Balancing the corrosion resistance and through-plane electrical conductivity of Cr coating via oxygen plasma treatment

• 作者: Xian-Zong Wang Hong-Qiang Fan Triratna Muneshwar Ken Cadien Jing-Li Luo
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2021,（2）
• 页码范围: 75-84
• 页数: 10页
• 语种: 英文

摘要

Developing an electrically conductive and corrosion-resistant coating is essential for metal bipolar plates of polymer electrolyte membrane fuel cells(PEMFCs).Although enhanced corrosion resistance was seen for Cr coated stainless steel(Cr/SS)bipolar plates,they experience a quick decrease of through-plane electrical conductivity due to the formation of a porous and low-conductive corrosion product layer at the plate surface,thus leading to an increase in interfacial contact resistance(ICR).To tackle this issue,the multilayer Cr coatings were deposited using the magnetron sputtering with a remote inductively coupled oxygen plasma(O-ICP)in the present study.After the O-ICP treatment,a Cr oxide layer(CrO*)is formed on the specimen surface.The CrO*/Cr/SS has a remarkably lower stable corrosion rate(iss)than that of the native Cr oxides(CrOn/Cr/SS).Compared with CrOn/Cr/SS,the excellent performance of CrO*/Cr/SS is attributed to a denser and thicker surface layer of CrO* with Cr being oxidized to its highest valence state,Cr(Ⅵ).More importantly,the through-plane electrical conductivity of the specimens treated by the opti-mized O-ICP decreases much slowly than CrOn/Cr/SS and thus,the increament of ICR of CrO*/Cr/SS after the potentiostatic polarization test is considerably smaller than that of CrOn/Cr/SS,which is benefited from the reduced iss that mitigates the deposition of corrosion products and hinders further oxidation of Cr coating.Therefore,CrO*/Cr/SS proves to be a well balanced trade-off between corrosion resistance and through-plane electrical conductivity.The results of this study demonstrate that O-ICP treatment on a conductive metal coating is an effective strategy to improve the corrosion resistance and suppress the increase of ICR over the long-term polarization.The technique reported herein exhibits its promis-ing potential application in preparing corrosion resistant and electrically conductive coatings on metal bipolar plates to be used in PEMFCs.