Study on the Corrosion Characteristics of Grounding Materials in Acid Red Soil

Round 1

Reviewer 1 Report

Corrosion is defined as "degradation of a material, usually a metal, by chemical and electrochemical reactions with the environment." Corrosion monitoring aims to identify possible corrosion of surface and depth equipment and therefore the need to control corrosion or its efficiency.

In the article, the authors determined the electrochemical parameters for 4 types of specimens of different materials after being buried in redsoil for 10 months.

Some observations:
- far too few cited bibliographic references, especially in such a well-studied field
- in figure 1a it is different from 1b, c, d (the abscissa axis differs, the legend differs), it does not appear on the figure which is b, c or d
- corrosion analysis (Electrochemical parameters and Evans curves) should have been done at at least 3 temperatures, not only at 60 degrees Celsius
- in figure 4, at the SEM analysis, it should have been indicated where the crystallographic structures identified in figure 5 appear
- usually, for maintenance engineers, it is important that the corrosion rate (corrosion wieght loss rate) be expressed in mm / year so that it can be more easily quantified.

Unfortunately, the authors have limited themselves to analyzing 4 materials whose behavior in corrosion in environments such as that specified in the article is already known. It is normal for carbon steel to have a much higher corrosion rate than Zn-Al coating or copper.

Author Response

Dear editor and reviewer
Coatings

We are very pleased to hear from you. We carefully revised the manuscript based on the comments of editors and reviewers. The manuscript was revised in response to each point. All major changes are shown in blue  in the revised paper. 

Response to associate editor:

First of all, I am very grateful to associate editor for your valuable comments. The answers are as follows:

Response to Reviewer 1
We are very grateful to reviewer 1 for his hard review and value comments on our papers. Reply to those comments as follows:

- far too few cited bibliographic references, especially in such a well-studied field

Reply: Thank you for your comments. We have added some new references according to your suggestions, please see the revised manuscript.

- in figure 1a it is different from 1b, c, d (the abscissa axis differs, the legend differs), it does not appear on the figure which is b, c or d

Reply: Thank you for your comments. It was revised in the revised manuscript.

 
- corrosion analysis (Electrochemical parameters and Evans curves) should have been done at at least 3 temperatures, not only at 60 degrees Celsius

Reply: Thank you for your comments. We carry out accelerated corrosion experiments in the laboratory and set the temperature to 60 degrees to obtain better accelerated corrosion results. Therefore, we only selected this temperature in a corrosive environment, which can carry out the experimental research better, and did not select other temperatures for further experimental research.

- in figure 4, at the SEM analysis, it should have been indicated where the crystallographic structures identified in figure 5 appear

Reply: Thank you for your comments. We first performed SEM analysis on the sample, and then performed XRD analysis on the sample. Because there are two kinds of testing instruments, it is difficult to determine the XRD analysis position in the SEM with our instrument. It is confirmed that EDS analysis is feasible in SEM.

- usually, for maintenance engineers, it is important that the corrosion rate (corrosion wieght loss rate) be expressed in mm / year so that it can be more easily quantified.

Reply: Thank you for your good suggestions. Corrosion weight loss rate is also a standard method to express the degree of corrosion. We study corrosion in the future, and we will use mm / year to express it.

 Unfortunately, the authors have limited themselves to analyzing 4 materials whose behavior in corrosion in environments such as that specified in the article is already known. It is normal for carbon steel to have a much higher corrosion rate than Zn-Al coating or copper.

Reply: We have carried out researches on the corrosion resistance of a variety of grounding materials in the red soil environment, and selected four typical grounding materials for research. Carbon steel has low cost and is used in some low-demand environments. Galvanized steel, zinc-aluminum steel, and copper have high costs and are used in areas with high environmental requirements. Carry out their corrosion resistance research to provide reference for use in different environments.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,
thank you for your paper focused on corrosion characteristics of grounding materials in acid red soil. My comments are:
- introduction is very short, it must be extended and supplemented by other literature. There are many articles in the field of corrosion of steel, zinc, and alloys.
- chapter 2 - it would be appropriate to add a figure of the device (diagram),
- chapter 2 - how many samples were taken and examined? were there any series of samples? More information about the samples needs to be added - dimensions, numbers, material, etc.
- chapter 2 - what does "Galvanized steel" mean? Is it a zinc, nickel, copper coating? What material was used for the coating in this case? What was the coating thickness?
- chapter 2 - what was the thickness of the Zn-Al coating?
- chapter 2 - you write that the samples were in the red soil for 10 months - what were the conditions? Humidity? Temperature? Was it in the lab or in situ? Additional information is required.
- FIG. 1 - missing denotation b), c) and d) Which is b)? Upper right or lower left? Y-axis designation - "log i" is used, not "logi". The designation of the x-axis - the designation "21E" is used 3 times, only the "E" is used once - what is the difference? Isn't it the same? What does 21E mean?
- Tab. 1 - there is (g / dm2.a), what does "a" mean? Is it time in months, days, years?
- I recommend broadening the conclusions and putting them in the form of bullets.

I think that a paper in this form is not suitable for publication and needs to be improved.

Best regards.

Comments for author File: Comments.pdf

Author Response

Dear editor and reviewer
Coatings

We are very pleased to hear from you. We carefully revised the manuscript based on the comments of editors and reviewers. The manuscript was revised in response to each point. All major changes are shown in blue  in the revised paper. 

Response to associate editor:

First of all, I am very grateful to associate editor for your valuable comments. The answers are as follows:

Response to Reviewer 2

Comments and Suggestions for Authors

Dear Authors,
thank you for your paper focused on corrosion characteristics of grounding materials in acid red soil. My comments are:
- introduction is very short, it must be extended and supplemented by other literature. There are many articles in the field of corrosion of steel, zinc, and alloys.

Reply: Thank you for your comments. We have added relevant content and literature to the introduction of the revised manuscript.

- chapter 2 - it would be appropriate to add a figure of the device (diagram),

Reply: The device has been added in the revised manuscript.

- chapter 2 - how many samples were taken and examined? were there any series of samples? More information about the samples needs to be added - dimensions, numbers, material, etc.

Reply: Thank you for your comments. Chapter 2 was has been revised in the revised manuscript.

- chapter 2 - what does "Galvanized steel" mean? Is it a zinc, nickel, copper coating? What material was used for the coating in this case? What was the coating thickness?

Reply: Galvanized steel is coated with a layer of zinc on the surface of carbon steel by electroplating. The thickness varies according to the size and thickness of the plated parts, and the thickness is generally below 100 microns. The thickness of the galvanized steel we use is about 30 microns.

- chapter 2 - what was the thickness of the Zn-Al coating?

Reply: The thickness of the Zn-Al coating is the average of  100 microns

- chapter 2 - you write that the samples were in the red soil for 10 months - what were the conditions? Humidity? Temperature? Was it in the lab or in situ? Additional information is required.

Reply: Red soil is a soil widely distributed in southern China, where the summer temperature exceeds 30 degrees Celsius and the humidity exceeds 50, which is a typical acid soil environment.

- FIG. 1 - missing denotation b), c) and d) Which is b)? Upper right or lower left? Y-axis designation - "log i" is used, not "logi". The designation of the x-axis - the designation "21E" is used 3 times, only the "E" is used once - what is the difference? Isn't it the same? What does 21E mean?

Reply: Thank you for your comments. It was revised in the revised manuscript.

- Tab. 1 - there is (g / dm2.a), what does "a" mean? Is it time in months, days, years?
- I recommend broadening the conclusions and putting them in the form of bullets.

Reply: Thank you for your comments. Here is the abbreviation of "a" every year.  It was revised in the revised manuscript.

We carefully revised the manuscript based on the comments of editors and reviewers. The manuscript was revised in response to each point. It was significantly improved in the revised manuscript.

Author Response File: Author Response.docx

Reviewer 3 Report

Dear Authors, 

1. I suggest you provide the reactions corresponding to the different proposed corrosion mechanisms and stages. It might not be obvious to a reader why an insufficient supply of oxygen aggravates the corrosion of grounding materials, for example.
2. The language of the article should be improved considerably prior to publication.
3. Additionally, I advise you to take the SEM images of highly oxidized surfaces either in low vacuum or in backscattered electron mode, since the secondary electron mode results in white-washing of the pictures  (Figure 4a).
4. All subscriptions on the images should be made in one font and easily readable.
5. The phases in Figure 5 are indicated in a really convoluted and counter-intuitive way. Please indicate them in a more readily understandable fashion. 
6. Line 109: "It increased the service life of the grounding material. " Please provide the estimations for the increase in the service life, as well as estimations of the corrosion rate of the steel after the protective coatings have fully corroded. 
7. A more in-depth discussion of the experimental results is necessary. Provide comparisons with previously published data in the literature.   

Author Response

Dear editor and reviewer
Coatings

We are very pleased to hear from you. We carefully revised the manuscript based on the comments of editors and reviewers. The manuscript was revised in response to each point. All major changes are shown in blue  in the revised paper. 

Response to associate editor:

First of all, I am very grateful to associate editor for your valuable comments. The answers are as follows:

Response to Reviewer 3

Comments and Suggestions for Authors

Dear Authors, 

1. I suggest you provide the reactions corresponding to the different proposed corrosion mechanisms and stages. It might not be obvious to a reader why an insufficient supply of oxygen aggravates the corrosion of grounding materials, for example.

Reply: Thank you for your comments. Corrosion mechanism has been added to the revised manuscript.

2. The language of the article should be improved considerably prior to publication.

Reply: Thank you for your good suggestions. We have invited experts whose native language is English to help us review the manuscript.

3. Additionally, I advise you to take the SEM images of highly oxidized surfaces either in low vacuum or in backscattered electron mode, since the secondary electron mode results in white-washing of the pictures  (Figure 4a).

Reply: Thank you for your comments. Figure 4a has been replaced in the revised manuscript.

4. All subscriptions on the images should be made in one font and easily readable.

Reply: Thank you for your comments. It was revised in the revised manuscript.

5. The phases in Figure 5 are indicated in a really convoluted and counter-intuitive way. Please indicate them in a more readily understandable fashion. 

Reply: We use XRD equipment to analyze the sample, and the data obtained is shown in Figure 5. Different icons are used to distinguish the phases, which can distinguish the products after the sample is corroded.

6. Line 109: "It increased the service life of the grounding material. " Please provide the estimations for the increase in the service life, as well as estimations of the corrosion rate of the steel after the protective coatings have fully corroded. 

       Reply: Thank you for your comments. It was revised in the revised manuscript.

7. A more in-depth discussion of the experimental results is necessary. Provide comparisons with previously published data in the literature. 

Reply: Thank you for your comments. It was revised in the revised manuscript.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

No comment.

Reviewer 2 Report

Dear Authors,
thank you for improving your paper. Despite the fact that there is always something to improve the article, I have no further comments.

Best regards.

Reviewer 3 Report

The quality of the manuscript has improved. However, I still have some gripes with English. Please check it once again, at least in the abstract.