Study of the Passivation Film on S32750 Super-Duplex Stainless Steel Exposed in a Simulated Marine Atmosphere

Round 1

Reviewer 1 Report

The reviewed manuscript entitled “Electrochemical and XPS Studies of Passivation Film on S32750 Super Duplex Stainless Steel Exposed in a Simulated Marine Atmosphere” investigates the electrochemical behavior of S32750 super DSS exposed in a cyclic corrosion salt spray chamber after different periods. The article is made at a good scientific and technical level, and its practical significance is beyond doubt. In order to improve the readability and clarity of the manuscript, some major concerns need to be addressed before the paper is to be accepted for publishing:

1-     The abstract requires some quantitative brief results. Since the abstract is a mini version of manuscript that proceeds. So, include introduction, methodology, results and concluding remarks in a precise but effective manner.

2-     Abstract: “…..were studied using electrochemical methods, such as XPS and SEM.” That’s wrong sentence. XPS and SEM are characterization techniques, while the electrochemical methods used in the current study are potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Please correct.

3-     Try to avoid lumped references in the introduction; a short comment should be included for each reference or two references in the same subject.

4-   The motivation for the study and the research gap are not clear enough. Please demonstrate in the introduction of the paper, the novelty of this research in relation to other thematically similar research papers. The introduction needs to be improved. The authors should indicate clearly what the available literature have learned from other studies, and the limitations of other studies. Besides, innovation of the manuscript needs to be clarified to improve the necessity of the work. The recent research works need to be mentioned, such as (Not limited): 10.3390/met10111481, 10.3390/ma14195532, 10.3390/cryst11091025, 10.1016/j.corsci.2012.11.024, 10.3390/met11081206, 10.3389/fmats.2020.00251, 10.1002/maco.201408185 … etc.

5-     L86: Please mention the percentage of each phase (Ferrite/Austenite) available in the S32750 microstructure.

6-     L117-118: “The corrosion products were analysed using EDS, XRD and XPS.” Unfortunately, XRD and EDS are missing. Please add both analysis.

7-     Figures 2, 4 & 9: Please use the same color sequence for each sample in the three graphs.

8-     Figure 4: In Nyquist plots, the scale of X and Y axis (Z’ and Z’’) must be by the same scale (300 in the current case).

9-     L136: “obtained using the Tafel extrapolation method.” Please include in the results section the calculated Tafel parameters.

10- Figure 11: In order to compare the surface morphology of each sample after corrosion, all SEM images must be captured using the same kV. Since the working volt is the main parameter for studying the surface topography, it should be constant during imaging.

11- Discussion is lack of scientific explanation for the obtained results. Authors should attribute the results achieved to a clear scientific reason.

12- The English language used in the paper is to be revised and improved before the subsequent manuscript submission. Please, read the text carefully before the next submission of the paper.

Author Response

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Reviewer 2 Report

The title is suitable for the manuscript reflecting the content and the journal is well selected .The abstract is informative 

As  manuscript merits it is to noticed that is  relatively well written but not well organized having  11 figures and no tables The summary is informative . But the paper has demerits  and it mandatory  to be changed before publication : 

a)       The majority of references are older  than five years or even 10 years and only 4 of them being really new ;

b)      The paper has not statistical analysis of the data  

c) The paper research design could be completed with XRD composition of the coatings 

d) There are not quantified data in tables about electrochemical procedures and presence of polarization resistance, current density, corrosion potential will be an improvement of data treatment permitting the evalution  of coating efficiency as well. All such data are going to be in the benefit of discussion which now is week and will sustain better the conclusion 

e)  the SEM has not arrows to indicate phases and dimensions 

Author Response

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Reviewer 3 Report

Although the proposed manuscript is interesting, there are enough weaknesses that need to be improved. This based on the following:

·        The title is confusing, because the authors mention the characterization techniques of what they want to study, the correct thing would be: Study of the passivation film on S32750 super duplex stainless steel exposed in a simulated marine atmosphere

·        Line 11-17: I consider that the abstract should be reviewed again because it is very general and the objective is not clear.

·        The scope of the study is not well defined, the authors could better express it in the abstract

·        In the keywords should not be acronyms

·        Line 20-79: Authors should enrich the introduction section

·        Authors must include the objective of the study, in a paragraph at the end of the introduction.

·        Table 1. It is necessary to indicate by which technique the chemical composition of the stainless steel was obtained. In addition, it must integrate the maximum and minimum of the chemical elements of the chemical composition.

·        The authors must indicate the metallographic preparation of the stainless steel. Figure 1. The microstructure was obtained by optical or electronic scanning microscopy, in addition to indicating the magnification.

·        Line 89: If the authors selected the NSS test, they must indicate the ISO 9227 standard.

·        In section 2.2 the authors should order their ideas, starting first with the type of specimens, then with the passivation treatment and then the exposure equipment. They must also justify the exposure times.

·        Line 107: potentiodynamic polarization (PP)

·        Line 107/108:  ….the potential range was… the correct thing is: the polarization range of the potential was….

·        Line 108: ………from −0.1 VSCE (vs. OCP) to +1.8 VSCE (vs. OCP). the correct thing is: ………from −0.1 to +1.8 VSCE (vs. OCP)-

·        In section 2.3 the authors must justify why they use these two electrochemical techniques.

·        Section 2.4 should be characterization of the passivation film.

·        All acronyms must be defined: such as SEM, XPS, EDS,  etc.

·        Line 128. ……All curves exhibited passivation zones. The authors must make a correction, there are areas with pseudopassivation

·        A table of results must be included where the values of the Potential, current density, corrosion rate, etc, etc.

·        Line 135-147: Values must be included in the paragraphs

·        Line: 150: Section 3.2.1 should be Electrochemical Impedance Spectroscopy

·        The authors must include the two Bode plots and in the Nyquist plot their axes must be squared, for example from 0 to 300 in imaginary Z and from 0 to 300 in real Z. also to include the frequencies. The fitting must be included in the Nyquist diagram.

·        A table of results of the impedance data obtained must be included.

·        Line 177-189: Values must be included in the paragraphs

·        The equivalent circuits of figure 5 must include the parameters such as resistances. The circuit of item (B) does not correspond.

·        Figure 7: XPS results should be checked again, settings are not clear, values need to be indicated.

·        Section 3.3 Surface appearances is incorrect, it should be section 3.3 Surface morphologies.

·        Cross-sectional analysis of passivated samples by SEM is not presented. Only superficial analysis is presented after the exposure time.

·        Figure 11: Surface morphologies were obtained by SEM using secondary electrons (SE) or Backscattered Electron (BE)

·        It is necessary that all SEM images mention the magnifications.

·        The authors should include a better discussion of results, because they are only described but there is no discussion.

·        It is recommended that the authors review the conclusions

·        Authors must review the entire manuscript because the line spacing changes, review the journal template

·        The authors present 35 references.  There is no self-plagiarism. The authors must correct the references (see journal format), the name of the journals is abbreviated, the name of the authors begins with the last name and check the punctuation, the year does not go in parentheses. The authors must also include more recent articles from 2020,2021 and 2022

Author Response

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Round 2

Reviewer 1 Report

The revision is satisfactory and the authors have provided amendments to all suggested queries. Therefore, I recommend this work for publication in Coatings

Author Response

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Reviewer 2 Report

The revision manuscript is an improved version .Now is a need only for minor revision taking into account the following : 

1. Without a complex statistical analysis in my opinion ant analysis has to introduced some statistical information
2. Some dimensions despite the fact that now are in the text will be better to be introduced in figures

Author Response

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Reviewer 3 Report

The authors made most of the suggestions in the manuscript, the work can be accepted after correcting some errors and integrating the new suggestions.

In SEM micrographs, the scale placed on the image and the magnification are not the same, the authors must indicate at what magnification the micrographs are being taken. for example 1000x or 5000x?

in table 1, it says “smple” and must be sample.

In figure 4. equivalent circuit, all elements must be defined and not only “Q”

Figure 1 and 9 are microstructures obtained by SEM? The foot of the figure should start like this. for example Figure 1. SEM-SE microstructure........

In section 2.4 it should be indicated which detector was used in the SEM, it was secondary electrons (SE) or Backscattered Electron (BE)

References must be placed according to what is indicated in the journal. the authors start with the last name, the journals are placed abbreviated etc etc

The authors should enrich the discussion section, they only integrated several reactions but did not explain why they are used or if they explain the corrosion mechanism.

The authors must indicate in the references the ASTM standard of chemical composition and that of saline chamber

Author Response

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Round 3

Reviewer 3 Report

The authors made most of the suggestions in the manuscript, The authors should enrich the discussion, they only integrated chemical reactions. In Table 1. You must put "Exposure time (d)" The references must be in accordance with what the journal indicates, for example the journals are placed abbreviated and in italics, the year of publication does not have parentheses. 1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.

Author Response

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