The Behavior Research Of Citrate In Electroplating Ferrous Alloys

Electroplating ferrous alloys had wonderful performances in its microhardness, mechanical intensity, corrosion resistance, magnetic and catalyzed active properties. Citrate used as a complexing agent was low cost and environmentally friendly. It could stabilize the electrolytes and make the crystal size of the alloy small and compact. In this paper, the behaviors of citrate in electroplating ferrous alloys were studied. The detailed research work was listed as follows:(1) The effects of citrate on Fe-Ni alloy deposits were discussed in this paper, such as the appearance, composition, density, microhardness, corrosion resistancs and adhesion ability. The effects of citrate on the electrodeposit velocity and cathodic current efficiency of the bath were also investigated. The structures of these alloy deposits from different citrate concentration electrolytes were detected by XRD (X-Ray Diffraction). The optimum citrate concentration under this condition was 0.12~0.65mol/l.(2) A new process of electroplating amorphous Fe-Ni-W alloy deposits in citrate electrolyte was proposed. Friction and wear behavior of Fe-Ni-W alloy deposit was studied and compared with that of chromium deposit. The corrosion properties against 5% sodium chloride, 5% sulfuric acid and 5% sodium hydroxide were also discussed in this paper. The structure and morphology of Fe-Ni-W alloy deposit were detected by XRD and SEM. The performances of this deposit from citrate electrolyte were better than chromium deposit. The citrate used as the complexing agent made the bath low cost and environmentally friendly. So it would find widely use in industries to replace the chromium deposit.(3) Combining with the experimental results described above, the possible structures of the citrate complexes in ferrous alloy electrolytes were proposed for the first time based on soft hard acid and basic theory and complexing theory. The possible discharging processes and active intermediate stuctures of the citrate complexes were also discussed using complex slow discharging theory and soft hard acid and basic theory.(4) A new method for quantification of citrate in ferrous alloy electrolytes was proposed. Citrate in these electrolytes was purified by Dowex 1X8-200 strong basic anion exchange resin and converted into ethyl ester with the catalyst boron trifluroride-aether. After washing...