Influence Of Zinc Sulfate Concentration In Baths On The Structure, Morphology And Tribocorrosion Properties Of Fe-Zn Alloy Coating

To address the glazing issue of impregnated diamond bit in drilling hard and compact rock formations, Fe-Zn alloys were electrodeposited from acid sulfate baths and the surface morphology, phase composition, micro-hardness and tribocorrosion property of the deposits were studied. As the ZnSO4 concentration increased from 0 g/L to 20 g/L, the morphology of deposits changed from fine-grained clusters to triangular based pyramids, and finally to granular grains. alpha phase, eta phase and a mixture of alpha phase and eta phase were identified in Fe-Zn coatings. And the microhardness of the deposits is influenced by the Zn content and grain size of Fe-Zn alloy. Furthermore, tribocorrosion behaviors of the deposits were investigated in NaCl solutions by electrochemical measures (potentiodynamic polarization, electrochemical current noise) with an abrasion-corrosion rig. Results of tribocorrosion tests showed that the primary form of the material loss was pure mechanical wear, except the deposit obtained at 20 g/L ZnSO4, whose mass loss due to corrosion-induced abrasion contributed most to its total material loss. The degradation mechanism of Fe-Zn deposits was also detailed in this paper.