Corrosion behavior of plasma nitrided SS316L biomaterial

Abstract

Objective: This research aims to determine corrosion behavior of SS316L biomaterial metals after plasma nitriding process. Methods: The plasma nitriding process on the surface of SS316L was performed at 350oC, 400oC, 450oC, 500oC, 550oC and 1.8 mbar nitrogen gas pressure for 3 hours. The surface Nitrogen concentration level distribution from the surface was examined using Energy Dispersive X-ray Spectroscopy, the phases formed after nitriding process were determined using X-ray Diffraction. The corrosion resistance was investigated using three-electrode cell polarization method. Result: The results showed that the percentage of nitrogen concentration atoms on the surface of the SS316L after plasma nitriding process was in range of 7.61-21.73%, in which the highest number 21.73% occurred at 500oC. Metal nitride formed on the surface of SS316L for all temperature variations are Fe4N, CrN and β-Cr2N phases were formed after nitriding process. Optimum corrosion resistance (8.21 × 10-4 mm/yr) occurs at 350oC.