A Modelling Study of the Correlation between the Layer Obtained by Selective Transfer and the Dislocations Movement at the Friction Surfaces Limit
Round 1
Reviewer 1 Report
Please clearly state in the abstract and in the section "Introduction", what new the Authors want to show in this manuscript?
The Authors present the figures (this remark applies to all the figures presented in the manuscript), but do not mention the references - is this the Authors' own work?
There is too much content in the manuscript, which makes the manuscript monotonous. Please correct.
It lacks confirmation about the results of experimental studies or references to the results of other researchers.
Author Response
Response Letter
for Reviewer 1
Manuscript ID metals-1495514
entitled:
"Study of the correlation between the layer obtained by selective transfer and the dislocations movement at the friction surfaces limit, by modelling",
by
Filip Ilie, George Ipate
Many thanks to the reviewer 1 for the comments and observations made!
Point 1: Please clearly state in the abstract and in the section "Introduction", what new the Authors want to show in this manuscript?
Response 1: Thank you for your comments and I would like to inform you that through the modifications and completions brought in the Abstract, namely: " This paper is a review and analyzes the STP based on dislocations movement to establish and know tensions field influence, the energy (about 0.25 J/m), and linear tension of dislocations (~2.42⸱10-9 N) in the contact surfaces zone of a friction pair, by which ensures a low wear state (~4.16⸱10-5 – 2.16⸱10-4 g/min), respectively a coefficient (~0.014 – 0.034), reduced. Therefore, the purpose of the paper is to analyse the STP based on the dislocations movement because is proved the existence (presence), importance, and utility of the dislocations, respectively the dislocations movement in the conditions selective transfer, at limit the friction surfaces, under the action of a tensions field, whose components are determined analytically by modelling, together with energy and the linear tension. Also, the layer formed through STP, has and the property to ensure in the deformation process an agglomeration of dislocations (structural defects) which protects him against destruction, so, self-regulation of the equilibrium processes, disturbed in the friction process, for to maintain the friction and wear of the friction pairs within reduced limits.” respectively in the Introduction, namely: “Hence, the aim of this paper is the analysis of the STP in correlation with dislocations theory, based on the movement of the dislocations that is useful and has importance, because in the friction process and in the conditions selective transfer, around dislocations is created a tensions field the energy and linear tension, which generates forces, necessary to their detachment, displacement, and anchoring, on contact surfaces, where the selective layer (already formed) is present, where the selective layer (already formed) is present, protecting it against destruction. Determination by modeling and knowledge of tensions field, energy, and linear tension of the dislocations, are necessary, because tensions field components size depends on the movement of the dislocations, having as the effect the maintaining of friction and wear of the friction pairs within reduced limits, by self-regulation of the phenomena and the equilibrium processes, disturbed in the friction process.” I consider that I have shown the novelties of this manuscript (see and the manuscript, those marked in yellow are completions (additions), and those in red are removed)!
Point 2: The Authors present the figures (this remark applies to all the figures presented in the manuscript), but do not mention the references - is this the Authors' own work?
Response 2: Thanks for the observation and as you will see in the manuscript all the references have been passed. (see and the manuscript).
Point 3: There is too much content in the manuscript, which makes the manuscript monotonous. Please correct.
Response 3: Thank you, it has been corrected and I think it is no longer monotonous (see manuscript).
Point 4: It lacks confirmation about the results of experimental studies or references to the results of other researchers.
Response 4: Thank you, it has been corrected and I think it is no longer monotonous Thank you, through the completions at the end of the paper (before the conclusions), namely: “Now replacing them in relation (21) can determine the density of dislocations, d for the bronze/steel pair, which works in the conditions of selective transfer and is obtained: d = 2.483·1014 dislocations/m2, T = 2.42 ·10-9 N, Fd = 1.56 N/m, and τ = 6.24·103 MPa. By comparing the value of the calculated mixed dislocation density (2.483·1014 dislocations/m2) with the value obtained experimentally by ferromagnetic resonance which is 2.55· 1014 dislocations/m2 confirms the correlation between the results obtained analytically and the experimental ones. Thus, it was proved that there is a correlation between theory and experiment; the results from experiments are validated by modeling, based on elasticity theory, but only from a distance very small from the core of the dislocation, using the model of a cylindrical body having an axis parallel with a direction of the tension field. At the same time, it is demonstrated that for the friction pairs that operate in the conditions of selective transfer, the specific dislocations are the mixed ones.”, respectively at the Conclusions, namely: “The analyze the STP based on dislocations movement allowed to establish and know tensions field influence, the energy (about 0.25 J/m), and linear tension of dislocations (~2.42⸱10-9 N) in the contact surfaces zone of a friction pair, by which ensures a low wear state (~4.16⸱10-5 – 2.16⸱10-4 g/min), respectively a coefficient (~0.014 – 0.034), reduced. Hence, it was proved that there is a correlation between theory and experiment; the results from experiments are validated by modeling.
It proved the existence, importance, and utility of the dislocations, respectively of their movement in the conditions selective transfer, at limit the friction surfaces under the action of tensions field.
The layer formed through STP, has and the property to ensure in the deformation process an agglomeration of structural defects which protects him against destruction, thus is assured the self-regulation of the equilibrium processes, disturbed in the friction process, with the aim to maintain the friction and wear of the friction pairs within reduced limits.
Therefore, knowing the tensions field, energy, and linear tension of the dislocations, in the conditions of selective transfer are important and useful for complexity analysis of the STP and the practical results for the operation of friction pairs with low wear and reduced friction coefficients.” (see the manuscript).
Thanks for understanding!
Date: Dec 29, 2021 Authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The study analyses the STP based on dislocations movement. The study is well presented, with specifics results and figures of poor quality. However, this topic has been studied several times in the bibliography and the novelty of this work is not really clear. Therefore I suggest several changes to improve the quality of the paper.
- Please, remak in the abstract what is the main contribution of this work in comparison with the related literature. What is the novelty? What is new?
- All figures should be revised, improving their quality and size in order to be able to read their content.
- It could give uniformity to the formatting of the text. There are equations with larger font size, italic or bold parameter. It is not clear why the formatting has been changed.
- In lines 458 to 473 of the conclusions reference is made to 3 cases that have not been clearly defined. I think it would be advisable to create a section where the cases are defined and subsequently developed.
Author Response
Response Letter
for Reviewer 2
Manuscript ID metals-1495514
entitled:
"Study of the correlation between the layer obtained by selective transfer and the dislocations movement at the friction surfaces limit, by modelling",
by
Filip Ilie, George Ipate
Many thanks to the reviewer 2 for the assessments, the comments and observations made!
Point 1: Please, remak in the abstract what is the main contribution of this work in comparison with the related literature. What is the novelty? What is new?
Response 1: Thank you for your comments and I would like to inform you that through the modifications and completions brought in the Abstract, we shown the main contribution and novelty, namely: " This paper is a review and analyzes the STP based on dislocations movement to establish and know tensions field influence, the energy (about 0.25 J/m), and linear tension of dislocations (~2.42⸱10-9 N) in the contact surfaces zone of a friction pair, by which ensures a low wear state (~4.16⸱10-5 – 2.16⸱10-4 g/min), respectively a coefficient (~0.014 – 0.034), reduced. Therefore, the purpose of the paper is to analyze the STP based on the dislocations movement because is proved the existence (presence), importance, and utility of the dislocations, respectively the dislocations movement in the conditions selective transfer, at limit the friction surfaces, under the action of a tensions field, whose components are determined analytically by modelling, together with energy and the linear tension. Also, the layer formed through STP, has and the property to ensure in the deformation process an agglomeration of dislocations (structural defects) which protects him against destruction, so, self-regulation of the equilibrium processes, disturbed in the friction process, for to maintain the friction and wear of the friction pairs within reduced limits.” (see and the manuscript, those marked in yellow are completions (additions), and those in red are removed)!
Point 2: All figures should be revised, improving their quality and size in order to be able to read their content.
Response 2: Thanks for the observation and all the figures have been revised and improving their quality (see the manuscript).
Point 3: It could give uniformity to the formatting of the text. There are equations with larger font size, italic or bold parameter. It is not clear why the formatting has been changed.
Response 3: Thanks, the formatting was not changed without any intention; I just don't know how it came about! However, I checked again and now they are all the same format (see the manuscript)
Point 4: In lines 458 to 473 of the conclusions reference is made to 3 cases that have not been clearly defined. I think it would be advisable to create a section where the cases are defined and subsequently developed.
Response 4: Thank you, to clarify this situation, section 7 Results and Discussions was created which we consider that the three cases were clearly defined and developed, marked with yellow that was added and with red and cut, which was removed as follows: " … and for comparison will be presented G1 = 8⸱1010 N/m2, for steel.
Thus, for the steel/bronze pair lubricated with glycerine, the dislocations formed in the steel and during start-up will always be attracted by the phase boundary surface, as G1 is considerably larger than G2 (G1 >>> G2, see the values above), for which the surface layer will solidify on the steel element. At the same time, more surface layers will solidify on the bronze element than on the steel element, because the dislocations formed in the layer near the surface are rejected from the separation surface.
The copper layer formed under the selective-transfer conditions alters the conditions for the interaction of the surface areas as well as of dislocations, in the separation layer of the surfaces. In this conditions, the dislocations produced in the steel are attracted by the separation surface, because G1 > G2. For bronze, the condition G1 < G2 is valid if it can be assumed that the copper layer possess a solid crystal lattice. In this case, the areas near the friction surface of the bronze element will be modified, as the dislocations are rejected from the surface.
Taking into account the results of the research on the structure of the copper layer under selective-transfer conditions [3, 33], where a layer softening is found during the friction process, then the adhesion at the areas of surface must be weaker. As a result, there is an accumulation of elastic energy in areas close to the surface. This ensures a condition, that lasts relatively long, leading to a particularly low wear of the friction pair.
Therefore, at the contact the two materials (bronze/steel) with the shear modules (transverse resistance modules) G1 (for base material, steel) and G2 (for the selective layer, bronze), the dislocations in steel with module G1 are displaced at the boundary of the two surfaces in contact, then condition G1 > G2 is met; and are rejected when condition G1 < G2 is valid. These conditions are also valid for the description of the interaction energy of dislocations with a surface covered with a homogeneous layer of thickness h.
Thus, if G1 > G2, the dislocation is drawn all the time to the surface, and if G1 < G2, the dislocation is drawn to the surface for, s >> h (s - distance from the surface at which the dislocation is located) and, s << h, the dislocation is rejected from the surface [12]. From this statement we can formulate the equilibrium condition, namely: if G2 > G1, then the dislocation is in equilibrium with the surface and s ≈ h.”
It should be noted that the Conclusions regarding the three cases have now been partially modified, namely: “At the contact of two materials with the shear modules different (here bronze/steel) G1 (for steel - the base material) and G2 (for bronze - the selective layer), the dislocations can be found in the following situations:
- the dislocations in the material with the G1 module are drawn to the limit of the two surfaces in contact when the condition G1 > G2 is satisfied;
- the dislocations in the material with the G1 module are rejected when the condition G1 < G2 is valid.
These conditions are valid to the description of the energy of interaction of the dislocations with a covered surface with a homogeneous layer of thickness h.
Hence, when the condition G1 < G2 is satisfied, the dislocation is drawn to the surface for, s >> h, and this is rejected from the surface for, s << h, and if G2 > G1, then the dislocation is in equilibrium with the surface and s ≈ h.
Because G1 >>> G2, at the contact of bronze/steel pair lubricated with glycerin, he dislocations formed in the steel, even and at the startup will always be attracted to the limit surface of the phases, i.e. a superficial layer will adhere on the steel element. At the same time, on the bronze element will more adhere superficial selective layer, than on the steel element, because the dislocations formed in the layer near the surface are rejected from the separation surface.
In the selective-transfer conditions the copper layer formed, alters the conditions for the interaction of superficial areas of the surfaces, as well as of dislocations, in the separation layer of the surfaces. “ (see and the manuscript).
Thanks for understanding!
Date: Dec 29, 2021 Authors
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I have no more comments.
Author Response
Response Letter
for Reviewer 1 (Round 2)
Manuscript ID metals-1495514
entitled:
"Study of the correlation between the layer obtained by selective transfer and the dislocations movement at the friction surfaces limit, by modelling",
by
Filip Ilie, George Ipate
Many thanks to the reviewer 1 for that has nothing to comment on!
Thanks for understanding!
Date: Jan 04, 2022 Authors
Author Response File: Author Response.pdf
Reviewer 2 Report
The modifications to the article have followed most of the recommendations above, but the figures still lack the necessary quality.
Improve the quality of all the figures and the information in some of the images is not visible.
Figure 1 (b) the S' is not clearly visible, increase the size.
Figure 2 Increase the size. Try to ensure that the d/2 does not step on the figure.
Figure 5 Increase the size of the stress components.
Figure 6 increase the size
Figure 7 increase the size. Figure 7b there are components that are stepped with the figure. They are not defined in the foot of the figure a, b and c.
Kind regards,
Author Response
Response Letter
for Reviewer 2 (Round 2)
Manuscript ID metals-1495514
entitled:
"Study of the correlation between the layer obtained by selective transfer and the dislocations movement at the friction surfaces limit, by modelling",
by
Filip Ilie, George Ipate
Many thanks to the reviewer 2 for the comments and observations made, with the necessary apologies for some omissions observed by you and the quality of all figures has been improved!
Point 1: Figure 1 (b) the S' is not clearly visible, increase the size.
Point 2: Figure 2 Increase the size. Try to ensure that the d/2 does not step on the figure.
Response 2: The size of Figure 5 has been increased and d/2 doesn’t step on the figure (see the manuscript).
Point 3: Figure 5 Increase the size of the stress components.
Response 3: The dimension of the stress components in Figure 5 have been increased (see the manuscript).
Point 4: Figure 6 increase the size.
Response 4: The size of Figure 6 has been increased (see the manuscript).
Point 5: Figure 7 increase the size. Figure 7b there are components that are stepped with the figure. They are not defined in the foot of the figure a, b and c.
Response 5: The size of Figure 7 has been increased and the components of each stepped of the figure have been defined (see the manuscript).
In addition, the section “Conclusions” was improved with the paragraph: "The analysis of the STP in correlation with dislocations theory is useful and has importance, because in the friction process and in the conditions selective transfer, around dislocations is created a tensions field, the energy and linear tension, which generates forces, necessary to their detachment, displacement, and anchoring, on contact surfaces, where the selective layer (already formed) is present, protecting it against destruction.”
Thanks for understanding!
Date: Jan 04, 2022 Authors
Author Response File: Author Response.pdf
Round 3
Reviewer 2 Report
After the changes made to the article by the authors, following the recommendations, I believe that the article may be of interest for publication.
Kind regards
