Preparation and Tribocorrosion Performance of Different Si-Doped TiSiN-Ag Coatings on Different Substrates in Seawater
Round 1
Reviewer 1 Report
The paper presents interesting results on TiSiN-Ag composite coatings on three different coatings and their tribocorrosion performances in artificial seawater. Before the paper could be accepted for publication, the authors should address the following questions as below:
1) Lines 25-28 of Introduction, these two sentences are difficult to follow and seems irrelevant to the importance of research.
2) Lines 111-113, the statement on the effects of Si-doping increase on hardness, corrosion and oxidation resistances are not convincing as there are not any experimental results to support or prove this herewith.
3) Lines 113-114, the authors explained that no XRD peak corresponding to Si3N4 phase was observed due to amorphous structure of Si3N4. What are reasons for no XRD peaks appearing for TiSi phase?
4) In Figure 2, better contrast should be made for scale bars.
5) Why the hardness values of the composite coatings on 316L and TC4 substrates are over two times greater than on Cu substrates?
6) The interpretation of polarization curves seems inappropriate in Lines 218-233. Polarization curves in Figure 5 should be processed using Tafel fitting and the fitting results of corrosion current densities, corrosion potentials and other parameters should be tabled in order for the clear and reasonable interpretation.
7) Lines 250-251, no experimental results support the statement "lower surface roughness".
8) Some terms should be changed with proper scientific terms. For example, the coatings have been "glued" in Line 281, and the "joint" action of "sticking wear and plastic deformation in Line 323.
Author Response
Title: Preparation and tribocorrosion performance of different Si-doped TiSiN-Ag coatings on different substrates in seawater
Authors: Ke Cai, Bailing Jiang, Jing Zhang, Xiaolei Su
Manuscript ID: coatings-1130433
Dear Reviewer,
We are very grateful to your comments for the manuscript (coatings-1130433). We have made revisions in our manuscript. We have indicated that how the manuscript has been revised in a separate Response Letter file. In order to highlight the changes what we have done, the color of text changed will become red in our point-by-point response. The manuscript has been polished by a native English expert. I hope this will make it more acceptable for publication.
Thank you very much!
Sincerely Yours,
Dr. Ke Cai
1) Lines 25-28 of Introduction, these two sentences are difficult to follow and seems irrelevant to the importance of research.
The two sentences have been deleted in the revised manuscript.
2) Lines 111-113, the statement on the effects of Si-doping increase on hardness and corrosion are not convincing as there are not any experimental results to support or prove this herewith.
The hardness, corrosion and oxidation resistances values have been shown in table 2 and Fig.5, respectively.
3) Lines 113-114, the authors explained that no XRD peak corresponding to Si3N4 phase was observed due to amorphous structure of Si3N4. What are reasons for no XRD peaks appearing for TiSi phase?
A lot of studies show that in the system of Si, Ti and N, tin or Si3N4 compounds are easy to form due to the electronegativity. Compared with the two compounds, TiSi compounds have higher binding energy, so TiSi compounds are not formed.
4) In Figure 2, better contrast should be made for scale bars.
The new scale bars with better contrast has been presented in the revised manuscript.
5) Why the hardness values of the composite coatings on 316L and TC4 substrates are over two times greater than on Cu substrates?
On the one hand, the hardness of copper substrate is much lower than that of 316L and TC4 substrate, on the other hand, the coating on the substrate is very thin, which leads to the hardness test results that the copper substrate is more weakened by the copper substrate, so it shows the given hardness value.
6) The interpretation of polarization curves seems inappropriate in Lines 218-233. Polarization curves in Figure 5 should be processed using Tafel fitting and the fitting results of corrosion current densities, corrosion potentials and other parameters should be tabled in order for the clear and reasonable interpretation.
Corrosion current density and corrosion potential was presented in the revised manuscript.
7) Lines 250-251, no experimental results support the statement "lower surface roughness".
The lower surface roughness has been deleted in revised manuscript.
8) Some terms should be changed with proper scientific terms. For example, the coatings have been "glued" in Line 281, and the "joint" action of "sticking wear and plastic deformation in Line 323.
The terms have been corrected in the revised manuscript.
Author Response File: 
Author Response.doc
Reviewer 2 Report
Materials and Methods:
- The authors say that: "The surface hardness of the coatings was measured by 83 HVS-1000A microhardness tester. The adhesion of the coatings was measured by CSM 84 revetest scratch tester" in order to describe the micro-hardness and adhesion evaluation. This is not acceptable simply because a reader can not reproduce these measurements.
- Why Si3N4 ball was used in this experiment?
Results:
- The authors say that: "It can be seen that there are no 127 obvious cracks, pores and other defects on the surface of the coatings." From Fig 2, there are some features (white circles, and pores) on the surface. Can the authors comment on that?
- In the description of the surface of the coating, the authors did not indicate what was the thickness of the deposited coatings.
- In the evaluation of the hardness it is quite important to know the thickness of the coating. Can the authors provide that information?
- Can you please, provide the hardness of the various substrates?
- Can you show the load displacement curves for your hardness measurements?
- What is the hardness of the coating without doping with Si? This should be included in order to appreciate the effect of Si doping.
- What is the maximum load during the scratch test?
- For the electrochemical study, I will recommend the authors to include in their current results that of the substrates as well as that of the coating without Si doping. These sample with be used as reference by the reader.
- What was the total area exposed to the electrolyte? Again the method was not described.
- The authors indicated that sea-water is highly corrosive, however, they did not mention any influence of the corrosion aspect on the overall wear results. What is the contribution of the corrosion on the global material loss. Synergetic contribution of wear on corrosion and vice versa.
Author Response
Title: Preparation and tribocorrosion performance of different Si-doped TiSiN-Ag coatings on different substrates in seawater
Authors: Ke Cai, Bailing Jiang, Jing Zhang, Xiaolei Su
Manuscript ID: coatings-1130433
Dear Reviewer,
We are very grateful to your comments for the manuscript (coatings-1130433). We have made revisions in our manuscript. We have indicated that how the manuscript has been revised in a separate Response Letter file. In order to highlight the changes what we have done, the color of text changed will become red in our point-by-point response. The manuscript has been polished by a native English expert. I hope this will make it more acceptable for publication.
Thank you very much!
Sincerely Yours,
Dr. Ke Cai
Materials and Methods:
The authors say that: "The surface hardness of the coatings was measured by 83 HVS-1000A microhardness tester. The adhesion of the coatings was measured by CSM 84 revetest scratch tester" in order to describe the micro-hardness and adhesion evaluation. This is not acceptable simply because a reader can not reproduce these measurements.
A large number of research results on coatings are basically characterized by micro hardness tester and scratch tester, and the data from this test is more intuitive. For the coating, because of its thin thickness, it may be more appropriate to use these two tests.
Why Si3N4 ball was used in this experiment?
The hardness of Si3N4 ball is about 2200HV, so it is reasonable to use it to test the coating. At the same time, the previous research of the research group is also using the grinding ball for testing, which is conducive to the continuity and contrast of the research work.
Results:
The authors say that: "It can be seen that there are no 127 obvious cracks, pores and other defects on the surface of the coatings." From Fig 2, there are some features (white circles, and pores) on the surface. Can the authors comment on that?
There are no obvious cracks, pores and other defects on the surface of the coatings and the large irregular-shaped crystals are dominant for the TiSiN-Ag composite coatings on 316L and TC4 substrates. Related expressions were shown in revised manuscript.
In the description of the surface of the coating, the authors did not indicate what was the thickness of the deposited coatings.
Thickness of the deposited coatings is about 7-8μm.
In the evaluation of the hardness it is quite important to know the thickness of the coating. Can the authors provide that information?
A picture of the cross section has been provided in the revised manuscript.
Can you please, provide the hardness of the various substrates?
The hardness values (HV) of TC4, 316L, and Cu substrates are 290, 260, and 150, respectively.
Can you show the load displacement curves for your hardness measurements?
Only hardness values have been presented, therefore there is no load displacement curves.
What is the hardness of the coating without doping with Si? This should be included in order to appreciate the effect of Si doping.
Due to the limitation of experimental conditions, there is no way to provide the relevant data of tin Ag coating. However, according to the relevant literature, the hardness of pure tin is too high, and it is easy to form abrasive wear in the friction process, which leads to the deepening of the degree of wear and the shortening of the service life. Through the addition of Ag, taking advantage of the good flexibility of Ag, the friction degree can be slowed down and the service life of the coating can be prolonged. However, on the other hand, due to the soft hardness of the coating, the doping of Si element can increase the hardness, which is expected to improve the overall life of the coating.
What is the maximum load during the scratch test?
The adhesion of the coatings was tested by the CSM Instruments Revetest. The indenter on the tester was of 0.2 mm radius and 120° taper angle. A normal load range of 0–120 N, a scratch length of 5 mm and a scratching velocity of 6 mm/min were used in the experiments.
For the electrochemical study, I will recommend the authors to include in their current results that of the substrates as well as that of the coating without Si doping. These sample with be used as reference by the reader.
For the electrochemical study, the related values of substrates were presented in the revised manuscript.
What was the total area exposed to the electrolyte? Again the method was not described.
The total area exposed to the electrolyte is about 20x20mm.
The authors indicated that sea-water is highly corrosive, however, they did not mention any influence of the corrosion aspect on the overall wear results. What is the contribution of the corrosion on the global material loss. Synergetic contribution of wear on corrosion and vice versa.
The corrosion in the friction process is a very complex problem, which is more difficult to prove in the actual working conditions, and can only be evaluated through the service life. The corresponding indicators include the relevant parameters of electrochemical corrosion, hardness and other parameters as evidence. However, compared with pure titanium nitride, its tribocorrosion performance will be better.
Author Response File: Author Response.doc
Reviewer 3 Report
Cai reported preparation and tribocorrosion performance of Si-doped TiSiN-Ag on the different substrates. This is very interesting in corrosion filed. However, there are some issues should resolve before acceptance for this manuscript.
-should mention to recent method for improving corrosion resistance such as PEO, PEO-DIP, so on. Here, some references should be cited in this paper such as Progress in Materials Science 112, 2020, 100663, Composite Science and Technology. 199, 2020, 108383, Surface and Coating Technology. 392, 2020, 125916, Chemical Engineering Journal 392, 2020, 123654, Advance in Colloid and interface Science. 283, 2020, 102245, Journal of Colloid and Interface Science 573, 2020, 31-44, Journal of Materials Science & Technology 50, 2020, 75-85, Materials Chemistry and Physics. 251, 2020, 123054, and Chemical Engineering Journal 356, 2019, 850-856.
-should indicate for chemical compounds.
-If possible, could you provide your paper with cross-sections for the prepared samples?
-Regarding the corrosion section, should add a table containing icorr, Ecorr, and corrosion resistance.
-What is the novelty of your work and the differences between your method and others.
-If possible, can you add a table or figure as a comparison?
-You think Si convert to SiO2 after corrosion?
Author Response
Title: Preparation and tribocorrosion performance of different Si-doped TiSiN-Ag coatings on different substrates in seawater
Authors: Ke Cai, Bailing Jiang, Jing Zhang, Xiaolei Su
Manuscript ID: coatings-1130433
Dear Reviewer,
We are very grateful to your comments for the manuscript (coatings-1130433). We have made revisions in our manuscript. We have indicated that how the manuscript has been revised in a separate Response Letter file. In order to highlight the changes what we have done, the color of text changed will become red in our point-by-point response. The manuscript has been polished by a native English expert. I hope this will make it more acceptable for publication.
Thank you very much!
Sincerely Yours,
Dr. Ke Cai
-should mention to recent method for improving corrosion resistance such as PEO, PEO-DIP, so on. Here, some references should be cited in this paper such as Progress in Materials Science 112, 2020, 100663, Composite Science and Technology. 199, 2020, 108383, Surface and Coating Technology. 392, 2020, 125916, Chemical Engineering Journal 392, 2020, 123654, Advance in Colloid and interface Science. 283, 2020, 102245, Journal of Colloid and Interface Science 573, 2020, 31-44, Journal of Materials Science & Technology 50, 2020, 75-85, Materials Chemistry and Physics. 251, 2020, 123054, and Chemical Engineering Journal 356, 2019, 850-856.
Related references have been added in the revised manuscript.
-should indicate for chemical compounds.
In fact, the Si-doped TiSiN-Ag coatings should be Si and Ag codoped TiN coating. However, many studies many scholars describe it in the form of Si-doped TiSiN-Ag Coatings .
-If possible, could you provide your paper with cross-sections for the prepared samples?
The cross-section has been shown in revised manuscript.
-Regarding the corrosion section, should add a table containing icorr, Ecorr, and corrosion resistance.
Icorr and Ecorr values have been added in the revised manuscript.
-What is the novelty of your work and the differences between your method and others.-If possible, can you add a table or figure as a comparison?
Because the coating prepared by different preparation methods is different from the substrate, its mechanical properties and corrosion resistance will also be very different. Therefore, the advantages of multi arc ion plating technology compared with other preparation technologies can only be given. Advantages are following:
(1) The cathode target can be arranged in any direction according to the shape of the workpiece, which greatly simplifies the fixture.
(2) High energy of incident particles, high density of film, good strength and durability, good adhesion strength.
(3) The ionization rate is high, generally up to 60% ~ 80%.
(4) From the point of view of application, its outstanding advantage is the fast evaporation rate.
-You think Si convert to SiO2 after corrosion?
Relevant studies show that: the coating will have a tribochemical reaction in the friction process to form amorphous SiO2, which will dissolve in seawater solution, and form a thin boundary lubrication film between the friction interfaces, thus reducing the friction coefficient.
Zhou, F.; Chen, K.; Wang, M.; et al. Friction and wear properties of CrN coatings sliding against Si3N4 balls in water and air. Wear 2008, 265(7-8): 1029-1037.
Zhou, F.; Wang, X.; Adachi, K.; et al. Influence of normal load and sliding speed on the tribological property of amorphous carbon nitride coatings sliding against Si3N4 balls in water. Surf. Coat. Technol. 2008, 202(15), 3519-3528.
Author Response File: Author Response.doc
Round 2
Reviewer 3 Report
The current form is suitable for publishing in coatings
