Buming CHEN
,
Zhongcheng GUO
,
Hui HUANG
,
Xianwan YANG
,
Yuandong CAO
金属学报(英文版)
doi:10.1016/S1006-7191(08)60111-8
The α-PbO2 electrodes are prepared by anodic electrodeposition on A1/conductive coating electrode from alkaline plumbite solutions in order to investigate the effect of the different current densities on the properties of α-PbO2 electrodes. The physicochemical properties of the α-PbO2 electrodes are analyzed by using SEM, EDS, XRD, Tafel plot, linear sweep voltammetry (LSV) and A.C. impedance. A compact and uniform layer of lead dioxide was obtained at the current density of 3 mA·cm-2. A further increase in current density results in smaller particles with high porosity. EDS and XRD analyses have shown that the PbO2 deposited in alkaline conditions is highly non stoichiometric, and the PbO impurities are formed on the surface layer besides the α-PbO2 . The corrosion resistance of α-PbO2 at the low current density is superior to that of the high current density. It can be attributed to a porous layer of deposited films at high current densities. When used as anodes for oxygen evolution in aqueous Zn2+ 50~g·L-1, H2SO4 150~g·L-1, the Al/conductive coating/α-PbO2 exhibits lower potential compared to Pb electrode. Al/conductive coating/α-PbO2 electrode with the best electrocatalytic activity was obtained at current density of 1mA·cm-2. The lowest roughness factor was obtained at 1 mA·cm-2.
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Alpha lead dioxide
,
null
,
null
,
null
,
null
Zhongcheng GUO
,
Xiaoyun ZHU
,
Dacheng ZHAI
,
Xianwan YANG
材料科学技术（英文）
Ni-W alloys and their composite deposits are electroplated on the metals when an appropriate complex agent is selected on the base of the theories of electrochemistry and complex chemistry, and the principle of induced codeposition. Effects of the bath composition, pH value, temperature and current density on the electrode position of Ni-W alloys and their composite deposits have been investigated, and the effect of heat treatment temperature on the hardness, structure and cohesive force of the amorphous Ni-W alloys and their composite deposits are also discussed. Results showed that the alloys containing more than 44 wt pet W content and the composite deposits containing 7.8 wt pet SiC content could be obtained by making use of the appropriate bath composition and plating conditions. Alloys and their composite deposits with over 44 wt pet W content show amorphous structure. The hardness of amorphous Ni-W alloys and their composite deposits increases obviously when heated, and can reach to 1350 HV and 1520 HV respectively for 46 wt pet W content. The cohesion on Cu, carbon steel and stainless steel is very good.
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