Corrosion behaviors of Cr-Al-N coatings deposited by reactive magnetron sputtering

摘要

CrN and Cr-Al-N coatings were deposited by reactive magnetron sputtering on the glass substrate,and their corrosion behavior was studied. The electrochemical tests using both DC(polarization curves) and AC techniques(EIS) were carried out on Potentiostat/Galvanstat(EG&G) in 3.5%(mass fraction) NaCl solution. After immersed into NaCl solution for 1 h,the mass of the CrN coating keeps constant with the time continuing. This can be explained by the passivation of the coating. The comparison between the corrosion potential(φcorr) of the Cr-Al-N coatings with different aluminum contents reveals that the corrosion potentials of the aluminum contain coatings are nobler than that of the CrN coatings. This means that the addition of aluminum shifts the corrosion potential to more positive potential value. Among these coatings,CrN in NaCl solution exhibits the worst corrosion resistance,while the corrosion resistance of Cr0.63Al0.37N in NaCl solution is the best. The polarization data and EIS data suggest that addition of aluminum can improve the corrosion resistance of CrN coating.