Improving corrosion resistance of 3D printed Ti-6Al-4V by TiN coating

Abstract

TiN thin films were deposited on biomaterial 3D printed Ti-6Al-4V substrates using two methods including direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). The coating times were compared between 5 min and 25 min. HiPIMS was developed based on DCMS by increasing degree of ionization in plasma and power densities in the order of kWcm-2 compared to Wcm-2 of DCMS. The film characteristics and mechanical properties were investigated by glancing incident x-ray diffractometer (GIXRD), field emission scanning electron microscope (FE-SEM), and atomic force microscope (AFM). Electrochemical behavior was analyzed by electrochemical impedance spectroscopy (EIS) in 1 M NaCl solution. The results showed that TiN films deposited by HiPIMS exhibited an equiaxed structure while those from DCMS had a columnar structure. As a consequence, corrosion resistance of HiPIMS films was better than the DCMS films. Furthermore, increasing coating time resulted in thicker TiN layer and therefore, promoted higher corrosion resistance.