Effect of Current Density, Reaction Temperature and Deposition Time on the Electrodeposition of ZrB₂ Coating

ZrB₂ coating was successfully prepared on molybdenum substrate by molten salt electrodeposition method in this study. The reaction medium was NaCl-KCl eutectic molten salt with K₂ZrF₆ as the zirconium source and KBF₄ as the boron source. The effect of electrodeposition parameters including the current density, reaction temperature and deposition time on the phase composition, surface and cross-sectional morphologies, thickness, and preferred orientation of ZrB₂ coating was investigated in detail. The influence mechanism of each condition was also discussed. The experimental results proved that all the three parameters could directly affect the electrodeposition process of ZrB₂ coating in molten salt. With the increase of the current density, the thickness and surface roughness of the coating increased. Higher reaction temperature could accelerate the mass transfer, weaken the concentration polarization, and increase the deposition rate of the coating. With the extension of the deposition time, the electrodeposition control process of ZrB₂ coating changed from single electrochemical polarization control to the combination of electrochemical polarization and concentration polarization control. The preparation of ZrB₂ coating by molten salt electrodeposition showed a wide process window. By adjusting the electrodeposition process parameters, ZrB₂ coatings with different microstructures, preferred orientation, and thickness could be prepared on the surface of molybdenum.