The Structural and Mechanical Properties of CrAlTiN-Si Nanostructured Coatings Deposited by the Means of High-Power Impulse Magnetron Sputtering

Round 1

Reviewer 1 Report

The paper should be improve with the inroduction. To point out what is the technical problem to be solved, different from a experimental report.

There are some format error and grammare errors.

Author Response

I attached the letter indicating the corrections made to the article.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors aimed to explore CrAlTiN-Si coatings created with the HiPIMS technique, known for enhancing cutting tool performance. They studied the impact of silicon on coating properties. Results showed that silicon content affected the composition, microstructure, and mechanical traits. Silicon levels from 0 to 1.0 at.% formed a solid solution, while 1.9 at.% led to a nanocomposite phase. Surface analysis confirmed oxide and silicon nitride presence. Coatings exhibited a distinct cauliflower-like morphology. Silicon incorporation increased nano-hardness, toughness, and fracture resistance. Some comments should be addressed in this paper.

1.      The abstract should focus more on quantitative aspects rather than qualitative ones. Including examples with numerical values would enhance the description of improved properties.

2.      Why do Table 1 and Table 2 exhibit significant differences? It appears that XPS data provide more reliable measurements than EDS.

3.      Why is there no peak for Silicon in Fig. 2?

4.      The XRD pattern does not indicate the presence of any silicon-containing phases. Does this mean that silicon exists as free atoms within the lattice without forming any distinct phases? Additionally, where are the titanium phases in this graph?

5.      Could the authors provide a cross-section of the samples to display the coating thickness? Is this coating a single-layer structure, or is it a multilayer with varying phase compositions?

6.      The author mentions that an increase in silicon content leads to a decrease in crystal size. Could the author explain the underlying mechanism for this phenomenon?

7.      The authors demonstrated that increasing the silicon content reduces grain size, but hardness and Young's modulus decrease at a certain point. What could explain this apparent contradiction?

8.      Adhesion of the coating to the substrate is a crucial aspect of coatings. Is there any evidence presented by the authors to demonstrate the strong adhesion of the coating?

9.      In the case of Sample M1 and others, changes in the composition of all elements make it challenging for readers to discern whether only silicon influences phase structure, nanohardness, and Young's modulus, or if other element changes might also have similar effects. Could the authors provide clearer clarification on this matter?

10.   As shown in Figure 1, there are variations in the distance between the coating surface and the sputtering substrate. Does this difference in distance impact the coating thickness, or is the coting thickness consistent across all samples?

11.   It is suggested that the authors include a ternary phase diagram and subsequently discuss phase formation based on this graphical representation.

Comments for author File: Comments.pdf

Moderate editing of English language required

Author Response

I attached the letter indicating the corrections made to the article.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors presented rather interesting results on the preparation and study of a coating on a Sono alloy with silicon additives. Despite the rather interesting results, the reviewer had some remarks when getting acquainted with their interpretation.

1. Page 1, line 35: K20 is an alloy? What is the composition of this alloy? The answer to this question in the Introduction section will clarify the further transition of the authors to the consideration of titanium nitride.

2. Pages 2-3, lines 83-84: Why was the Ar-N2 mixture chosen as the working gas?

3. Page 3, lines 92-95: How do 3 concentrations and 4 samples fit together?

4. Why is the face-centered cubic lattice deciphering mentioned only on page 5 and not at the first mention (page 2, line 50)?

5. How do the authors explain the discrepancy between the silicon content in the samples obtained from the EDS and XPS data? Why is there no carbon in the EDS analysis data, the presence of which was shown by the results of another analysis?

6. Was the mapping of the samples carried out to record the distribution of silicon over the surface of the samples? If the distribution is non-uniform, then this could somehow explain the absence of Si signals in the XPS spectra.

7. What does the reflex at 2theta ~64 refer to? For samples M1, M2, and M4, the peaks have a rather high intensity.

8. According to Table 5, the highest H/E ratio is shown for the sample without silicon (M1). How can this be explained?

These remarks do not reduce the level of the presented work but help to improve the readability of the paper.

Author Response

I attached the letter indicating the corrections made to the article.

Author Response File: Author Response.pdf

Reviewer 4 Report

General Evaluation: The manuscript presents an extensive study on the effects of silicon (Si) incorporation in CrAlTiN coatings deposited using the High-Power Impulse Magnetron Sputtering (HiPIMS) technique.

Strengths:

• Originality and Relevance: The research explores a pertinent topic in materials science, focusing on the influence of Si incorporation in CrAlTiN coatings. This is important for improving the performance of cutting tools.
• Experimental Rigor: The authors have conducted a comprehensive experimental investigation, including chemical composition analysis, morphology studies, X-ray diffraction analysis, and nano-hardness testing. This detailed characterization enhances the credibility of the findings.
• Clarity and Presentation: The manuscript is well-structured and clearly presented, aided by figures and tables that enhance understanding.
• Comprehensive Investigation: The article provides a thorough investigation into CrAlTiN-Si coatings, covering chemical composition, microstructure, and mechanical properties. This comprehensive approach enhances our understanding of these coatings.
• Incorporation of Silicon: The study examines the influence of silicon content on the coatings, which is a relevant and interesting aspect, as it can have a significant impact on the properties of the coatings.
• Use of HiPIMS: The use of High-Power Impulse Magnetron Sputtering (HiPIMS) is a positive aspect of the research. HiPIMS is known for producing high-quality coatings with improved properties, adding credibility to the results.
• Characterization Techniques: The article employs various characterization techniques, such as XRD, SEM, and XPS, providing a thorough analysis of the coatings' properties and contributing to the reliability of the findings.

Drawbacks:

• Organization and Clarity: The manuscript could benefit from improved organization for better clarity. Restructuring certain sections would create a smoother flow of ideas.
• Contextualization: The authors should provide more context for the significance of their findings, especially in relation to existing literature. This would help readers better understand the contribution of the study.
• Discussion of Mechanical Properties: While the article mentions nano-hardness and elastic modulus testing, a more detailed discussion of these mechanical properties, particularly their relationship with silicon content, is needed.
• Practical Applications: The practical implications and industry relevance of the coatings are briefly mentioned but would benefit from a more extensive discussion.
• Lack of Discussion on Adhesion: The article does not provide information on the adhesion properties of the coatings, which is crucial for evaluating their suitability for real-world applications.
• Comparison: Including a comparison of the findings with previous research on similar coatings would provide context and help readers understand the novelty or significance of the study.
• Discussion of XPS Results: The authors should provide a more in-depth discussion of the chemical states and bonds of the elements detected by XPS, especially those involving silicon.
• Si Content Variation Rationale: The manuscript mentions variations in Si content but does not explain the rationale behind selecting specific Si concentrations. A clear justification for these values is needed.
• Tribological Testing: Given the focus on cutting tool applications, it would be beneficial to include tribological testing results to evaluate the coatings' performance under realistic conditions.
• Comparison of Crystal Structure Changes: The authors briefly mention the effect of Si on the lattice parameter and crystalline size. A more detailed comparison with previous studies or theoretical predictions regarding the impact of Si incorporation on the crystal structure is necessary.

Conclusion: In conclusion, the manuscript provides valuable insights into the influence of Si incorporation on CrAlTiN coatings. However, addressing the mentioned drawbacks, particularly providing a more in-depth discussion of XPS results and the rationale for Si content selection, is necessary to strengthen the manuscript. I recommend revisions and further experiments to address these issues. Once these concerns are addressed, the manuscript has the potential to make a significant contribution to the field. For now, I recommend Major Revisions.

Author Response

I attached the letter indicating the corrections made to the article.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors took into account the reviewers’ comments and significantly improved the readability of the paper.

Reviewer 4 Report

After thorough examination and considering the authors' responses to previous suggestions, it is my assessment that the authors have adequately addressed the feedback and implemented the necessary revisions. The manuscript now demonstrates a high level of quality and readiness for publication. I commend the authors for their diligence and responsiveness in addressing the concerns raised during the initial review process. Their efforts have significantly improved the clarity, coherence, and overall quality of the manuscript.