Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the...Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the anisotropy effects of pure titanium(CP-Ti) sheet on the springback behavior and forming properties during the microstamping process. Thin sheets of CP-Ti specimens with different orientations were examined using uniaxial tensile tests to assess the effects of anisotropy on their mechanical properties. Then an anisotropic constitutive model considering the off-axis elastic modulus was developed based on orthotropic elasticity and Hill's yield criterion. Numerical modeling and simulation of the microstamping process for fabricating multi-channel structures were performed. The effects of anisotropy on the springback of multi-channels were investigated and compared with experimental results;the effects of tool dimension parameters on the formability of microchannel structures were also analyzed. The results showed that the anisotropy of thin titanium sheets causes various degrees of forming loads and springback in the microstamping of microchannels at different orientations. This study accurately predicts the springback of thin titanium sheet used to fabricate microchannel structures and is a good guide to the formation of such structures.展开更多
The membrane electrode assembly(MEA)plays a crucial role in the functionality of proton exchange membrane fuel cells(PEMFCs).The channels present within the catalyst layer of MEAs exhibit a disordered configuration,wh...The membrane electrode assembly(MEA)plays a crucial role in the functionality of proton exchange membrane fuel cells(PEMFCs).The channels present within the catalyst layer of MEAs exhibit a disordered configuration,which consequently give rise to low efficiency in mass transportation.In order to enhance the mass transfer performance and the corrosion resistance of the catalyst layer,this paper developed a double-side ordered MEA based on TiN nanorod arrays.We synthesized TiN nanorod arrays on the ITO surface by a seed-assisted hydrothermal reaction and nitriding treatment,and coated the catalyst uniformly on the TiN support by ultrasonic spraying.Then the double-side ordered MEA was fabricated by transfer printing,and achieved a peak power of 678.30 mW cm^(-2) with a cathode platinum loading of 0.2 mg cm^(-2) at 80℃ and anode saturated humidity.After 200 hours of accelerated stress test(AST)at 90℃ and 30/30%relative humidity,the peak performance only dropped by 4.8%.These results provide substantial evidence for the effectiveness of our developed double-side ordered MEA which can mitigate catalyst polarization corrosion.Thus,this study reveals the immense potential of the TiN nanorod array-based double-side ordered MEA in advancing the development of efficient and stable MEAs.展开更多
基金supported by the National Key R&D Program of China(No.2019YFC1509503)the National Natural Science Foundation of China(No.U1809220)the Key Research and Development Program of Zhejiang Province(No.2022C01113),China.
文摘Ultra-thin sheets of titanium for fabricating microchannels have been used in fuel cells due to their good corrosion resistance and high strength-weight ratio. This paper presents a constitutive model for studying the anisotropy effects of pure titanium(CP-Ti) sheet on the springback behavior and forming properties during the microstamping process. Thin sheets of CP-Ti specimens with different orientations were examined using uniaxial tensile tests to assess the effects of anisotropy on their mechanical properties. Then an anisotropic constitutive model considering the off-axis elastic modulus was developed based on orthotropic elasticity and Hill's yield criterion. Numerical modeling and simulation of the microstamping process for fabricating multi-channel structures were performed. The effects of anisotropy on the springback of multi-channels were investigated and compared with experimental results;the effects of tool dimension parameters on the formability of microchannel structures were also analyzed. The results showed that the anisotropy of thin titanium sheets causes various degrees of forming loads and springback in the microstamping of microchannels at different orientations. This study accurately predicts the springback of thin titanium sheet used to fabricate microchannel structures and is a good guide to the formation of such structures.
基金The authors acknowledge the financial support from the National Natural Science Foundation of China(U1809220)Key Research and Development Program of Zhejiang Province(2022C01113)Key Research and Fundamental Research Funds for the Central Universities(2022FZZX01-06).
文摘The membrane electrode assembly(MEA)plays a crucial role in the functionality of proton exchange membrane fuel cells(PEMFCs).The channels present within the catalyst layer of MEAs exhibit a disordered configuration,which consequently give rise to low efficiency in mass transportation.In order to enhance the mass transfer performance and the corrosion resistance of the catalyst layer,this paper developed a double-side ordered MEA based on TiN nanorod arrays.We synthesized TiN nanorod arrays on the ITO surface by a seed-assisted hydrothermal reaction and nitriding treatment,and coated the catalyst uniformly on the TiN support by ultrasonic spraying.Then the double-side ordered MEA was fabricated by transfer printing,and achieved a peak power of 678.30 mW cm^(-2) with a cathode platinum loading of 0.2 mg cm^(-2) at 80℃ and anode saturated humidity.After 200 hours of accelerated stress test(AST)at 90℃ and 30/30%relative humidity,the peak performance only dropped by 4.8%.These results provide substantial evidence for the effectiveness of our developed double-side ordered MEA which can mitigate catalyst polarization corrosion.Thus,this study reveals the immense potential of the TiN nanorod array-based double-side ordered MEA in advancing the development of efficient and stable MEAs.
