Stainless steel fiber felt is a porous sheet made from sintered stainless-steel fibers. It is not nickel fiber felt, not titanium felt, and not a woven or knitted wire cloth. In anion-exchange membrane water electrolysis (AEMWE), buyers and researchers discuss it as a porous transport layer (PTL) or gas-diffusion medium, and sometimes as a substrate that itself contributes to the oxygen evolution reaction (OER). A filtration-accuracy number from a catalogue table is not a PTL specification, and a foam PPI value does not describe felt. This guide covers how the material differs from nickel or titanium felt, how to read published AEMWE results, and what to send for a quotation. It is not a ranking claim or a list of fixed HuiRui catalogue numbers.
Felt, metal and duty are different questions
A drawing that says only “metal felt” or “stainless felt” still leaves the alloy, the structure and the job in the cell ambiguous:
- Stainless steel fiber felt is a sintered stainless-steel fiber network. For an electrolyzer enquiry, start with the alloy designation if you already have one, thickness (and whether it is free or under a defined load), porosity or fiber diameter if known, cut size, and whether the sheet is bare or coated. Product context: stainless steel fiber felt.
- Nickel fiber felt is a different metal and is the usual nickel-fiber starting point for many alkaline and AEM discussions; see nickel fiber felt porosity and thickness for alkaline and AEM electrolyzers and the nickel fiber felt product page.
- Titanium fiber felt is the usual discussion starting point for PEM anode PTLs, not a drop-in substitute for a stainless-steel AEM part; see titanium fiber felt porosity and thickness for PEM.
If you are still choosing the electrolyzer type, ALK, PEM, AEM and SOEC outlines where nickel, titanium and other materials typically appear. Woven or knitted mesh, foam and sintered multilayer wire-mesh laminates are different constructions and use different specification fields.
The same stainless-steel fiber felt family is also used as a filtration medium. Filtration enquiries should state the separation duty, fluid or gas, and how retention will be checked. Those fields are not interchangeable with a PTL specification.
Where stainless steel felt shows up in AEMWE
As a combined PTL and OER-active substrate. Chen et al. (2023) ran AEMWE cells with stainless-steel felt and no separate anode catalyst layer. In that study the stainless-steel felt was highly active for OER, while nickel felt showed much lower OER activity under their comparison. They therefore recommended nickel felt, not stainless-steel felt, when the aim is to study an added anode catalyst with less OER contribution from the PTL itself. That is a testing-method point from their cells, not a rule that stainless-steel felt is always the better hardware choice.
Morphology and composition. Kreider et al. (2025) compared fiber-based PTL morphology and composition in AEMWE, including nickel fiber PTLs and alloy PTLs. In their cells, a stainless-steel PTL gave a substantially higher current density than their nickel-fiber comparison, including cases without an added Co3O4 layer, which they attributed in part to catalytic activity of the PTL material. The same work also reported restructuring and corrosion of the alloy PTLs after testing. Those results belong to that study’s materials and electrolyte; they are not a HuiRui performance or lifetime figure.
Fiber diameter and compression. Xu et al. (2020) used a reference electrode in an anion-exchange-membrane electrolyzer to separate anode and cathode responses. In their cells, the fiber diameter of stainless-steel gas-diffusion layers affected anode performance, while changing the thickness of the cathode diffusion layer affected both electrodes because it changed internal mechanical pressure. Thickness, fiber diameter and stack compression therefore need to be stated together; a single thickness value without a load condition is incomplete.
Contamination and electrolyte. Hagner et al. (2026) tested stainless-steel PTL electrodes as AEMWE anodes and found iron transported into the membrane and onto the cathode. In that work, metal leaching and precipitation depended strongly on pH and KOH concentration, and also on how the cell was operated (for example concentrated versus more dilute alkali, and dry versus wet cathode conditions). Early voltage rise in their tests was attributed largely to anode deactivation. Those pathways are a reason to state the intended electrolyte and duty in an enquiry; they are not a prediction of every stack’s durability.
Production context. Li et al. (2025) report work on producing a porous transport layer based on stainless-steel felt for AEMWE. The paper is cited here for that production context only; its process settings are not used as HuiRui manufacturing claims.
None of these papers sets a single “correct” thickness, porosity, fiber diameter or alloy for every AEMWE design.
What to specify (and what not to copy)
Alloy grade. Give the stainless-steel designation your project already requires (for example 316L, if that is what the drawing or standard names). Do not assume that “stainless steel felt” implies one grade, or that grades are interchangeable in every electrolyte.
Thickness. State the finished thickness and whether it is a free (uncompressed) thickness or a thickness under a load already written on the drawing. Xu et al. showed that diffusion-layer thickness and compression can change both anode and cathode behaviour in an assembled cell. Published micrometre values in the papers above are study samples, not defaults for a quotation.
Porosity, fiber diameter and pore size. If you already have a target porosity, a fiber diameter, a mean pore size, or a measurement method, send them. Two felts can share a similar porosity and still differ in fiber diameter and pore-size distribution. PPI belongs to foam discussions and is not a direct felt specification.
Role in the cell. Say whether the sheet is only a PTL between the catalyst and the flow field, a combined PTL and catalyst substrate, or another duty. Chen et al. and Kreider et al. both show that stainless-steel felt can itself contribute OER activity in AEMWE cells. If you will apply a coating or a catalyst layer, say which face is coated and point to your coating specification.
Electrolyte and compatibility. State whether the feed is pure water, dilute KOH, or a more concentrated alkaline electrolyte, if you already know it. Hagner et al. and Kreider et al. both show that alloy or stainless-steel PTLs can corrode or release metal under some AEMWE conditions. Compatibility has to be assessed for the full stack; it cannot be inferred from the product name.
Sheet size and edges. Give length × width or a cut-part drawing, plus any flatness, edge or tab requirement you already have, and whether you need samples first.
Do not treat a filtration catalogue row as a PTL rating. Product pages may list illustrative filtration models or ranges for quotation discussion. Filtering accuracy, bubble-point, permeability or dirt-holding figures are not verified AEMWE current-density, lifetime or contamination results, and they are not copied here as company facts. Dimensions, grade, thickness condition and any coating are confirmed per enquiry.
Stainless steel, nickel and titanium felt: a quick comparison
| Form | Structure | Where it tends to be discussed | What to specify first |
|---|---|---|---|
| Stainless steel fiber felt | Sintered stainless-steel fibers | AEMWE PTLs and some combined PTL/OER substrates; also filtration duties | Alloy grade if known, thickness (free or loaded), porosity or fiber diameter if known, cut size, bare or coated, electrolyte context |
| Nickel fiber felt | Sintered nickel fibers | ALK electrodes / supports; many AEMWE nickel PTLs (43460) | Thickness (free or loaded), porosity if known, cut size, bare or coated |
| Titanium fiber felt | Sintered titanium fibers | PEM anode PTLs and related titanium duties (43391) | Thickness, porosity if known, cut size, coating if required |
A higher current density for stainless steel than for nickel in one published cell does not mean stainless steel replaces nickel on every drawing, especially where corrosion or metal contamination has to be managed.
What to send for a quote
You do not need a complete laboratory list to contact HuiRui. A sketch, a drawing, or an approximate size and duty is enough to start. The items below help when you already have them:
- The job: AEMWE PTL or diffusion medium, combined PTL/catalyst substrate, filtration, or another use.
- Electrolyte context if known (for example pure-water AEMWE, dilute KOH, or a stated KOH concentration)—compatibility still has to be assessed for the full stack.
- The stainless-steel grade if your project already names one.
- Thickness, and whether that number is free or under a load already on the drawing.
- Target porosity, fiber diameter or mean pore size if you already have them, and how they will be checked.
- Cut size or blank size, quantity, and whether you need samples first.
- Bare or coated; if coated, the type and which face(s), or a pointer to your coating specification.
- Any flatness, edge or inspection record required by the project.
We supply stainless steel fiber felt. Related electrolyzer materials include nickel fiber felt and titanium fiber felt. Grade, dimensions, thickness condition and any coating are confirmed per enquiry. Do not treat product-page filtration tables, or the literature results above, as verified cell performance for every design. Send the drawing and the items you already know, and we will reply with what we can make.
References
- B. Chen, A.L.G. Biancolli, C.L. Radford and S. Holdcroft, “Stainless Steel Felt as a Combined OER Electrocatalyst/Porous Transport Layer for Investigating Anion-Exchange Membranes in Water Electrolysis”, ACS Energy Letters (2023). https://doi.org/10.1021/acsenergylett.3c00878
- Q. Xu, S.Z. Oener, G. Lindquist, H. Jiang, C. Li and S.W. Boettcher, “Integrated Reference Electrodes in Anion-Exchange-Membrane Electrolyzers: Impact of Stainless-Steel Gas-Diffusion Layers and Internal Mechanical Pressure”, ACS Energy Letters (2020). https://doi.org/10.1021/acsenergylett.0c02338
- M.E. Kreider et al., “Porous Transport Layers for Anion Exchange Membrane Water Electrolysis: The Impact of Morphology and Composition”, ACS Electrochemistry (2025). https://doi.org/10.1021/acselectrochem.4c00207
- L. Hagner et al., “Stainless-steel electrodes for anion-exchange membrane water electrolysis: modes of metal contamination and stable operation”, Journal of Power Sources (2026). https://doi.org/10.1016/j.jpowsour.2026.240253
- L. Li et al., “Production of the porous transport layer based on stainless steel felt for anion exchange membrane water electrolysis”, Electrochimica Acta (2025). https://doi.org/10.1016/j.electacta.2024.145598