Optimum Processing of Absorbable Carbon Nanofiber Reinforced Mg–Zn Composites Based on Two-Level Factorial Design
Round 1
Reviewer 1 Report
the current study investigates several factors that influence magnesium implants such as compaction pressure, sintering temperature and time and CNF percentage. The measured outputs were E, hardness and weight loss. The authors employ design of experiments to analyse the studied outputs.
Line 67-69 is too long consider breaking down or shorten it.
Line 67-78 is not necessary the authors should consider removing design of experiments are well known and it is not necessary to explain them.
The literature is good but needs more work, the authors should discuss several past studies similar to their work and discuss what they did and what were their findings and then explain how their work is different from the others.
The authors need to add the following in materials and method section
- Image for one or some of the samples
- Image for some of the machine/equipment used in the study with setup/preparation of samples in them if possible
Line 135-18 is already mentioned before please remove it
Section 3.1 feels more like it belongs to the materials and method section
The paper discussion section reads more like a manual on what is ANOVA and what is design of experiments. The authors should consider focusing more on analysing the results scientifically as well as what they did analysing them statistically.
The paper does not read well in the current structure, it is strongly recommended to merge sections 3 and 4 together so that the readers can follow up the results and discussion all together.
the authors must add all the data for E, hardness and weight loss in the form of graphs and show error bars on collected results. there is only statistical data showing in the paper which is not enough to capture the findings of the study
Author Response
Dear Reviewer,
Thank you so much for your time that you have spent to review our manuscript. We really appreciate it. I attached a file of our response to your comments/concerns.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
It is suggested that this paper can be accepted for publication in Metals after the following points are considered:
- Line 146th, how did the EDX confirm the homogeneous distribution of alloying elements? When the content of elements is low, the EDX is insensitive to them. In addition, how about the statistical analysis accuracy of such a method?
- Line 149th, the authors identified the peaks at 35 to 40 degree as the Mg-Zn solid solution, but in the Figure 1, they also identified them as MgxZnY phase. Please the authors clarify this confusion.
- In Figure 1, around at 73 degree, why is the intensity of carbon peak for Mg-Zn/0.1CNT the highest? In this alloy, the content of CNT is the lowest.
- The fonts in Figure 2, 3 and 4 are too small to be read clearly.
Author Response
Dear Reviewer,
Thank you so much for your time that you have spent to review our manuscript. We really appreciate it. I attached a file of our response to your comments/concerns.
Thank you.
Author Response File: Author Response.pdf
Reviewer 3 Report
This paper aimed to identify conditions using CNF to improve strength and resistance to degradation of Mg-Zn alloy composites. They measured the effect of 4 parameters - CNF wt%, sintering temp, sintering time, and compaction pressure. They found that adding 2% CNF, along with increased compaction pressure yielded stronger composites. The optimized parameters were strongly correlated with improved strength, hardness, and degradability. They did an excellent job of outlining the study, explaining the methods, and results. The statistics were well done. The major weakness of this paper, is that there is a lack of context of how meaningful these properties would be to prevent pre-mature failure of stents or fixation screws in orthopaedic applications. The range of 50-100% degradation in only 3 days in PBS seems to be still very degradable. It is not clear whether the optimized conditions in this paper are sufficient to yield clinically meaningful materials. Other specific comments are listed here:- Is toughness or torsional strength also relevant here?
- Please expand on how your results may impact clinical applications
- These results show that design parameters yielded statistically significant results, but practically, are these results meaningful? What is a goal for %degradation? some of the samples degraded 100-50% after only 3 days in PBS. Is this sufficient improvement to meet the issues with fixation stability and corrosion introduced in the beginning of the paper?
Author Response
Dear Reviewer,
Thank you so much for your time that you have spent to review our manuscript. We really appreciate it. I attached a file of our response to your comments/concerns.
Thank you.
Author Response File: Author Response.pdf
Reviewer 4 Report
The paper uses a DOE method to optimize the material design and process based on CNF composition, compaction pressure, sintering temperature and time. The paper is discussing design optimization of an important resorbable implant material and worth being considered in the Journal. However, there are some questions and modifications that needs to be answered:
- Page 2 line 51- What do you mean by “high interface of CNF”?
- Page 2 line 91: It is mentioned that the upper and lower limits chosen for the two factorial model is explained in the “chemometrics in spectroscopy” by Howard Mark. Although the algebra associated with the study is thoroughly explained in the reference, it is better to indicate for example why the authors chose a maximum 2 wt% for the CNF in the material. A short explanation is required to make it easier for the readers.
- Page 4 line 118, Do the authors looked into the microstructure after grinding up to 1000 Sic paper. Was there any polishing involved using polishing pads, collide silica and diamond past? If so the current sentence doesn’t convey the message properly and needs to be revised.
- Page 4 line 129. Did the authors rinse the samples in water or ethanol? A complete picture of the experimental procedure is required to be addressed.
- Page 5 line 152: the phases and planes indices associated with each peak needs to be provided.
- Page 9 line 204. The authors have nicely shown the interrelationship of the parameters naming CNF percentage, compaction pressure, sintering temperature with mechanical and corrosion properties. However, in line 203-205 there is a comment on the size of the particles. Although the comment is correct, but it seems that the model is actually lacking the size effect. Therefore, I believe there should be at least a future work focused on the size of the particles.
- The model here shows that the optimize condition is mostly achieved for the upper limits (2%CNF, 400MPa pressure and 500° C sintering temperature). Could it be that if a higher limit values than the current values was chosen, it was possible to achieve an even better results on mechanical properties? It seems that the authors need to rationalize the model’s function on how the optimum condition is achieved in the discussion section.
- What is the difference between Figure 2 and 4. A comparison between can provide the readers with better understanding.
Author Response
Dear Reviewer,
Thank you so much for your time that you have spent to review our manuscript. We really appreciate it. I attached a file of our response to your comments/concerns.
Thank you.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Table 1 instead of saying factor A-D and Response 1-3 (1) elastic modulus, (2) hardness, and (3) weight loss) it is better to write wha tare these factors and what are these responses
In Table 1 there is some issue in Run 2 Response 1, the value is 28667 is this correct! it seems to be odd from all other data in that column
the authors must add a table showing the levels of the factors used, its confusing to know that from Table 1.
I think Table 1 have some issue, for example check run 29 and 36 there is a vlaue of 1.05 and 0.1 and 2 is this a two level factorial? or is this a two level with centre points? it is confusing, more details should be added on the design fo experiment (short and clear description).
I think that presenting the data in table form makes the interperation of results difficult by the readers, especially there were 36 runs.
One last question how many times each test with same factors was repeated?
Author Response
Dear Reviewer,
Thank you so much for your time that has been spent to review our manuscript. We really appreciate it. Please refer our response from the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
authors addressed my concerns. ty.
Author Response
Dear reviewer,
Thank you so much for your time that has been spent to review again our manuscript. We really appreciate it.
Reviewer 4 Report
The revision contains all the mentioned points and therefore is acceptable for publication.
Author Response
Dear reviewer,
Thank you so much for your time that has been spent to review again our manuscript. We really appreciate it.
Round 3
Reviewer 1 Report
Authors have answered all questions
