Modeling the Interfacial Bonding Strength of Al-Zn-Si Alloy between Substrates with Linear Surface Roughness and Its Coating

Round 1

Reviewer 1 Report

In this work, the effects of substrate roughness on the interfacial bonding strength of Al-Zn-Si alloy are mathematically modeled. The surface roughness of the substrate is modeled by different contour curves.

1- The innovation and scientific gap in the literature should be clearly explained for the present research.

2- The presented figures have low quality. The quality of the figures should be improved. Also, the drawn curves in some figures are not clear, such as Figures 7 and 8. To better recognize the curves, use various colors. If figures are related to a specific report, please cite the reference.

3- The results presented in the article are few and predictable. Few scientific interpretations are presented in the article. Scientific interpretations should be added to the research.

4- The application of the results of the present research in the real industry field should be further explained.

5- The presented results are stated without acceptable validation with theoretical or experimental results and are not reliable.

6- The literature review in the introduction section is not comprehensive. It is recommended that the following articles be explained in detail:

DOI: 10.3390/coatings13020397. DOI: 10.1016/j.corsci.2023.111015. DOI: 10.1016/j.carbpol.2021.118871. DOI: 10.1016/j.cclet.2020.10.043. DOI: 10.1016/j.cclet.2021.10.007

7- The English written language of the article should be improved.

8- The defects and advantages of the utilized method should be stated especially in comparison with rough surfaces in real industry.

9- The conclusion part of the present manuscript is very incompletely explained. The conclusion section should be completely revised. Please explain briefly about the report, and afterward, describe important results.

The English written language of the article should be improved.

Author Response

We gratefully appreciate for your valuable suggestions, and the responses as follows:

1. According to the recommends, we added the innovation and scientific gap in Introduction part to further explained.
2. We have improved the quality of presented figures as much as possible. To better recognize the curves, all the Figures were modified.
3. The results of this manuscript were displayed in Experimental verification to verify the results of the established models. We added the scientific interpretations in this part.
4. The application of the results of the present research in the real industry field was explained in the results part.
5. The experiment results were used to verify the accuracy of the established modeling.
6. According to the recommends, we added the literature review in the introduction section related to bonding strength of coatings in this manuscript to review the current research achievements comprehensively.
7. We have improved the grammar, expression and spelling of the manuscript as much as possible.
8. The defects and advantages of the utilized method need to be investigated, and to improve the application in real industry.
9. We revised this manuscript according to the comments. The conclusion part have been completely revised to explain briefly about the report.

Reviewer 2 Report

It has already been shown in experimental results that the coating on the part of the characteristic parameters is closely related to the properties and surface roughness of the substrate. The size of the peak and valley of the micro surface used to evaluate the roughness and its composition unit width is one of the important factors influencing the interfacial bond strength. The authors report that under the same condition of coating, component materials, and the coating thickness, the coating strength of the substrate was changed along with the substrate roughness. Moreover, the adhesion between the coating and the substrate is not always increased with the higher roughness on the same surface. They argue that based on the surface roughness and its evaluation parameters, there is an optimal roughness evaluation and selection range. They aim at verifying the mathematical model which is based on linear substrate surface micro-contour.

Although according to what the authors themselves admit the universality of the mathematical model needs to be further improved, and the coating system roughness selection range needs further theoretical and experimental research. However, this research work is sufficiently informative and admirable. I propose this work in its present form for acceptance.

Please check the text for some typos and grammatical errors.

Author Response

We gratefully appreciate for your valuable suggestions and comments. We will improve the universality of the mathematical model, and the coating system roughness selection range needs further theoretical and experimental research.

Reviewer 3 Report

What is the main question addressed by the research?

The paper discusses the importance of interfacial bonding strength between the substrate and its coating for improving the service life of parts. The authors establish a mathematical model that quantitatively describes the microscopic surface roughness and its anti-corrosion coating adhesion strength. They use this model to demonstrate that controlling the surface roughness of the substrate can improve the anti-corrosion life of the part. The authors find that the interfacial bonding strength between the coating and substrate changes with the substrate's roughness. However, there is an optimal roughness evaluation and selection range. The authors note that the adhesion between the coating and substrate is not always increased with higher roughness on the same surface. The results of their experiments align with their theoretical predictions. The authors conclude that surface roughness prediction is helpful and mainly based on cutting parameters, and sometimes other parameters, to attain the desired surface quality. Overall, the paper is well-written, organized, and provides insightful information regarding the interfacial bonding strength of Al-Zn-Si alloy.

Is it relevant and interesting?
The paper discusses the interfacial bonding strength between a coating and substrate, specifically focusing on the linear surface roughness of an Al-Zn-Si alloy substrate. The authors propose a mathematical model that quantitatively describes the surface roughness and anti-corrosion coating adhesion strength, and they establish a relationship between interfacial bond strength and substrate roughness.

To develop their model, the authors conducted experiments in which they varied the substrate roughness between 37.1 μm and 48.4 μm and measured the corresponding coating strength. The authors note that the adhesion between the coating and substrate is not always increased with higher roughness, and they propose an optimal roughness evaluation and selection range.

The authors also conducted surface roughness prediction experiments based on cutting parameters and other parameters, and they discuss the effects of surface roughness on coating properties such as corrosion protection. The authors cite a number of previous studies that support the importance of substrate surface treatment for improving interfacial bond strength, and they suggest that the use of Al-Zn alloys for anti-corrosion coating is particularly promising due to their excellent wear resistance and other properties. The authors appear to use a combination of experimental data and previous research to develop their model and support their conclusions. The paper includes a number of technical details, such as the specific range of substrate roughness used in the experiments, and the authors appear to take a systematic approach to their research.

How original is the topic?

The article presents the experimental materials and methods used to produce the samples and measure the roughness, as well as the coating preparation and determination of coating and substrate bonding strength. The results of the experiment are discussed and analyzed, showing that the bonding strength between the coating and substrate improves with increasing substrate surface roughness up to a certain point, after which the strength begins to decline. The authors suggest that the roughness of the substrate surface should be kept within an optimum range to ensure good combining effects between the coating and substrate. The article is well-written and provides a detailed account of the experiment, making it a valuable source for those interested in this topic.

Is the text clear and easy to read?

The text is clear and easy to read.

Are the conclusions consistent with the evidence and arguments presented?

The conclusions drawn in the text seem to be consistent with the evidence and arguments presented. The authors conducted an experiment to investigate the influence of substrate surface roughness on coating bond strength. The experiment involved processing the substrate surface using different mechanical cutting methods to obtain different substrate surfaces with various sets of roughness. The authors then measured the bonding strength between the coating and the substrate and observed the microstructure of the surface and cross-sectional using scanning electron microscopy.

The authors found that when the surface roughness of the substrate increased, the bonding strength between the coating and the substrate also increased. However, when the roughness exceeded a certain value (50μm in this study), the bonding strength declined. They also found that the bonding strength was significantly different when the substrate's roughness was achieved by diverse processing methods, even though the substrate's roughness was the same. Therefore, the authors concluded that the roughness of the surface should be confined to the optimum range to ensure the best combination effect between coating and substrate.

The authors' conclusions are supported by the experimental results and the analysis of the data. They have also discussed the implications of their findings and highlighted the directions for future research. Therefore, the conclusions appear to be consistent with the evidence and arguments presented in the text.

Do they address the main question posed?

The article achieved the results stated at the beginning at a high rate.

Author Response

Thank you for your rigorous comments and nice suggestions. We revised this manuscript according to the comments. The conclusion part have been revised to explain briefly about the report and the further work.

Reviewer 4 Report

Overall, the article is at a low level in the current version. The article is supported by an appropriate literature review. The methodology and results of the verification are not clearly presented. Experimental (verification) tests are presented in such a way that they cannot be repeated. There are many generalities and mental abbreviations that are difficult to understand. The work contains errors.

Critical comments to the article:

1. What does the sentence refer to: "The Materials and Methods should be..."  - section 2.2, 5th line from the bottom?

2. What do the Authors think the sentence means: "According to the traditional methods, comparison of surface measurements is described in the above Table 1"? What are traditional methods according to the Authors? (section 3)

3. Table 1 is described incorrectly. Contains surface structures due to the directionality of the surface. In the description it is written that it is a division due to surface roughness.

4. Roughness designations are incorrect (parameter designation in the index, e.g. R_a). According to the ISO standard, the roughness parameters are recorded in a uniform size (not in the index). (section 4, p.3)

5. Why were only the roughness parameters Ra, Rz, Ry adopted? There is an argument on page 3: "Usually adopt one of the following parameters...".From a scientific point of view, a better parameter is Rq - mean square deviation from the profile. Statistically speaking, this is the standard deviation.Why were the parameters characterizing the stereometry of the surface not adopted? (e.g. degree of isotropy, frequency parameters of the structure).

6. The assumptions in section 5.1 are too general, e.g.: "The granularity of coating material is enough". Exactly what is the granularity? How to repeat the research with such assumptions? Another assumption: "Anticorrosion coating is thick enough". Is thick?

7. What are the points (1, 2, 3...) in section 5.4.1? The points are not related to the text of section 5.4.1 presented above.

8. What does the sentence refer to: "This section may...."  - section 6, p. 11?

9. What does "certain average" mean? - p.12, first sentence from above.

10. What does the sentence refer to: "Authors should discuss..." - section 7, p. 14?

11. The article shoudl be written in the passive voice - section 7.

12. The conditions of the verification tests are described in such a way that the experiment cannot be repeated, e.g. what exact mechanical treatments were used, what technological parameters, what tools?

13. What does a certain roughness value mean - section 7.2, 5 sentence?

14. The first conclusion (section8) is half wrong. How are the bond strength affected by the evaluation parameters? How can the method of evaluation affect a physical phenomenon?

                       

 

Author Response

Thank you so much for your careful check. The qualitative statements are not the good practice, so we try our best to quantify these statements. For the comments in PDF, we revised the manuscript according to the suggestions. The changes were marked in red in this manuscript.

1. We rephrase the sentence to convey the message.
2. We further explain the traditional methods in this manuscript according to the comments.
3. We revised the Table according to the comments.
4. We revised the wrong parameter designation in this manuscript.
5. Surface roughness parameters、and prescribed numerical value respectively, which were used to calculate the established models. The other parameters, including degree of isotropy and frequency parameters of the structure, will be considered to improve the proposed models.
6. We further explained it.
7. In this section, we established the model of the substrate surface contour. This section is the base of the following models and calculations.
8. We revised this manuscript according to the comments.
9. We rephrased these sentences according to the comments.
10. Thank you for your careful check, we deleted these sentences.
11. We revised this section according to the comments.
12. The experiment was used to verify the accuracy of the established modeling.
13. We rephrased this sentence to express the meaning accurately.
14. We revised this manuscript according to the comments. The conclusion part have been completely revised to explain briefly about the report. Moreover, we have improved the grammar, expression and spelling of the manuscript as much as possible.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

All the essential amendments have been made. The manuscript is acceptable and can be posted in the journal.