Nb-Ti-Co氢分离合金的显微组织和耐腐蚀性能  

Microstructure and Corrosion Resistance of Nb-Ti-Co Hydrogen Separation Alloy

作　　者：狄翀博 王金华 闫二虎 王星粤 陈运灿 贾丽敏[2] 徐芬[1] 孙立贤[1] DI Chongbo;WANG Jinhua;YAN Erhu;WANG Xingyue;CHEN Yuncan;JIA Limin;XU Fen;SUN Lixian(Guangxi Key Laboratory of Information Materials,Guilin University of Electronic Technology,Guilin 541004,China;School of Materials Science and Engineering,Hebei University of Science and Technology,Shijiazhuang 150001,China)

机构地区：[1]桂林电子科技大学广西信息材料重点实验室,桂林541004 [2]河北科技大学材料科学与工程学院,石家庄150001

出　　处：《材料导报》2021年第18期18109-18115,共7页Materials Reports

基　　金：国家自然科学基金项目(52161034,51761009);广西自然科学基金项目(2020GXNSFAA159163);桂林电子科技大学研究生教育创新计划项目(2019YCXS109);广西信息材料重点实验室基金项目(191021-Z)资助。

摘　　要：目前,传统商业用氢分离合金Pd膜资源稀缺且价格昂贵,亟待开发新型氢分离合金膜,Nb-Ti-Co合金可以很好地满足上述要求。不过,上述合金膜过滤的混合气体中常常混有少量的酸性气体,如CO_(2)、H_(2)S和HCl等,对合金膜造成不同程度的腐蚀。到目前为止,关于氢分离合金膜耐腐蚀性能的研究鲜有报道,合金组织和耐腐蚀性能之间的关系尚未建立。基于此,本工作针对Nb-Ti-Co氢分离合金的显微组织和耐腐蚀性能开展了一系列研究,首先利用扫描电镜(SEM)和X射线衍射(XRD)等设备研究了合金显微组织结构,得出其与合金成分之间的本征关系;其次,通过一系列电化学实验测量了上述合金膜的耐腐蚀性能,阐明了其随合金成分和组织(或相结构)变化的变化规律;最后,利用X射线电子能谱(XPS)等设备分析了合金腐蚀后表面元素的价态变化,提出了Nb-Ti-Co合金的耐腐蚀机理。结果表明:除Nb_(30)Ti_(35)Co_(35)合金之外,其他合金均由初生α-Nb相和共晶相(α-Nb+TiCo)构成,并且,前者体积分数随着Nb含量和Ti/Co比率的增加而增加,后者随之降低;伴随上述变化,腐蚀电流(I_corr)逐渐增加,相反,腐蚀电压(E_(corr))逐渐减小,上述二者与初生Nb相体积分数之间的关系分别为:E_(corr)=-0.25259-1.30818×10^(-4)e^(V_(bcc-Nb)/-11.01588)和I_corr=2.10147+3.51536×10^(-5)e^(V_(bcc-Nb)/-3.94597)。另外,腐蚀后Nb、Ti和Co元素易于在合金表面富集并生成Nb_(2)O_5、TiO_(2)和CoO氧化层,并伴随着氧化还原、析氢和复分解反应,促进腐蚀的进一步发生,上述反应过程首次揭示了高Nb含量合金耐腐蚀性能相对较弱的根本原因。Nowadays,the traditional commercial hydrogen separation alloy Pd membrane resources are scarce and expensive,so it is urgent to deve-lop a new hydrogen separation alloy membrane.Nb-Ti-Co alloy can meet the above requirements well.Nevertheless,the mixed gases filtered by the alloy membranes are often mixed with a small amount of acid gases,such as CO_(2),H_(2)S and HCl,which cause varying degrees of corrosion to the alloy membranes.So far,there have been few reports on the corrosion resistance of hydrogen separation alloy films,and the relationship between alloy microstructure and corrosion resistance has not been established.The microstructure and corrosion resistance of Nb-Ti-Co hydrogen separation alloy were studied in this paper.Firstly,the microstructure of the alloy was studied by means of SEM and XRD;secondly,the corrosion resistance of the alloy film was measured by a series of electrochemical experiments,and the variation of the film with the alloy composition and microstructure(or phase structure)was clarified;lastly,the change of the valence state of the surface elements after corrosion is analyzed by using XPS and other equipment,and their corrosion resistance mechanism is put forward.The results show that all the alloys except Nb_(30)Ti_(35)Co_(35)are composed of primaryα-Nb phase and eutectic phase(α-Nb+TiCo),and the volume fraction of the former increases with the increase of Nb content and Ti/Co ratio,and the latter decreases.Along with the above changes,the corrosion current of the alloy increases gradually,on the contrary,the corrosion voltage decreases gradually.The relationship between the above two and the integral number of the primary Nb phase is as follows,E_corr=-0.25259-1.30818×10^(-4)e^(V)bcc-Nb/^(-11.01588)and I_corr=2.10147+3.51536×10^(-5)e^(V)bcc-Nb/^(-3.94597).Moreover,this is due to the easy enrichment of Nb,Ti and Co elements on the alloy surface after corrosion and the formation of Nb_(2)O_(5),TiO_(2)and CoO oxide layers,accompanied by redox,hydrogen evolution and double decom

关 键 词：Nb-Ti-Co氢分离合金 显微组织 耐腐蚀性能 

分 类 号：TG139[一般工业技术—材料科学与工程]