Preparation And Degradation Behavior Of Mg-Zn-Ca Bulk Metallic Glass Matrix Composite Reinforced By Fe Particle With Electroless Copper Coating

Mg-Zn-Ca amorphous alloy is a magnesium alloy with excellent mechanical properties and unique functional properties.Its good biodegradability and degradation properties of azo dye have attracted wide attention in academic circles.However,the plasticity of Mg-Zn-Ca amorphous alloys is almost zero in the room temperature,which limits the further application of the alloy.In addition,the chemical mechanism of azo dye degradation by Mg-Zn-Ca amorphous alloy is still poorly understood,and further research is needed.In this study,The Mg-Zn-Ca amorphous matrix composites reinforced by plastic Fe particles were prepared by the way of electroless copper coating to Fe particles to improving the wettability of Fe particles and Mg₆₆Zn₃₀Ca₃Sr₁ amorphous alloy matrix.The compressive deformation behavior and the degradation properties of azo dyes were studied systematically.The following main results were obtained.Based on micron sized spherical Fe particles,a method of electroless copper plating with thin thickness and fine coating structure is designed in this paper.The thickness of the coating was controlled accurately by adjusting the parameters of the main salt concentration and the composition of the complexing agent by method.Based on the theory,a compact copper coating with a thickness of about 40 nm was coated on the surface of the spherical Fe particles with a diameter of about 20 m.The Fe/Mg₆₆Zn₃₀Ca₃Sr₁ amorphous matrix composites has been successfully prepared by induction smelting-copper mold casting.It is found that the thickness of the electroless Cu-coating on the surface of Fe particles can significantly affect the microstructure and mechanical properties of the composites.When the copper thickness is less than 40 nm,the composites can still completly maintain amorphous structure,while the thickness is 400 nm,the composites grow Mg₇Zn₃ in the center of the composites.The quasi-static axial compression test shows that the mechanical properties of the amorphous alloy reinforced by Fe with thick Cu-coating can not be significantly increased due to crystallization of the matrix leading to the degradation of matrix properties.However the composite materials reinforced Fe particles with thin Cu-coating exhibit excellent mechanical properties.When the volume fraction of Fe particles is 30%,the strength of the composites reaches 807 MPa,and the plasticity reaches about 5%.In addition,It is found that the degradation efficiency of azo dyes can be significantly improved by the proper NaCl in simulated sewage,when MgZn based amorphous alloy was used to degrade azo dyes in this study.The rapid degradation of direct blue 6?DB6?can be achieved by adding more than 2 wt%.When the amorphous alloy powder was added to the wastewater for 30min,the degradation rate of DB6 could reach above 90%.In addition,it is also found that the Fe/Mg₆₆Zn₃₀Ca₃Sr₁ amorphous composite ribbon has stronger azo dye degradation ability than micron Fe powder and Mg₆₆Zn₃₀Ca₄ amorphous alloy ribbon in this paper.It is found that the mechanism of MgZn based amorphous alloys and its composites to degrade DB6 is consistent,through the analysis of the evolution process of the surface micromorphology of the samples during the degradation of DB6 sewage.The rate of degradation of DB6 is positively related to the corrosion rate of the alloy itself in the DB6solution.Both of them disconnect the azo bonds through their own corrosion chemical reactions,while the sheet like nano ZnO structures produced on the surface of amorphous alloys have strong chemical adsorption and photocatalysis,which can effectively degrade azo dyes under ultraviolet light.