Tribological Properties of Nanoparticles in the Presence of MoDTC
Round 1
Reviewer 1 Report
The authors here report on a relevant critical topic: improving lubricant performance. the authors display good experimental work with good discussions, but some minor issues should be added, such as
1. the used ultrasonic vibration instrument should be added to the experiment apparatus (is ultrasonic prob or cup horn or bath).
2. the structure of dispersing agent 155 (CAS: 01211-16-7) should be added.
Author Response
- The used ultrasonic vibration instrument should be added to the experiment apparatus (is ultrasonic prob or cup horn or bath).
Answer: The dispersant was mixed with base oil and nanoparticles with magnetic stirring for 10 min, then treated with ultrasonic bath for 20 min vibration to ensure an even distribution of nanoparticles. This sentence was shown in the materials section from line 141 to 143, which is facilitate the description of lubricant preparation. In order to avoid the repetition, the ultrasonic bath was not shown in the experimental apparatus section.
- The structure of dispersing agent 155 (CAS: 01211-16-7) should be added.
Answer: The molecular structure of dispersing agent 155 has been added to the manuscript as Figure 2.
Reviewer 2 Report
Review of the article "Comparison Study of Lubricating Performance Between Chemical Synthetic and Mechanical Ball-milled Nanoparticles" by Weiwei Wang, Miao Yu, Jiandong Ma and Yuanming Jia.
In this work, a comparative analysis of the effect on the tribological characteristics of suspensions of synthetic and ball-milled kaolin and serpentine nanopowders is carried out.
There are the following remarks about the work:
1. In the work, serpentine and kaolin powders were used as additives that improve typological characteristics. At the same time, another well-known additive, MoDTC, was used in the experiments. However, its use is not indicated in the title of the article. Although, judging by the results, it is she who plays the main role.
2. The obtained results and conclusions on the work do not allow to reliably determine the influence of the nature of powder additives. Without the MoDCT addition, ball-milled serpentine and kaolin, made in a had a lower coefficient of friction than their synthetic powders (Fig. 5a). After the introduction of the MoDCT additive, a general decrease in the friction coefficients for all powder additives is observed; this pattern disappears (Fig. 5b).
3. Moreover, for "synthetic kaolin + MoDCT" and "ball-milled serpentine + MoDCT", the curves (Fig. 5b) show atypical dependences - a sharp decrease in friction coefficients at temperatures from 70 to 110°C. The authors explain this drop by the formation of MoS2. Why is MoS2 not formed when using "synthetic serpentine+ MoDCT" and "ball-milled kaolin + MoDCT"?
4. Fig. 10 it is not clear what the 235.7° peak refers to.
5. References 7 and 21 are identical.
6. In the conclusions of the work:
- the conclusion that synthetic nanoparticles produce more MoS2 when mixed with MoDTC contradicts the results presented.
- The role of the MoDTC additive is not indicated in any way.
I think that the work needs serious improvement.
Author Response
- In the work, serpentine and kaolin powders were used as additives that improve typological characteristics. At the same time, another well-known additive, MoDTC, was used in the experiments. However, its use is not indicated in the title of the article. Although, judging by the results, it is she who plays the main role.
Answer: The title of the paper has been revised to: Tribological properties of nanoparticles in the present of MoDTC.
- The obtained results and conclusions on the work do not allow to reliably determine the influence of the nature of powder additives. Without the MoDTC addition, ball-milled serpentine and kaolin, made in a had a lower coefficient of friction than their synthetic powders (Fig. 5a). After the introduction of the MoDTC additive, a general decrease in the friction coefficients for all powder additives is observed; this pattern disappears (Fig. 5b).
Answer: In Figure 6 (b), when the BD was compounded with nanoparticles and MoDTC, the overall friction coefficient reduced to a lower level than the “BD + nanoparticles” formulation.
The Figure 5b has been revised as Figure 6b. The above sentence shows the friction coefficient results, which is shown from line 219 to line 221.
- Moreover, for "synthetic kaolin + MoDCT" and "ball-milled serpentine + MoDCT", the curves (Fig. 5b) show atypical dependences - a sharp decrease in friction coefficients at temperatures from 70 to 110°C. The authors explain this drop by the formation of MoS2. Why is MoS2 not formed when using "synthetic serpentine+ MoDCT" and "ball-milled kaolin + MoDCT"?
Answer: The friction coefficient "BD + synthetic serpentine + MoDTC" shows the lowest value, which may due to the minimal ploughing effect of synthetic serpentine nanoparticles, thus the MoS2 was retained on friction surface. However, the friction coefficient of "BD + ball-milled kaolin + MoDTC" do not show decrease tendency from 90 °C to 110 °C. Com-pared with other additive, more protrusions was found on friction surface in Figure 8, and the flat area of surface lubricated with "BD + ball-milled kaolin + MoDTC" is not clean than other surfaces. It is believe that the ploughing effect of coarse ball-milled kaolin is more severe than other nanoparticles, which reduced the MoS2 existing on friction surface, thus the friction coefficient was high.
The above sentence shows the detailed explanation of friction coefficient drops, which is shown from line 248 to line 256. The Figure 5b has been revised as Figure 6b.
- Fig. 10 it is not clear what the 235.7° peak refers to.
Answer: The 235.7 peak refers to MoOX, which is shown in line 334.
- References 7 and 21 are identical.
Answer: The reference 21 has been deleted. The number of references has been refreshed.
- In the conclusions of the work:
- the conclusion that synthetic nanoparticles produce more MoS2 when mixed with MoDTC contradicts the results presented.
- The role of the MoDTC additive is not indicated in any way.
Answer: the conclusion has been improved, and the role of MoDTC has been highlighted, and the influence of nanoparticles to the production of MoS2 has been described with detail, which is shown from line 368 to line 379.
Round 2
Reviewer 2 Report
Thanks to the authors for corrections and replies to comments.
