A Physical Approach to Simulate the Corrosion of Ceramic-Coated Magnesium Implants

Round 1

Reviewer 1 Report

1. The manuscript presented some simulation works to examine the corrosion behavior on magnesium-based biodegradable materials. It’s difficult to find key factors related to the corrosion process in their simulation works. The authors may think to re-write their abstract and conclusion and summary their important findings from their works.
2. The context is not well organized. Fig. 1 to 3 may be re-organized to Sec. 2 to describe the material corrosion theory and induce their simulation theory. Later on, the following section for experiments can be delivered.
3. 3, 4 and 6 are common knowledge to electrochemical readers, they can be deleted to diminish figures in the paper.
4. It’s suggested to new title “A physical approach to simulate the corrosion of ceramic-coated magnesium implants:”

Comments for author File: Comments.docx

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

In the paper the problem of corrosion of magnesium implant is studied. Expermimental and simplified numerical results are presented. This is the strongest point of the work. However, the paper in the present form cannot be published in the journal.

General remarks:

1. Please, make some introduction to the Section 2 - explain what and for what reason is done in your study. Outline the simplifications that are made in your numerical model.
2. What kind of the finite element is utilized in the computations (in both models). Make some comments about the mesh convergence study in the text. The numerical model is described very laconicaly if compared with the experiments.
3. In the revierwer's opinion the results presented in the paper do not justify the conclusion that the magnesium corrosion is a transport controlled phenomenon. The model, as described, does not take into account any other effects that the mass transport and the agreement between the numerical and experimental results is strongly dependent on the chosen diffusion coefficent. Please, make some extended discussion in this context. 
4. Please, describe shortly, for the sake of clarity, the modified simulated body fluid preparation procedure. 
5. Please, comment the results shown in Figure 15. At the first glimpse no differenes are visible between the bare and coated sample.

Technical remarks:

1. Place the equations close to the part of the text they refere to.
2. Indicate units in all figures in the paper. Specify also clearly the quantites which are nondimensional ([-]).
3. Describe clearly the series in the legend in Figures 11,12.
4. Use the same font size in (2) and (3) (for Magnesium concentration).
5. Notice, that the ML (Mass Loss) as well as CL (Coating Layer) acronyms are not explained in the text. 
6. Enlarge the font size in Figure 3.
7. Improve the quality of Figure 5.
8. Add the dimensions o the screw in Figure 8, if it is possible.
9. Some language improvements can be introduced, e.g. the sentence in line 210-211 suggests somehow, that Figure 15 depicts the comparison between the numerical and experimental results, whereas it shows only the numerical ones. 
10. Consider some reorganization of the paper content taking into account that:

• In section 2.2 two groups of samples are distinguished. However, the coating procedure is described in the next section. This is in some sense non logical. 
• In section 3.1 the model parameter calibration is disussed. However, in the last paragraphs the screw corrosion is considered. 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The revised version is much improved and suitable for publication.

Reviewer 2 Report

My previous comments have been taken into account and the paper has been improved appropriately. In my opinion the work can be published in the journal.

Some technical remarks:

1. There is something wrong with the dimension lines in Figure 8.
2. Remove the background color in Figure 4.
3. Use kg/m³ instead of Kg/m³.