Microstructure and Mechanical Properties of Magnetron Sputtering TiN-Ni Nanocrystalline Composite Films

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In the paper, properties of TiN-Ni nanostructured composite films with different Ni contents prepared by magnetron sputtering method on silicon substrate are reported on. The composition, microstructure and mechanical properties of composite films were analyzed by various methods. The results presented in the paper should help to design of high-strength and toughness TiN-Ni films and to better understand the mechanism of  formation of nanocomposite structures. In general, the paper is well written and the data look scientifically correct. My major comment relates to the Conclusion section. In this section, the authors basically simply list the RESULTS that they obtained, rather than drawing CONCLUSIONS. What do these results mean to the scientific community? What lessons, so to speak, can be learned from them, etc. This section should be re-written. Minor comments relate to the Figures. In the caption to Fig. 5, image (f) is omitted (though commented on in the text). In the caption to Fig. 4, the squares and dashed line should be explained. The reviewer believes that after minor revision this paper can be published in Nanomaterials, 

Author Response

The authors would like to thank the editor and reviewers for the valuable comments and suggestions. Per your suggestions, the manuscript has been carefully revised. The following is the point by point response to the reviewers’ comments. Please note that all reviewer comments are shown in times new roman, while our response italics.

Reviewer #1: In the paper, properties of TiN-Ni nanostructured composite films with different Ni contents prepared by magnetron sputtering method on silicon substrate are reported on. The composition, microstructure and mechanical properties of composite films were analyzed by various methods. The results presented in the paper should help to design of high-strength and toughness TiN-Ni films and to better understand the mechanism of formation of nanocomposite structures. In general, the paper is well written and the data look scientifically correct.

1. My major comment relates to the Conclusion section. In this section, the authors basically simply list the RESULTS that they obtained, rather than drawing CONCLUSIONS. What do these results mean to the scientific community? What lessons, so to speak, can be learned from them, etc. This section should be re-written.

Re: Thank you to the reviewers for recognizing our work and suggesting valuable changes. In response to your suggestion, we have rewritten the conclusion section in the revised version.

2. Minor comments relate to the Figures. In the caption to Fig. 5, image (f) is omitted (though commented on in the text).

Re: Thanks for your advice. We have added the description of figure 5f in the revised version.

3. In the caption to Fig. 4, the squares and dashed line should be explained. The reviewer believes that after minor revision this paper can be published in Nanomaterials, 

Re: Thank you for the reviewer's feedback. We have provided explanations for the dashed lines and squares in the revised version.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. Improvement is needed in the manuscript's English language usage. For example, the following sentence appears incomplete: “However, excellent wear resistance not only depends on the improvement of film hardness.”

 

2. Figure 5f is not referenced in the caption.

 

3. Figure 8f is not acknowledged in the caption.

 

4. What corroborates the assertion of a nanocrystalline structure when the authors state, "It can be seen from Figure 5a and b that 150 the composite film with 4.9 at.% Ni exhibits a nanocrystalline structure."?

 

5. The authors assert that the columnar grain size in Figure 5a and 5b is around 20 nm, but the figure does not illustrate anything close to 20 nm as the scale bar indicates 50 nm.

 

Comments on the Quality of English Language

Needs improvement.

Author Response

The authors would like to thank the editor and reviewers for the valuable comments and suggestions. Per your suggestions, the manuscript has been carefully revised. The following is the point by point response to the reviewers’ comments. Please note that all reviewer comments are shown in times new roman, while our response italics.

Reviewer #2:

1. Improvement is needed in the manuscript's English language usage. For example, the following sentence appears incomplete: “However, excellent wear resistance not only depends on the improvement of film hardness.”

Re: Thanks for your advice.We have made language improvements in the revised version.

2. Figure 5f is not referenced in the caption.

Re: Thanks for your advice. We have added the description of figure 5f in the revised version.

3. Figure 8f is not acknowledged in the caption.

Re: Thanks for your advice. We have added the description of figure 8f in the revised version.

4. What corroborates the assertion of a nanocrystalline structure when the authors state, "It can be seen from Figure 5a and b that 150 the composite film with 4.9 at.% Ni exhibits a nanocrystalline structure."?

Re: The figures 5a shows planar TEM images of 4.9 at.% Ni composite films. The figure 5b shows the dark field image of the corresponding region obtained by selecting the TiN (111) diffraction ring from the electron diffraction pattern. The bright spots in the figure represent a TiN grain that meets the diffraction conditions of the (111) plane.According to measurements, the size of these grains is approximately 10nm, indicating that the thin film has formed a nanocrystalline structure.

5. The authors assert that the columnar grain size in Figure 5a and 5b is around 20 nm, but the figure does not illustrate anything close to 20 nm as the scale bar indicates 50 nm.

Re: Thank you for the reviewer's feedback. This is an error. The grain size of the columnar crystal here should be approximately 10nm. We have made corrections in the revised version.

 

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents investigation of microstructure and mechanical properties of nanocomposite films prepared by sputtering. The authors focus on the relation between the Nickel content in Titanium Nitride films and the mechanical behavior of the films such as fracturing. Experimental data were obtained using different methods of structural analysis and nanoindentation. The results are well presented with clear figures. I am certain to recommend the manuscript for publishing.

I would like to mention few corrections.

Line 80, “the working air pressure …” the term is unclear. Please correct.

The film thickness is not indicated. Please clarify how you estimated the amount of deposited Ni from the RF power?

What is the indenter type, Berkovich ?

In Abstract, the grain size is 20 nm (line 20). In the text, it is 25 nm (line 130). Please correct.

How did you calculate the grain size in fig.3? Please add.

Line 194, an abbreviation “OM” is not clear.

A “filamentous structure” in fig.5d is not obvious. Please indicate.

The statement “the Ni content in this film far exceeds the solid solubility of the TiN lattice” (line 162) is interesting and needs additional discussion. Is there Ni solubility data ? Can you estimate it?

 

Author Response

The authors would like to thank the editor and reviewers for the valuable comments and suggestions. Per your suggestions, the manuscript has been carefully revised. The following is the point by point response to the reviewers’ comments. Please note that all reviewer comments are shown in times new roman, while our response italics.

Reviewer #3:

The manuscript presents investigation of microstructure and mechanical properties of nanocomposite films prepared by sputtering. The authors focus on the relation between the Nickel content in Titanium Nitride films and the mechanical behavior of the films such as fracturing. Experimental data were obtained using different methods of structural analysis and nanoindentation. The results are well presented with clear figures. I am certain to recommend the manuscript for publishing.

 

I would like to mention few corrections.

1. Line 80, “the working air pressure …” the term is unclear. Please correct.

Re: Thanks for your advice. We have corrected it to 'working pressure' in the revised version.

2. The film thickness is not indicated. Please clarify how you estimated the amount of deposited Ni from the RF power?

Re: Thank you for the reviewer's suggestion. We have indicated the thickness of the film in Figure 1 of the revised version. In addition, the content of Ni is not estimated through RF power, but is measured using EDS. We have also explained this in the revised version.

3. What is the indenter type, Berkovich ?

Re: The nanoindentation used in this work is equipped with a Berkovich indenter. Thank you for your suggestion, we have supplemented it in the revised version.

4. In Abstract, the grain size is 20 nm (line 20). In the text, it is 25 nm (line 130). Please correct.

Re: Thank you for your suggestion. We have made corrections in the revised manuscript.

5. How did you calculate the grain size in fig.3? Please add.

Re: The grain size in Figure 3 is calculated based on the experimental results of XRD using the Scheler formula. Thank you for your suggestion, we have provided explanations in the revised version.

6. Line 194, an abbreviation “OM” is not clear.

Re: Thank you for your suggestion. We have provided explanations in the revised version.

7. A “filamentous structure” in fig.5d is not obvious. Please indicate.

Re: Thank you for your suggestion. We have indicated it on Figure 5d in the revised version.

8. The statement “the Ni content in this film far exceeds the solid solubility of the TiN lattice” (line 162) is interesting and needs additional discussion. Is there Ni solubility data ? Can you estimate it?

Re: In the thermodynamic equilibrium state, TiN and Ni are completely immiscible systems. However, during the unbalanced magnetron sputtering process, the limitations of dynamic conditions result in Ni atoms solidly soluble in the lattice of TiN. The research on TiN/Ni nanocomposite films by Li et al. [1] shows that when Ni:Ti ratio is less than 1:24, Ni dissolve within the TiN matrix, forming a mechanical mixture of TiNiN. As Ni:Ti ratio rises to 4:21, due to the thermodynamic incompatibility between Ni and TiN, Ni phase can divide TiN crystals into nanocrystallites as an interfacial phase. In our work, it can be seen from the results in Figure 4 that as the Ni content increases, the maximum intragranular Ni content can reach about 5 at.%.

 

Reference

[1] Li, P. Liu, S. Zhao, K. Zhang, F.C. Ma, X.K Liu, X.H Chen, D.H. He, Microstructural evolution, mechanical properties and strengthening mechanism of TiN/Ni nanocomposite film. J. Alloys Compd. 691 (2017) 159-164.

 

 

Reviewer 4 Report

Comments and Suggestions for Authors

This work by Bingyang Ma et al. deals with microstructure and mechanical properties of magnetron sputtering TiN-Ni nanocrystalline composite films. It is an interesting paper and can be further considered after revision:

Line 76. “The substrate is monocrystalline silicon wafer.” A) I suppose the film grows on the native oxide of the silicon wafer. Please clarify. B) I do not see any Si diffraction in Fig. 2. Why?

Lines 78-86. What I understand is that the authors do co-deposition under Ar and nitrogen gas flow. It is well-known in literature that Ni also forms nitrides. In Fig. 2 one may see only TiN diffraction. Could it be possible to form small amount of Ni nitrides too that could not be detected by XRD?

Line 147: Put a space between “the” and “intragranular”.

Line 234 and on: If it was known that one needs only 1-2 at.% Cu to promote superhardness in ZrN-Cu composite films, why the authors here used larger amounts of Ni?

Author Response

Response to the Reviewer’s Comments

The authors would like to thank the editor and reviewers for the valuable comments and suggestions. Per your suggestions, the manuscript has been carefully revised. The following is the point by point response to the reviewers’ comments. Please note that all reviewer comments are shown in times new roman, while our response italics.

Reviewer #4:

This work by Bingyang Ma et al. deals with microstructure and mechanical properties of magnetron sputtering TiN-Ni nanocrystalline composite films. It is an interesting paper and can be further considered after revision:

1. Line 76. “The substrate is monocrystalline silicon wafer.” A) I suppose the film grows on the native oxide of the silicon wafer. Please clarify. B) I do not see any Si diffraction in Fig. 2. Why?

Re: The monocrystalline silicon wafer is a commonly used substrate in thin film preparation. We are not sure if there should be a native oxide layer on it surface. The substrate used in this work is (111) plane monocrystalline silicon. Its diffraction peak appears at the position of 2θ=28.447°. Due to the range of 2θ in figure2 is 30-80°, there is no diffraction peaks of the Si substrate.

2. Lines 78-86. What I understand is that the authors do co-deposition under Ar and nitrogen gas flow. It is well-known in literature that Ni also forms nitrides. In Fig. 2 one may see only TiN diffraction. Could it be possible to form small amount of Ni nitrides too that could not be detected by XRD?

Re: The previous research on TiN/Ni composite films generally does not believe that Ni nitrides will form in the films [1-3]. Even in ZrN/Ni [4], CrN/Ni [5] and other systems, there have been no reports of Ni nitrides formation. Pui et al. [6] could not even detect the presence of Ni-N bonds in CrN/Ni nanocomposite films using XPS. Therefore, Ni nitrides should also not be present in the film of this work.

3. Line 147: Put a space between “the” and “intragranular”.

Re: Thanks for your suggestions, we made corrections in the revised version.

4. Line 234 and on: If it was known that one needs only 1-2 at.% Cu to promote superhardness in ZrN-Cu composite films, why the authors here used larger amounts of Ni?

Re: The purpose of this work is not to obtain superhard TiN/Ni composite films, but to prepare nc-TiN/Ni nanocomposite structures, thereby toughening TiN films. According to the experimental results of this paper, when the Ni content is relatively low, Ni mainly exists in the crystal lattice of TiN in the form of solid solution. Only when the Ni content increased to 12.6 at.%, the film formed a nanocomposite structure of nc-TiN/Ni.

 

References

1. Akhter, A. Bendavid, P. Munroe, Effect of Ni content on the microstructure and mechanical properties of TiNiN coatings, Appl. Surf. Sci.573 (2022) 151536.
2. P. Sahu, M. Ray, R. Mitra, Structure and properties of Ni_1-xTi_xN thin films processed by reactive magnetron co-sputtering, Mater. Charact. 169 (2020) 110604.
3. Li, P. Liu, S. Zhao, K. Zhang, F.C. Ma, X.K Liu, X.H Chen, D.H. He, Microstructural evolution, mechanical properties and strengthening mechanism of TiN/Ni nanocomposite film. J. Alloys Compd. 691 (2017) 159-164.
4. Musil, P. Karvankova, J. Kasl, Hard and superhard ZrNiN nanocomposite films, Surf. Coat. Technol. 139 (2001) 101-109.
5. Karvankova, H.D. Mannling, C. Eggs, S. Veprek, Thermal stability of ZrN–Ni and CrN–Ni superhard nanocomposite coatings, Surf. Coat. Technol. 146-147 (2001) 280-285.
6. C. Wo, P.R.Munroe, Z.T. Jiang, Z.F. Zhou,K.Y. Li, Z.H. Xie, Enhancing toughness of CrNcoatings by Ni addition for safety-critical applications, Mater. Sci. Eng.A. 596(2014)264-274.

 

Reviewer 5 Report

Comments and Suggestions for Authors

The paper studies TiN film grown with the co-deposition of Ni by magnetron sputtering. The goal is to control the mechanical properties of the nitride, typically used as a coating to improve wear resistance. The Authors deposited films with different concentrations of Ni and analyzed them using different tools. The scientific quality and soundness are good, and the results, discussion, and conclusions are self-consistent and convincing, although different from previous studies. However, a few issues still must be addressed:

1.       Results: The EDAX analysis is announced in the Experimental session but needs to be clearly presented in the results, even if the Authors mention the Ni atomic percentages. A table presenting all Ti, N, and Ni stoichiometries is necessary to define the correct Ti/N ratio.

2.       Figure 5c, f: The Authors should change the red color to improve clarity.

3.       Some repetitions are present (lines 41-42, 65-66, etc.). Some typos are present (lines 69, 87, etc.).

Comments on the Quality of English Language

English language quality is very good, a few typos are present.

Author Response

The authors would like to thank the editor and reviewers for the valuable comments and suggestions. Per your suggestions, the manuscript has been carefully revised. The following is the point by point response to the reviewers’ comments. Please note that all reviewer comments are shown in times new roman, while our response italics.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I see minor corrections were made in the revised version.

This manuscript does not have a significant scientific novelty. The manuscript lacks substantiation regarding the presence of Ni within the thin films. Furthermore, the manuscript does not offer a scientific rationale for how the incorporation of Ni has positively influenced the properties of the thin film. Although the abstract mentions the utilization of EDS analysis, no corresponding EDS data is included within the manuscript.

 

Author Response

Response to the Reviewer’s Comments

The authors would like to thank the editor and reviewers for the valuable comments and suggestions. The following is the point by point response to the reviewers’ comments. Please note that all reviewer comments are shown in times new roman, while our response italics.

Reviewer #2:

I see minor corrections were made in the revised version.

1. This manuscript does not have a significant scientific novelty. The manuscript lacks substantiation regarding the presence of Ni within the thin films.

Re: Thank you for your suggestion. In fact, the proof of the existence of Ni is provided. The EDS analysis results in figure 1 show that the Ni content in the thin film increases with the increase of Ni target power. The XRD results in Figure 3 demonstrate the absence of crystalline Ni in the film. The results in figure 5 indicate that not all the Ni atoms are solidly soluble in the lattice of TiN. The excess Ni may exist at grain boundaries in amorphous form. The TEM results in figure 6 further confirm this conclusion.

2. Furthermore, the manuscript does not offer a scientific rationale for how the incorporation of Ni has positively influenced the properties of the thin film.

Re: The results of figures 7, 8, 9, and 10 indicate that with the increase of Ni content, although TiN-Ni thin films lose some of their hardness, their toughness is significantly improved.

3. Although the abstract mentions the utilization of EDS analysis, no corresponding EDS data is included within the manuscript.

Re: Thank you for your suggestion. In fact, the manuscript contains EDS data. The figure 1 shows the variation of Ti, Ni, and N contents with Ni target power obtained using EDS analysis. We have indicated it in the revised manuscript.