Corrosion Resistance of Multilayer Coatings Deposited by PVD on Inconel 718 Using Electrochemical Impedance Spectroscopy Technique

Coatings ID 789013- MDPI

Corrosion Resistance of Multilayer Coatings Deposited by PVD on Inconel 718 Using Electrochemical Impedance Spectroscopy Technique

C. Gaona-Tiburcio¹, M. Montoya-Rangel¹, J. A. Cabral-M¹, F. Estupiñan L¹. P. Zambrano-R¹, R. Orozco C², J. G. Chacón-Nava³, M.A. Baltazar Z⁴, F. Almeraya-Calderón^1*

Reviewer 1

Referee Commentaries

Correction attended

please add some new references in the Introduction section about new insights in the field of PVD coatings (as for instance, doi: 10.1016/j.surfcoat.2020.125659; 10.3390/coatings10030281; 10.3390/coatings9010007; 10.1007/s12034-020-2069-9);

Attended:

New references added in the introduction (including those suggested by the reviewer). Are marked using red colour letters.

There are some mistakes in the 2.2 paragraph (PVD coatings deposition), since either the target temperature or the process time are not specified. So, please revise the entire paragraph;

Attended:

The paragraph was amended and the changes indicated were made in the revised manuscript  and are marked using  red colour letters

Please specify the acronyms the first time you use them. For example, in line 124;

Attended: root mean square, rms

please provide new Figures with higher resolutions for the EDX maps of all the investigated samples; alongside with a new Figure 1b showing a higher image quality;

Attended:

All suggested changes were made in the paper (the SEM images were changed with higher quality).

please revise the units within the all manuscript (for example in lines 146);

Attended:

Units were corrected (for example lines 146:  µ was changed µm)

In line 123 it has been reported a concentration of NaCl of 5 %wt, whereas in other parts of the manuscript 3.5 %wt. Which is the correct value?

Attended:

The correct value is 3.5 wt.% NaCl solution.

in Figures 2 and 3, it would be better reporting the fitting values as line, rather than symbols in order to make the reading easier;

Attended:

The fitting values as line in the Nyquist diagrams have already been corrected

the caption of Figure 4 is incomplete, (b) circuit is not described;

Attended:

Be annexed (b) in caption of figure 4.

please revise the equations in lines 198-199;

Attended:

If the equation is correct: the constant phase element (CPE).

https://doi.org/10.1016/S0022-0728(98)00115-6

·         : https://doi.org/10.1007/s10008-013-2262-5

·         https://doi:10.1016/j.bioelechem.2008.01.004

Book. Baboian R. Corrosion Tests and Standards. 2^nd edtition. Chapter 7- Electrochemical Test. P 114

Please revise the digits in both Table 2 and Table 3. Furthermore, in the text, data should not be reported with the scientific mode (as 1.03E04 in line 235);

Attended:

The digits in both Table 2 and Table 3 were corrected and in the text.

the conclusions should be more specific and clearer, please revise them;

Attended:

All suggested changes were made in the paper.

Within the whole manuscript, lots of mistakes are present. Therefore, the paper should be entirely revised, in particular focusing on the text formatting, punctuation and English language. For example: lines 76, 86-89, 97, 120, 185, 207, 210, 216, 257 and so on.

Moreover, it would be better to write the chemical elements completely rather than using the chemical formula (as in line 80, N and Cl-).

Attended:

All indications throughout the manuscript were reviewed.

They were written  the chemical elements completely

Coatings ID 789013- MDPI

Corrosion Resistance of Multilayer Coatings Deposited by PVD on Inconel 718 Using Electrochemical Impedance Spectroscopy Technique

C. Gaona-Tiburcio¹, M. Montoya-Rangel¹, J. A. Cabral-M¹, F. Estupiñan L¹. P. Zambrano-R¹, R. Orozco C², J. G. Chacón-Nava³, M.A. Baltazar Z⁴, F. Almeraya-Calderón^1*

Reviewer 2

Referee Commentaries

Correction attended

Introduction

·         It is written well, perhaps only the following reference is missing: Electrochemical impedance spectroscopy investigation of alloy inconel 718 in molten salts at high temperature; JL Trinstancho-Reyes, M Sanchez-Carrillo… - Int. J. Electrochem. Sci, 2011.

·         Line 39:  "Coatings have been applied since the 50's as a method of surface protection that does not have enough intrinsic resistance to corrosion at high temperatures [1]."

·         Something is missing in this sentence.

·         Line 76: providea ⇒ “provide”

·         Line 77: system., ⇒ “system.”

Attended:

All changes indicated (line: 39, 76, 77) were made in the revised manuscript  and are marked using  blue colour letters-.

New references added in the introduction

Experimental

·         What was the accelerating voltage by EDS-analysis?

·         Line 105: What kind of unit is “sccm”

·         Line 106: E-4 ⇒ 10-4

·         Line 107: “temperature XX C”. What is the meaning of this?

·         Line 115: Energy dispersive X-ray ⇒ “Energy dispersive X-ray Spectroscopy”

Attended:

All changes indicated (line: 106, 107, 115) were made in the revised manuscript  and are marked using  blue colour letters

Results

·         Fig. 1: Both electron micrographs and EDS-spectra should be improved

·         Line 138: SEM imagens ⇒ “SEM micrographs”

·         Line 146: one micrometer μm not just μ.

·         Figure 2: It is difficult to see the exact shapes of the curves. It would be better if "fitted" was a continuous line. Indicate semicircles.

·         Line 257: the lowest lower

Attended:

All changes indicated (fig 1, line 138, fig 2, line 257)  were made in the revised manuscript  and are marked using  blue colour letters.

Units were corrected (for example lines 146:  µ was changed µm)

The fitting values as line in the Nyquist diagrams have already been corrected

Conclusions

·         Lines 263−266: “The PVD AlCrN/TiSiN and AlCrN/TiCrSiN coatings did not present a homogeneous and compact bonding with the bottom layer and substrate, it could have been due that atoms of the top layer did not diffuse into the bottom layer and substrate, respectively.”

·         Please provide better SEM-images for the evidence.

Attended:

All suggested changes were made in the paper.

the SEM images were changed with higher quality