Microstructure and Properties of Ti6Al4V Surface Processed by Continuous Wave Laser in Different Atmospheres
, Yanfei Zhao 1, Yaoyao Liu 1, Hongyu Zheng 2,*, Zhongchen Du 3 and Jian Liu 3Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe work is aimed at studying the microstructure, XRD and properties (hardness and anti-corrosion performance) of the Ti6Al4V surface processed by continuous wave laser in different atmosphere (in air and in compressed oxygen). The paper contains new scientific results. However, the mechanism of formation of protective coatings itself is not given. For a better understanding of the paper, I suggest the authors look at my comments.
1. In the introduction, reflect the more current state of the research with appropriate references.
2. Fig. 2, 4 and 5 scale markers are not visible. Needs to be corrected.
3. In Fig. 7 shows the results of SEM micro morphologies of sample Ti-O15. Deep ditches are clearly visible along the entire length of the cross-sectional. It is necessary to explain what their formation is connected with. And explain whether this is typical for other compositions.
4. It is not clear why the results of measuring the hardness of only two samples of Ti-A10 and Ti-O10 are given. The question also arises as to whether cracks were detected from the edges of the post-indentation sites in these samples.
5. It is not clear why the results of measuring anti-corrosion performances of only two samples of Ti-A10 and Ti-O10 are presented.
6. The conclusion needs to be corrected. Using “much thicker”, “were significantly improved” - not scientific. It is necessary to provide numerical dependencies. It is necessary to indicate how much the width of melting area increased.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper describes a study of Ti alloys surfaces after irradiation by a cw laser in different atmospheres to modify the surface to protect it. the work seems to be competently done.
The word is irradiated not irritated.
Element names are not capitalized except to start a sentence.
Figure 1. Use a different color than red for the size marking.
What kind of camera with what speeds was used?
All figures. Try to use a different color than red as labels in the figuresas it does not stand out enough.
Table 3. Do they really know the EDS results to two decimal; places in percent. I would be surprised if they did. Please also give error bars. The same for Table 5
What is R-type TiO2? If they mean rutile, then just say rutile.
Line 196 compressed not compress.
Line 222. The average surface hardness values cannot be that accurate to a decimal place. What are the error bars on the average hardness values?
I really do not think that they have measured the corrosion potentials to 4 decimal places in volts. Please give a reference to the untreated Ti results. Line 233. Also, is the current also good to that many places considering the small size of some values?
These are issues that can be readily addressed in a revision.
Comments on the Quality of English Language
some issues are noted.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsIn the manuscript by Huang et al., a study of the surface modification of Ti-6Al-4V alloy caused by heating by a laser beam under air and compressed oxygen atmosphere is reported. The work is topical because the enhancement of the surface stability of these materials is desirable for applications such as medical implants, etc. The work has been carried out carefully, however, the interpretation of some of the data is somewhat questionable and, in my opinion, some comparative experiments are missing. I, therefore, recommend to re-evaluate some of the results and to revise the manuscript.
Major:
l. 88: Details on EDS are missing (depth of analysis). Signals of Ti-Kbeta and V-Kalpha overlap in this method, how was it treated?
l. 132-133: It is not true for oxygen... The material analysed in point 3 (Figure 2) seems to be unaffected... Why is there so much O and N? What is the depth of EDS – can be such results explained by surface oxidation when treated with Kroll’s reagent? What about possible fluorine content? The same questions stay for analysis of other samples (Spot 4 in Tables 4 and 5). Analysis of cross-sections of untreated material should be done for comparison.
Figure 5: Figure 5 (b) does not correspond to a highlighted inset in Figure 5 (a), please, mark the right region.
When a reader finishes the article, the simple question arises – why the experiments were not performed under a simple N2 atmosphere? Such results are missing, especially when TiN forms a more resistant/hard coating...
Minor/formal:
l. 19-20: ...layer enriching of N was formed in the bottom... rather ...N-enriched layer was formed at the bottom...
l. 140-142: The sentence is hard to understand – should it mean: ...Although TiO2 is a more stable phase than TiN, synchrotron X-ray radiation studies have shown that due to reaction kinetics, TiN is produced faster/earlier than TiO2...?
l. 235: A higher/lower terminology is a bit complicated when speaking about redox stability. Please, use “more negative potential”. The potential mentioned here is lower, not higher.
Comments on the Quality of English LanguageThere are several clumsy formulations, mentioned in "Suggestions for Authors" part.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have made edits to almost all comments. However, please note that: 1. The authors did not respond to Comments 1: In the introduction, reflect the more current state of the research with appropriate references. The authors provide additional links from 2010 and 2013 - these are not modern works that do not show relevance. The authors need to study the current state of the issue. 2. It is necessary to add scale markers to the figure. 7 and 9.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors addressed all objections, and provided appropriate explanation. I support publication of the paper in the present form.
Author Response
Thanks a lot for your kind work.
