Characterization of the low alloy steel modified superficially with ions of titanium and nitrogen

Abstract

T he three-Dimensional Ion Implantation technique (3DII) causes ions to collide with a solid surface in a perpendicular way regardless of the geometry of the solid (Khvesyuk & Tsygankov, 1997;Dougar-Jabon, Dulce-Moreno & Tsygankov, 2002). The steel AISI SAE 4140 has been used as substrate because of its wide use in the transport of oil industry, the specimens of steel underwent surface modification with Titanium ions (Ti) and the combined ions of titanium and nitrogen (Ti+N), with energy of 10keV for 5min and 10min. The superficially modified and unmodified specimens were characterized by Electrochemical Impedance Spectroscopy (EIS), noting among the most outstanding results the electrochemical double layer system capacitive characteristics under all tested conditions, the best corrosion performance was obtained for implanted substrates with Ti ions for 10min, having a charge transfer resistance much higher than those implanted with Ti+N and the non-implanted. Additionally it was determined that all the implanted systems can be simulated by using one equivalent circuit with a constant phase element instead of a capacitor and the non implanted substrate from day 15 can be simulated through another equivalent circuit. ABSTRACT CARACTERIZACIÓN DEL ACERO DE BAJA ALEACIÓN MODIFICADO SUPERFICIALMENTE CON IONES DE TITANIO Y NITRÓGENO CARACTERIZAÇÃO DO AÇO DE BAIXA LIGA ALTERADO SUPERFICIALMENTE COM IONES DE TITÂNIO E NITROGÊNIO 136L a técnica de implantación iónica tridimensional (3DII) consigue que los iones a implantar colisionen perpendicularmente con la superficie sin importar la geometría del sólido (Khvesyuk & Tsygankov, 1997;Dougar-Jabon et al., 2002). Se ha usado un acero de herramientas AISI SAE 4140 como sustrato por su amplio uso en la industria del transporte de hidrocarburos. Las probetas de acero se sometieron a la modificación superficial con iones Titanio (Ti) y Titanio+Nitrógeno (Ti+N) a energía de 10keV durante 5min y 10min. Los sustratos modificados y no modificados superficialmente fueron caracterizados mediante la técnica de espectroscopia de impedancia electroquímica (EIS), observando entre los resultados más resaltantes que la doble capa electroquímica del sistema en estudio presenta características capacitivas en todas las condiciones evaluadas, donde el mejor desempeño frente a la corrosión lo presentan los sustratos implantados con iones de Ti durante 10min, debido a que poseen una resistencia a la transferencia de carga mucho mayor que los implantados con iones de Ti+N y los no implantados. Adicionalmente se determinó que todos los sistemas implantados pueden ser simulados mediante el uso de un circuito equivalente, el cual posee un elemento de fase constante en lugar de un capacitor y que el sustrato sin implantar a partir del día de inmersión 15 se puede simular a través de otro circuito equivalente diferente.A técnica de implantação iônica tridimensional (3DII) consegue que os iones a serem implantados colidam perpendicularmente com a superfície sem importar a geometria do sólido (Khvesy...

Electrochemical Behavior of a Stainless Steel Superficially Modified with Nitrogen by Three-dimensional Ion Implantation

“…This particular case is physically interpreted by means of a Randle circuit (order I) (Figure 6a), which compromises the following: the resistance offered by the solution, a capacitance that represents the interface electrolyte-substrate, and the charge transference resistance representing the base material. The identical behavior may be attributed to the fact that, at relatively short periods of implantation time, the layer deposited upon the surface of the substrates will not be as stable as those implanted with higher doses or for longer periods, thus offering little protection against electrochemical corrosion (Valbuena-Niño et al, 2016;.…”