M. Metzner

Bio: M. Metzner is an academic researcher. The author has contributed to research in topics: Nitriding & Intergranular corrosion. The author has an hindex of 1, co-authored 1 publications receiving 3 citations.

Corrosion process in NaCl/Na2SO4 solutions of AISI 316L stainless steel treated by ionic nitriding

Abstract: This work is a corrosion study of an AISI 316L austenitic stainless steel after different plasma ion nitriding conditions. The properties of the coated AISI 316L were measured. The corrosion resistance was evaluated by cyclic voltammetry and salt spray testing. Sample surfaces were characterised by SEM and the phase determination with XRD analysis. Nanohardness was determined by using a Vickers indenter. The nitrided samples treated at 400°C, in a gaseous mixture of 5%N2 and 95%H2 for 4 and 5 h, had the best corrosion resistance. For the salt spray test, where the potential range is near the equilibrium potential, the nitrided material presented a reduced corrosion resistance. Through the control of the process parameters it is possible to improve the stainless steel surface hardness, combined with a good corrosion resistance. The highest value of temperature and N2 proportion increased the surface roughness and hardness, though it caused a decrease in corrosion resistance.

Effect of nitrogen plasma immersion ion implantation on the corrosion protection mechanisms of different stainless steels

Abstract: The influence of nitrogen plasma immersion ion implantation (N-PIII) on the corrosion mechanisms of austenitic, duplex, martensitic and ferritic stainless steels (SS) was evaluated through open circuit potential, cyclic voltammetry and electrochemical impedance spectroscopy. The nitrided SS exhibited high hardness (>1000 HV0.01) and high corrosion resistance, evidenced by transpassive potential increase and polarization resistance values on the order of 106 Ω cm2. Expanded phases developed a diffusion mechanism within the passive film of the austenitic and duplex SS, whereas iron nitrides provided a barrier against corrosion, inhibiting localized corrosion on the ferritic SS and inducing uniform corrosion on the martensitic SS.

Role of thickness on electrochemical behaviour of Ni2Si coatings in NaCl solution

Abstract: Ni2Si intermetallic coatings were deposited on a substrate of 420 stainless steel using a high velocity oxy-fuel (HVOF) process. The electrochemical corrosion behaviour of the coatings in 3.5% NaCl solution was investigated by means of Tafel polarisation tests and electrochemical impedance spectroscopy (EIS) measurements. Two coatings with different thicknesses, 55 and 115 μm, were investigated. The results showed that the corrosion rate of the thicker coating was lower than that of stainless steel by one order of magnitude. Local attack of the substrate was observed after the polarisation test of this coating, while the coating was still intact. The thinner coating and the stainless steel substrate showed similar corrosion rates. In this case, the substrate was severely attacked after the polarisation test. Two time constants were observed in the EIS spectra of both coatings which were related to charge transfer processes and pore resistance, respectively.