Study on Diffusion Kinetics and Law of Chromium on the Surface of Low-Carbon Steel

Round 1

Reviewer 1 Report

1: The authors need to expand the introduction and use more modern references.  

2: Chemical composition of low carbon steel.

3: The authors need to determination of diffusion coefficient model.

4: The authors need to Calculation of activation energy.

Author Response

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Reviewer 2 Report

Please check the sentences undelined or added boxes, in order to improve the writing of the text. Please see the attached paper revised.

Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

Dear Editor,

In this manuscript authors investigated the diffusion of Cr in low alloyed steel.  For these purposes they employed experimental investigation and simulation analysis.

Generally, the topic addressed in the manuscript is interesting, however authors should considerably improve the introduction section of the paper. They should perform the better literature review and address the state of the art in the field by addressing specifically the Cr diffusion in steel, to better highlight the need for further investigation in the field. Experimental part has detailed information but it is not well organised it is hard to follow what has been done. Paper lacks a high quality discussion. Therefore discussion of the results should be significantly improved throughout the manuscript and performed with referring to other works and results from the field.  The English language in the paper is mostly all right but the writing should be improved, especially in the results and discussion section, so the paper should be more easier for readers to follow. The introduction of the results, especially the introduction of figures, should be improved and the results on the figures should be better explained.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

NA

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Dear authors,

by answering to my general remarks you improved the manuscript, however there are still a lot of parts to improve. In the previous step of the review I had a list of additional remarks on your manuscript but accidentally they were sent only to the Editor, and you did not get them, I`m sorry for that. I am sending you them again and you should answer to them.

Introduction section Sentence: It is very important to understand the macro and micro diffusion laws and mechanisms of chromium in the surface of low carbon steel for efficient preparation of Cr / low carbon steel surface composites. You should answer to the question why is this important.

Section 2.2. Sentence: ”The simulation model is assumed to be an ideal semi-infinite wide Cr / Fe diffusion couple model, and is thermally diffused in different crystal forms temperature range at atmospheric pressure. “ should be improved to convey the idea more clearly.

In Section 2.2. the grammar should be considerably improved. Try to stick to one tense…

Page 2 Section Experiment. Authors should specify the exact designation of steel that is used for the investigation presented in manuscript. The chemical composition of the steel is not enough.

In my opinion authors does not use adequately the word “drugs” and “medicine” throughout the manuscript.  Please exchange these with more appropriate words.

Section 3. Results –  The structure of the research papers in MDPI is defined in the instruction for authors. If authors have Results section it should be followed also by discussion section later on in the paper. Or, you should make Results and discussion section. So far the structure of the paper is like in this second case, so name it appropriately or change the structure of the paper.

Improve the introduction of the results, especially the introduction of figures, point out when you refer to experimental data and when to the simulated or calculated data.

In Figure 4 Give general explanation what is shown in Figure. Designate all the images by a, b, c, d, e, f and give explanation in figure caption what is shown in each image. I have doubts whether these images are really needed in the manuscript.

In Figure 5., in the images indicate the chromium layer, the steel and the diffusion layer. Remove (crop) the dark layers from these images.

In Figures 6., 10., 11. and 13. fonts have to be increased, they are too small.

Generally all figure captions should be contain more information what is presented on every image in the figure.

It is not completely clear in the paper, how can you directly correlate the diffusion results from the experiment with chromium/steel couple with the simulation of chromium diffusion in pure iron. This topic should be addressed in the experimental part and later in the Results and discussion section.

In paper it is not mentioned any characterization of a corrosion process, therefore it is not clear to what authors refer to, by the statement in 3.1.1. on page 6: “corrosion at the grain boundary is more serious”.

Section 3.1.2. sentence> “Figure 6 is the distribution curve of the percentage content of each element along the depth direction of the sample after high-temperature solid-state diffusion.” Grammar should be improved. And should be stated that the images show GDOES profiles of chemical composition…

The presentation of the results in the text authors should be more specific, especially where authors refer to their own diagrams. There are numerous places in the manuscript where authors refer to some figures and it is not clear whether the result on the figure is their own result or it is taken from the literature, or something in between. Therefore it is not easy to follow the paper, it is ambiguous. The examples for these case are the following sentences Figure 7 shows the variation of diffusion coefficient of chromium atoms with concentration at different temperatures; Figure 8 shows the law of the average diffusion coefficient of chromium atoms in the low carbon steel surface at different temperatures.; The molecular dynamics of z-axis data in Fe / Cr system are screened layer by layer, and the relationship between atom concentration and diffusion depth at different temperatures are shown in Figure 10. These and the similar sentences should be improved throughout the manuscript..

Considering that the Cr/steel interface is not sharp (Figure 5), authors should comment on the glow discharge spectrometry (GDOES) results presented in Figure 6 from that point of view. Because in these analysis of chemical composition through the depth of the material uneven or rough interfaces greatly affect the obtained results. The region on the curves from these uneven interfaces is averaged and therefore it does not resemble real situation.

Most of the discussion given in the paper (3.1.4.; 3.2.1) is based mostly on self-interpretation of the results. Authors should discuss the result from the point of view of other investigations from the field, and make a connection between their data and the data da that exist in the literature.  

Author Response

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