LAUSR

Abstract Superhard CrB2 coatings with hardness around 45.7 ± 1.6 GPa were deposited on cemented carbide substrates via a direct current magnetron sputtering at the deposition temperature of 300 °C. The composition, microstructure and corrosion resistance of the deposited coatings were investigated. The results revealed that the deposited CrB2 coating had a preferred (0 0 1) orientation and dense nanocolumnar structure. The great improvement in corrosion resistance of CrB2 coated substrate was obviously observed from potentiodynamic polarization and electrochemical impedance spectroscopy. The formation of Cr2O3 was supposed to be the key factor for the obvious passivation phenomenon. Consequently, the corrosion current density was reduced by 100-fold in combination with a higher polarization resistance compared with the pristine substrate.