Mechanical, Corrosion and Wear Characteristics of Cu-Based Composites Reinforced with Zirconium Diboride Consolidated by SPS

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for involving me for the reviewing of the manuscript entitled "Mechanical, corrosion, and wear characteristics of Cu-based composites reinforced with zirconium diboride consolidated by SPS". There are some detailed suggestions as follows:  

Major problems: 

1) The abstract needs to be rewritten, and keywords also need to be re selected and sorted. 

2) What is the reason and basis for the author to choose 850℃ and 950 ℃? 

3) Suggest to provide the roughness and hardness of counter balls. In addition, has the experiment been repeated? How many times have you repeated it? Is a brand new sample used for repetition or is a single sample used for all tests? Is the data you used from only one time or on average? 

4) Figure 10-13: The structure of the figure needs to be redesigned, for they are difficult to understand. Suggest changing the black background to a light color.

5) Figure 15: The differences between each image should be identified, such as wear marks, transfer films, and different debris.

6) Table 2: The presentation of data is not satisfactory. It is recommended to use a line chart or other better methods. 

7) The language of the entire paper needs to be improved, and a professional polishing is recommended.

 

Minor problems:

1) Figures: The numbering of sub-images should be supplemented with left parentheses, such as Figures 1, 3, 7, 9, 14, and 15. 

2) Page3 line131: What's the meaning of ELBIT? 

3) The last few lines of the References should be removed. 

Comments on the Quality of English Language

Moderate editing of English language required. 

Author Response

Comments 1

• The abstract needs to be rewritten, and keywords also need to be re selected and sorted.

Response 1

The abstract has been corrected.

Comments 2

• What is the reason and basis for the author to choose 850℃ and 950 ℃?

Response 2

The properties of the composite materials produced depend on many factors, including the parameters of the technological process, which include temperature, pressure and sintering time. The optimal sintering parameters are determined by correlating them with the produced composites' determined physical and mechanical properties. The SPS process was carried out at temperatures of 850 and 950 °C, which was aimed at determining the optimal sintering temperature of copper-based composites. Each material was assessed after the sintering process in terms of the degree of densification to determine whether the appropriate sintering conditions were used. Therefore, in the first stage of the research, the apparent density (ρ) and open porosity (Po) were determined for the sintered materials. The authors conducted their experiments sintering at a temperature of 750 °C. However, low density below 80% of the theoretical density and high porosity above 8% were obtained for all sintered materials. Therefore, in the next stage, these materials' mechanical, tribological and corrosion properties were not determined. Currently, research is being carried out to optimize copper-based composites' pressure and sintering time. The results of these studies will be published in another paper.

Comments 3

• Suggest to provide the roughness and hardness of counter balls. In addition, has the experiment been repeated? How many times have you repeated it? Is a brand new sample used for repetition or is a single sample used for all tests? Is the data you used from only one time or on average?

Response 3

The counter balls made of bearing steel (AISI52100, diameter of 3.175 mm) were used. These are commercial balls. The manufacturer's technical specifications do not provide information on the roughness of the ball's surface. At room temperature, the hardness of AISI52100 steel is 60-67 HR. Two tests were performed using the ball-on-disc method under the same conditions for each sintered material. Following the standards, a new ball was used in each test, which was first washed in ethyl alcohol in an ultrasonic cleaner. The presented data (friction coefficient and wear index - Table 1 and Figure 10) are average results from two tests. Due to the large number of 3D profile results, only selected examples of the abrasion profile analysis results (Fig.11-15) were presented in the article.

Comments 4

• Figure 10-13: The structure of the figure needs to be redesigned, for they are difficult to understand. Suggest changing the black background to a light color

Response 4

It has been improved.

Comments 5

• Figure 15: The differences between each image should be identified, such as wear marks, transfer films, and different debris.

Response 5

It has been corrected.

Comments 6

• Table 2: The presentation of data is not satisfactory. It is recommended to use a line chart or other better methods. 

Response 6

It is prevalent to present the results of corrosion tests in a table. However, presenting such many results in a graph will not improve the quality of the article because it will require too many graphs.

A similar method of presenting results can be found in other articles; therefore, we decided to leave it in tabular form for easier reading of the data.

Examples:

https://doi.org/10.1016/j.corsci.2024.112351

https://doi.org/10.1016/j.corsci.2024.112377

https://doi.org/10.1016/j.corsci.2024.112340

Comments 7

• The language of the entire paper needs to be improved, and a professional polishing is recommended.

Response 7

The language was improved.

Minor problems:

Comments 1

1. Figures: The numbering of sub-images should be supplemented with left parentheses, such as Figures 1, 3, 7, 9, 14, and 15.

Response 1

The numbering of the sub-images has been updated

Comments 2

2. Page3 line131: What's the meaning of ELBIT?

Response 2

The word "ELBIT Innovation – Implementation Company" has been corrected to clarify its meaning.

Comments 3

3. The last few lines of the References should be removed.

Response 3

The last few lines of the References have been removed.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors investigated the effect of ZrB2 in Cu+ZrB2 composites on the microhardness, friction coefficient, wear resistance, and corrosion resistance. There is still a need for improvement in the sections of introduction and results as follows.

2. In introduction, it is necessary to clarify the specific application fields of Cu+ZrB2 composites, because various engineering applications in the electronics, energy, automotive, and manufacturing industries.

1. In addition, they have shown references of ZrB2 in Cu matrix. It is needed to briefly summarize the related references on ZrB2 compared with the other reinforcing phases of oxides, carbides, nitrides, and borides. Then, it can lead to the purpose of the study, because the goal of this work is not clear.

3. In Results, the study investigated mechanical, corrosion, and wear properties. It is suggested that the results are divided into sub-sections. Thus, it is easy to find the related or interested sections for readers.

4. In phase analysis, they only used EDS analysis to identify the different phases. It should include the XRD results to support the EDS analysis, because EDS results only provide the chemical positions, but not the phase structures.

5. In Figures 6 and 7, they can provide phase maps included the grain boundaries, so that we can clearly see the particle size of reinforcing phase ZrB2 and Cu. 

6. The authors show the fraction of ZrB2 phase in Figures 6 and 7. As designed additions of 5, 10, 15 and 20, however, we can find the corresponding fractions of 39.6, 47.8, 52.7 and 63.5% ZrB2 phase. There is large difference in the phase fraction between designed and measured. It should be discussed.

7. The authors show some references of ZrB2 obtained from different production methods. It is also suggested to discuss their results compared with the references in terms of different properties.     

 

Author Response

Comments 1

1. In introduction, it is necessary to clarify the specific application fields of Cu+ZrB₂ composites, because various engineering applications in the electronics, energy, automotive, and manufacturing industries.

Response 1

The introduction has been updated to clarify the specific application fields of Cu+ZrB₂ composites.

Comments 2

2. In addition, they have shown references of ZrB2 in Cu matrix. It is needed to briefly summarize the related references on ZrB2 compared with the other reinforcing phases of oxides, carbides, nitrides, and borides. Then, it can lead to the purpose of the study, because the goal of this work is not clear.

Response 2

The relevant references on ZrB₂ in the Cu matrix have been summarized, with comparisons to other reinforcing phases such as oxides, carbides, nitrides, and borides. This summary now leads to a more precise statement of the study's purpose.

Comments 3

3. In Results, the study investigated mechanical, corrosion, and wear properties. It is suggested that the results are divided into sub-sections. Thus, it is easy to find the related or interested sections for readers.

Response 3

The results section has been divided into sub-sections to address the mechanical, corrosion, and wear properties separately, making it easier for readers to locate the sections of interest.

Comments 4

4. In phase analysis, they only used EDS analysis to identify the different phases. It should include the XRD results to support the EDS analysis, because EDS results only provide the chemical positions, but not the phase structures.

Response 4

The phase analysis section has been updated to include XRD results to support the EDS analysis.

Comments 5

5. In Figures 6 and 7, they can provide phase maps included the grain boundaries, so that we can clearly see the particle size of reinforcing phase ZrB2 and Cu.

Response 5

Thank you for your valuable feedback. The EBSD results presented are preliminary findings from microstructural tests focused on the composites' phase analysis. Unfortunately, we currently do not have phase maps that include grain boundaries. We are conducting detailed microstructural tests on composites sintered at 950 °C, where the most favourable properties were observed. These tests include SEM with EBSD analysis, TEM EDX and STEM. We will publish the results of these studies in a subsequent paper.

Comments 6

6. The authors show the fraction of ZrB2 phase in Figures 6 and 7. As designed additions of 5, 10, 15 and 20, however, we can find the corresponding fractions of 39.6, 47.8, 52.7 and 63.5% ZrB2 phase. There is large difference in the phase fraction between designed and measured. It should be discussed.

Response 6

Thank you for your comment. We know the differences in the EBSD test results compared to the planned ZrB₂ content. The significant discrepancy between the designed and measured ZrB₂ phase fractions arises from the surface preparation for testing and the nature of EBSD analysis. When preparing the metallographic microsection of copper-based composites, the soft copper matrix tends to grind away faster than the hard ceramic, causing ZrB₂ particles to "protrude" above the matrix. This results in the matrix being obscured (an effect known as the edge artefact) during EBSD testing. Additionally, the data used to calculate the phase fraction is not derived from a cross-sectional plane but rather from a specific volume on the sample surface (the electron beam's excitation area). If the ZrB₂ phase was located just below the tested surface, it was also detected and included in the EBSD results presented.

Comments 7

7. The authors show some references of ZrB2 obtained from different production methods. It is also suggested to discuss their results compared with the references in terms of different properties.

Response 7

The section discussion of results includes information on the comparison of properties of the Cu-based composites, which were produced by different methods.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have adequately addressed my concerns and the issues I have raised. I think it is ready for publication now. 

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have significantly improved the Section of Introduction as suggested. They describe more on the applications based on their new materials. In addition, they also modify the Results by including three Subsections of 3.1 Physical and mechanical properties, 3.2 Microstructures, and 3.3 Wear properties, so that man can easily understand and find the key points of this study. Besides, they also included and compared with the other references to enhance their discussion. Thus, I think the present quality meets the requirements expected, so that it can be accepted now.