Sreeparna Ghosh and Mitra PK
The corrosion behaviors of two materials 316L Stainless Steel and 316LN Stainless Steel have been investigated for use as biomaterials. These samples were electrophoretically coated with Dicalcium phosphate dihydrate, and dip coated with polyvinyl alcohol. Time, current, concentration and voltage were the variables during electrophoresis. Dip coating was done for the same periods of time as was done during electrophoresis. Corrosion resistance properties were measured in Ringer’s solution by Gamry Potentiostat. The ICORR and ECORR values were estimated using Gamry Echem Software and Tafel’s extrapolation method. Coated samples were immersed in SBF solution for different periods of time, viz., 1 second, 24hours, 72hours and 1week and then further ICORR and ECORR values were estimated in Ringer’s solution. For coated samples Electrochemical Impedance Spectroscopy were also done. Different parameters like Rp, alpha, Wd of EIS were used to evaluate the effectiveness of the coatings. Comparison of corrosion resistance among the coated samples revealed a few interesting characteristics. While DCPD coated Stainless Steel showed considerable improvement in corrosion resistance compared to as received sample, dip coated samples did not show appreciable improvement. Coated 316L shows better corrosion resistance than 316LN. Dip coated 316LN shows better corrosion resistance than 316L. So Electrophoretic Deposition gave much better coating in comparison to Dip coating. Coated samples were further studied by The Scanning Electron Microscope and Energy Dispersive X-Ray Spectroscopy. While SEM was done to ascertain uniformity of coating, EDAX was done to see the variation of calcium deposition as a function of different deposition parameters. Electrophoretic deposition gave much better coating and uniform variation of calcium compared to dip coating.