Effect of Spraying Power on the Tribological Properties of Alumina and Alumina-Graphite Coatings
, Žydrūnas Kavaliauskas 2, Romualdas Kėželis 2 and Mitjan Kalin 3
Round 1
Reviewer 1 Report
Reviewer Comment
Manuscript Number: Coatings-2419636
Dear Editor,
The effect of arc current of plasma spraying power on the tribological properties of Al2O3 composite coatings was investigated. XRD, EDX and SEM along with the tribometer of pin on disc techniques were implemented to evaluate phase composition, chemical analysis, microstructure and tribological properties of the composite coatings.
The introduction section is written with a good flow which ensured a well understanding.
However, several aspects should be considering:
1-The space between reference brackets and the text should be ensured.
2-The usage of the terms should be consistence throughout the text. For example, Al2O3, mm2... Not using Alumina somewhere, using Al2O3 elsewhere and Al2O3 somewhere else.
3-Line 188, Fig. 3b ?
4-The quality of figures 4, 5, & 6 can be improved.
5-The plagiarism rate is high but considering most of these similarities are not avoidable due to borrowing them from previous authors' works, this is considered acceptable.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
1. At the end of the introduction, indicate the purpose of the work.
2. In the table. 1 designate each series of experiments with a number or a letter.
3. In the table. 1 shows the average plasma temperature and velocity at the nozzle outlet. Given their errors, the difference between the values is practically not visible. The work needs to be clarified.
4. Give justification for choosing a counterbody made of Al2O3, which rubs the surface of the same Al2O3 material. It is also necessary to justify the choice of tribological parameters used in the work.
5. P.4, Line 161-164: fig. 1 does not support this assertion. To confirm this statement, it is necessary to provide an SEM of the initial particles.
6. Fig. 1-3, 9 the scale marker is not visible, needs to be corrected
7. P 5, Line 186-187 “The surface images of com- 186 posite coatings” – which composite coatings are we talking about? What acts as a matrix?
8. In fig. 5 it is necessary to identify each characteristic peak. Reading the description on P.6 is not clear and not convenient.
9. In fig. 6b it can be seen that the coefficient of friction constantly increases with time. It is necessary to substantiate this result. It is also incorrect to speak of an average coefficient of friction that is constantly increasing. Accordingly, the authors made the wrong conclusion. The conclusion states that the presence of graphite reduced the friction coefficient of Al2O3-graphite coatings from 30% up to 49%.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
1. The English language of the article is very much defective. This article needs to be re-written in standard English before it can be evaluated from science point of view.
Very poor
Author Response
A detailed correction of the English language was made according to the reviewer's recommendations.
Reviewer 4 Report
Comments on coatings-2419636
Title: Effect of spraying power on the tribological properties of alumina and alumina-graphite coatings
The study used atmospheric plasma spraying to deposit alumina and alumina-graphite composite coatings and analyzed the influence of arc currents on their microstructure, roughness, elemental composition, and phase composition. The tribological properties of the coatings were also analyzed using a tribometer with a ball-on-disc configuration. The results showed that the roughness of the coatings increased and the size of granules decreased with an increase in plasma temperature. The friction coefficients and wear rates were slightly reduced for Al2O3 coatings sprayed at higher arc currents, while Al2O3-graphite coatings had lower friction coefficient values than Al2O3 coatings under dry sliding conditions.
Grammar issues:
Typos and minor grammar errors (including punctuation) and formatting mistakes (font change, etc) are common in the manuscript. A considerable number of sentences are not comprehensible, some of which can be due to typos or grammar errors. Careful proofreading is mandatory for this case.
Only for the introduction section:
1. The sentence structure is complex and difficult to follow.
2. There are several instances of unclear or awkward phrasing.
3. The use of technical terminology may be difficult for non-experts to understand.
4. There are a few instances of incorrect grammar, such as the use of "be" instead of "to" in the first sentence.
5. The citation style is inconsistent, with some citations using brackets and others using parentheses.
6. The writing could benefit from more concise and direct language.
Specific comments:
1. The cross-sectional images of the alumina with and without graphite must be provided for all states in this work. As can be seen, there are SEM images only from the surface of the coated layer.
2. ICDD reference codes must be provided for all detected phases in XRD results.
3. Authors must describe why they used different APS parameters for alumina and alumina graphite coatings in section 2.
4. The number of passes and spraying angle also must be included in the APS spraying parameters.
5. In this manuscript, results are almost well presented, but a discussion on the obtained results focused on the role of graphite on tribological properties and coating microstructure must be completely provided in this manuscript. As can be seen, a “comprehensive” and “comparative” discussion is missed in this work. This should be provided as well.
6. There is no description of the future plans for research in the first part of the “Conclusions” section. This should be completed in this section.
7. Recently published references are beneficial for this work. Please check and use new references focused on your work.
Please see the above comments (grammar issues).
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The second responded to almost all comments. But no answer:
1. why Al2O3 was chosen as the counterbody, and not other ceramics, such as Si3N4, SiC, ZrO2, etc.
2. note 7: The surface images of composite coatings” – which composite coatings are we talking about? What acts as a matrix?
3. in the article, give a link to the size of the initial particles could be found in our other articles (remark 5).
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The article has considerably improved. However, there are still some points that need to be considered, as follow:
- Please use present tense in the Abstract
- The language of article is much better than before, but further edit can improve the quality.
- Line 29: “Therefore, in perspective the results are high coating efficacy and commendable surface characteristics.” This sentence is not understandable. Please amend it.
- Line 31: “The relative applications include sacrificial coats as in paper industries, hydraulic valve plungers etc. [1,5–7].” Please clarify this statement. How Plasma spry coating can be used in paper industry is not clear to me.
- Line 32: “Within coatings, plasma sprayed Al2O3 and alumina composite coatings are customary industrial-materials due to high hardness, proficient strength and toughness, superior tribological and insulation characteristics [8–12].” Please edit the statement to read:
“Plasma sprayed Al2O3-based coatings can provide district preparties due to their high hardness, proficient strength and toughness, as well as superior tribological and insulation characteristics [8–12].”
- Line 41: “ increase of torch power from 25 to 45 kW” Please correct
- It is suggested that the results obtained are compared with similar works reported in the literature, and novelty of work is highlighted accordingly.
- How the work can be distinguished from pervious research works? Please add it to Introduction.
- Please cite https://doi.org/10.1039/C6FD00005C
As mentioned, English language of the presentation has considerably been improved comparing to the first version, but it can still be further improved to increase quality of the work.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 4 Report
Accept after final proofreading.
A careful proofreading is required before acceptance.
Author Response
The reviewer did not provide any comments.
