탈기된 3.5 wt.NaCl 용액 환경에서의 스테인리스 강에 증착된 CrN 박막의 Si 첨가에 따른 영향 평가

Abstract

CrSiN coatings of stepwise changing Si concentration were deposited on stainless steel by closed field unbalanced magnetron sputtering (CFUBM) system. Microstructure of the films due to the Si concentration is measured by XRD. The corrosion behavior of CrSiN coatings in deaerated 3.5% NaCl solution was investigated by potentiodynamic test, electrochemical impedance spectroscopy (EIS) and surface analyses. The microstructure of CrSiN film depends on the Si concentration. When Si/(Cr+Si) was under 11.7%, preferred orientation is defined at CrN(220), CrN(311) and Cr2N(111). The results of potentiodynamic polarization tests showed that the corrosion current density and porosity decreased with increasing Si/(Cr+Si) ratio. EIS measurements showed that the corrosion resistance of Si-bearing CrN was improved by phase transformation of the film, which leads to increase of pore resistance and charge transfer resistance. At the Si/(Cr+Si) ratio of 20, the Si-bearing CrN possesses the best corrosion resistance due to the highest pore resistance and charge transfer resistance.