Corrosion Properties of S-Phase/Cr2N Composite Coatings Deposited on Austenitic Stainless Steel.

Sebastian Fryska,Jolanta Baranowska

doi:10.3390/ma15010266

Sebastian Fryska, Jolanta Baranowska

Open Access

https://doi.org/10.3390/ma15010266

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Abstract

In order to study the suitability of the S-phase layers as the interlayer for Cr2N chromium nitride coatings, a number of composite coatings were deposited by the reactive magnetron sputtering (RMS) method on austenitic steel substrates with various initial surface conditions (as delivered and polished) and their corrosion resistance was assessed. Coatings with S-phase interlayer were deposited at three different nitrogen contents in the working atmosphere (15%, 30%, and 50%), which influenced the nitrogen concentration in the S-phase. Coatings with chromium, as a traditional interlayer to improve adhesion, and uncoated austenitic stainless steel were used as reference materials. Detailed microstructural and phase composition studies of the coatings were carried out by means of scanning electron microscopy (SEM), optical microscopy (LM), and X-ray diffraction (XRD) and were discussed in the context of results of corrosion tests carried out with the use of the potentiodynamic polarization method conducted in a 3% aqueous solution of sodium chloride (NaCl). The performed tests showed that the electrochemical potential of the S-phase/Cr2N composite coatings is similar to that of Cr/Cr2N coatings. It was also observed that the increase in the nitrogen content in the S-phase interlayer causes an increase in the polarization resistance of the S-phase/Cr2N composite coating. Moreover, with a higher nitrogen content in the S-phase interlayer, the polarization resistance of the S-phase/Cr2N coating is higher than for the Cr/Cr2N reference coating. All the produced composite coatings showed better corrosion properties in relation to the uncoated austenitic stainless steel.

Highlights

Hard ceramic coatings produced by physical vapour deposition (PVD) methods, including reactive magnetron sputtering (RMS) methods, such as chromium nitrides or titanium nitrides, are commonly used as protective coatings in cutting tools, injection molds, and injection nozzles for plastics, as well as for decorative coatings or electrodes in fuel cells [1,2,3,4,5,6,7,8,9,10]
Such a wide range of applications stems from their high hardness and wear resistance, as well as high corrosion resistance [11,12,13,14,15,16,17,18,19,20,21,22,23]
Many studies attempt to determine the influence of the initial state of the substrate and the parameters of the deposition process on the number and type of defects of the coating and its functional properties

Summary

Introduction

Hard ceramic coatings produced by physical vapour deposition (PVD) methods, including reactive magnetron sputtering (RMS) methods, such as chromium nitrides or titanium nitrides, are commonly used as protective coatings in cutting tools, injection molds, and injection nozzles for plastics, as well as for decorative coatings or electrodes in fuel cells [1,2,3,4,5,6,7,8,9,10]. Various types of interlayers and multilayer coatings have been proposed as methods of reducing the number of defects in coatings and increasing the material density, which reduces the penetration of corrosive agents through the coating [12,23,28,29,30,31,32,33]

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