In vitro corrosion resistance of plasma source ion nitrided austenitic stainless steels.
Plasma source ion nitriding has emerged as a low-temperature, low-pressure nitriding approach for low-energy implanting nitrogen ions and then diffusing them into steel and alloy. In this work, a single high nitrogen face-centered-cubic (f.c.c.) phase (gammaN) formed on the 1Cr18Ni9Ti and AISI 316L austenitic stainless steels with a high nitrogen concentration of about 32 at % was characterized using Auger electron spectroscopy, electron probe microanalysis, glancing angle X-ray diffraction, and transmission electron microscopy. The corrosion resistance of the gammaN-phase layer was studied by the electrochemical cyclic polarization measurement in Ringer's solutions buffered to pH from 3.5 to 7.2 at a temperature of 37 degrees C. No pitting corrosion in the Ringer's solutions with pH = 7.2 and 5.5 was detected for the gammaN-phase layers on the two stainless steels. The high pitting potential for the gammaN-phase layers is higher, about 500 and 600 mV, above that of the two original stainless steels, respectively, in the Ringer's solution with pH = 3.5. The corroded surface morphologies of the gammaN-phase layers observed by scanning electron microscopy are consistent with the results of the electrochemical polarization measurement.
Department of Materials Engineering, Dalian University of Technology, People's Republic of China. mklei@dlut.edu.cn
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D001672:Biocompatible Materials / Q000737:chemistry*; D003343:Corrosion; D004563:Electrochemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008422:Materials Testing; D008854:Microscopy, Electron; D009584:Nitrogen; D019736:Prostheses and Implants; D013193:Stainless Steel / Q000737:chemistry*; D013499:Surface Properties
D001672:Biocompatible Materials; D013193:Stainless Steel; D009584:Nitrogen