Effect of Al Content on the Long-Term Corrosion Behavior of Arc-Sprayed ZnAl Alloy Coatings

Round 1

Reviewer 1 Report

My comments are stated below:

1- Please check the spelling for each word in the draft. I detected at least two words misspelled. 

2- Line 175, remove "obviously".

3- Any particular reason for choosing 0, 15 and 50% Al? why not 0, 25 and 50% Al? Any reference paper behind this selection?

4- In the FESEM images, please label the compounds or corrosion products. Example Figure 10. 

Some spelling mistakes were detected. Sending the draft to proofreading would be great. 

Author Response

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Reviewer 2 Report

In this work Zn-Al coatings deposited onto a steel substrate and corrosion processes were investigated. Various physical methods (SEM, XRD and electrochemical methods) have been used to characterize the materials. Authors showed that ZnAl50 compound demonstrated high corrosion protection capability in chloride containing solution. The article is well written and can be accepted after minor revision.

 

Please, enlarge the description of XRD method: 2theta range, 2theta step, time per step, etc. How the indexing of XRD patterns was performed? There are no references to PDF or some other databases.

Page 6. One can easily define if there is Al0.403Zn0.597 intermetallic compound. Its symmetry is P-1. So there should be lots of extra lines or at least huge peak broadering.

fig 2. 2theta range can be cut up to 30-90 degrees. There are no lines at 10-30 degrees.

Author Response

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Reviewer 3 Report

In the work, the deposition of coatings from the glory of ZnAl (with different aluminum content) was carried out using the plasma-arc method. Further, the authors carried out systematic studies of the effect of aluminum content on the structure and corrosion behavior of coatings.

The authors have shown that the corrosion rate of the ZnAl coating decreases as the Al content increases. At the same time, the content of aluminum impurity in alloy 50 turned out to be the most promising.

The authors showed that the long-term protective properties of the ZnAl50 coating are due to the powerful barrier effect and the self-healing effect of the stable and compact LDH corrosion product.

 

The work is good written. However, there are some minor remarks on the work.

1) In the introduction, it is necessary to single out modern works aimed at fundamental research of arc discharges in the process of coating.

A I Saifutdinov 2022 // Plasma Sources Sci. Technol. 31 094008DOI 10.1088/1361-6595/ac89a7

T. Zhu, M. Baeva, H. Testrich, T. Kewitz,· R. Foest.  Efect of a Spatially Fluctuating Heating of Particles in a Plasma Spray Process // Plasma Chemistry and Plasma Processing (2023) 43:1–24 https://doi.org/10.1007/s11090-022-10290-y

Here it is necessary to highlight the work: as well as from the list of references.

2) Another remark is the absence of the brand of the plasma torch used for coating.

3) In addition, the authors write that air was used as the working gas. At the same time, both zinc and aluminum tend to form oxides, which will eventually affect the final properties of the coatings. By the way, the authors write about this in paragraph 3.3. In this regard, the question arises, why did the authors use a palsmotron with air as a carrier gas? Perhaps it would be promising to use the carrier inert gas argon in an inert atmosphere, which would make it possible to exclude the formation of zinc oxides.

 

4) It is also known that in alloys of light metals, gas inclusions, in particular hydrogen (which is always present in atmospheric air) can form gaseous microporosity during crystallization (Campbell, Castings, Butterworth-Heinemann, Oxford (1991)). Was the formation of microporosity evaluated depending on the aluminum content?

 

After responding to these comments and finalizing the article, the work can be accepted for publication.

Author Response

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Reviewer 4 Report

The manuscript studies the effect of Al content on the long-term corrosion behavior of arc-sprayed ZnAl alloy coatings. The manuscript is not appropriate for publication in its current form:

1- The English language of the manuscript should be revised by a native speaker who is an expert in the field.

2- The introduction is confusing and I could not find the motivation of the work. The authors should first review the corrosion properties of the alloys with different surface treatments and explain the novelty of the work and the motivation for this study. Please cite the following references:

https://doi.org/10.1007/s40430-021-03148-5

https://doi.org/10.1016/j.elecom.2021.107169

https://doi.org/10.1016/j.jmrt.2022.11.111

3- I could not find a deep discussion about the role of Al and the mechnism of the effect. Please improve the disucssion section.

4- The overview of the corrosion products is not accurate. Please explain in detial the corrosion products with the composition and stoichiometry. 

5- If there is the effect of corrosion product on the corrosion rate, pelase clarify t he mechnism of that.

6- Conclusion is trivial and you need to add more detials about the corrosion products and the mechanism of change in corrosion rate.

 

 

The English language of the manuscript should be revised by a native speaker who is an expert in the field.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 4 Report

The answers to the comments and the corrections are satisfactory and therefore, I recommend publishing the manuscript.

A minor revision in style and English language is required.