摘要
为了提升钛双极板的导电性和耐腐蚀性,利用氮气等离子体原位渗氮法对钛片(TA2)进行表面改性,制备了系列氮化钛涂层,系统研究了反应温度和渗氮时间对涂层表面形貌、疏水性、界面导电性和耐腐蚀性的影响.结果表明,温度过高会导致氮化钛生长过快,颗粒尺寸较大;温度较低不利于表面反应,涂层不能完全覆盖钛基底;渗氮时间较短,表面生成不规则的纳米生长核,致使涂层不平整、钛基底裸露;渗氮时间过长,涂层呈阶梯堆垛状,平整度降低.650℃下渗氮90 min制备的氮化钛涂层(TiN-650-90)均匀平整,组成为TiN0.26;TiN-650-90的水接触角提升至105.4°,表面疏水性有利于改善燃料电池的水管理性能;界面接触电阻(ICR)随加载压力增大而降低,2.75 MPa时TiN-650-90的ICR稳定至6.5 mΩ·cm^(2),满足美国能源部(DOE)要求(≤10 mΩ·cm^(2));TiN-650-90的腐蚀电流密度为0.56μA·cm^(–2),–0.1 V恒电位下的电流密度为0.67μA·cm^(–2),耐腐性和稳定性较钛的明显提升.该方法制备氮化钛涂层表面改性钛双极板,具有沉积温度低、速度快,疏水性、导电性和耐腐蚀性优良等优点,可为金属双极板表面改性提供方法借鉴和工艺参考.
In this study,the surface modification of titanium plates was performed using in situ nitriding via plasma-enhanced chemical vapor deposition to improve the conductivity and corrosion resistance of the plates.A series of titanium nitride(TiN)coatings were synthesized at different nitriding temperatures and durations.The influence of nitriding temperatures and durations on the surface morphology,hydrophobicity,interfacial conductivity,and corrosion resistance of the as-prepared coatings was investigated.The results indicated that faster growth and larger particle size of TiN are observed at higher temperatures.However,lower temperatures are unfavorable for surface reactions;thus,the coating cannot entirely cover the titanium substrate.Moreover,a shorter nitriding time results in irregular nanogrowth nuclei on the surface,leading to an uneven coating and bare titanium substrate.Conversely,longer nitriding time encourages the continuous accumulation of TiN nanoparticles and forms a uniform coating of the titanium substrate but decreases the flatness because of the stacking of the coatings due to the long nitriding time(120 min).The TiN coating prepared by nitriding at 650℃for 90 min(TiN-650-90)is relatively compact and smooth with the composition of TiN0.26 and has an increased water contact angle of 105.4°.The change from hydrophilicity to hydrophobicity in TiN is beneficial to fuel cell water resistance.At a loading pressure of 1.5 MPa,the contact resistances of the coatings prepared at a nitriding time of 60 min can satisfy the U.S.Department of Energy requirement of less than 10 mΩ·cm^(2).Despite a contact resistance of 13.2 mΩ·cm^(2)for the TiN-650-90 coating,the contact resistance decreases with increasing loading pressure and is stable at 6.5 mΩ·cm^(2)under a loading pressure of 2.75 MPa.The corrosion current density of the TiN-650-90 coating is 0.56μA·cm-2,and the corrosion potential positively shifts from-0.37 to-0.05 V at room temperature.The corrosion current density tested in the simulated operating environment of fuel cells is higher than that at room temperature but much lower than that of titanium(4.2μA·cm-2).Furthermore,the current density is stable at 0.67μA·cm-2 and at a-0.1 V constant potential,indicating superior corrosion resistance and stability than titanium.The titanium bipolar plates modified by this method exhibit the advantages of relatively low deposition temperature,quick deposition speed,and good hydrophobicity,conductivity,and corrosion resistance.This work can pave the way for efficient surface modification of metal bipolar plates.
作者
冯利利
侯玉星
汤思遥
李栓
郑捷
李星国
FENG Li-li;HOU Yu-xing;TANG Si-yao;LI Shuan;ZHENG Jie;LI Xing-guo(School of Chemical and Environmental Engineering,China University of Mining and Technology,Beijing 100083,China;Beijing National Laboratory of Molecular Sciences,State Key Laboratory of Rare Earth Materials Chemistry and Applications,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871,China)
出处
《工程科学学报》
EI
CSCD
北大核心
2023年第4期602-610,共9页
Chinese Journal of Engineering
基金
国家重点研发计划资助项目(2018YFB1502104,2021YFE0107200)
越崎学者专项资金资助项目(2020QN11)
中央高校基本科研业务费资助项目(2022YJSHH20)。
关键词
钛双极板
表面改性
等离子体增强化学气相沉积
原位渗氮
氮化钛涂层
titanium bipolar plates
surface modification
plasma-enhanced chemical vapor deposition
in situ nitriding
titanium nitride coatings
作者简介
通信作者:李星国,E-mail:xgli@pku.edu.cn;通信作者:李栓,E-mail:15652783232@163.com。
