Study of Corrosion Behavior and In Vitro Bioactivity of Single NbSi2and Duplex NbSi2/Nb5Si3Coatings on Nb Substrates for Biomedical Applications

Single NbSi(2)and duplex NbSi2/Nb(5)Si(3)coatings were successfully applied on Nb substrates using halide activated pack cementation (HAPC) method at 1100 and 1300 degrees C, respectively. Duplex NbSi2/Nb(5)Si(3)coating with Nb(5)Si(3)inner barrier layer, higher thickness, and lesser micro-cracks considerably decreased the infiltration of simulated body fluid (SBF) solution. This deduction was pertained to the high corrosion potential and lowest corrosion current density for the NbSi2/Nb(5)Si(3)coated Nb alloy in corrosive solution. The Nb(5)Si(3)inner barrier layer can protect the Nb substrate from corrosive solution when it passes through from NbSi(2)top layer. Moreover, higher charge transfer resistance (R-ct), impedance modulus at a low-frequency (vertical bar Z vertical bar) and phase angle were also observed for the duplex NbSi2/Nb(5)Si(3)coated Nb alloy. On the other hand, in vitro bioactivity test indicated higher capability of apatite formation on the silicide coatings compared to uncoated Nb substrate in SBF solution. In fact, modification of chemical composition and surface morphology of Nb substrate surface can provide suitable nucleation sites for apatite formation and growth in SBF solution.