Cailiao Baohu (Apr 2022)
Corrosion Resistance and Conductivity of Graphite Coatings with Different Thickness Deposited on 316L Stainless Steel Bipolar Plate by Magnetron Sputtering
Abstract
In order to improve the corrosion resistance and conductivity of 316L stainless steel bipolar plate, the magnetron sputtering was employed to deposit the graphite coatings with different thickness on the surface of 316L stainless steel trough controlling the sputtering time of graphite target. The optimal thickness of graphite coatings was determined by the comparison of the property of graphite coatings with different thickness. In addition, the surface micro morphology of the bipolar plate after corrosion was observed by scanning electron microscope (SEM). Under the simulation of work environment of proton exchange membrane fuel cell (PEMFC) bipolar plate, the corrosion resistance of five kinds of coatings was tested by electrochemical test method. X-ray photoelectron spectroscopy (XPS) was used to analyze the C-bonding characteristics of four kinds of graphite coatings. Moreover, the interfacial contact resistance (ICR) of several kinds of coatings was compared, and the surface contact angle of the coatings was measured to evaluate the hydrophilicity and hydrophobicity of the coatings. Results showed that all the coatings could improve the corrosion resistance and conductivity of 316L stainless steel. Among them, C-3 graphite coating was the best, the corrosion current density under constant potential polarization was stable at 2.26 × 10-7A/cm2, and the interface contact resistance (ICR) was 5.6 mΩ·cm2. Besides, C-3 and C-4 had a high proportion of sp2 hybrid atoms, and the optimal thickness of graphite coating was about 400 nm.
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