Pitting Corrosion of TiN Coated Dental Cast Alloy with Casting Methods

In order to investigate the pitting corrosion of TiN coated dental cast alloy with casting methods, three casting alloys(A:63Co-27Cr-5.5Mo, B:63Ni-16Cr, C:63Co-30Cr-5Mo) were prepared for fabricating partial denture frameworks with various casting methods. The casting morphologies were analyzed using field emission scanning electron microscopy(FE-SEM), energy dispersive X-ray spectroscopy(EDS), and optical microscopy(OM). TiN coatings were carried out by using RF-sputtering. The pitting corrosion properties of the samples were examined through electrochemical method in 0.9% NaCl solutions at 36.5 degrees C. The casting defects of alloy decreased in the order of centrifugal casting, high frequency induction casting, and vacuum pressure casting. In the case of 63Co-27Cr-5.5Mo and 63Co-30Cr-5Mo alloy, alpha-Co and epsilon-Co were appeared at matrix and gamma'-Ni2Cr second phase showed in 63 Ni-16Cr alloy. the corrosion potential and pitting potential of the TiN coated alloy are comparatively higher than that of non coated alloys. Especially, pitting potential and surface stability with casting methods incresed in the order of vacuum pressure casting, high frequency induction casting, and centrifugal casting method.