Effect of Heat Treatment on the Electrochemical and Tribological Properties of Aluminum-Bronze Coatings Deposited Used the Thermal Spraying Process

Round 1

Reviewer 1 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

The article details an investigation into the effects of heat treatment on the corrosion and wear resistance of aluminum-bronze coatings deposited on a naval brass substrate via the thermal (flame) deposition process. However, there are a few areas that could be improved as I wrote in my previous referee report.

 

·       The novelty of the research should be better emphasized in both the introduction and abstract. What unique insights or significant contrasts does your study offer in comparison to previous research works?

·       In Figure 2, it would be more appropriate to use arb. units instead of a.u.

·       To validate the data, would it be possible for the authors to estimate the crystalline size using other techniques, such as TEM?

The conclusion section should be improved to help a reader not familair with the topic.

 

The authors should include  a comparative analysis with other coating materials to provide a more robust context for the study's findings. Further controls that should be considered include long-term performance tests under real-world conditions to assess the coatings' durability over time.

 

Comments on the Quality of English Language

The english should be improved. 

Author Response

Dear Reviewer 1,

 

Thank you for your review of our article, "Effect of heat treatment on the electrochemical and tribological properties of aluminum-bronze coatings deposited using the thermal spraying process". We have addressed your questions and concerns below.:

 

• The novelty of the research should be better emphasized in both the introduction and abstract. What unique insights or significant contrasts does your study offer in comparison to previous research works?

R./ The article were improved

• In Figure 2, it would be more appropriate to use arb. units instead of a.u.

R./ the units were changed.

• To validate the data, would it be possible for the authors to estimate the crystalline size using other techniques, such as TEM?

R./ We agree with the evaluator. However, for future work we will confirm the crystalline size using other techniques, such as TEM.

The conclusion section should be improved to help a reader not familair with the topic.

R./ Conclusions were improved

The authors should include  a comparative analysis with other coating materials to provide a more robust context for the study's findings. Further controls that should be considered include long-term performance tests under real-world conditions to assess the coatings' durability over time.

R./ While I appreciate your feedback, the initial stage of this research had a specific focus, and performance studies in marine environments weren't included. The project was implemented within the national shipyard industry, where it has achieved significant success and improvements in repair processes and functionality to date.

Comments on the Quality of English Language: improved

The English should be improved.

R./ The English has improved.

 

Reviewer 2 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Dear authors,

Your work is interesting, but some adjustments need to be made.

1. This work's most significant numerical results must be added to the abstract.

2. In the introduction, to increase readers' interest, it is necessary to discuss alternative surface treatment methods to improve anti-corrosion and tribological properties. As a new and exciting work on surface treatment with the PEO method, I propose to use the following literature:

Elinor Zadkani Nahum, Svetlana Lugovskoy, Alex Lugovskoy, Barbara Kazanski, Alexander Sobolev, The study of hydroxyapatite growth kinetics on CP – Ti and Ti65Zr treated by Plasma electrolytic oxidation process, Journal of Materials Research and Technology, Volume 24, 2023, Pages 2169- 2186, https://doi.org/10.1016/j.jmrt.2023.03.128.

 

In addition, it is necessary to indicate the advantages and disadvantages of the applied method compared to alternative surface treatment technologies.

3. At the end of the introduction, it is necessary to express the novelty of the research more clearly, its purpose, and the methods used to achieve it.

4. Figure 2 – It is necessary to increase the font. Each phase found must be assigned an ICDD number.

5. Figure 3 – It is necessary to add the average statistical deviation to the graph.

6. P. 3.1 It is necessary to calculate the amorphous and crystalline phases ratio and provide a semi-quantitative phase analysis.

7. It is necessary to provide data on the average thickness of the coating and its porosity before and after heat treatment.

8. Figure 5 has a very small font and small photographs. It needs to be fixed. The EDS spectra plots should be removed, and the chemical analysis results should be presented in tabular form.

9. Figure 10 Graphs of EDS spectra should be removed, and the results of chemical analysis should be presented in the form of a table in the body of the work.

10. Figure 11 b – The x and y scales should be visible. You must also add a Nyquist plot. The discussion requires an explanation of the equivalent circuit used and the purpose of each element. In addition to this, it is necessary to present the measured capacitances and resistances and the accuracy of the experimental data approximation in a separate table.

11. Table 2 How was the polarization resistance calculated? The slopes of the linear Tafel sections must be added to the table. Rp – cannot be negative.

12. It is necessary to compare the data obtained by the EIS method and potentiodynamic studies. In addition to this, it is necessary to add appropriate electrochemical reactions during the corrosion process.

13. The conclusions should be revised considering the above comments, and it is also necessary to indicate the most significant numerical results.

14. Most of the references in the bibliography are pretty old. They need to be updated.

Author Response

Dear Reviewer 2,

 

Thank you for your review of our article, "Effect of heat treatment on the electrochemical and tribological properties of aluminum-bronze coatings deposited using the thermal spraying process". We have addressed your questions and concerns below.:

1. This work's most significant numerical results must be added to the abstract.

 

R./ We rewrote the abstract to more clearly emphasize the study's results.

 

2. In the introduction, to increase readers' interest, it is necessary to discuss alternative surface treatment methods to improve anti-corrosion and tribological properties. As a new and exciting work on surface treatment with the PEO method, I propose to use the following literature:

 

Elinor Zadkani Nahum, Svetlana Lugovskoy, Alex Lugovskoy, Barbara Kazanski, Alexander Sobolev, The study of hydroxyapatite growth kinetics on CP – Ti and Ti65Zr treated by Plasma electrolytic oxidation process, Journal of Materials Research and Technology, Volume 24, 2023, Pages 2169- 2186, https://doi.org/10.1016/j.jmrt.2023.03.128.

 

In addition, it is necessary to indicate the advantages and disadvantages of the applied method compared to alternative surface treatment technologies.

 

R./ We appreciate the reviewer's insightful suggestions regarding the discussion of new coating techniques and their associated advantages and disadvantages. We will carefully consider these points in our future publications.

 

3. At the end of the introduction, it is necessary to express the novelty of the research more clearly, its purpose, and the methods used to achieve it.

R./ The introduction was improved to reflect the innovation of this study"

4. Figure 2 – It is necessary to increase the font. Each phase found must be assigned an ICDD number.

R./ The figure is modified and the font size of the letters is enlarged.

5. Figure 3 – It is necessary to add the average statistical deviation to the graph.

R./ The figure 3 is update

6. 3.1 It is necessary to calculate the amorphous and crystalline phases ratio and provide a semi-quantitative phase analysis.

R./ The combined effects of the coating and the substrate prevented the quantification of the amorphous phase using the chosen technique. While alternative methods exist, they were not explored in this study.

7. It is necessary to provide data on the average thickness of the coating and its porosity before and after heat treatment.

 

R./ The average thickness was determined as described in the Materials and Methods section. Calculations of porosity percentages were performed and the results were added to this article.

8. Figure 5 has a very small font and small photographs. It needs to be fixed. The EDS spectra plots should be removed, and the chemical analysis results should be presented in tabular form.

R./ The elemental distribution maps generated through EDS allow visualization of the changes and diffusion patterns of the elements under study.

9. Figure 10 Graphs of EDS spectra should be removed, and the results of chemical analysis should be presented in the form of a table in the body of the work.

R./ The energy-dispersive X-ray spectroscopy (EDS) spectra graphs were omitted, and the dimensions of the data table were enlarged for improved legibility.

10. Figure 11 b – The x and y scales should be visible. You must also add a Nyquist plot. The discussion requires an explanation of the equivalent circuit used and the purpose of each element. In addition to this, it is necessary to present the measured capacitances and resistances and the accuracy of the experimental data approximation in a separate table.

R./ We appreciate your comments and suggestions. In response to your observations:

1. We have reviewed Figure 11b and ensured that the scales on the x and y axes are visible in the revised version of the manuscript.

 

2. Regarding the Nyquist plot, we have added this graph as supplementary material in the revised manuscript. We chose to include the Nyquist plot in the supplementary material because it presents the same information as the Bode plot with the phase angle. Furthermore, we believe that the provided information, which includes the Bode diagram: the impedance versus frequency graph, and the phase angle versus frequency graph, is sufficient. We consider these data to adequately support the corrosion results presented in our study.

 

As for the discussion of the equivalent circuit, we have provided a detailed explanation of each circuit element in the discussion section of the manuscript. Each circuit element is discussed with its purpose and its contribution to the interpretation of the impedance data.

 

The methodology section includes a comprehensive explanation of the equivalent circuit used in the study. This explanation details the purpose and function of each element, further clarified by a supplemental table.

11. Table 2 How was the polarization resistance calculated? The slopes of the linear Tafel sections must be added to the table. Rp – cannot be negative.

R./ We appreciate your observation regarding the polarization resistance (Rp) value. We understand that polarization resistance cannot be negative in a real physical system. The negative value reported in the manuscript draft was an inadvertent error during data processing.

We have reviewed our calculations and corrected the error. In the revised version of the manuscript, we have ensured that all Rp values are positive, as they should be. We have also added the slopes of the linear Tafel sections to Table 2, as you suggested.

 

To calculate polarization resistance, we used the potentiodynamic polarization technique and followed the ASTM G59 standard[1]. In this method, polarization resistance is calculated from the slopes of the linear Tafel sections. This standard proposes the following equation for its calculation:

Where:  B is in V, icorr is mµA/cm2 and Rp is ohm-cm2

 

[1] ASTM International., “ASTM Standard G59-97 ‘Standard Test Method for Conducting Potentiodynamic Polarization Resistance Measurements.’” ASTM International, West Conshohocken, pp. 1–4, 2014. doi: 10.1520/G0059-97R20.

 

12. It is necessary to compare the data obtained by the EIS method and potentiodynamic studies. In addition to this, it is necessary to add appropriate electrochemical reactions during the corrosion process.

R./ Thank you for your valuable suggestion. We have compared the data obtained by the Electrochemical Impedance Spectroscopy (EIS) method and potentiodynamic studies. We found that both methods provide consistent and complementary results, reinforcing the validity of our findings. The complete impedance results associated with the Bode diagrams were included in the manuscript to complement the results obtained by potentiodynamic polarization. In addition, we have added the appropriate electrochemical reactions that occur during the corrosion process in the corresponding section of the manuscript.

13. The conclusions should be revised considering the above comments, and it is also necessary to indicate the most significant numerical results.

R./ Conclusions updated

14. Most of the references in the bibliography are pretty old. They need to be updated.

R./ The bibliography incorporated recent article publications.

 

 

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

1. Abstract is too simple, which does not contain useful information. What are the thermal treatment conditions? How does thermal treatment affect the composition, morphology, and physical properties of the coatings？The conclusions have the same problems.

2. Introduction, large space has been used to introduce the effects of aluminum content on mechanical properties of aluminum-bronzes. However, this has limited relationship to this research.

3. There is investigation on improving the properties of the aluminum-bronze coating. The authors should review these in the Introduction, and point out the difference between them and this study. Additionally, the innovation points of this study should be clearly provided.

4. How to determine the heat treatment temperature?

5. The coating fabrication parameters should be provided in detail.

6. Fig. 3 shows that the crystal sizes are in a range of 25-26 nm. However, it cannot determine the crystal sizes from SEM images. Please add them.

7. Fig. 8, what is the heat treatment temperature? Why choose this condition? What about other conditions? Other figures have the same problem.

8. The cross-sectional images of the coating after corrosion should be provided.

9. The references are very old, and many important references are ignored.

Comments on the Quality of English Language

The language should be improved.

Author Response

Dear Reviewer 3,

 

Thank you for your review of our article, "Effect of heat treatment on the electrochemical and tribological properties of aluminum-bronze coatings deposited using the thermal spraying process". We have addressed your questions and concerns below.:

 

Comments and Suggestions for Authors

1. Abstract is too simple, which does not contain useful information. What are the thermal treatment conditions? How does thermal treatment affect the composition, morphology, and physical properties of the coatings？ The conclusions have the same problems.

 

R./ To better highlight the article's core argument, the summary and conclusions were rewritten to emphasize the key findings and implications.

 

2. Introduction, large space has been used to introduce the effects of aluminum content on mechanical properties of aluminum-bronzes. However, this has limited relationship to this research.

 

R./ New information was included on the effects of heat treatment on aluminum bronze coatings

 

3. There is investigation on improving the properties of the aluminum-bronze coating. The authors should review these in the Introduction, and point out the difference between them and this study. Additionally, the innovation points of this study should be clearly provided.

 

R./ The introduction was rewritten to more clearly emphasize the study's innovative aspects

 

4. How to determine the heat treatment temperature?

 

R./ The University conducted a series of experiments to identify the optimal temperature and duration of heat treatment for aluminum-bronze coatings. We tested three temperatures (300, 500, and 800 degrees Celsius) for two different durations (one hour and ten hours). The results of these tests will be used to determine the appropriate parameters for further studies.

 

5. The coating fabrication parameters should be provided in detail.

 

R./ The Materials and Methods section provides a detailed explanation of the parameters used for projecting each coating, including the specific pressures applied.

 

6. 3 shows that the crystal sizes are in a range of 25-26 nm. However, it cannot determine the crystal sizes from SEM images. Please add them.

R./ The dimensions of the crystallites were characterized by R X diffraction, following the methodology described in the Materials and Methods section.

7. 8, what is the heat treatment temperature? Why choose this condition? What about other conditions? Other figures have the same problem.

R./ As detailed in the methods section, we employed a temperature of 500°C for a duration of 10 hours. The rationale behind this specific temperature selection is explained in response to question 4.

8. The cross-sectional images of the coating after corrosion should be provided.

R./ Electrochemical testing was employed to assess the corrosion resistance of the coatings. While surface evaluation was conducted, a transversal analysis was omitted.

9. The references are very old, and many important references are ignored.

R./ New references were included for the most recent introduction

Comments on the Quality of English Language: improved

The language should be improved.

R./ The English has improved.

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

Dear authors,

please, see the file attached.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

Dear Reviewer 4,

 

Thank you for your review of our article, "Effect of heat treatment on the electrochemical and tribological properties of aluminum-bronze coatings deposited using the thermal spraying process". We have addressed your questions and concerns below.:

 

The work attempts to study the influence of heat treatment on tribological properties and corrosion resistance of aluminum bronze coatings on steel obtained by thermal spraying process. The study is relevant, contains important results and the research layout and tests are adequate. The conclusions are supported by the results. Nevertheless, the text could be rewritten in a better way. Also, there are some comments and questions that will help to improve the manuscript.

 

 

1. Bronze, in this case, is an alloy of copper with Thus, writing “aluminum-bronze coating” is confusing. Should it be “aluminum bronze” or does it mean that aluminum is added to the regular Cu-Sn alloy? Please, revise it throughout the text and the title.
2. References [2] and [3], apparently, refer to sentence lines 42-45, not Please, check.

R./ Delete

 

3. Lines 46-50. The information that tribological properties of Al alloys are being studied is broad and It is better to provide some findings in that area, that support the idea of using Cu-Al compounds for the abovementioned applications.

R./ include

4. Lines 51-52. It is better to specify the influence of Al on the mechanical properties and other properties and what kind compromise is usually solved (strength-conductivity, hardness-ductility, tribology-corrosion resistance and so on). It will help in problem

R./ Include

5. Line 46-47. The sentence seems redundant as the same idea is written in lines 51-

   R./ Rewrite

6. Lines 72-74. The authors generally mentioned the actions undertaken, but failed to give the results. Make it more useful for the problem Furthermore, reference [6] does not comply with “We” if “We” stands for the authors of the manuscript.

 

       R./ Rewrite.

7. Line What work does this research refer to? If [11], then it should not be a new paragraph.

R./ Rewrite

8. The Introduction could be structured better and include more publications published in last 5

 

R./ Recent studies on aluminum bronze are limited, with most of the available references focusing on other topics but include new reference in article.

 

9. Since heat treatment is a central part of the work I would recommend to add a Table to Section 2 describing all the main parameters of HT of each The same with tribology.

 

    R./ Include in article

10. The parameters of EDX study are

R./ The Parameters was deleted.

11. Please, provide information on the feedstock material for the coatings. Raw material should also be analyzed the way the coatings were to track the changes.

 

R./ A coating made from Commercial PROXON®21071 was applied. The coating has the following chemical composition:

• Aluminum: 10%
• Silicon: Up to 0.6%
• Iron: 2%
• Copper: Balance

 

12. Line Did the authors manage to measure adhesion? If so, please, provide the values.

R./ While adherence was assessed in the first phase, it became redundant at later stages and has been removed for clarity.

13. SEM and EDX maps are small. Please, provide figures in higher resolution. Otherwise, it hardly supports the EDX results description. EDX plot (Figure 14) also contains Co What contains it?

      R./ The Figure 14 was improved and deleted

14. The authors write about increased adhesion as a result of HT, however, no tests were undertaken to measure it. What reasons such statements? Could HT decrease the adhesion so that the coating would be no longer useful for the mentioned applications? It should be addressed in the

R./ In article removed sections adhesion. Tests focused solely on the coating's own behavior, and while the coating itself did not delamination or crack.

15. The manuscript contains grammar and spelling mistakes, although the layout is adequate. I would recommend extensive English editing to improve coherence and readability.

R./ The article underwent thorough English editing, resulting in improved clarity, grammar, and flow.

 

I would recommend major revision.

Round 2

Reviewer 1 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

I recommend the publication of this article. 

Comments on the Quality of English Language

moderate revision 

Author Response

 

Reviewer 1

We really appreciate your feedback on this article.

Regards 

Jose M.

Reviewer 2 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Good job!

Author Response

Reviewer 2

We really appreciate your feedback on this article.

Regards 

Jose M.

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

The authors' reply makes it impossible to track the changes. Some points are not addressed adequately. Some specific comments on the revised version:

1."However, aluminum reduces machinability". Do not agree. Provide references for support.

2. "Aluminum-bronze", "Aluminum-copper". Are those supposed to mean the same?

3. EDX parameters are still appreciated.

4. EDX maps are also useful. Why would the authors first improve and then delete figure 14?

5. Information on feedstock material is still absent in the revised version. 

6. Check the references in the introduction. Some statements and research have no references (e.g. line 127). 

 

Comments on the Quality of English Language

English was improved.

Author Response

Reviewer 4,

We really appreciate your feedback on this article.

 

1."However, aluminum reduces machinability". Do not agree. Provide references for support.

R./ High Strength: Aluminum bronze is stronger than pure aluminum. This makes it harder to cut through, leading to increased tool wear and shorter tool life. A study by Medicus et al. (2001) exploring high-speed milling of aluminum bronze (C95800) confirms this. While it demonstrates the possibility of high-speed machining for this material, it also highlights the challenge of tool wear due to the material's strength [1].

Heat Transfer: Aluminum bronze has high thermal conductivity. This can cause heat to build up during machining, warping the material and further reducing machinability [1].

Reference:

 

[1] Medicus, K., Davies, M., Dutterer, B., Evans, C., & Fielder, R. (2001). Tool Wear and Surface Finish in High Speed Milling of Aluminum Bronze. Machining Science and Technology, 5(2).

 

2. "Aluminum-bronze", "Aluminum-copper". Are those supposed to mean the same?

 

R./ Yes, "Aluminum-bronze" and "Aluminum-copper" mean the same. It was changed everywhere to Aluminum-bronze.

3. EDX parameters are still appreciated.

R./ Thank you very much for your comments. We are not sure we understand your question. Could you clarify why you do not want us to show the EDX parameters?

 

4. EDX maps are also useful. Why would the authors first improve and then delete figure 14?

 

R./ Due to the inclusion of a new graph, figure 14 became figure 15

 

5. Information on feedstock material is still absent in the revised version.

 

R./ Include in section 2 Materials and Methods.

 

6. Check the references in the introduction. Some statements and research have no references (e.g. line 127).

 

R./ For a more comprehensive understanding, the introduction has been expanded to include additional references.

 

I've included the latest version of the article in this message.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper, aluminum-bronze coatings were deposited on brass substrates by flame spraying technique. Microstructures, electromechanical and tribological properties of the coatings before and after heat treatment were studied. There are some corrections should be made.

1.     Figure. 3, the pictures of (a-c) are not clear, please replace them with clearer pictures with constant magnifications.

2.     Page 7, the discussions on the microhardness results for the coatings with and without heat treatments are not enough. What are the porosity levels of the CuAl-1 and CuAl-2 coatings? Why CuAl-2 coating has lower hardness value than CuAl-1 coating? Please clarify.

3.     Figure 6, please modify this figure. What is the unit of x axis? The values (0.3 & 0.4?) on y axis are not correct.

4.     Figure 7, what is the unit of y axis? Please clarify.

5.     Page 9, Please show the SEM images of the wear tracks for all the specimens. Please delete the EDS spot marks on the image.

6.     Figure 9 (c), which EDS spot does it represent?

7.     Figure 15, what do ‘Net Int’, ‘K ratio’, ‘Z’, ‘R’, ‘A’ and ‘F’ stand for? Please clarify.

8.      In the ‘Conclusions’ section, please summary the main research findings with a series of bullet points.

 

 

Comments on the Quality of English Language

There are some grammar errors in the manuscript. Please carefully go through the manuscript and revise.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, to be able to publish your work, you need to make the following adjustments.

1. At the end of the introduction, it is necessary to indicate the goals of the work and methods for studying the results obtained.

2. Item 2 Specify the furnace cooling rate.

3. Figure 1 To each peak, a designation characterizing its phase composition must be added. In the text, it is necessary to add the phase numbers from the ICDD library.

4. <For example, the peaks of the applications with heat treatment exhibit a shift to the right due to the diffusion phenomena generated during annealing.> – Diffusion of what and where?

5. Explanations of the effect of temperature on the phase composition should be described in more detail; it is also necessary to conduct a comparative characteristic without heat treatment and with it. Peak intensities, their presence or absence.

6. It is unclear how the crystallite size was calculated and what was taken as an analytical peak.

7. Figure 3 It is not very clear where the substrate is, where the coating is, and where the plastic is. It should be noted. In addition, a more detailed analysis is needed rather than a statement of facts.

8. EDS: EDS mapping for samples without and with heat treatment is required. You need to add a table with the elemental composition. Based on the data you obtained, it is impossible to judge zinc's diffusion into the coating volume. More rigorous proofs are needed. In your case, these are just guesses.

9. In item 2, it is written that you did an electrochemical impedance. It's not in the results.

10. It is necessary to provide impedance spectroscopy data (Nyevist, Bode, equivalent circuit, table with results). In addition, it is required to justify the choice of the equivalent circuit and compare the obtained results with those of Tafel.

11. Based on what corrosion products were determined, for example, CuCl? EDS analysis does not allow this.

 

General conclusion:

In this form, the work represents an unfinished technological report. Considering the comments mentioned above, a profound revision of the article and a re-analysis of the results obtained are necessary.

Comments on the Quality of English Language

English must be sent for correction.

Reviewer 3 Report

Comments and Suggestions for Authors

The article details an investigation into the effects of heat treatment on the corrosion and wear resistance of aluminum-bronze coatings deposited on a naval brass substrate via the thermal (flame) deposition process. However, there are a few areas that could be improved:

 

·       The novelty of the research could be better emphasized in both the introduction and abstract.

·       In Figure 1 (b), it would be more appropriate to use arb. units instead of a.u.

·       To validate the data, would it be possible for the authors to estimate the crystalline size using other techniques, such as TEM?

Comments on the Quality of English Language

Moderate editing of English language.