Investigation on the Surface Properties of 5A12 Aluminum Alloy after Nd: YAG Laser Cleaning
Round 1
Reviewer 1 Report
The study aims to identify the best conditions to clean the 5A12 aluminum alloy. The effects were characterized by different techniques such as SEM-EDS and Vickers.
Page 1, Line 37. The reference 9 is not about the text referenced. There are better studies to be referenced here.
Page 1, Line 31. "and et al." is not in the context of the paragraph
Is Figure 1 from the authors or from a book/article? If the latter, it should be referenced. If it was composed by the authors with information from studies, they should be referenced too.
Text in Fig. 5 needs better contrast, maybe in white.
Page 9, Line 229. The sample cleaned at 98 W is not more brilliant than the others, it reflects the light from the light bulb. Change the photograph for other one in which the light is not reflected.
Table 5 and 6, it is necessary to indicate the analysis technique in the caption.
Page 9, Line 250. Mg and Al have to be changed to Magnesium and Aluminium.
Some misspellings: Table 1: frcation instead of fraction; Table 5 and 6: elemen instead of element; Section 3.1.2: macroscopic instead of microscopic; Fig. 5: Unclend instead of Uncleaned; Page 11. Line 301: NaCI instead of NaCl.
There is an excessive number of figures and tables, mainly because they show the same information and they result repetitive. Table 3 and Fig. 3 can be unified together, as Table 4 and Fig. 4. In addition, they could be the same figure separated by (a) and (b). However, the roughness maps and the scale have to be increased since they are not distinguished. Fig. 9 is not necessary since the Tables 5 and 6 have the chemical analyses.
Errors have to be added to the Ra and microhardness results.
Author Response
Dear Reviewer:
Thank you very much for your comments on our manuscript. We would like to express our sincere appreciation for your careful reading and invaluable comments. These comments are very valuable and helpful in improving our manuscripts, and they have important guiding significance for our thesis writing and research work. We have carefully revised the manuscript based on your comments and revised it through the English editing service of MDPI. Our description of the revision based on your comments is stored in the below.
Dear Reviewer:
Thank you very much for your comments on our manuscript. We would like to express our sincere appreciation for your careful reading and invaluable comments. These comments are very valuable and helpful in improving our manuscripts, and they have important guiding significance for our thesis writing and research work. We have carefully revised the manuscript based on your comments and revised it through the English editing service of MDPI. The following is our description of the revision based on your comments.
Point 1: Page 1, Line 37. The reference 9 is not about the text referenced. There are better studies to be referenced here.
Response 1: I am very sorry for the citing errors in the manuscript. we have replaced the new reference.
Point 2: Page 1, Line 31. "and et al." is not in the context of the paragraph
Response 2: Thank you for your comments. Corrections have been made in the new manuscript.
Point 3: Is Figure 1 from the authors or from a book/article? If the latter, it should be referenced. If it was composed by the authors with information from studies, they should be referenced too.
Response 3: Figure 1 is based on the contents of the literature and made by ourself. We have added references to illustrate it.
Point 4: Text in Fig. 5 needs better contrast, maybe in white.
Response 4: Thank you for your comments. We have changed the color of the text in the figure to white.
Point 5: Page 9, Line 229. The sample cleaned at 98 W is not more brilliant than the others, it reflects the light from the light bulb. Change the photograph for other one in which the light is not reflected.
Response 5: We have replaced new picture according to your opinion. The samples in the new picture will not have reflective problems.
Point 6: Table 5 and 6, it is necessary to indicate the analysis technique in the caption.
Response 6: We have added analysis techniques (EDS) to the title of the original table based on your comments.
Point 7: Page 9, Line 250. Mg and Al have to be changed to Magnesium and Aluminium.
Response 7: Thank you again for your comments. We have revised these questions according to your opinion.
Point 8: Some misspellings: Table 1: frcation instead of fraction; Table 5 and 6: elemen instead of element; Section 3.1.2: macroscopic instead of microscopic; Fig. 5: Unclend instead of Uncleaned; Page 11. Line 301: NaCI instead of NaCl.
Response 8: We are very sorry for such mistakes. These spelling mistakes will not appear in the new manuscript.
Point 9: There is an excessive number of figures and tables, mainly because they show the same information and they result repetitive. Table 3 and Fig. 3 can be unified together, as Table 4 and Fig. 4. In addition, they could be the same figure separated by (a) and (b). However, the roughness maps and the scale have to be increased since they are not distinguished. Fig. 9 is not necessary since the Tables 5 and 6 have the chemical analyses.
Response 9: We have deleted unnecessary tables and figures, such as Table 3, Table 4, and Figure 9. Roughness maps and scales have been added to the new manuscript, and they will appear in the new manuscript in the form of three-dimensional topography, which will make the results more intuitive.
Point 10: Errors have to be added to the Ra and microhardness results.
Response 10: Thank you very much for your comments. We have added errors to the Ra and microhardness results.
Thank you again for your attention to our manuscript. We would be glad to respond to any further questions and comments that you may have.
Reviewer 2 Report
Manuscript #578388 with title “Investigation on the Surface Properties of 5A12 2 Aluminum Alloy after Nd:YAG Laser Cleaning” investigates the optimum laser cleaning parameters for the removal of oxidation from 5A12 aluminum alloy through the evaluation of a number of laser cleaning trials using various operative parameters.
The paper refers to a case study on a specific material and the work discussed necessitates further discussion and justification. A number of important questions are summarized here:
1. Which is the reference surface? Is it the non-irradiated (but encrusted) or the non-oxidised Al?
2. Which is the damage thresholds for the a) Al alloy and b) the oxidation layer?
3. How do the authors define the optimum cleaning level? Which are the criteria for optimum/under-/over- cleaning?
These questions should be discussed and defined in a separate section “scope of this research” after the “1. Introduction” and before the “2. Materials and methods” which would describe in detail the work behind this research and the reason for choosing the specific evaluation analysis and diagnostics.
A very important point that urges for further discussion and revision is the choice of the optimum cleaning level, where do you want to reach? And as a consequence, which is the reference surface for all you measurements? Is it the non-irradiated but oxidized surface (as a reader can conclude from this manuscript) or the initial Al surface prior to its oxidation and the formation of corrosion oxides on its surface? Why the perfect surface roughness is compared to the non-irradiated surface and not to the non-oxidised one?
As one can see in Section 3, the whole research is based on the initial choice of parameters on the basis of Surface roughness (corresponding to 98W and 3.0 mm/s) which has a reference point the “non-cleaned” surface, which practically refers to the non-irradiated one (as also confirmed by the discussion of Fig 7). Here another logical question is why the authors accept as optimum a surface roughness value that is lower (0.87μm) than their “reference” one (0.98μm), which is the non-irradiated surface. Actually the authors must explain this decision. Why a surface smoother than the reference/initial one is chosen? Why did you choose as an optimum laser power the 98W which results into a surface roughness of 0.87μm rather than the 110 W which results into 0.90μm, a value closer to the untreated one (0.98μm)?
Most importantly have you done measurements on an Al surface prior to its oxidation? Could you please present these measurements, as this is the actual reference surface for all your study and comparisons given that it represents the surface you would like to reach which is different from the initial non-irradiated and oxidized surface that you want to clean. Moreover, please discuss how do you discriminate, from the surface roughness point of view, a perfectly cleaned surface and a melted Al surface?
Another discussion that must be also done is how do you discriminate between molten oxidation corrosion layer and molten aluminum alloy surface? why the surface presented in Figure 5d is a preferred one, given that as discussed in lines 181-182 this is the result of molten metal (“It can be inferred that the energy generated by the laser power at this time is enough to fill the cavity with molten metal liquids”)???
Another issue that necessitate further attention before the publication of this manuscript is the English context and syntax. The manuscript would be greatly enhanced after a thorough revision in English.
Other minor points for revision:
Introduction Section: In this section there is an inconsistency in the number of the bibliographic references for example, Ref # 8 by Siano et al , which refers to the application of laser cleaning in Cultural Heritage (CH), is marked as # 9 in line 36. Actually in line 35 the use of terms “repair and maintenance of artworks and sculptures” is not correct. Lasers have been used to remove unwanted layers and encrustation of artworks in order to enhance their appearance and ensure their longevity. The terms “repair” and maintenance” do not describe these actions in CH.
Line 23, Introduction: “and electronic industry and et. al [2-4]”. Please revise
Line 31, Introduction: “and pollution of the environment and et. al.” Revision is necessary
Line 38, Introduction: what do you mean by “cleaning without grinding”? Suggested revision “without changing the surface morphology..”
Line 52, Introduction: the binding force is not “destroyed” but “disrupted”, so it is suggested to replace the word.
Line 56, Introduction and also Figure 1. Could the authors give further info on this Figure; is it a figure that has been created through experiments by them or it refers to data given at a paper or a database? Please explain and revise.
Lines 57-58, Introduction: the sentence “For aluminium alloy, when the laser wavelength is 1064 nm, the absorption rate of laser is better” needs revision in English
Line 58, Introduction; what do you mean by “acoustooptic”? Please explain further
Lines 69-75, Materials and Methods; Why this info is important? Isn’t it generally known how a Q-switched laser system is working?
Lines 85-89, Materials and Methods; suggested revision.. “is discussed..” and “ is investigated”… the rest of the description may stay in past tense…
Line 100, Materials and Methods; Possibly here as well as in the whole manuscript you may use the term “reference sample/material/surface” for the “not cleaned” specimens.. Actually even for the treated samples the correct term is not “cleaned” but “laser irradiated” or “laser treated” as cleaning may not be achieved in all cases…
Lines 102-104, Materials and Methods; please revise in English
Lines 107-109, Materials and Methods; please revise in English
Line 118, Materials and Methods; What is a “Tafel polaristaion curve”? possibly here you need to add further discussion: “Then the Tafel polarization curve was obtained which shows++++ or gives info on +++++”
Line 123, Results and Discussion; Please explain further the sentence “we first tested the roughness of samples under different power and different cleaning speeds”. Do you mean that for every different power you tested different cleaning speeds? What is the cleaning speed for data shown in Table 3 and similarly which is the power for the data of Table 4?
Line 132, Results and Discussion; “to a minimum of 0.87 μm at 98 W laser power” why the minimum value of surface roughness is chosen? Actually this value (0.87) is lower than the reference one (0.98), so why is it chosen? How do you discriminate, from the surface roughness point of view, a perfectly cleaned surface and a melted Al surface?
Lines 145-154, Results and Discussion; The “above analysis and discussion” needs further explanation. Please discuss further the “trend of increasing-decreasing-increasing-decreasing”, what do you mean? What are the parameters that influence this “trend”? what do you mean by “flatness”?
Lines 148-154, Results and Discussion; Text must be revised in English
Lines 156-191, Results and Discussion; This whole paragraph needs revision in English so to better present the discussion on the observed SEM analysis. For example how do you discriminate between molten oxidation corrosion layer and molten aluminum alloy surface? The holes of Figure 5b2 are due to molten Al alloy or corrosion? Do you want to reach into a molten Al alloy surface? Is this an optimum cleaning? why the surface presented in Figure 5d is a preferred one, given that this is the result of molten metal (“It can be inferred that the energy generated by the laser power at this time is enough to fill the cavity with molten metal liquids”)???
Line 165, Results and Discussion; Which is Figure 5(a2)?
Line 187, Results and Discussion; Figure 11? You mean Fig 5f?
Figure 5, a) uncleaned
Lines 200-202, Results and Discussion; “It may be that the cleaning speed is too slow and ablation occurs on the surface of aluminium alloy, leaving black holes to form ablation holes” what do you mean? Please explain.
Lines 206-211, Results and Discussion; This paragraph must be revised in English.
Figure 7; a Scale must be added also a photo of a reference surface prior to oxidation
Lines 227, Results and Discussion; Which is the “true color of the substrate”? How this is defined?
Line 236, Results and Discussion; “In this paper, the effect of cleaning oxide film is mainly measured by the content of oxygen”; Actually this statement is very important and crucial and should be mentioned and discussed in the beginning of the paper into a section that would present the “scope of this research” and the criteria for discussion.
Lines 250-255, Results and Discussion; the issue on the reduction of Mg content after cleaning must be further discussed and also should be mentioned in the introduction and the “scope of this research” section (that must be added)
Line 275-278, Results and Discussion; what about the micro-hardness that corresponds to cleaning speed of 1mm/s?
Line 283-293, Results and Discussion; why the residual stress is “compressive” and “tensile” what does this mean actually? How do they affect the final result? How the absence of Mg and the increase of residual stress in the aluminum alloy affect the final decision on the laser-cleaning result?
Author Response
Dear Reviewer: Thank you very much for your comments on our manuscript. We would like to express our sincere appreciation for your careful reading and invaluable comments. These comments are very valuable and helpful in improving our manuscripts, and they have important guiding significance for our thesis writing and research work. We have carefully revised the manuscript based on your comments and revised it through the English editing service of MDPI. Our description of the revision based on your comments is stored in the following World file.
Author Response File: 
Author Response.pdf
Round 2
Reviewer 2 Report
the manuscript has been significantly revised by the authors , how have carefully responded to the reviewing comments.
The manuscript is ready to be published.
