Investigation on thickness size effect on ductility of magnetron sputtered Niobium coatings on SS316L substrate for forming of precoated metallic bipolar plates

Metallic bipolar plates (BPPs) are key components of the proton exchange membrane fuel cell (PEMFC). To lower the fabrication cost of metallic BPPs, precoated BPPs have attracted much attention due to the high efficiency of precoating-stamping process. However, precoatings on metallic substrate tend...

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Bibliographic Details
Published in:IOP conference series. Materials Science and Engineering 2022-12, Vol.1270 (1), p.12111
Main Authors: Li, C Z, Xu, Z T, Peng, L F, Lai, X M
Format: Article
Language:English
Subjects:
Coatings
Corrosion resistance
Cracking (fracturing)
Ductile fracture
Ductile-brittle transition
Ductility
Ductility tests
Fracture mechanics
Grain size
Magnetron sputtering
Niobium
Plates
Production costs
Proton exchange membrane fuel cells
Size effects
Substrates
Tensile tests
Thickness
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Summary:Metallic bipolar plates (BPPs) are key components of the proton exchange membrane fuel cell (PEMFC). To lower the fabrication cost of metallic BPPs, precoated BPPs have attracted much attention due to the high efficiency of precoating-stamping process. However, precoatings on metallic substrate tend to crack during the forming process, leading to deterioration or even complete loss of corrosion resistance. Therefore, to avoid micro cracks of formed precoated BPPs, development of coatings with high ductility is necessary. In this study, Niobium coatings with different thicknesses on SS316L substrate are prepared with magnetron sputtering process, and uniaxial tensile tests are then conducted for the precoated specimens to evaluate their ductility. The microstructure and fracture behaviour of the Niobium precoatings are characterized by XRD, SEM, TEM, laser confocal microscope analysis. It is found that with the increase of coating thickness, the number of micro cracks at the same strain decreases significantly, and the strain for the first crack to appear also increases. Furthermore, a brittle-to-ductile transition of fracture mechanism is observed. The grain size of Niobium nanocrystalline coating increases with the thickness, which leads to the improvement of plasticity and failure strain. Therefore, the application of precoated metallic BPPs is further advanced.
ISSN:1757-8981
1757-899X
DOI:10.1088/1757-899X/1270/1/012111