Improved Combustion Performance of Fluororubber-Coated Micro-Nano Composite Aluminum Powder

Round 1

Reviewer 1 Report

The work as a whole seems interesting, it contains novel results in the cross-disciplinary area of Materials Science and Combustion Science, which were obtained using a variety of modern research techniques.

But the English language of the manuscript is not passable: it contains a lot or errors in the English grammar and stylistics. Besides, there are terminological and physical errors. In many cases the text is misleading, most probably because of incorrect translation.

The reviewer believes that even a minor error or ambiguity in the underlying physics results in a large error in Materials Science and Combustion Science, so the authors are supposed to be very accurate in definitions and explanations.

In the reviewer's opinion, the reason for many errors is that the authors have probably resorted to the help of online translators, which in many cases, especially for scientific text, give the results opposite to what the authors might have meant.

It is not the reviewer's duty to point out to all errors in the English grammar and stylistics. Here only some most noticeable or amusing examples are listed with emphasis made on those distorting the physical meaning of the text.

It is strongly recommended that the authors have their manuscript carefully read by a native English speaker who is familiar with this area of knowledge or by a person who has proficiency in writing scientific papers in the English language in this or adjacent area.

Also, it is recommended to use term "micron-sized aluminum powder” rather than "micron aluminum powder" throughout the text.

Particular comments:

1. P.1, line 25-26: "Aluminum powder can release a large amount of heat after combustion". Actually, heat is released during combustion but not after it.

2. P.1, line 34-35: "nano aluminum powder is easy to spontaneously combusts during preparation..." First there is a grammar error. Second, it is not entirely so. This powder is prone to self-ignition in oxygen-containing environment; combustion and ignition are two different things. Besides, in Combustion Science verb "to combust" is seldom used whereas noun "combustion" is used very often.

3. P.1, line 36: "Except that, it is also easy to melt and agglomerate". The phrase sounds not English, and the physical meaning is distorted. The authors might have meant "Along with that, it easily melts and agglomerates".

4. P.1, line 43: "the content and microstructure between micro and nano...". What is "microstructure between"? Do the authors mean "microstructure differences between..." ?

5. P.2, lines 48-49: "highly active aluminum content of micron aluminum powder ". It is the aluminum itself that can be "highly active" but not the "content".

6. P.2, lines 51-52: "wrapping a layer of nano aluminum powder at the periphery of a micron aluminum". According the rules of the English language, one can wrap a subject in something (e.g. in a blanket)) or wrap something around something, but not "at". So, the text sounds incorrect.

7. P.2, lines 53-54: "Nano aluminum powder reacts forward...". What does it mean? And can anything react backward?

8. P.2, lines 55-56: "When aluminum powders start to release energy, the ambient temperature at the end of the detonation does not drop too low.". How can it be? At the end of detonation, the "ambient temperature" typically rises but not drops.

9. P.2, line 58: "molten agglomeration". What is this? Once again, the authors are supposed to be accurate in definitions and terminology.

10. P.2, lines 59-60: "a layer of gas-producing material is coated on the surface of micro and nano aluminum powder." Typically, in English we say "a material is coated with a layer of another material" but not "the layer is coated...".

The reviewer will not concentrate on other grammar and stylistic errors, which are abundant in the text.

11. P.3, lines 95-96. First, the text is not readable. Second, in formula (1) there is no diameter, it describes only the skin effect (parameter "delta"). Thus, the authors are supposed to formulate unambiguously how this formula was used to determine the wire diameter. Third, parameter "sigma" is not defined in the text below the formula.

12. P.3, lines 102-103: "nano-aluminum formed will be tightly adsorbed to the micron aluminum ... because of electrostatic forces". The question is: what is the origin and particular role of these forces? Are they attractive (+ to -) or repulsive (+ to +)? Once again, ambiguity in describing the underlying physics eventually results in a large error in understanding the processes of materials synthesis.

13. P.3, line 114: "were obtained by passing through a 40-mesh sieve..." Why "passing" and not sifting or sieving?

14. P.3, lines 116-122: the text is not readable and contains many physical errors. The authors speak about electrical explosion of a wire, which does not contain nano- or microparticles. Then how it happen that "... the metal droplets were formed by micron aluminum"? Maybe the other way round? Line 122: "gas-producing material cladding layer." What is it, i.e. what is the "cladding layer" which is "gas-producing"? This as another example of how incorrect English completely distorts the physical meaning.

15. P.4, lines 132-133. The text looks amusing: it were not the authors but the laser who observed the ignition. And what does "400 mg" refer to? 400 mg of what?

16. P.4, lines 134-139: "the non-isothermal kinetics was analyzed by calculating the activation energy." It is not so: the authors only calculated the activation energy using two methods but they did not analyze the kinetics, i.e. a particular kinetic mechanism of the product formation.

17. P.4: text in lines 146-152 is not readable.

18. Caption to Fig.2 should contain a brief description of what (a) through (g) denote.

19. P.4, line 158: "... powder was wrapped in epoxy resin". How can it be? Did the authors really wrap every single powder particle in the resin? Or they just used impregnation?

20. Caption to Fig.3 should contain a brief description of what (a) through (h) denote.

21. P.5, line 165: "...By sectioning the surface sweep..." What is "surface sweep"? This term is used in radars but not in Materials or Combustion Science.

22. P.5, line 176: "The oxygen bomb IC results ". What is IC? Any abbreviation should be decoded in the text. If it is the method, it should be described in Part 2 of the manuscript. The same refers to abbreviation XPS that first appears on P.6.

23. P.6, line 199. What is "passivated aluminum", which is first mentioned only here? If it is another material used in this work, it should be described in Part 2. If it was passivated by a certain method, the latter should also be described.

24. P.6, line 200: "the Pt data". What does it mean? Where and how did the authors use platinum (chemical symbol Pt)? A reviewer reads what is written, he/she is not obliged to solve puzzles.

25. P.6, line 201: "ability to do work." Which work?

26. P.6, line 201: "...boosted rate...". What is it? Who and how has boosted the rate?

27. P.7, Fig.6: parameter P is not described in the text. If it is pressure, then why it is measured in some strange units "KPa" (see Fig.6)? Is it Kelvin (K) times Pascal (Pa)?

28. P.7, line 217: "According to the thermal deflagration theory...". Here the authors deal with the ignition theory (Semenov-Zeldovich theory) but not the "deflagration theory". It is not the reviewer's duty to explain to the authors the principal difference between them, which is described in numerous books on combustion and explosion.

29. P.7, line 217: "radiation energy work on the surface". What is this?

30. P.8, lines 227-231. There aren't frames 6, 106 and 302 in Fig.8; they are indicated as X5 (not 6!), X106, etc.

31. P.9, line 256: what are the strange notations COn and AlFm in formula (5)?

32. P.9, line 260: "As shown in Figure (7), the second stage...". Actually, Figure 7 has nothing to do with this text.

33. P.9, line 266: "...in air atmosphere is shown in Figure 8.” Why Fig.8 and not Fig.9?

34. P.10, Table 1. The Kissinger and Ozawa methods used for estimating the activation energy should be mentioned in Part 2 of the paper. And why the activation energy is measured in J rather than J/mol?

35. P.11, Table 2. The heat capacity and heat conductivity are measured in strange units: J/(kg*C) and J/(kg*C), i.e. C is used rather than K. The authors should use standard units for these physical parameters. If they look attentively at the equations they solved, they will clearly see why it is incorrect.

36. P.11, lines 304-305: "In order to simulate the temperature rise ... the calculation is carried out by building a finite element model." This text is completely disposed of physical meaning. Any professor in Materials Science and/or Combustion Science always teaches his/her students that a finite element model (FEM) is no more than a numerical method, which is used to solve particular equations for a certain shape of the calculation domain. Mentioning the method without writing the equations is misleading. Thus, the equations of the ignition theory must be presented in the paper, all the more that they are not very cumbersome. Without them the text looks entirely 'blind' and meaningless.

37. P.12, formulas 9 and 10 and the text below them (lines 334-338). What is the "the mass of aluminum molecule"? How many atoms are there in this "molecule"? The Arrhenius exponent, which appears in these formulas, should include the activation energy of gasification (here denoted as Ev) rather than its enthalpy (see line 336). If the authors use enthalpy instead of the activation energy, this should be thoroughly justified in the text.

38. P.12, line 345: what are T0 and delta T?

39. P.12, line 352-353: what is "deeper response per unit of time"? Response to what? Deeper in comparison with what?

40. P.13, line 359: "powder burns layer by layer to release energy." The term "layer by layer combustion" is used in the area of Combustion Synthesis, or the so-called Self-propagating High-temperature Synthesis (SHS), it has a strict physical meaning and refers only to a macroscopic specimen. Why do the authors use this term here in regard to a microscopic particle, and what physical meaning do they put into it?

41. P.13, line 367: "fluororubber coated with aluminum powder". Why not the other way round, as follows from the whole previous text?

42. P.13, Fig.13. Term "Reunion" is typically used in social or political sciences. What is meant here under "reunion"?

43. Fig.13. The dispersion and especially "reunion" of the aluminum particles during detonation of the explosive were not studied in this work. So, this figure is unnecessary and actually leads away from the main results of the work.

44. P.13. Since in conclusion (3) the authors outline "the results of heat transfer calculation", then the equations that are solved must be presented in the paper (also, see comment 36).

 Thus, major revision is recommended.

 

Author Response

Thanks for the comments. Those are very important and helpful for the author and this manuscript. This manuscript has been carefully read and the errors in the English grammar and stylistics has been corrected. The point-by-point responses are shown in this file "Response 1". Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript ID: metals-2229469

Manuscript title: Improved Combustion Performance of Fluororubber-coated Micro-nano Composite Aluminum powder

In this manuscript, the authors reported that the structural and ignition properties of performance of fluororubber-coated micro-nano composite aluminum powder. The experimental was clearly described, and the conclusions were solid supported by the experimental results. Therefore, I can suggest its publication after considering following minor comments.

a)     The introduction is suggested to re-organize, make the motivation to be more clearly.

b)     Why fluororubber-coated? What is the motivation?

c)     Please mention what is the standard shape and size of the SEM test specimen.

d)     Do you have any comparable study on the same micro—nano composite by other methods? If yes, please compare with them.

e)     Please mention what is the standard shape and size of the ignition test specimen.

f)      There is a need to quantify the results in the conclusion to show the major findings

g)     There are few grammatical mistakes Authors are requested to proof read complete manuscript and check for English grammar.

 

 

 

 

Author Response

Thanks for these important comments and suggestions. Those are very important and helpful for the author and this manuscript. The point-by-point responses are as follows in this file "Response 2", and please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript metals-2229469 is an experimental study on how to improve the combustion of aluminum (Al) powder.

The authors propose that a powder made up of micro-Al spheroids with a surface deposition of nano-Al spheroids will retain the advantages of both scales, i.e., a larger amount of Al and a shorter reaction time, respectively. In particular, this prevents the nano-al spheroids from agglomerating during their melting, before their combustion is complete, and further adding a fluorubber layer around the micro-nano spheroids further enhances dispersion and thus combustion.

They describe the deposition process and the laser ignition and thermal decomposition analyses of this powder, whose properties they compare with those of other powders. Thus they demonstrate a significant advantage of their micro-nano-fluorubber compound powder, which they back-up with a simple modelling.

This is an excellent study, well-conducted and detailed. I recommend its publication subject to minor changes without a second peer review. The authors may wish to include some additional comments on whether the shape of the powder components might affect the results, i.e. flakes vs. spheroids. Some sentences should be simplified, typically by using the active voice instead of the passive voice, wherever possible.

L330: The last sentence "And then ... (10)." should be rephrased, e.g., "The reactivity is described by the relations".

Author Response

Thanks for the comments, and it is very important for this manuscript. It is interesting to do some experiments about whether the shape of the powder components might affect the results. In this manuscript, the aluminum powder is only spherical, and the flakes may be studied in the following work. The study may be written in the next article.

As for sentences and grammar, the author made many mistakes. After the careful reading and revising, the new manuscript has been written. L330: The last sentence "And then ... (10)." should be rephrased, e.g., "The reactivity is described by the relations". That has been replaced already.

Round 2

Reviewer 1 Report

1. In their response to the reviewer's comments on the 1st version, the authors have agreed with comment 43 that Figure 13(b) should be deleted. But in the revised version Figure 13(b) is still present. Thus, it should be deleted. 

2. There are still some minor errors in the English language, hence the text should be edited once again. Certain (but not all) examples are below:

(a) what is "diffences" (P.2, line 48)?

(b) "energy will been released" (P.2, line 56)

(c) "which likes a sea urchin" (P.2, line 59). Who likes what?

(d) "the problem of agglomerate" (P.2, line 65). Also, see line 70. Agglomerate is a verb or, when used as a noun, is the result of agglomeration.

(e) "Visualization ... were observed" (P.4, lines 158-159). 

(f) "The influence law of the microstructure ... on the heat transfer performance" (P.4, lines 170-172). Sounds not English.

(g) "From Figure 2 (d) to (g), there are" (P.5, lines 182-183). Sounds not English.

(h) "can be shown clearly in Figure 2 (g)." (P.5, line 185). Can be shown or is shown?

(i) "The micro structure of the prepared sea urchin structure" (P.6, line 201).  The text is tautological. How many structures are there?

(j) "shows a tendency," (P.6, lines 209-210). A tendency to what?

(k) "due to low content or amorphous." (P.6, lines 217-218). What is amorphous?

(l) "The XPS result can be shown" (P.7, line 224). Can be shown or is really shown? Same refers to line 226 ("can be found").

(m) "the capacity to apply work" (P.7, line 237). Which "work" is meant?

(n) "adiation intensity" (P.8, line 246). What is "adiation"?

(o) "were pushed loosely" (P.8, line 248). Why "pushed"?

(p) "the laser works on the surface" (P9, line 257). Which "work" is meant?

(q) "It indicates that the decomposition ... and the combustion..." (P9, line 273-274). What means "that"?

(r) "react with the oxidizer of air." (P11, line 307). What can oxidize air?

(s) In the text on P.12 and in Table 1, parameters "n", "alpha" and "a" are not explained.

(t) "heat transfer equation can be shown"  (P13, line 360). Equaitions are not shown, they are written.

(u) "To simplify the model, this points is assumed that" (P14, line 384). First, it sounds not English. Second, English grammar rules should be observed throughout the text (also, see line 389).

(v) "is mentioned form Boltzmann’s law."  (P14, line 388). What does it mean?

Hence, minor revision is recommended.

Author Response

Thanks for these comments and they are accurate and very helpful. There are many errors in the English language and these errors make this manuscript misunderstanding. It is the authors’ duty to edit the text once again.

The point-by-point responses are as follows.

And please see the attachment.

Author Response File: Author Response.pdf