, mesh-reinforced nickel felt, nickel mesh and multi-layer sintered mesh.
- Send us: stack type (PEM / alkaline / AEM), active area per cell, target thickness, porosity, coating requirement and annual volume.
- You get: a specification confirmation within one business day, sample sheets for stack trials, and consistent batch data.