摘要
金属Ti因其密度小(仅为不锈钢的0.6倍)和比强度高等特点,是轻量化空间燃料电池金属板材料的首要选择,但其在弱酸性环境中长时间工作容易被腐蚀。为了改善金属Ti双极板耐蚀性,采用多弧离子镀技术在金属Ti表面制备了由Ti过渡层及TiN表层构成的Ti/TiN复合涂层,研究制备工艺参数对Ti/TiN复合涂层微观结构及力学、电化学性能的影响规律。利用场发射扫描电子显微镜(SEM)分析涂层的微观形貌,利用X射线衍射仪分析涂层的相组成,利用纳米压痕仪评价涂层的力学性能,利用电化学工作站评价涂层在模拟质子交换膜燃料电池(PEMFC)阴极工作环境下的耐蚀性。结果表明:制备工艺参数优化后的Ti/TiN复合涂层具有优异的表面质量和良好的耐蚀性,腐蚀电流密度为6.383μA/cm^(2),是金属Ti腐蚀电流密度的0.6倍,Ti/TiN复合涂层显著提高了金属Ti的耐蚀性,可为空间燃料电池金属双极板表面改性提供技术支持。
Proton-exchange membrane fuel cells(PEMFCs)are currently widely investigated for the development of space power systems for future deep-space exploration and lunar research stations in China.Key technological research pertaining to PEMFCs for space applications must be conducted urgently.The bipolar plate,which is the core component of PEMFCs,significantly affects the weight and cost of the battery stack.Titanium is the preferred metal-plate material for lightweight space fuel-cells owing to its low density(only 0.6 times that of stainless steel)and high specific strength.However,they are susceptible to corrosion when used in weak acidic environments for long durations.To improve the corrosion resistance of titanium bipolar plates,a Ti/TiN composite coating composed of a Ti transition layer and a TiN surface layer is prepared on the surface of titanium via multi-arc ion plating technology,which is a physical vapor deposition technique.The effects of preparation process parameters such as the substrate temperature and arc current on the microstructure and mechanical/electrochemical properties of the Ti/TiN composite coating are investigated.The cathode sputtering target material is imported titanium metal(purity=99.995%),the sputtering gas is high-purity argon(purity=99.99%),and the reaction gas is high-purity nitrogen(purity=99.99%).The sheet of titanium was sequentially sonicated in acetone,anhydrous ethanol,and deionized water for 15 minutes to remove oil stains and attachments on the surface of the sample.Then,nitrogen flow was used to blow dry the surface moisture of the sample to ensure that there were no residual water stains on the surface.After that,the sample was placed in a drying dish for later use.When the vacuum degree of the equipment is better than 5.0 mPa,perform ion source cleaning to remove the oxide layer on the surface of the Ti substrate and activate the surface of the Ti substrate.When preparing the Ti transition layer on the titanium metal substrate,the target substrate distance is set to 23 cm,the arc current is 70 A,the substrate temperature is 150℃,and the deposition time is 10 min.When preparing TiN layers on the Ti transition layer,two different substrate temperatures(150,230℃)and arc currents(50,120 A)are selected.A field-emission scanning electron microscope(Carl Zeiss AG Corporation)is used to analyze the micromorphology of the Ti/TiN composite coating.An X-ray diffractometer(Rigaku Corporation)is used to analyze the phase composition of the coating.A nanoindentation instrument(Anton Paar)is used to evaluate the mechanical properties of the coating.The indentation depth is controlled to be less than 10%of the thickness of the Ti/TiN composite coating.During testing,the maximum load is increased linearly to 5 mN at a loading and unloading rate of 10 mN/min.A TalySurf CCI Lite optical interferometric surface profilometer(Taylor Hobson)is used to test the surface roughness and thickness of the Ti/TiN composite coating.An electrochemical workstation is used to evaluate the corrosion resistance of the coating under a simulated operating environment of a PEMFC cathode.The results show that the Ti/TiN composite coating prepared under a substrate temperature of 150℃and an arc current of 50 A offers the best surface quality,the lowest surface roughness,and the lowest corrosion current density.The Ti/TiN composite coating with optimized preparation process parameters exhibits excellent surface quality and high corrosion resistance,with a corrosion current density of 6.383μA/cm^(2)(i.e.,0.6 times the corrosion current density of titanium).Furthermore,the Ti/TiN composite coating significantly improves the corrosion resistance of titanium.This study provides technical support for the surface modification of metal bipolar plates used in space fuel-cells.
作者
马文彬
张辉
姚伟
蒋钊
MA Wenbin;ZHANG Hui;YAO Wei;JIANG Zhao(Qian Xuesen Laboratory of Space Technology,China Academy of Space Technology,Beijing 100094,China;Lanzhou Institute of Physics,Lanzhou 730000,China)
出处
《中国表面工程》
EI
CAS
CSCD
北大核心
2024年第2期16-26,共11页
China Surface Engineering
基金
国防科工局基础科研项目(JCKY2020203B056)。
关键词
多弧离子镀
Ti/TiN复合涂层
耐腐蚀性能
multi-arc ion plating
Ti/TiN composite coating
corrosion resistance property
