Influence of the Thickness of Multilayer Composite Nano-Structured Coating Ti–TiN–(Ti,Al,Si)N on the Tool Life of Metal-Cutting Tools and the Nature of Wear

Round 1

Reviewer 1 Report

Paper needs major revision, at least

1. Paper lacks novelty. Nano-composite coatings have been intensively studied by various research groups. first of all by Veprek. What is the significant difference between previous and presented studies?
2. Paper is too long and contains excessive amount of data (24 figures).
3. It is well known that the optimal PVD coatingthickness should be within 3-5 microns. All the commercial coatings from Kennametal, Sandvik, Balzers are within  this  range of the thickness.
4. What is novel?
5. Paper lacksd information on residual stresses data. This is mandatory data to  be presented and related to micro-mechanicacal properties and wear resistance of the coatings studied.

Author Response

Comments and Suggestions for Authors

The authors are grateful to the Reviewer for valuable comments and help in improving the quality of the article.

Paper needs major revision, at least

1. Paper lacks novelty. Nano-composite coatings have been intensively studied by various by Veprek research groups. first of all by Veprek. What is the significant difference between previous and presented studies?

Authors with undoubted respect for the writings of Professor Stanislav Veprek and his colleagues. A section has been added to the Introduction that considers the contribution of this scientific group to the development of nanocomposite coatings. Of course, the authors do not claim to invent a coating based on the system (Ti, Al, Si) N. The Introduction provides a fairly comprehensive overview of the works exploring this wear-resistant coating. The authors believe (and hope) that the novelty of this article is as follows:

The nature of deposition and the structure of nanocomposite coatings are considered, including an extremely large (for the PVD method) thickness. It was established that the coating structure (including the thickness of nanolayers) does not change over the entire thickness of the coating, and the deposition rate does not depend on the thickness of the coating. the rational thickness of the wear-resistant coating layer was established when turning the material of the machinability group P (steel C45), at various cutting speeds. This thickness was 5-7 microns (when turning AISI 321 steel - machinability group M according to ISO 513, in previous studies this thickness was 3-5 microns) differences in the nature of wear and failure of coatings of various thicknesses during steel turning are considered. The effect of coating thickness on its hardness and the nature of failure during scratch testing was investigated. using TEM, the process of formation of a coating nanostructure, its crystalline and phase structure is considered

2. Paper is too long and contains excessive amount of data (24 figures).

Some figures were combined and their number has now decreased

3. It is well known that the optimal PVD coating thickness should be within 3-5 microns. All the commercial coatings from Kennametal, Sandvik, Balzers are within  this  range of the thickness.

This study shows that a tool with coatings in which the wear-resistant layer has a thickness of 5-7 μm (total coating thickness of 6-8 μm) showed the best resistance period. This thickness is slightly larger than the thickness commonly used and indicated by the Reviewer.

4. What is novel?

The authors tried to answer this question above.

5. Paper lacksd information on residual stresses data. This is mandatory data to  be presented and related to micro-mechanicacal properties and wear resistance of the coatings studied.

The authors fully agree with the Reviewer and also believe that the study of residual stresses is necessary. However, given the large volume of this article, the authors decided to devote a separate article to the study of residual stresses in coatings, depending on their thickness. Such an article has now been completed and will be sent for consideration to the Coatings in the near future.

Reviewer 2 Report

In this paper, the authors studied the effect and relationship between the tool life and the cutting speed of the multilayer composite thickness of Ti-TiN-(Ti,Al,Si,)N with varying thicknesses. They found that the higher thickness (11-15 µm) drastically reduces the tool life with an increase in the cutting speed. They also studied the defects and cracks associated with the coatings. Overall, the study and analysis are detailed. The references are also relevant and recent. The aim of the study is clear and the title is also informative and the abstract matches the rest of the article. I have the following minor comments for the authors.

Please cite some statements where necessary. For example, on page 2, line 55, "There are several studies............for different cutting conditions." Kindly provide references for this statement. Since there are already a lot of figures in this article I would recommend the authors to merge Table 2  with Fig. 4. By doing so reads will be able to correlate the sample name and sample thickness with clarity and also the number of Figures will reduce.   Page 5, line 189. There is no Figure 2b. Page 17, line 298. Incorrect table number. In figure 15, I suggest the authors to label the figures with cutting speed inside the graph. Readers should be able to understand the figure without reading the figure caption. I also suggest the authors to combine the Figs. 17-23 as one group. Readers will be able to better compare and understand the difference in the wear and failure for the different samples.

Author Response

Comments and Suggestions for Authors

The authors are grateful to the Reviewer for valuable comments and help in improving the quality of the article.

In this paper, the authors studied the effect and relationship between the tool life and the cutting speed of the multilayer composite thickness of Ti-TiN-(Ti,Al,Si,)N with varying thicknesses. They found that the higher thickness (11-15 µm) drastically reduces the tool life with an increase in the cutting speed. They also studied the defects and cracks associated with the coatings. Overall, the study and analysis are detailed. The references are also relevant and recent. The aim of the study is clear and the title is also informative and the abstract matches the rest of the article. I have the following minor comments for the authors.

1. Please cite some statements where necessary. For example, on page 2, line 55, "There are several studies............for different cutting conditions." Kindly provide references for this statement.

references added

2. Since there are already a lot of figures in this article I would recommend the authors to merge Table 2  with Fig. 4. By doing so reads will be able to correlate the sample name and sample thickness with clarity and also the number of Figures will reduce.  

In accordance with the recommendations of the Reviewer, some Figures were combined and, thus, the number of figures was reduced. However, in this case, the authors consider it not entirely advisable to combine Table 2, which represents the initial deposition conditions (it is in the Materials and Methods section) and Figure 4, which presents the results of the study of the coating structure (it is located in the Results section).

3. Page 5, line 189. There is no Figure 2b.

Corrected. Thank you!

4. Page 17, line 298. Incorrect table number.

Corrected. Thank you!

5. In figure 15, I suggest the authors to label the figures with cutting speed inside the graph. Readers should be able to understand the figure without reading the figure caption.

Designation of cutting speeds added directly to the graphs

6. I also suggest the authors to combine the Figs. 17-23 as one group. Readers will be able to better compare and understand the difference in the wear and failure for the different samples. 

The figures have been combined wherever possible.

Reviewer 3 Report

The manuscript “Influence of the thickness of multilayer composite nano-structured coating Ti-TiN-(Ti,Al,Si)N on the tool life of metal-cutting tools and the nature of wear” coauthored by Vereschaka et al. had been carefully reviewed.

This work contributes useful results to the field of wear-resistant coatings for cutting tools. It is believed that the readers will be interested in this work. I have only a few suggestions as below for improving the readability of the manuscript.

The description of the experimental method is not clear, especially in the coating process. To make it easier for the readers to understand the experimental details, I strongly encourage the authors to draw a diagram of the coatings depositing system to assist in explaining how to prepare the samples and their deposition parameters. Besides, what is the material of the “carbide tools” mentioned in this work? Is it tungsten carbide? In addition, the English needs to be polished.

Author Response

Comments and Suggestions for Authors

The authors are grateful to the Reviewer for valuable comments and help in improving the quality of the article.

1. The manuscript “Influence of the thickness of multilayer composite nano-structured coating Ti-TiN-(Ti,Al,Si)N on the tool life of metal-cutting tools and the nature of wear” coauthored by Vereschaka et al. had been carefully reviewed.

This work contributes useful results to the field of wear-resistant coatings for cutting tools. It is believed that the readers will be interested in this work. I have only a few suggestions as below for improving the readability of the manuscript.

The description of the experimental method is not clear, especially in the coating process. To make it easier for the readers to understand the experimental details, I strongly encourage the authors to draw a diagram of the coatings depositing system to assist in explaining how to prepare the samples and their deposition parameters.

Additional diagram added in Figure 5a

2. Besides, what is the material of the “carbide tools” mentioned in this work?

Is it tungsten carbide?

Added carbide grade. (79%WC, 15%TiC, 6%Co, KZTS, Russia)

3. In addition, the English needs to be polished.

English is additionally verified

Round 2

Reviewer 1 Report

Accept