| The Pb-Ag alloy has been widely used in zinc electrowinning industrial as anode materials at present. However, these materials have some defects restricted their application, such as high oxygen evolution overpotential, large density makes difficult to assemble, and high consumption of silver. Titanium base lead dioxide anode has a broad application prospect, because of its good corrosion resistance, electrical conductivity, and high catalytic activity. As a result of large (3-PbO2 internal stress, the coating is easy to fall off, so that most researchers think to reduce internal stress and improve electrochemical performance of titanium base lead dioxide anode through adding an intermediary. But the problem of too high electrode resistance and large internal stress cannot be fundamentally solved by these method. It makes the wide application of titanium base PbO2 anode largely restricted.Aiming at the problems of titanium base lead dioxide anode, a new type of tungsten carbide modified titanium base composite lead dioxide inert anode materials without intermediary were prepared by using the method of direct current deposit and doping tungsten carbide micron particles and nonionic surfactant O-7. The active particles, organic additive content and different process conditions influenced on anode material surface microstructure and electrochemical properties has been studied by kinds of test methods, such as scanning electron microscopy, anodic polarization curves, Tafel curves and electrochemical impedance spectroscopy. The optimal preparation conditions determined by single factor experiment are:Pb(NO3)2210g/L, NaF 0.5g/L, Cu(NO3)225g/L, WC 40g/L,O-7 0.5g/L, current density 25mA/cm2, temperature 55 ℃, stirring speed 300r/min, working time 60min.SEM figure showed that:Suitable amount of WC particles withβ-PbO2 composite oxide deposition in plating solution refined the grain size and increased the specific surface area, the coating was more flat and compact, thus electrode surface morphology was improved; Nonionic surfactants O-7 could control coating crystal grain size, change the structure of the electrode material, and make the electrode smooth, densification, uniform. The electrochemical test results showed that:It made exchange current density and polarization resistance larger of the anode material by adding suitable amount of WC and O-7 and suitable process conditions, so the electric catalytic properties and corrosion resistance were enhanced.The WC and O-7 influence on lead dioxide deposition process was explored through cyclic voltammetry method. The results showed that:The WC and O-7 in the plating solution all increased the amount of lead dioxide deposition on the substrate. But the addition of O-7 had no effect on equilibrium potential of lead dioxide and initial deposition potential. The XRD spectrum showed that:Adding O-7 and WC did not change the coating composition, but the diffraction peak intensity of the prepared electrode material had changed. It meant that adding O-7 and WC all changed the crystal orientation in the (101) and (301) crystal plane, so the coating electrode surface morphology was improved.The cell voltage, current efficiency and electrode life of different kinds of anode were compared in simulation zinc electrolyte. The results showed that:The cell voltage of inert anode materials Ti/β-PbO2-WC was lower than traditional Pb-Ag(0.75wt%) anode for about 30mv, the oxygen electric catalytic performance of inert anode material was very good, so it can reduce energy consumption in electrolytic zinc; The current efficiency of inert anode materials Ti/β-PbO2-WC was higher than Pb-Ag(0.75wt%) for about 1%; However, the results of reinforcement corrosion experiment showed that the theoretical work time of Ti/0-PbO2-WC electrode was lower than Pb-Ag(0.75 wt%) for 280h. It shows that the preparation of inert anode materials needs to improve on the service life. |
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