Zhou Zhaoyu;Liu Yu;Fu Yanyan;Yu Qinghe;Mi Jing;Hao Lei;

• 1:New Energy and Eco-Environmental Materials Division
• 2: GRIMAT Engineering Institute Co.
• 3: Ltd.
• 4:National Engineering Research Center of Nonferrous Metals Materials and Products for New Energy

Abstract：

The gas diffusion layer(GDL),a cornerstone of proton exchange membrane(PEM) electrolyzers,undertakes two functions:enabling efficient electron transport and managing the simultaneous flow of gases and liquids within the cell.However,the anode GDL operates under extreme conditions—prolonged immersion in acidic electrolytes,exposure to oxygen-rich environments,and sustained high electrochemical potentials,all of which demand exceptional mechanical robustness and chemical inertness.Current commercial anode GDLs,primarily fabricated from sintered pure titanium fibers(titanium felt),face critical challenges.Pure titanium tends to exhibit brittle fracture during titanium felt forming process due to its inherent processing characteristics,while its limited corrosion resistance under acidic conditions accelerates material degradation.These shortcomings hinder the structural integrity and longevity of titanium felt in PEM electrolyzersystems,driving the need for advanced materials with enhanced porosity(to optimize fluid dynamics) and superior corrosion resistance.Addressing these issues requires a dual approach:improving the plasticity of titanium to enable the production of ultrafine fibers and developing novel titanium alloys tailored for acidic environments.Recent research highlights two promising strategies:microalloying hexagonal close-packed(hcp) titanium with trace elements(e.g.rare earth metals) to refine grain structures and modify crystallographic textures,thereby enhancing ductility;and incorporating corrosion-resistant elements like niobium(Nb) to stabilize protective oxide layers.In this study,Ti-Nb alloys(Ti-xNb,x=0,0.8,1.5,1.8,and 2;%,mass fraction) were synthesized via vacuum arc melting using high-purity Ti and Nb powders.The ingots underwent multi-pass hot rolling at 800℃ to achieve a 2 mm thickness,followed by air cooling to preserve microstructure.Advanced characterization techniques including metallographicanalysis for grain size,X-ray diffraction(XRD) for phase identification,and electron backscatter diffraction(EBSD) for texture mappingrevealed that all alloys maintained a single α-Ti phase when Nb content was≤2%.Ti-1.5Nb alloy exhibited peak ductility with an elongation after fracture of 67.5%(compared to 36% for TA1 pure titanium),attributed to refined grains and dominant■textures that activated favorable slip systems.When Nb element addition reached 2%,the grain structure of the alloy was further refined,while the elongation after fracture decreased to 38.5%.The predominant texture components evolved into ■.This texture evolution suppressed the activation of pyramidal second-order slip systems,thereby leading to a marked reduction in the room-temperature ductility of the alloy.Electrochemical testing in simulated PEM conditions demonstrated a steady increase in corrosion resistance with increasing Nb content,evidenced by impedance arc growth(1.27 to 4.01 kΩ·cm~(-2)).The Ti-1.5Nb alloy,striking an ideal balance between ductility(67.5% elongation after fracture) and corrosion resistance,outperformed conventional TA1 titanium,making it a superior candidate for next-generation PEM electrolyzer GDL substrates.This work underscored the importance of synergistic alloy design,combining texture engineering and corrosion-resistant microalloyingto advance high-performance materials for sustainable hydrogen production technologies.

Key Words： Ti-Nb alloy;room-temperature plasticity;texture analysis;electrochemical impedance

Abstract:

Keywords:

Foundation: 国家重点研发计划项目（2022YFB4002002）资助

Authors: Zhou Zhaoyu;Liu Yu;Fu Yanyan;Yu Qinghe;Mi Jing;Hao Lei;

DOI: 10.13373/j.cnki.cjrm.XY25020010

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