| Steel is one of the most widely used and most important metal materials in industrial production,but its corrosion resistance is very low.Hot dip galvanizing is a widely used,economical and effective method for steel and iron corrosion prevention.However,galvanizing of Si-containing steels has always been a technical challenge for researchers all the time.Dull grey coatings with abnormally thickness will be formed when the steel containing Si element They are poorly adherent to the steel substrates.The surface is easy to fall off.Adding an adequate alloy elements to the molten zinc bath,the coating structure and performance can be improved effectively.Adding a small amount of V element to the zinc bath can weakened the Sandelin effect and improve the coating quality.Studies have shown that adding moderate Sb to zinc bath can contribute to form a beautiful flower in the coating of the workpiece,reduce the surface tension of liquid zinc,enhance the mobility of zinc bath,reduce Zinc consumption,and improve the 'quality-cost' ratio.However,the synergistic effect of V and Sb on the microstructure of galvanized coating is relatively few.The information of phase equilibra and the thermodynamic describing of the Zn-Fe-V-Sb quaternary system are very important to understand the combined effect of V and Sb in the hot-dip.In present work,the equilibrium alloy method was used in this experiment,combining with the equipments of the scanning electron microscopy and energy dispersive spectrometer(SEM-EDS)and X-ray diffractometer(XRD)to determine the phase relations in the Zn-rich coner of the 450? and 600? isothermal section of Zn-Fe-V-Sb quaternary system with Zn being fixed at 93at.%.The experimental results show that the Zn-rich corner of the 450? isothermal section of the Zn-Fe-V-Sb quaternary system contains four four-phase regions and nine tri-phase regions.The four-phase regions measured by the experiment were L + Sb2Zn3 + ? +VZnSb,L + V3Sb + ? + VZnSb,L + V3Sb + ? + T and L + V3Sb + VZn3 + T.The tri-phase regions were L + Sb2nZm + ?,L + Sb2Zn3 + VZnSb,L + VZnSb + V3Sb,L +V3Sb + VZn3,L L VZn3 + T,L + ? + T,L + ? + VZnSb,L + V3Sb + ? andL + V3Sb +T.The experimental results show that the Zn-rich corner of the 600? isothermal section of the Zn-Fe-V-Sb quaternary system contains three four-phase regions and seven tri-phase regions.The four-phase regions measured by the experiment were L+ V3Sb + ? + ??L + ? + ?-V + V3Sb and L + ?-V + V3Sb + VZn3.The tri-phase regions were L + ? + V3Sb?L + ?+??L + ? + V3Sb?L + ? + ?-V?L + ?-V + V3Sb?L + ?-V + VZn3 and L V3Sb + VZn3.In addition,no new ternary compound or quaternary compound was found in the study.In this paper,the effect of different V and Sb content and the hot dipping time on the thickness and quality of the alloy layer were studied with Q235 steel as the base material(silicon content of 0.202 wt.%),Final results show:The addition of V and Sb elements into the zinc bath can effectively inhibit the Fe-Zn reaction rate,which can inhibit the growth of intermetallic compounds such as FeZn13;When the substrate material is Q235 steel,the ideal coating can be obtained by adding 0.1wt.%V and 0.05wt.%Sb to zinc bath,and the dipping time is three minutes. |
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