LaNiAl储氢合金表面镀铜与SiO2包覆改性研究  

Study on the Surfaces of LaNiAl Alloy Modified by Cu plating and SiO_2 Coating

作　　者：唐有根[1] 谢正和[1] 万伟华[1] 唐仁英 

机构地区：[1]中南大学,湖南长沙410083 [2]湖南稀土金属材料研究院,湖南长沙410014

出　　处：《稀有金属材料与工程》2008年第2期312-315,共4页Rare Metal Materials and Engineering

基　　金：国家“863”计划资助项目(2001AA501433)

摘　　要：采用电弧熔炼铸造LaNiAl储氢合金,研究了退火处理、退火合金表面镀铜和包覆二氧化硅对合金性能的影响。结果表明:合金退火处理后衍射峰的强度增强,衍射晶面的半高宽减小,说明在退火过程中偏析元素发生扩散,消除了偏析晶枝,合金变得均匀,表面更为光滑;包覆前后表面组成由La,Ni和Al的富集到Si和O的富集表明Si以SiO2的形式包覆在粉末的表面。改性处理后的LaNiAl合金试样表现出良好的性能,其中退火合金镀铜处理后的性能最好,放电电压高、平台长;包覆二氧化硅处理后放电电压降低,但放电平台最长。退火处理、退火后镀铜和SiO2包覆处理试样的25次循环容量衰减分别为7%,4%和5%,而未处理的铸造合金衰减21.8%。LaNiAl hydrogen storage alloys were prepared by arc melting method. The effects of annealing-treatment, Cu plating and SiO2 coating on the surfaces of annealing-treatment alloys were investigated. The results show the intensities of diffraction peaks increase after the alloy was annealed, revealing that the alloy was recrystalllzed and dendritic segregation was eliminated during the annealing process. the result that the surface compositions changed from the enrichment of La, Ni and Al to that of Si and O indicates that Si was coated on the powder surfaces in the form of SiO2. Electrochemical study indicates that the alloys treated show excellent performance. The discharge voltage increases and discharge curves become smooth. It is found that the annealed alloy coated with Cu shows the best performance with high discharge voltage and long discharge platform. The annealed alloy coated with SiO2 shows low discharge voltage, and longest discharge platform. The capacity losses of the alloys annealed, plating with Cu, and coated with SiO2 over 25 cycles are 7%, 4% and 5.5%, respectively. However, capacity loss of the alloys without modification is 21.8%.

关 键 词：LaNiAl储氢合金 改性处理 电化学性能 

分 类 号：TG139.7[一般工业技术—材料科学与工程]