Review Reports - Impact Resistance of CVD Multi-Coatings with Designed Layers

Round 1

Reviewer 1 Report

The work is good but It is required to incorporate the suggestions/comments.

1. There are two types of milling up and down. In one impact resistance is required. It is not very clear that which type author want to discuss. calrify.

2. The abstract should be quantitative.

3. The author should elaborate more on the objective of the work.

4. The author should report the supplier name, model and make of equipment.

5. Impact test is to type Izod and Charpy. But the author did indentation test. How has been the author relates the two different test and name as impact test. Further, it is a kind of fatigue test rather then impact test. Justify.

6. The scientific explanation of the obtained results are missing. It is required.

7. The conclusion should also be quantitative in terms of percentage improvement.

Author Response

Dear Reviewer:

Thank you for your comments concerning our manuscript entitled “Impact resistance of CVD multi-coatings with designed layers”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections which we hope meet with approval. The main correction in the manuscript and the response to the reviewer’s comments are as flowing:

Question: There are two types of milling up and down. In one impact resistance is required. It is not very clear that which type author want to discuss. calrify.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript. The simulation in this article is down milling, as the blade cuts into the surface of the workpiece during the down milling process, which is consistent with the fatigue impact situation simulated in the experiment.

The impact resistance test methods was propsed to simulate the impact due to cut-in during down milling process.

Question: The abstract should be quantitative.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Obtain the load by setting an impact depth of 25/30/35 µm, record the impact force during the impact process, and calculate the contact stress; It was found that at the impact depth of 25/30/35 µm, the download loads were around 9/11/13 N, while the contact stresses were all around 1 GPa.

Experiments have shown that an increase in coating thickness and total coating thickness reduces impact resistance by about 10%. The impact resistance of coating samples without TiN surface layer also decreased by about 10%.

Question: The author should elaborate more on the objective of the work.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Through the damage situation of various coated tools obtained from this study, we look forward to selecting the most high-performance coated tools, and hope to have some experience and summary on the impact of coating thickness on tool performance. This will help to further change the layer thickness parameters of CVD tools and improve their performance in the future.

After analyzing the above results, it was found that the presence of TiN coating mainly changes the surface damage form of the coating (radial cracks or circular cracks). The thickness of the TiN surface should not be too small, otherwise surface peeling may occur. In this experiment, an increase in the total thickness of the coating slightly reduced its performance. Therefore, among the four coating tools, Coating tool A has the best performance, Coating tool D has the worst performance, and Coating tool B and Coating tool C have similar performance, both slightly lower than Coating tool A. In subsequent research, coating tools with different coating parameters can be further prepared to obtain the optimal coating thickness through experiments.

Question: The author should report the supplier name, model and make of equipment.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

The mechanical motion module of the cyclic impact test device is composed of a linear motor and a two-dimensional slide. The linear motor adopts Kollmorgen's linear motor rotor (model IC22150A2TRP1) and linear motor stator (model MC1500512001), supplemented by marble base, guide rail drag chain, roof, and grating ruler. The overall representation is in the form of a linear motor in Figure 2. The linear motor actuator and the linear motor stator rod, as well as the guide rail drag chain, are used to achieve the relative motion of the fixed part of the electric motor. The grating ruler is used to provide accurate position information, and the roof is placed on the linear motor actuator to load the "piezoelectric actuator" onto the linear motor. The linear motor is driven by Kollmogen's AC (alternating current) driver (model AKD-P01206-NBEC-0000), Thus achieving linear motion of piezoelectric actuator. The schematic diagram of the entire device is shown in Figure 2, and the main parameters of the linear motor device are shown in Table 2.

Question: Impact test is to type Izod and Charpy. But the author did indentation test. How has been the author relates the two different test and name as impact test. Further, it is a kind of fatigue test rather then impact test. Justify.

Response: Thanks for the reviewer’s professional suggestion, The experiment in this article is not an indentation test, but rather a simulated failure of each cutting tooth surface under a cyclic stress of 30Hz under milling conditions. In fact, it is indeed a fatigue test. Since the piezoelectric actuator generates a stress impact perpendicular to the coating surface, it is called a cyclic impact test.

Question: The scientific explanation of the obtained results are missing. It is required.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

By comparing the damage situation of four coating tools, it was found that they were subjected to similar stress conditions, but their damage was different. The surface morphology of coating tool A was the most complete among the four samples, indicating that coating tool A has the best ability to resist compressive and tensile stresses; The surface damage of coated tool B is slightly increased compared to coated tool A in terms of radial cracks, but no circular cracks have yet appeared, indicating that coated tool B has a better ability to resist tensile stress, but its ability to resist compressive stress is slightly lower than that of coated tool A; The surface damage of coating tool C is mainly caused by circular cracks, without obvious radial cracks, indicating that its resistance to compressive stress is slightly stronger than that of coating tools A and B, but its resistance to tensile stress is poor; Coating tool D exhibited a large number of radial cracks at an impact depth of 25 µm, and surface delamination occurred at an impact depth of 35 µm, indicating its poor compressive stress ability, but its resistance to tensile stress cannot be determined yet. In summary, coated tool A has the best fatigue resistance, while coated tools B and C are slightly weaker, while coated tool D exhibits the worst fatigue resistance.

Question: The conclusion should also be quantitative in terms of percentage improvement.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Coating tool B increased the total layer thickness of coating A by 1.3 times. The study found that under the same impact cyclic load, the surface damage of coated tool B increased by about 10% compared to that of coated tool A, indicating that the fatigue impact resistance of coated tool A with an increase in total thickness was slightly lower than that of coated tool A.

However, the experiment found that this thickness change would cause more cracks to appear in coated tool D. When the impact depth was 30 µm, the surface cracks of coated tool D increased by more than 50% compared to coated tool A. At an impact depth of 35 µm, there was even a phenomenon of surface layer peeling.

Reviewer 2 Report

In the manuscript "Impact resistance of CVD multi-coatings with designed layers" four different CVD coatings with different layer thickness were designed and prepared. The impact resistance test methods was propsed to simulate the impact due to cut-in and cut-out during milling process. The impact forces were recorded during the impact process and the contact stresses were calculated. The failure morphology of coating surface was investigated after the impact process.
The comments on the manuscript are as follows:
1. In Figure 5, the scale bars are very poorly visible.
2. In the methods part does not describe which substrate was coated (alloy and approximate composition).
3. In conclusion 2, the designation of the coating is missing, with which the coating C is compared.
4. From the methods part it is not clear how many coatings were studied for each type of sample. How statistically reasonable is it to draw conclusions about the coincidence of the results obtained from this number of samples?
5. Comparison of coatings is carried out in the form of a statement of the fact of the formation of cracks without comparing the mechanical properties of individual components of the coating.
6. It would be necessary to add a change in the composition of the coating in depth on the SEM images.

Minor editing of English language required.

Author Response

Dear Reviewer:

Question: In Figure 5, the scale bars are very poorly visible.

Response: Thanks for the reviewer’s professional suggestion, the scale of Figure 5 in the text has been changed.

Question: In the methods part does not describe which substrate was coated (alloy and approximate composition).

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

The substrate is made of hard alloy material produced by Xiamen Golden Egret Special Alloy Co., Ltd., brand GU20. Its chemical composition is 10.3% Co and 89.7% WC and others, with a grain size of 0.8 µm.

Question: In conclusion 2, the designation of the coating is missing, with which the coating C is compared.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Comparing coating A and coating C, the difference between the two coatings is that coating tool C removes the TiN layer and increases the thickness of the Al₂O₃ and TiCN layers, and the overall thickness remains almost unchanged.

Question: From the methods part it is not clear how many coatings were studied for each type of sample. How statistically reasonable is it to draw conclusions about the coincidence of the results obtained from this number of samples?

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

In order to ensure that the test results do not have contingency, three points at different positions on the sample were randomly selected for fatigue test in each group of tests, and three control experiments were carried out. Through observation, it was found that the results of the three groups of experiments were consistent.

Question: Comparison of coatings is carried out in the form of a statement of the fact of the formation of cracks without comparing the mechanical properties of individual components of the coating.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Therefore, among the four coating tools, Coating tool A has the best performance, Coating tool D has the worst performance, and Coating tool B and Coating tool C have similar performance, both slightly lower than Coating tool A.

Question: It would be necessary to add a change in the composition of the coating in depth on the SEM images.

Response: Thanks for the reviewer’s professional suggestion. The change in the composition of the coating in depth on the SEM images are set in fig.1

Reviewer 3 Report

1. The subject addressed in the article is of current interest and consistent with the journal's profile.

2. It is not recommended to use abbreviations in the article abstract. When an abbreviation is used for the first time in the text of the article, it is necessary to immediately explain its meaning (see the abbreviations CVD, PVD, AC, etc.).

3. On page 2, the wording " Taking coating A as the benchmark, the difference between coating B and A is that the thickness of each layer of coating B is magnified by 1.3 times in equal proportion to coating A; while coating C is removed from the TiN layer, the ratio of TiN layer and Al2O3 in the overall sample is changed, and its total thickness is close to coating A; coating D is mainly changed the ratio of Al2O3 and TiCN, and the total thickness is consistent with coating A." is long, and the idea is not clearly expressed.

4. In the last paragraph on page 5, a simple enumeration of the linear motor components is not recommended. It is desirable to have clarifications of the functional roles of the respective components. In the text, it is mentioned "piezoelectric ceramic actuator", while in Figure 2, it is written "piezoelectric ceramic brake". In the same paragraph, it is mentioned "The linear grating system and the AC servo driver are used for accurate feed-back of linear displacement of the linear motor.", in Figure 2 neither the AC servo driver nor the "grating" system are highlighted.

5. In line 117, it is mentioned that " The sample material is attached to the vibration output terminal ". The expression is unclear: not the sample material is attached, but the sample itself. Moreover, there are quite a few unclear elements in explaining how the equipment used works. For example, in lines 125-126, it is mentioned that "The dynamometer sensor is a Kistler type 9203 single component micro force sensor that is fixed to the linear motor through a thread", but in Figure 2, no connection between the dynamometer and the linear motor (the figure says "Linear motors", which would mean there are many motors).

6. It is useful to mention the manufacturers of the various components of the research equipment used.

7. Where is the vibration amplitude of the sample mentioned?

8. Lines 149-150 mention using an ultrasonic generator, but the impact frequency (1-1000 Hz, according to the information in line 136) does not belong to the ultrasonic field.

9. The formulation "One end of the dynamometer is attached to the indenter, while the other end is connected to a charge amplifier" is confusing. According to the schematic representation in Figure 2, the second end of the dynamometer appears to be attached to the slide.

10. An impact frequency of 30 Hz when milling at a rotational speed of 1800 rpm would only be valid if the milling cutter had only one cutting tooth, which was not mentioned in the paper.

11. The symbols used in the (unnumbered) relationship on page 9 were not explained.

12. The first paragraph of the conclusions section mentions that "A cyclic impact system based on piezoelectric ceramic actuator is invented". The novelty elements of this system could be compared, for example, with the system shown in Figure 14 in the paper of Bouzakis, Konstantinos‐Dionysios, Skordaris Georgios, Bouzakis Emmanouil, Michailidis Nikolaos. Characterization methods and performance optimization of coated cutting tools. ANNALS of Faculty Engineering Hunedoara – International Journal of Engineering, Tome XII [2014] – Fascicule 1 [February], 121-132, https://annals.fih.upt.ro/pdf-full/2014/ANNALS-2014-1-19.pdf.

13. The method of entering references in the list of references is not recommended by the journal.

14. A definition of the concept of "fatigue impact load increase" could be included in the paper.

15. Some sections required by the template proposed by the journal are missing (Author contribution, Funding, Conflicts of Interest).

16. Authors should pay more atention to article editing and English expression.

There are thus editing mistakes. For example, in line 13, "impat" was written instead of "impact". In line 40, the reference to a reference was made as an index. In numerous cases in the article, no blank spaces were left between the word and the following bibliographic reference (in line 34, ”resistance [1]” instead of ”resistance[1]”, in line 37, ”loads [4] ” instead of ”loads[4]”, etc.), between the number and the unit of measure (in line 42, ”1 kHz”, instead of ”1kHz”, in line 61, ” 40-200 m/min [13,14]" instead of "40-200m/min[13,14]" and in some tables and figures in the article, etc.).

In line 71, the definite article "The" begins with a capital letter, even though it is inside a sentence.

In line 55, "duration time" is used, but the two words have partially overlapping meanings.

In line 89, a comma is also required before the word "respectively".

In line 91, in the wording "Table 1 below shows", the word "below" is not necessary.

In Table 1, one could write "Outer layer TiN (μm)" instead of "OuterLayer TiN(μm)" (the use of a capital letter at the beginning of the word "layer" is not justified, a blank space is required before the bracket).

Generally, a blank space is left after the period used as a spelling mark (at the end of a sentence). Such a convention is not followed, for example, in the first paragraph of the conclusion section. Also, the second sentence in the paragraph ends with a semicolon, after which the next sentence begins with a capital letter.

Page 3 contains no text from the paper.

The title of section 3.1 could start with a capital letter.

16. Many of the expressions in the article are confusing. A reanalysis of the article's content by the authors is needed for a clearer presentation of their arguments. It is necessary to check the sentences in the article by someone who knows English better.

See the comments for the authors.

Author Response

Dear Reviewer:

Question: It is not recommended to use abbreviations in the article abstract. When an abbreviation is used for the first time in the text of the article, it is necessary to immediately explain its meaning (see the abbreviations CVD, PVD, AC, etc.).

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Question: On page 2, the wording " Taking coating A as the benchmark, the difference between coating B and A is that the thickness of each layer of coating B is magnified by 1.3 times in equal proportion to coating A; while coating C is removed from the TiN layer, the ratio of TiN layer and Al2O3 in the overall sample is changed, and its total thickness is close to coating A; coating D is mainly changed the ratio of Al2O3 and TiCN, and the total thickness is consistent with coating A." is long, and the idea is not clearly expressed.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Firstly, coating A was prepared as a TiN layer with a thickness of 1.47 μm. The thickness of the Al₂O₃ layer is 4.33 μm, TiCN layer thickness is 9.45 μm. Coating B was formed by increasing the thickness of each layer of coating A by 30%; Coating C only has two layers with 5.08 μm of Al₂O₃ and 9.96 μm of TiCN; Coating D reduces the thickness of TiN layer and Al₂O₃ layer but increases the thickness of TiCN layer, making its total thickness consistent with coating A.

Question: In the last paragraph on page 5, a simple enumeration of the linear motor components is not recommended. It is desirable to have clarifications of the functional roles of the respective components. In the text, it is mentioned "piezoelectric ceramic actuator", while in Figure 2, it is written "piezoelectric ceramic brake". In the same paragraph, it is mentioned "The linear grating system and the AC servo driver are used for accurate feed-back of linear displacement of the linear motor.", in Figure 2 neither the AC servo driver nor the "grating" system are highlighted.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Question: In line 117, it is mentioned that " The sample material is attached to the vibration output terminal ". The expression is unclear: not the sample material is attached, but the sample itself. Moreover, there are quite a few unclear elements in explaining how the equipment used works. For example, in lines 125-126, it is mentioned that "The dynamometer sensor is a Kistler type 9203 single component micro force sensor that is fixed to the linear motor through a thread", but in Figure 2, no connection between the dynamometer and the linear motor (the figure says "Linear motors", which would mean there are many motors).

Response: Thanks for the reviewer’s professional suggestion. In line 117, it should actually be 'the sample is connected to the vibration output terminal'. In addition, the dynamometer sensor is the Kistler 9203 single component micro force sensor, which is fixed on a two-dimensional slider through a thread (rather than a linear motor), and a charge amplifier is connected to the back of the Kistler 9203. It has been revised in the manuscript.

The dynamometer sensor is a Kistler type 9203 single component micro force sensor that is fixed to the two-dimensional slider through a thread.

Question: It is useful to mention the manufacturers of the various components of the research equipment used.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Question: Where is the vibration amplitude of the sample mentioned?

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

The impact depth H of this experiment is set to 20/25/30/35 µm (the piezoelectric actuator used in the experiment is P-843.40 produced by PhysikInstrumente. The amplitude of the piezoelectric actuator is controlled by controlling the voltage output from the signal generator. The amplitudes of 20/25/30/35 µm correspond to voltage signals of 3.33/17/5.83 V respectively),

Question: Lines 149-150 mention using an ultrasonic generator, but the impact frequency (1-1000 Hz, according to the information in line 136) does not belong to the ultrasonic field.

Response: Thanks for the reviewer’s professional suggestion, the “ultrasonic generator” here should be “piezoelectric actuator”, and it has been revised in the manuscript.

Question: The formulation "One end of the dynamometer is attached to the indenter, while the other end is connected to a charge amplifier" is confusing. According to the schematic representation in Figure 2, the second end of the dynamometer appears to be attached to the slide.

Response: Thanks for the reviewer’s professional suggestion, the dynamometer is fixed on a two-dimensional sliding platform through a thread, with one end connected to a diamond indenter and the other end connected to a charge amplifier through a data cable. The article has redrawn the schematic diagram of the device connection.

Question: An impact frequency of 30 Hz when milling at a rotational speed of 1800 rpm would only be valid if the milling cutter had only one cutting tooth, which was not mentioned in the paper.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

In the cyclic impact test, the impact time is set to 240 seconds. During the milling process, the speed of the milling cutter is usually 1800r/min, and each cutting tooth is impacted 30 times per second. Therefore, the impact frequency is set to 30Hz to simulate the impact on the cutting tooth at a milling speed of 1800r/min.

Question: The symbols used in the (unnumbered) relationship on page 9 were not explained.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Question: The first paragraph of the conclusions section mentions that "A cyclic impact system based on piezoelectric ceramic actuator is invented". The novelty elements of this system could be compared, for example, with the system shown in Figure 14 in the paper of Bouzakis, Konstantinos‐Dionysios, Skordaris Georgios, Bouzakis Emmanouil, Michailidis Nikolaos. Characterization methods and performance optimization of coated cutting tools. ANNALS of Faculty Engineering Hunedoara – International Journal of Engineering, Tome XII [2014] – Fascicule 1 [February], 121-132, https://annals.fih.upt.ro/pdf-full/2014/ANNALS-2014-1-19.pdf.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

In [26], the sample is attached to a two-dimensional slide, while in this platform, the sample is attached to the sample stage and connected to a piezoelectric actuator through a thread. At the same time, the pressure head is connected to the force measuring instrument and fixed on the two-dimensional slide. This improvement makes it more efficient to replace the sample in practical applications.

Question: The method of entering references in the list of references is not recommended by the journal.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Question: A definition of the concept of "fatigue impact load increase" could be included in the paper.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

(Taking coating A as an example, when the impact depth is 25 µm is the fatigue impact load of 9.42N, and when the impact depth is 35 µm is the fatigue impact load of 13.21N).

Question: Some sections required by the template proposed by the journal are missing (Author contribution, Funding, Conflicts of Interest).

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Question: Authors should pay more atention to article editing and English expression.

In line 71, the definite article "The" begins with a capital letter, even though it is inside a sentence.

In line 55, "duration time" is used, but the two words have partially overlapping meanings.

In line 89, a comma is also required before the word "respectively".

In line 91, in the wording "Table 1 below shows", the word "below" is not necessary.

Page 3 contains no text from the paper.

The title of section 3.1 could start with a capital letter.

Response: Thanks for the reviewer’s professional suggestion. It has been revised in the manuscript.

Round 2

Reviewer 1 Report

No Comments

Author Response

Thank you so much for your attention and time.

Reviewer 2 Report

The comments have been corrected and the manuscript may be published.

Minor editing of English language required

Author Response

Thank you so much for your attention and time.

Reviewer 3 Report

In principle, the authors responded adequately to the comments made. There is still the possibility of making some corrections when editing the final version of the paper (1. Blank spaces between numbers and units of measure; write "1800 r/min" instead of "1800r/min" in line 178 and other places in article 2. The word "coating" may begin with a low letter in lines 104 and 105, after the semicolon; 3. A blank space is necessary in line 201, after the period, before the word "By"; 4. The highlighting mode of the "Author contributions" does not seem to be the recommended one (it is recommended to use the initials of the first and last names of the authors); 5. The list of bibliographic references is not prepared in compliance with all the recommendations in the article template. It is not polite to use the abbreviation "et al." when there are more than three authors. Abbreviated journal titles must be used. A comma is required between the last name and the first initial of each author's first name. The separator between author names is a semicolon, not a comma, etc.), etc.).

See the comments for the authors.

Author Response

Please see the attachment.

Author Response File: Author Response.docx