Surface treatments for components used in the gas and petroleum industry ? a XAS study.

FACUNDO CARLOS HERRERA; MIZRAHI, MARTIN; FELIX REQUEJO

Campinas

Congreso; LNLS 28th Annual Users? Meeting (RAU); 2018

LNLS CNPEM

In Gas and Petroleum Industry, the effect of premature damage of the metal components due to combination of the corrosion-abrasion phenomena causes substantial economic losses. One of the most common types of damages in the ferrous materials (pipes, encasings, pistons, etc.), occurs when micro fractures are generated by the extreme thermal and pressure conditions. In order to mitigate these damage mechanisms, we have begun to evaluate a series of surface treatments involving the generation of an interface between different materials. We focus on a combination of Plasma Nitriding (PN) and Physical Vapor Deposition(PVD). [1] The main advantage of these techniques is that they generate a gradual transition of hardness, governed by the diffusion mechanism of nitrogen in the base metal, resulting in a surface hard layer of the same material, reaching a hardness of 3000 HV. Although this type of treatment has great advantages with respect to the obtained, using the thermal spay technique, it has been observed that, under certain experimental conditions of nitriding, deterioration in the resistance to the corrosion is found. The decreasein resistance to the corrosion could be explained by an excessive formation of chromium nitride (CrN). The formation of this kind of nitrides is very sensitive to the temperature, time and atmosphere of the nitriding treatment, as well as to the type of steel used. For this reason, it is extremely important to obtain an estimation of the amount of the different nitrides presents. To check our hypothesis that the presences of chromium nitrides are responsible for the premature corrosion, we perform XANES and EXAFS measurements to be correlated with electrochemical characterizations (used to determine the corrosionresistance), with the different nitriding conditions and the steel used (AISI 316L and AISI 420). [2]REFERENCES:[1] Handbook of Vacuum Arc Science and Technology; R.L. Boxman, D.M. Sanders and P.J. Martin eds.,Noyes D.T., Park Ridge, New Jersey, 1995.[2] AISI 316L (Fe, 16-18% Cr, 10-14% Ni, 2-3% Mo,