Review Reports

Round 1

Reviewer 1 Report

The paper is of interest and can be accepted. It has however a somehow weird English which shall be thoroughly corrected as well as a number of errors which needs author attention on revision as follows:

1. Generic comment: The term “sinter” used seems to be an equivalent of “slag” and requires more details of explanation.
2. Line 16: The parameter R as defined is not in % units, it is unitless.
3. Line 29: The statement “…liquid phase condenses during the sintering process…” is incorrect because the liquid phase is already a condensed phase, it has to be replaced by “liquid phase solidifies during the sintering process…”
4. Line 30: The statement “binder liquid phase…” shall be corrected to “binder glass phase…”
5. Line 35: The units of compressive strength are N/m2 not N/m3.
6. Line 60 onward: Authors start to use the term “slag”, please specify whether the slag is the same as sinter or what is the difference between the slag and the sinter.
7. Line 76: Note that crystallized glass is a glass crystalline material (abbreviation GCM) which is thermodynamically a more stable material compared the original glass before crystallization – see e.g. https://doi.org/10.3390/su13084117 and Fig. 5 in https://doi.org/10.3390/ceramics4020011.
8. Line 93: The sentence “The ingredients are shown in Table 1 and Table 2” needs modification to explain the Table 1 is for samples at Al2O3 constant content of 10 wt.% and Table 2 is for samples at constant R=1.0.
9. 1 (which is for crystalline phases) has unexplained (temperature scale and coloured lines) and difficult to read parts (text on the left part).
10. Table 1: is the LT (liquid temperature) liquidus temperature?
11. Line 121: Sinter Process shall be modified to Sinter Preparation
12. Line 122: The sentence “The sample was put into…” shall be modified to “The sample precursor (green body) was put into…
13. Line 145: The statement “The samples were measured using…” shall be replaced by “The samples were analysed using…”
14. Line 160: The “steamed bread peak” is not really a peak and is typically termed “the hump”. Presence of any peak within XRD patterns would indicate on presence of crystalline phases.
15. Line 161: The statement “…several glass phases synthesized are pure phases” shall be amended to be “…several glass phases synthesized are pure vitreous phases”.
16. Line 187: The wrong claim “ glass phase quenched in liquid nitrogen at 950°C” needs to be modified to “glass phase quenched in liquid nitrogen and then kept at 950°C for crystallization…” 
17. Line 188: Replace the word “precipitated” by “formed”.
18. Line 309: Replace the word “steps” by “phases”
19. Lines 393-394: The statement “The formation of the glass phase in the sinter improves the metallurgical properties of the sinter” is irrelevant and shall be either proved within the manuscript or deleted.
20. Line 396: The parameter R is not in % units, it is unitless.

Author Response

Dear Reviewers,

Thank you for your helpful and constructive comments and suggestions, which greatly improved our manuscript. We had revised the manuscript according to the comments/suggestions. The response for the revision corresponding to comments and suggestions from Reviewers has been given at the end of this letter.

Best wishes,

R-F Xin and X-M Guo

The response to Reviewers is as following.

Response to Reviewer 1 Comments

Point 1: Generic comment: The term “sinter” used seems to be an equivalent of “slag” and requires more details of explanation.

Response 1: According to your suggestion, the “slag” was modified to “the binding phase liquid phase in the sinter”.

Point 2. Line 16: The parameter R as defined is not in % units, it is unitless.

Response 2: Thank you for your suggestion, the corresponding location has been modified

Point 3. Line 29: The statement “…liquid phase condenses during the sintering process…” is incorrect because the liquid phase is already a condensed phase, it has to be replaced by “liquid phase solidifies during the sintering process…

Response 3: Thank you for your suggestion, the corresponding location has been modified

Point 4. Line 30: The statement “binder liquid phase…” shall be corrected to “binder glass phase…”

Response 4: Thank you for your suggestion, the corresponding location has been modified

Point 5. Line 35: The units of compressive strength are N/m2 not N/m3.

Response 5: Thank you for your suggestion, the corresponding location has been modified

Point 6. Line 60 onward: Authors start to use the term “slag”, please specify whether the slag is the same as sinter or what is the difference between the slag and the sinter.

Response 6: we agree with your suggestion, The glass phase based on the crystallization of the binder liquid phase in the sinter is studied in this paper. Due to the lack of research in the field of sinter, the paper on the mold slag for continuous casting mold is cited here for reference. They all belong to the CaO-SiO₂-Al₂O₃ slag system.

Point 7. Line 76: Note that crystallized glass is a glass crystalline material (abbreviation GCM) which is thermodynamically a more stable material compared the original glass before crystallization – see e.g., https://doi.org/10.3390/su13084117 and Fig. 5 in https://doi.org/10.3390/ceramics4020011.

Response 7:  we have re-checked, supplied two recent references used in the manuscript as following.

[8] Ojovan, M.I. The Modified Random Network (MRN) Model within the Configuron Percolation Theory (CPT) of Glass Transition. Ceramics. 2021, 4, 121-134.

[9] Ojovan, M.I., Petrov, V.I., Yudintsev, S.V. Glass Crystalline Materials as Advanced Nuclear Wasteforms. Sustainability. 2021, 13, 4117.

Point 8. Line 93: The sentence “The ingredients are shown in Table 1 and Table 2” needs modification to explain the Table 1 is for samples at Al2O3 constant content of 10 wt.% and Table 2 is for samples at constant R=1.0.

Response 8: Thank you for your suggestion, the corresponding location has been modified.

Point 9. 1 (which is for crystalline phases) has unexplained (temperature scale and coloured lines) and difficult to read parts (text on the left part).

Response 9: Very good suggestion, redraw and explain for better presentation.

Point 10. Table 1: is the LT (liquid temperature) liquidus temperature?

Response 10: Thank you for your suggestion, it has been explained in the paper according to your suggestion.

Point 11. Line 121: Sinter Process shall be modified to Sinter Preparation

Response 11: Thank you for your suggestion, the corresponding location has been modified.

Point 12. Line 122: The sentence “The sample was put into…” shall be modified to “The sample precursor (green body) was put into…

Response 12: Thank you for your suggestion, the corresponding location has been modified.

Point 13. Line 145: The statement “The samples were measured using…” shall be replaced by “The samples were analysed using…”

Response 13: Thank you for your suggestion, the corresponding location has been modified.

Point 14. Line 160: The “steamed bread peak” is not really a peak and is typically termed “the hump”. Presence of any peak within XRD patterns would indicate on presence of crystalline phases.

Response 14: Thank you for your suggestion, the corresponding location has been modified.

Point 15. Line 161: The statement “…several glass phases synthesized are pure phases” shall be amended to be “…several glass phases synthesized are pure vitreous phases”.

Response 15: Thank you for your suggestion, the corresponding location has been modified.

Point 16. Line 187: The wrong claim “glass phase quenched in liquid nitrogen at 950°C” needs to be modified to “glass phase quenched in liquid nitrogen and then kept at 950°C for crystallization…”

Response 16: Thank you for your suggestion, the corresponding location has been modified.

Point 17. Line 188: Replace the word “precipitated” by “formed”.

Response 17: Thank you for your suggestion, the corresponding location has been modified.

Point 18. Line 309: Replace the word “steps” by “phases”

Response 18: Thank you for your suggestion, the corresponding location has been modified.

Point 19. Lines 393-394: The statement “The formation of the glass phase in the sinter improves the metallurgical properties of the sinter” is irrelevant and shall be either proved within the manuscript or deleted.

Response 19: Thank you for your suggestion, the corresponding location has been deleted.

Point 20. Line 396: The parameter R is not in % units, it is unitless.

Response 20: Thank you for your suggestion, the corresponding location has been deleted.

Reviewer 2 Report

PLEASE SEE MY COMMENTS HERE:

Line 22: “[SiO₄]^4- “ is not right. Each Silicon centered tetrahedra does not require any charge to be balanced, so I would modify it with “SiO₄ tetrahedra”.

Line 41-43: the sentence about Ding et al. previous study is not clear. Please reword it.

Line 67-69: please reword these sentences about the two possible Aluminium coordinations.

General reccomendation: when a crystalline phase is mentioned, the authors usually mention only the chemical formula of it. For example CaSiO3. As several polymorphs may exist for a given chemical formula, it would be better to mention also the crystallographic name of a phase.

Line 227-228: the are 2 sentences. For clearity I would put both together like “Raman spectroscopy could give the quantitative structural information of the CaO-SiO2-Al2O3 glass phase like, for example, its degree of polymerization".

Line 241-243: please reword the sentence about the trend to use peak area.

Line 256-257: please reword this part.

Line 272: “Alkaline” should be changed into “alkaline”.

Line 276: same of line 22.

Line 342: “Significant” should be changed into “significant”.

Line 348: “destroyer” should be changed into “modifier”.

Line 403: same of line 22.

Although the largest part of the paper (considering also the title) is focussed on Raman spectroscopy results, I would suggest to the authors (for this paper less realistically, for future paper more realistically) to give more importance to XRD and SEM data. For the former, Quantitative Phase Analysis (QPA) by RIR-Rietveld method could be a good tool to quantify crystalline phases development. For the latter, more detailed imaging analysis can be useful to evaluate spatial distribution of crystalline phases as well as their typical size that, I presume, increases with temperature and soaking time.

Author Response

Dear Reviewers,

Thank you for your helpful and constructive comments and suggestions, which greatly improved our manuscript. We had revised the manuscript according to the comments/suggestions. The response for the revision corresponding to comments and suggestions from Reviewers has been given at the end of this letter.

Best wishes,

R-F Xin and X-M Guo

The response to Reviewers is as following.

Response to Reviewer 2 Comments

Point 1: Line 22: “[SiO4]^4- “is not right. Each Silicon centered tetrahedra does not require any charge to be balanced, so I would modify it with “SiO4 tetrahedra”.

Response 1: Thank you for your suggestion, the corresponding location has been modified.

Point 2: Line 41-43: the sentence about Ding et al. previous study is not clear. Please reword it.

Response 2: Thank you for your suggestion, this reference has been deleted because it is less relevant to this paper.

Point 3: Line 67-69: please reword these sentences about the two possible Aluminium coordinations.

Response 3: Thank you for your suggestion, the corresponding location has been modified.

Point 4: General reccomendation: when a crystalline phase is mentioned, the authors usually mention only the chemical formula of it. For example CaSiO3. As several polymorphs may exist for a given chemical formula, it would be better to mention also the crystallographic name of a phase.

Response 4: Thank you for your suggestion, the corresponding location has been modified.

Point 5: Line 227-228: the are 2 sentences. For clearity I would put both together like “Raman spectroscopy could give the quantitative structural information of the CaO-SiO2-Al2O3 glass phase like, for example, its degree of polymerization".

Response 5: Thank you for your suggestion, the corresponding location has been modified.

Point 6: Line 241-243: please reword the sentence about the trend to use peak area.

Response 6: Thank you for your suggestion, the corresponding location has been modified.

Point 7: Line 256-257: please reword this part.

Response 7: Thank you for your suggestion, the corresponding location has been modified.

Point 8: Line 272: “Alkaline” should be changed into “alkaline”.

Response 8: Thank you for your suggestion, the corresponding location has been modified.

Point 9: Line 276: same of line 22.

Response 9: Thank you for your suggestion, the corresponding location has been modified.

Point 10: Line 342: “Significant” should be changed into “significant”.

Response 10: Thank you for your suggestion, the corresponding location has been modified.

Point 11: Line 348: “destroyer” should be changed into “modifier”.

Response 11: Thank you for your suggestion, the corresponding location has been modified.

Point 12: Line 403: same of line 22.

Response 12: Thank you for your suggestion, the corresponding location has been modified.