Mechanical and corrosion resistance properties of in-situ formed ZrN/ZrO2 composite coatings.

A novel ZrN/ZrO 2 corrosion-resistant composite coating was fabricated by radiofrequency (RF) magnetron sputtering method. The effects of sputtering power and deposition temperature on the microstructure, mechanical property and corrosion resistance of ZrN/ZrO 2 composite coatings were examined through X-ray diffraction, scanning electron microscopy, nanoindentation and electrochemical impedance spectroscopy. The results indicate that the crystallinity of the ZrN/ZrO 2 composite coating increases with the increase of sputtering power and deposition temperature, becoming smoother and denser and behaving a better mechanical property. Moreover, the corrosion resistance of the coating has been significantly increased under the deposition parameters of a sputtering power of 300 W and a deposition temperature of 300 °C. The electrochemical corrosion test reveals a corrosion rate for the coating of 1.39 × 10−4 mm/yr, which is 5.5 times lower than that of the 316L substrate, and a charge transfer resistance of 4.37 × 106 Ω cm2, which is 11.5 times higher than that of the 316L substrate. The effects of phase structure, crystallinity, coating defects, and residual stress on the mechanical properties and electrochemical corrosion resistance were discussed in details. Our study provides a new insight into produce corrosion-resistant coatings for structural materials used in fusion reactor tritium breeding blanket, where the corrosion of lithium compound still be a thorny issue. [ABSTRACT FROM AUTHOR]