Titanium felt is a porous sheet made from titanium fibers formed into a network and sintered. The spaces between the fibers allow fluid to move through the structure, while the connected metal forms a supporting and conducting framework.
Porosity is one useful way to describe this material. It becomes more informative when read alongside pore size, thickness and the structure at the sheet’s surface, particularly when titanium felt is being considered as a porous transport layer in a PEM water electrolyzer.
Porosity and pore size describe different features
Porosity is the fraction of the material’s overall volume occupied by void space, usually expressed as a percentage. It describes how much space is present within a given volume.
Pore size describes the dimensions of those spaces or their connecting openings, according to the measurement method used. A fibrous network has a distribution of pore sizes rather than one repeated opening. Two samples with the same total porosity can therefore have different pore structures.
Permeability describes how readily a fluid moves through the material under a pressure difference. It depends on the connected flow paths. Fluid-permeability testing for porous sintered metals treats this as a measured property. Porosity alone does not specify a flow rate, a filtration rating or an electrolyzer performance level.
The role of titanium felt in a PEM porous transport layer
At the anode of a PEM water electrolyzer, a porous transport layer sits between the catalyst layer and the flow-field structure. Its connected pores provide routes for water and oxygen, while its solid framework contributes to electrical contact and mechanical support.
This combination makes both the interior and the surface of the felt important. The interior describes the available paths through the sheet. The surface describes how the felt meets the adjacent catalyst-coated membrane or electrode layer.
In research comparing sintered and felt-based commercial titanium transport layers under differential pressure, lower-porosity samples produced lower cell voltage and less hydrogen crossover within the tested set. The researchers linked these results to improved contact and reduced membrane deformation. The finding illustrates a trade-off in that cell design; it does not establish a universal best porosity or a performance value for HuiRui felt.
Read the structure as a combination
Thickness, fiber dimensions, pore distribution and surface contact describe different parts of the same sheet. A thinner sample and a thicker sample can have similar porosity while presenting different path lengths and mechanical geometry in an assembly.
The way the sheet is installed also matters to its dimensions and contact. An uncompressed thickness describes the free-standing material, while an installed thickness describes its state in the component. Keeping those descriptions clear helps make laboratory comparisons and component drawings easier to interpret.
Surface treatment is another distinct part of the material description. Research on surface-patterned titanium felt has examined how wettability and local structure affect water and oxygen transport. Such a treated research sample should be compared as a complete material system, including its treatment.
Explore titanium felt and related forms
HuiRui’s titanium fiber felt page lists the material’s available thickness and porosity information. Titanium woven wire mesh and titanium foam provide other porous structures for projects that call for a different form.
For titanium felt product information or a quotation, contact HuiRui.