Effect of yttrium modification on the corrosion behavior of AZ63 magnesium alloy in sodium chloride solution

The microstructures and corrosion behaviors of Mg-6%Al-3%Zn and Mg-6%Al-3%Zn-(0.251.0)%Y in 3.5 wt.%Na Cl solution are investigated via morphology observation,phase characterization,immersion and electrochemical methods.The experimental results suggest that yttrium alloying can improve the corrosion resistance of Mg-6%Al-3%Zn throughout the immersion.The initial enhanced corrosion resistance of magnesium alloy is attributed to the Y alloying,which gives rise to the increasing content of Al_(2)O_(3)in oxide layer.The promoted protectiveness of oxide layer on Mg-6%Al-3%Zn-1.0%Y alloy arouse a filiform corrosion as revealed by in-situ metallographic observation.Furthermore,the Y-containing magnesium alloys still perform higher corrosion resistance compared with that of Mg-6%Al-3%Zn alloy even if the oxide layer is exhausted.This phenomenon is owing to two factors,one is the gradual transformation of intermetallic phases from continuous Mg_(17)Al_(12)to discrete Al_(2)Y in matrix,by which the micro-galvanic corrosion betweenα-Mg grains and intermetallic phases is alleviated;the other is the morphology variation of corrosion products,the uniform and compact products layer on Y-containing alloys provide a barrier that effectively prevent the corrosive ions from penetrating into and reacting with Mg matrix.

Electrochemical behavior of Mg-Al-Zn-Ga-In alloy as the anode for seawater-activated battery

The effect of indium alloying on the corrosion and discharge behaviors of Mg-Al-Zn-Ga alloys is investigated via materials characterization,immersion test and electrochemical methods.The results indicate that indium alloying can effectively modify the distribution of intermetallic phases in Mg matrix via promoting the segregation of Al in the form of Mg17Al12 in matrix.The addition of indium can effectively activate Mg-Al-Zn-Ga alloy evidenced by increased hydrogen evolution volume and weight loss,negative shift of corrosion and discharge potentials,increase of corrosion current density,decrease of polarization resistance and promoted Faradic efficiency.Nonetheless,excessive indium alloying(2.0 wt.%)would strikingly deteriorate the electrochemical performance of Mg-Al-Zn-Ga anode due to the exorbitant active effect.The Mg-6 wt.%Al-3 wt.%Zn-1 wt.%Ga-1 wt.%In in as-cast state with acceptable corrosion rate and desirable discharge performance is a low cost,non-toxic and well-performance magnesium alloy,which is a promising anode materials for seawater-activated batteries.

Fabrication of three-dimensional WO_(3)/ZnWO_(4)/ZnO multiphase heterojunction system with electron storage capability for significantly enhanced photoinduced cathodic protection performance

A novel three-dimensional hierarchical WO_(3)photoelectrode was prepared by solvothermal method,and ZnO was deposited on its surface by electrochemical method.The WO_(3)/ZnWO_(4)/ZnO multiphaseheterojunction photoelectrode was prepared by further annealing treatment to explore the photoinduced cathodic protection(CP)performance.Compared with WO_(3)and ZnO,the photoinduced CP and electron storage capacity performance of WO_(3)/ZnWO_(4)/ZnO is significantly improved in 3.5%NaCl solution without adding any hole scavenger.The electron storage capacity of the WO_(3)/ZnWO_(4)/ZnO heterojunction makes it possible to continuously protect metallic materials in the dark after switching off the light,which can realize long-term and effective photoinduced CP.

Significantly enhanced photocatalytic hydrogen production performance of g-C_(3)N_(4)/CNTs/CdZnS with carbon nanotubes as the electron mediators

The electron mediator can effectively improve the performance of the direct Z-scheme heterojunction photocatalysts. However, it is still a great challenge to select cheap and efficient electron mediators and to design them into the Z-scheme photocatalytic system. In the present paper, the g-C_(3)N_(4)/CNTs/CdZnS Z-scheme photocatalyst was prepared using carbon nanotubes(CNTs) as the electron mediators, and its photocatalytic hydrogen production performance was studied. Compared with single-phase g-C_(3)N_(4),CdZnS and biphasic g-C_(3)N_(4)/CdZnS photocatalysts, the photocatalytic hydrogen production performance of the prepared g-C_(3)N_(4)/CNTs/CdZnS has been significantly enhanced. Meanwhile, g-C_(3)N_(4)/CNTs/CdZnS possesses very good photocatalytic hydrogen production stability. The enhanced photocatalytic hydrogen production performance of g-C_(3)N_(4)/CNTs/CdZnS is attributed to the fact that CNTs, as an electron mediator,can accelerate the recombination of the photogenerated holes in the valence band of g-C_(3)N_(4) and the photogenerated electrons in the conduction band of CdZnS, which makes the g-C_(3)N_(4)/CNTs/CdZnS Zscheme photocatalyst be easier to escape the photogenerated electrons, increases the concentration of the photogenerated carriers and prolongs the lifetime of the photogenerated carriers. This work provides a theoretical basis for the further development and design of CNTs as the intermediate electron mediator of the Z-scheme heterojunction photocatalyst.