Corrosion protection of steels by PVD TaN thin films

Abstract

Purpose

To investigate the protective properties of tantalum nitride (TaN) thin films deposited on to various steels immersed in a 3 per cent NaCl solution.

Design/methodology/approach

TaN thin films with a thickness of 250 nm were deposited on UNS G10180, UNS S30400 and UNS T11302 steels by means of magnetron sputtering technique. The electrochemical behaviour has been studied in 3 per cent NaCl solution using electrochemical impedance spectroscopy and potentiodynamic polarization. The crystalline structure of the films was investigated by X‐ray diffraction. Surface analysis of the corroded samples was performed using scanning electron microscopy and light optical microscopy. The electrochemical impedance spectra were analysed in the context of equivalent circuit models (ECs).

Findings

The ECs incorporate a charge transfer process representing the TaN film on UNS G10180 steel, two time constants for that deposited on UNS T11302 and diffusion behaviour for the TaN film on UNS S30400 steel. TaN films demonstrate their protection properties, which were evidenced by increase of the electrochemical properties compared with the substrate. The major corrosion damage of coatings is caused by defects, pores, droplets and pinholes that allow the electrolyte penetration through the films.

Practical implications

Corrosion protections of steels by TaN thin films.

Originality/value

The information related to corrosion behaviour of TaN films in a chloride solution is poor. This paper presents not only a completely electrochemical characterization, but also the surface analysis of the corroded samples.

Citation

Flores, J.F., Valdez S., B., Schorr, M. and Olaya, J.J. (2006), "Corrosion protection of steels by PVD TaN thin films", Anti-Corrosion Methods and Materials, Vol. 53 No. 2, pp. 88-94. https://doi.org/10.1108/00035590610650785