Effect of Zr Target Current on the Mechanical and Tribological Performance of MoS2–Zr Composite Lubricating Coatings
Round 1
Reviewer 1 Report
Literature citing should be formatted according to the standard requirements. But not [6-13], [22-35] or [31-35]. What has been done in [6]? What is the difference between research results in [7] and [8]? Why information was presented in [9] ir taip toliau? Careful elaboration is required on these questions.
In part 3.1, a lot of experimental results are introduced, however they are not properly explained. I do not think it is enough to just say that they are consistent with previous findings. Is it definitely true that in all the sources mentioned the results are similar? I suggest elaborating on the results from fig 2 to fig 12.
The statement on intrinsic stress is not clear. Only the stress equation is given, but it is not clear where are the counting methods. Fig 8 gives the results of the intrinsic stress experiment that should be explained in more detail.
The figure and its title must be in the same page.
Author Response
Dear Reviewer:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Effect of Zr target current on the mechanical and tribological performance of MoS2-Zr composite lubricating coatings” (ID: coatings-681646). These 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. In order to clearly show the changes of the manuscript to the editors and reviewers, the function of "Track Changes" in Microsoft Word was used, and the revised manuscript can be displayed properly by clicking the final status without markup in the review tab. The main corrections in the paper and the responds to the reviewer’s comments are as flowing:
Responds to the reviewer’s comments:
Comments and Suggestions for Authors
Literature citing should be formatted according to the standard requirements. But not [6-13], [22-35] or [31-35]. What has been done in [6]? What is the difference between research results in [7] and [8]? Why information was presented in [9]? Careful elaboration is required on these questions.
Response:
Considering the Reviewer’s suggestion, the literature citing was formatted according to the standard requirements, and elaboration was provided in the introduction as follows:
Early hard coatings are mainly composed of binary nitrides, carbides and oxides such as TiN [2], TiC [3] and Al2O3 [4]. With the rapid development of material science and coating technology, the multi component composite coatings and multilayer composite coatings, such as TiCN [5], AlCrN [6], TiAlN [7,8], CrSiCN [9], TiAlSiN [10-12] and so on [13], have attracted increasing research, which exhibit much higher surface hardness and more excellent tribological properties.
In order to enhance the tribological properties of pure MoS2 coating, an appropriate amount of metal has been added into the sulfide matrix. Because of the addition of metal, the MoS2-metal lubricating coatings, such as MoS2-Ti [23-25], MoS2-Cr [26,27], MoS2-W [28], MoS2-Zr [29-33], MoS2-Ni [34] and MoS2-Pb [35], exhibit better properties in surface hardness and wear resistance, and have been successfully used in the machining field, such as drilling and turning.
Based on the theoretical and experimental studies, the MoS2-Zr lubricating coatings through adding Zr additives can effectively enhance the tribological properties in sliding wear tests [29,30] and dry cutting tests [31,32]. Meanwhile, the effects of test conditions [29,33], such as applied load and sliding speed, on the tribological behaviors were also studied. The MoS2-Zr composite coatings have been mainly applied in the intermittent cutting and continuous low-speed machining due to the sensitive to high temperature (>550 °C) [31].
In part 3.1, a lot of experimental results are introduced, however they are not properly explained. I do not think it is enough to just say that they are consistent with previous findings. Is it definitely true that in all the sources mentioned the results are similar? I suggest elaborating on the results from fig 2 to fig 12.
Response:
Considering the Reviewer’s suggestion, elaborating on the results of the figures in part 3.1 was provided in the corresponding paragraph. The main modifications are as follows
The surface morphologies of the composite coatings with different Zr current are shown in Figure 2. Figure 2a shows the SEM micrograph of pure MoS2 coating without addition of Zr. Because the thickness of the pure MoS2 coating was just about 0.55 μm (see Figure 11), the grain structure of WC/TiC/Co substrate can still be seen through surface coating. Figures 2b-f show the micrographs of the MoS2-Zr composite coatings with the Zr current from 30 A to 100 A. The substrate surface with composite coatings can no longer be seen owing to a significant increase in thickness. However, the surface voids of the composite coatings were obvious, and the number void increased with Zr current, which can lead to the increase of surface roughness. Figure 3 show the coating surface topography measured by the NT9300 optical profiling tester, and the average values of coating surface roughness under different Zr current are summarized in Figure 4. As shown in these figures, the coating surface became rougher with the increase of Zr current. The pure MoS2 coating exhibited the minimum surface roughness (Ra 49±5 nm), and the composite coatings with the Zr current of 100 A revealed the roughest topography with the roughness of Ra 91±5 nm, which was consistent with the surface morphologies in Figure 2. This was probably because the increasing deposition current of Zr target resulted in the much stronger ion bombardment effect on the coating surface.
Figure 5 shows the X-ray diffraction analysis result of the MoS2-Zr coatings with the Zr current of 30A. It revealed that a very broad band pattern indicating a structure consisting of quasi-amorphous MoS2, and so it would appear that addition of Zr into MoS2 coating led to the vanishing of MoS2 crystalline phase. It was also reported by the previous findings that the addition of metal (Ti, Cr, Zr, etc.) to MoS2 to form the MoS2/metal composite coatings has resulted in the distortion of MoS2 lattice parameters and X-ray amorphous microstructure [28-35].
The adhesive strength between the substrate and coating was determined by the curve slope of friction coefficient and friction force owing to the coating spalling. The curves of friction coefficient and friction force in scratch test are plotted in Figure 7. From the figure, the curves were relatively steady and smooth at the beginning of scratch test. As the scratch load increased to 58 N, the coatings scraped off gradually, and the curves of friction coefficient and friction force began to increase rapidly; when the load exceeded 64 N, the test curves both reached steady state with relatively high values owing to the wear and tear off of coatings. The adhesive strength of the coatings at Zr current of 30 A was determined as about 58 N. Figure 8 shows the average value of adhesive strength at different deposition current of Zr. It revealed that the adhesive strength increased and reached the maximum value (68 N) at 45 A with the increase of Zr current. However, further increase of deposition current may lead to the decrease of adhesive strength, from about 63 N at 60 A down to 53 N at 100 A.
……
Figure 12 shows the surface micro-hardness of the composite coatings. It was evident that the micro-hardness of the MoS2-Zr composite coatings was increased greatly compared with that of the pure MoS2 coating. The surface hardness of the pure MoS2 coating was only 3.4 GPa. In contrast, the hardness of MoS2-Zr composite coatings was increased along with the increase of Zr current, from 7.8 GPa at 30 A up to 11.1 GPa at 100 A. The hardness improvement of the composite coatings can be attributed to the addition of Zr, which can lead to the distortion of the MoS2 lattice accompanied with a denser coating structure. Among the MoS2-Zr composite coatings with different current, more Zr content in the composite coatings led to higher hardness.
The statement on intrinsic stress is not clear. Only the stress equation is given, but it is not clear where are the counting methods. Fig 8 gives the results of the intrinsic stress experiment that should be explained in more detail.
Response:
Fig 8 gives the average value of adhesive strength at different deposition current of Zr, and it not the results of the intrinsic stress experiment. The test equipment and test conditions of adhesive strength were indicated in the 2nd paragraph of section 2.1, the test quantitative analysis methods was shown in the 4th paragraph of section 3.1.
In addition, due to the limitation of test condition and time, the intrinsic stress was just given theoretical analysis by the stress equation, and the quantitative test cannot be carried out.
Considering the Reviewer’s suggestion, the related information of adhesive strength in Fig 7 and 8 was added in the 4th paragraph of section 3.1 as follows:
From the figure, the curves were relatively steady and smooth at the beginning of scratch test. As the scratch load increased to 58 N, the coatings scraped off gradually, and the curves of friction coefficient and friction force began to increase rapidly; when the load exceeded 64 N, the test curves both reached steady state with relatively high values owing to the wear and tear off of coatings. The adhesive strength of the coatings at Zr current of 30 A was determined as about 58 N. Figure 8 shows the average value of adhesive strength at different deposition current of Zr. It revealed that the adhesive strength increased and reached the maximum value (68 N) at 45 A with the increase of Zr current. However, further increase of deposition current may lead to the decrease of adhesive strength, from about 63 N at 60 A down to 53 N at 100 A.
The figure and its title must be in the same page.
Response:
We are very sorry for our negligence, the figure and its title were put in the same page according to the Reviewer’s suggestion.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but can be tracked down in revised paper by clicking "Track Changes".
We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Once again, thank you very much for your comments and suggestions.
Best Regards,
Corresponding author: Wenlong Song
E-mail: [email protected]
Reviewer 2 Report
I have read your work and I think that it can be improved.
In line 12 you state that “mediate frequency magnetron sputtering method” was used. Probably it’s radio frequency magnetron sputtering.
In line 29 PVD can modify the components and structure. I fail to understand what you mean by components.
In line 51 you state “solid solution strengthening of metal” – please rephrase. In materials science a metal, in this context, is composed of a single type of atoms (pure metal) therefore it cannot undergo solid solution strengthening.
Also I fail to see how solid solution strengthening can improve adhesive strength of a coating, as you state in line 52-53.
In line 58 and 60 you use the term comprehensive which is not quite appropriate for your study, while on line 60 you negate – “… and the influence mechanisms have not been comprehensively studied”. What is the point of the statement?
Line 83 “test time 60S”, use lower case s
Line 96 – please rephrase
Line 99 –D8 ADVANCE, Germany
Line 108 – figure 2a exhibits – please rephrase
Line 110 Figure 3 indicates – please rephrase
Regarding figure 2 – there are two lines with a description what the figure represents, but no discussion is performed on the micrographs. What type of detector was used? In fig. 2.a two constituents can be seen, while in fig. 2.b to 2.f an increasing fraction of pores? Voids? A discussion is necessary for this figure – it is relevant for your roughness results.
Regarding figure captions – please rephrase most figure captions. As stated it can be understood that the analysis was performed using Zr current
In fig. 5 only one XRD pattern is presented. Is there a reason why? The XRD patterns for all tested samples need to be presented, preferably in one plot for easy comparison. Why do you think that it is quasi-amorphous MoS2?
Line 142 – what do you mean by curve mutation?
Figure 8 – until now you presented measurements units (m.u) as “/m.u.” and in fig. 8 you use “(m.u.)”. Use a consistent notation, as specified by the journal.
Figure 9 – there is partly covered text. “Uncoated” something. Please fix.
Line 168 – “alloying of Zr in the MoS2…” – I would not use alloying in this context.
Line 200-201 – this statement is quite problematic. Please see fig. 2, 4, 6 and 11 – I do not think that the reduction of the MoS2 content is the culprit. Also I suggest a section analysis of the coating to clearly see how morphology changes with increasing Zr content.
Fig. 15 – the spectra do not have measurement units
Line 274 – please rephrase conclusion 4.
Author Response
Dear Reviewer:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Effect of Zr target current on the mechanical and tribological performance of MoS2-Zr composite lubricating coatings” (ID: coatings-681646). These 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. In order to clearly show the changes of the manuscript to the editors and reviewers, the function of "Track Changes" in Microsoft Word was used, and the revised manuscript can be displayed properly by clicking the final status without markup in the review tab. The main corrections in the paper and the responds to the reviewer’s comments are as flowing:
Responds to the reviewer’s comments:
Comments and Suggestions for Authors
I have read your work and I think that it can be improved.
In line 12 you state that “mediate frequency magnetron sputtering method” was used. Probably it’s radio frequency magnetron sputtering.
Response:
Considering the Reviewer’s suggestion, the words “mediate frequency magnetron sputtering” in the manuscript were all changed to “radio frequency magnetron sputtering”.
In line 29 PVD can modify the components and structure. I fail to understand what you mean by components.
Response:
Considering the Reviewer’s suggestion, the words “modify the components and structure” were deleted.
In line 51 you state “solid solution strengthening of metal” – please rephrase. In materials science a metal, in this context, is composed of a single type of atoms (pure metal) therefore it cannot undergo solid solution strengthening.
Response:
Considering the Reviewer’s suggestion, the words “solid solution strengthening of metal” in line 51 were changed to “the addition of metal”.
Also I fail to see how solid solution strengthening can improve adhesive strength of a coating, as you state in line 52-53.
Response:
Considering the Reviewer’s suggestion, the sentence “Because of the solid solution strengthening of metal, the MoS2-metal lubricating coatings, ……, exhibit better properties in adhesive strength, surface hardness and wear resistance, and have been successfully used in the machining field” in line 52-53 were changed to “Because of the addition of metal, the MoS2-metal lubricating coatings, such as MoS2-Ti, MoS2-Cr, MoS2-W and MoS2-Zr, exhibit better properties in surface hardness and wear resistance, and have been successfully used in the machining field”.
In line 58 and 60 you use the term comprehensive which is not quite appropriate for your study, while on line 60 you negate – “… and the influence mechanisms have not been comprehensively studied”. What is the point of the statement?
Response:
Considering the Reviewer’s suggestion, the term “comprehensive” in line 58 and 60 was deleted. The statement “the influence mechanisms have not been comprehensively studied” means it is necessary to investigate the effects of Zr current on the mechanical and tribological properties of the MoS2-Zr coatings because of few related literatures.
Line 83 “test time 60S”, use lower case s
Response:
According to the Reviewer’s suggestion, "test time 60S" was changed to "test time 60 s ".
Line 96 – please rephrase
Response:
Considering the Reviewer’s suggestion, the statement “All the experiments were implemented three times for the average values.” in Line 96 was corrected as “All the experiments were repeated three times and the average values were presented.”
Line 99 –D8 ADVANCE, Germany
Response:
According to the Reviewer’s suggestion, "D8 ADVANCE, Germany" was changed to "D8 ADVANCE, Bruker, Germany".
Line 108 – figure 2a exhibits – please rephrase
Response:
According to the Reviewer’s suggestion, "Figure 2a exhibits " was changed to "Figure 2a shows".
Line 110 Figure 3 indicates – please rephrase
Response:
According to the Reviewer’s suggestion, "Figure 3 indicates" was changed to "Figure 3 show".
Regarding figure 2 – there are two lines with a description what the figure represents, but no discussion is performed on the micrographs. What type of detector was used? In fig. 2.a two constituents can be seen, while in fig. 2.b to 2.f an increasing fraction of pores? Voids? A discussion is necessary for this figure – it is relevant for your roughness results.
Response:
The surface morphologies of the composite coatings are investigated by scanning electron microscope (SEM, INCA Penta FETXS, UK), and the test results are shown in Figure 2. Figure 2a exhibits the SEM micrograph of pure MoS2 coating without addition of Zr. Because the thickness of the pure MoS2 coating was just about 0.55 μm (see Figure 11), the grain structure of WC/TiC/Co substrate (not coating) can still be seen through coating. Figures 2b-f show the micrographs of the MoS2-Zr composite coatings with the Zr current from 30 A to 100 A. Due to a significant increase in thickness (see Figure 11), the substrate surface with composite coatings can no longer be seen. However, the surface voids of the composite coatings were obvious, and the number void increased with Zr current, which can lead to the increase of surface roughness.
According to the Reviewer’s suggestion, the related information about Fig. 2 is added in the 1st paragraph of section 3.1 as follows:
The surface morphologies of the composite coatings with different Zr current are shown in Figure 2. Figure 2a shows the SEM micrograph of pure MoS2 coating without addition of Zr. Because the thickness of the pure MoS2 coating was just about 0.55 μm (see Figure 11), the grain structure of WC/TiC/Co substrate can still be seen through surface coating. Figures 2b-f show the micrographs of the MoS2-Zr composite coatings with the Zr current from 30 A to 100 A. The substrate surface with composite coatings can no longer be seen owing to a significant increase in thickness. However, the surface voids of the composite coatings were obvious, and the number void increased with Zr current, which can lead to the increase of surface roughness.
Figure 3 show the coating surface topography measured by the NT9300 optical profiling tester, and the average values of coating surface roughness under different Zr current are summarized in Figure 4. As shown in these figures, the coating surface became rougher with the increase of Zr current. The pure MoS2 coating exhibited the minimum surface roughness (Ra 49±5 nm), and the composite coatings with the Zr current of 100 A revealed the roughest topography with the roughness of Ra 91±5 nm, which was consistent with the surface morphologies in Figure 2. This was probably because the increasing deposition current of Zr target resulted in the much stronger ion bombardment effect on the coating surface [36].
Regarding figure captions – please rephrase most figure captions. As stated it can be understood that the analysis was performed using Zr current
Response:
Considering the Reviewer’s suggestion, the figure captions (Figure 3, 4, 8, 11 and 14 ) were corrected.
In fig. 5 only one XRD pattern is presented. Is there a reason why? The XRD patterns for all tested samples need to be presented, preferably in one plot for easy comparison. Why do you think that it is quasi-amorphous MoS2?
Response:
Figure 5 shows the X-ray diffraction analysis result of the MoS2-Zr coatings at the Zr current of 30A. It revealed that a very broad band pattern indicating a structure consisting of quasi-amorphous MoS2, and so it would appear that addition of Zr into MoS2 coating led to the vanishing of MoS2 crystalline phase. It was also reported by the previous findings [28-35] that the addition of metal (Ti, Cr, Zr, etc.) to MoS2 to form the MoS2/metal composite coatings has resulted in the distortion of MoS2 lattice parameters and X-ray amorphous microstructure. The XRD patterns of coated samples with Zr current from 30 A to 100A are almost similar owing to the vanishing of MoS2, and we won't go into details here.
According to the Reviewer’s suggestion, the related information about Fig. 5 is added in the 2nd paragraph of section 3.1 as follows:
Figure 5 shows the X-ray diffraction analysis result of the MoS2-Zr coatings with the Zr current of 30A. It revealed that a very broad band pattern indicating a structure consisting of quasi-amorphous MoS2, and so it would appear that addition of Zr into MoS2 coating led to the vanishing of MoS2 crystalline phase. It was also reported by the previous findings that the addition of metal (Ti, Cr, Zr, etc.) to MoS2 to form the MoS2/metal composite coatings has resulted in the distortion of MoS2 lattice parameters and X-ray amorphous microstructure [24,28,29,32].
Line 142 – what do you mean by curve mutation?
Response:
The curves of friction coefficient and friction force in scratch test are plotted in Figure 7. From the figure, the curves were relatively steady and smooth at the beginning of scratch test. As the scratch load increased to 58 N, the coatings scraped off gradually, and the curves of friction coefficient and friction force began to increase rapidly; when the load exceeded 64 N, the test curves both reached steady state with relatively high values owing to the wear and tear off of coatings. The adhesive strength of the coatings at Zr current of 30 A was determined as about 58 N.
Considering the Reviewer’s suggestion, “curve mutation” were changed to “curve slope”.
Figure 8 – until now you presented measurements units (m.u) as “/m.u.” and in fig. 8 you use “(m.u.)”. Use a consistent notation, as specified by the journal.
Response:
We are very sorry for our negligence, and the measurements units of figures were corrected using a consistent notation.
Figure 9 – there is partly covered text. “Uncoated” something. Please fix.
Response:
We are very sorry for our negligence, and the covered text in Figure 9 was corrected.
Line 168 – “alloying of Zr in the MoS2…” – I would not use alloying in this context.
Response:
According to the Reviewer’s suggestion, the word "alloying" was changed to "addition".
Line 200-201 – this statement is quite problematic. Please see fig. 2, 4, 6 and 11 – I do not think that the reduction of the MoS2 content is the culprit. Also I suggest a section analysis of the coating to clearly see how morphology changes with increasing Zr content.
Response:
Considering the Reviewer’s suggestion, the statement in Line 200-201 was deleted. Due to the limitation of time and test conditions, the related test cannot be completed in the short term. The future investigation work will be carried out on the morphology, microstructure and tribological properties under different test conditions (humidity, temperature, etc.). The statement about the further work was added in the end of section 3.3 as follows:
The future investigation work will be carried out on the morphology, microstructure, tribological properties of MoS2-Zr coatings under different test conditions (humidity, temperature, etc.), and the dynamic crack resistance.
Fig. 15 – the spectra do not have measurement units
Response:
According to the Reviewer’s suggestion, the measurement unit was added in Fig. 15.
Line 274 – please rephrase conclusion 4.
Response:
Considering the Reviewer’s suggestion, the conclusion 4 was changed from “The mechanism responsible for the differences of tribological performance was mainly attributed to the different components and mechanical properties of the coatings caused by various Zr current.” to “The mechanism responsible for the differences of tribological performance was mainly attributed to the different mechanical properties of the coatings caused by various Zr current.”.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but can be tracked down in revised paper by clicking "Track Changes".
We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Once again, thank you very much for your comments and suggestions.
Best Regards,
Corresponding author: Wenlong Song
E-mail: [email protected]
Reviewer 3 Report
Review is in the attachment.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Effect of Zr target current on the mechanical and tribological performance of MoS2-Zr composite lubricating coatings” (ID: coatings-681646). These 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. In order to clearly show the changes of the manuscript to the editors and reviewers, the function of "Track Changes" in Microsoft Word was used, and the revised manuscript can be displayed properly by clicking the final status without markup in the review tab. The main corrections in the paper and the responds to the reviewer’s comments are as flowing:
Responds to the reviewer’s comments:
Comments and Suggestions for Authors
The article is interesting, but requires additions and editing:
In what temperature range is it planned to use the analyzed coatings? What details are these coatings intended for? This needs to be clarified. The lack of such information does not allow us to determine the practical value of the article.Response:
According to the author's previous studies [30-33], When the temperature reaches to 550 °C, MoS2-Zr composite coatings begin to be oxidized to form MoO3, which can significantly decrease the lubricity of the composite coatings. The composite coatings have been mainly applied in the intermittent cutting and continuous low-speed machining.
Considering the Reviewer’s suggestion, the related information is added in the last paragraph of Introduction as follows:
The MoS2-Zr composite coatings have been mainly applied in the intermittent cutting and continuous low-speed machining due to the sensitive to high temperature (>550 °C).
Molybdenum disulfide (MoS2) is a well-known solid lubricant for tribosystems running in vacuum or dry gases. Problems arise due to its sensitivity to humidity, which is a drawback for its application under ambient conditions. MoS2-Zr composite lubricating coatings were prepared on the WC/TiC/Co carbide surface, but humidity of wear tests is only 40%. Perhaps tests in liquids are needed to correct evaluate the service properties of these coatings?Response:
Ultra-low friction of MoS2 coating has been identified by running friction tests in the absence of oxygen and/or water vapor. To obtain a harder, much more wear resistant and also less sensitive, a certain amount of metals such as Ti, Cr, Zr or W is co-deposited in the MoS2-based coating, The MoS2-Zr composite coatings have just been successfully applied to low-speed machining operation due to its sensitivity to temperature [30-33]. However, the optimal deposition conditions of the MoS2-Zr coatings, such as Zr target current, and the influence mechanisms have not been comprehensively studied. Therefore, this work is just to present the mechanical and tribological behaviors of the MoS2-Zr coatings, and it is necessary to perform a specially investigation on the influence of test conditions, such as humidity, on the service properties of these coatings in the future study.
Considering the Reviewer’s suggestion, the statement about the further work was added in the end of section 3.3 as follows:
The future investigation work will be carried out on the morphology, microstructure, tribological properties of MoS2-Zr coatings under different test conditions (humidity, temperature, etc.), and the dynamic crack resistance.
The dispersion of all investigated parameters (within the boundaries of the figures 4, 6, 8, 11, 12, ) have the same value. But, it is impossible. This is either an error in calculating the variance, or its incorrect graphical representation. It is necessary to clarify the number of experiments performed and the number of data obtained for each figure. How was calculated the dispersion of experimental results?Response:
As indicated in the 2nd paragraph of section 2.2, all the experiments were repeated three times and the average values were presented. So, the test results of the figures 4, 6, 8, 11, 12 were the average values of three experiments. The dispersion of experimental results of the figures was obtained according to the measured values of each test and the calibration precision of test equipment. The average error value of testing results of the figures was about 4.4-6.1%. Hence, the dispersion of all investigated parameters (within the boundaries of the figures 4, 6, 8, 11, 12) have the similar value.
An increase in the amount of zirconium can reduce the dynamic crack resistance of a surface with concentrators of stress https://www.sciencedirect.com/science/article/abs/pii/S0167844215301993 Did the authors consider this effect?Response:
Sorry, we have not considered the effect. Considering the Reviewer’s suggestion, the future investigation work will be performed on the dynamic crack resistance of MoS2-Zr coatings, and the statement about the further work was added in the end of section 3.3 as follows:
The future investigation work will be carried out on the morphology, microstructure, tribological properties of MoS2-Zr coatings under different test conditions (humidity, temperature, etc.), and the dynamic crack resistance.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but can be tracked down in revised paper by clicking "Track Changes".
We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Once again, thank you very much for your comments and suggestions.
Best Regards,
Corresponding author: Wenlong Song
E-mail: [email protected]
Round 2
Reviewer 2 Report
Good work on revising your paper.
A minor observation: line 105 EDX, D8 ADVANCE, Bruker, German - add "y", Germany
In fig. 8 you state that adhesion strength is measured in [N]. Strength is measured in [Pa]. Also you state that the adhesion strength was determined using the slope of the curve of coefficient of friction and friction force - I'm not sure on the parameters used for computation, but if no area is included than it would be "adhesion force" not "adhesion strength". Please check the measurement units according to your estimation procedure.
I am sorry that I did not see that earlier.
Author Response
Dear Reviewer:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Effect of Zr target current on the mechanical and tribological performance of MoS2-Zr composite lubricating coatings” (ID: coatings-681646). These 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. In order to clearly show the changes of the manuscript to the editors and reviewers, the function of "Track Changes" in Microsoft Word was used, and the revised manuscript can be displayed properly by clicking the final status without markup in the review tab. The main corrections in the paper and the responds to the reviewer’s comments are as flowing:
Responds to the reviewer’s comments:
Comments and Suggestions for Authors
Good work on revising your paper.
A minor observation: line 105 EDX, D8 ADVANCE, Bruker, German - add "y", Germany.
Response:
Considering the Reviewer’s suggestion, the words “German” in line 105 was changed to “Germany”.
In fig. 8 you state that adhesion strength is measured in [N]. Strength is measured in [Pa]. Also you state that the adhesion strength was determined using the slope of the curve of coefficient of friction and friction force - I'm not sure on the parameters used for computation, but if no area is included than it would be "adhesion force" not "adhesion strength". Please check the measurement units according to your estimation procedure.
Response:
Considering the Reviewer’s suggestion, the words “adhesion strength” in the manuscript were all changed to “adhesion force”.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but can be tracked down in revised paper by clicking "Track Changes".
We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Once again, thank you very much for your comments and suggestions.
Best Regards,
Corresponding author: Wenlong Song
E-mail: [email protected]
Reviewer 3 Report
Accept in present form.
Author Response
Dear Reviewer:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Effect of Zr target current on the mechanical and tribological performance of MoS2-Zr composite lubricating coatings” (ID: coatings-681646).
We appreciate for your warm work earnestly, and hope that the manuscript will meet with approval.
Once again, thank you very much for your comments and suggestions.
Best Regards,
Corresponding author: Wenlong Song
E-mail: [email protected]
