Thermal stability and electrochemical properties of CrZr–Si–N films synthesized by closed field unbalanced magnetron sputtering

In this work, CrZr–Si–N films with various Si contents from 0 to 23.5 at.% were synthesized by closed field unbalanced magnetron sputtering with vertical magnetron sources. The characteristics such as crystalline structure, surface morphology, and hardness of the films as a function of the Si content were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), and microhardness tester. The thermal stability of the films as a function of the Si content was evaluated by annealing the films at temperatures between 300 and 800 °C for 30 min in air. In addition, their corrosion behaviors in a deaerated 3.5 wt.% NaCl solution at 40 °C were investigated by potentiodynamic polarization tests.From the annealing test results, it was found that the addition of the Si into the CrZrN film improved its thermal stability. While the Cr37.7Zr12.0N50.3 film without any Si content oxidized completely at 600 °C and its hardness decreased significantly from approximately 32 to 6 GPa after annealing. The Cr19.7Z7.5–Si23.5–N49.2 film maintained its hardness of approximately 25 GPa even after annealing at up to 800 °C. In addition, the potentiodynamic test results showed the corrosion resistance of the CrZr–Si–N films was significantly better than the CrZrN films and their corrosion current density (icorr), corrosion potentials (Ecorr) and corrosion rate decreased with increasing Si content.