Effect of CaF2 on the Viscosity and Microstructure of CaO–SiO2–Al2O3 Based Continuous Casting Mold Flux
Round 1
Reviewer 1 Report
Page 1, Lines 22–23:
”… increases to 287, … is only 17"
What is the unit for 287 and 17? (per what?)
Page 1, Line 34:
“470 million tons” per what?
Page 1, Line 28, Introduction:
The work by Hayashi et al. (Hayashi, M., Nabeshima, N., Fukuyama, H. and Nagata, K. (2002), ISIJ Int., Vol. 42, p.352–358.) which is concluded as “CaF2 addition to the samples having a constant value of (mol%CaO)/(mol%SiO2) does not change the degree of polymerization.” must be cited and it must be discussed in the paper.
Page 3, Fig. 1:
Explain the figure in the text, although it is written at the top of the figure (the sentence starting with ”projection (Liq-Oxyfluoride)…..”).
Page 3, Table 1:
It is not clear which component is replaced by CaF2 when the CaF2 amount is changed.
Page 3, Line 113:
“Brookfield rotational viscometer test device (Chongqing, China)”
Brookfield is located in the US.
Page 4, Fig. 2:
The schematic illustration of the viscometer part is not for the Brookfield viscometer.
Page 5, Fig. 4:
Why it does not have the data at 1300 C, which is shown in Fig. 3
Page 5, Table 2:
Consider the significant figures. It should be at most 4 or 5 digits.
Page 6, Line 176:
“dynamic and stable”
How can it be dynamic AND stable?
Page 6, Line 177:
The sentence starts with “Since the interaction …”.
It is difficult to understand.
Page 6, Table 3:
The information of the liquidus and/or solidus temperatures in the table will help to interpret the experimental results.
Overall:
It is difficult to read through the manuscript due to the bad structure. I suggest restructuring the manuscript based on the basic structure, i.e.
1. Introduction
2. Experimental
Materials (Tables 1 and 3, Fig. 1)
Procedure (Fig. 2)
3. Results (Figs. 3, 4, Table 2)
4. Discussion (The rest of the figs and tables)
5. Conclusion
Author Response
Dear Metals Editors and Reviewer 1:
Thank you for your useful comments and suggestions on the report of our manuscript. We have revised the paper, and would like to re-submit it for your consideration. We have modified the manuscript accordingly, and detailed corrections are listed below point by point:
Response to Reviewer 1 Comments
Point 1: Page 1, Lines 22–23:”… increases to 287, … is only 17” What is the unit for 287 and 17 ? (per what?)
Response 1: The unit is one, indicating how many keys are in a box.
Thank you for your advice!
Point 2: Page 1, Line 34: “ 470 million tons ” per what ?
Response 2: This information is obtained through an official website. (http://www.cnpowder.com.cn/news/32516.html)
Thank you for your advice!
Point 3: Page 1, Line 28, Introduction: The work by Hayashi et al. (Hayashi, M., Nabeshima, N., Fukuyama, H. and Nagata, K. (2002), ISIJ Int., Vol. 42, p.352–358.) which is concluded as “CaF2 addition to the samples having a constant value of (mol % CaO)/(mol % SiO2) does not change the degree of polymerization.” must be cited and it must be discussed in the paper.
Response 3: Considering the reviewer’s suggestions, we have added some references and updated bibliographic reviews.
Hayashi, M.; Nabeshima, N.; Fukuyama, H.; Nagata, K. Effect of Fluorine on Silicate Network for CaO-CaF2-SiO2 and CaO-CaF2-SiO2-FeOx Glasses. ISIJ International. 2002, 42, 352–358. (Doi:10.2355/isijinternational.42.352)
Thank you for your advice!
Point 4: Page 3, Fig. 1: Explain the figure in the text, although it is written at the top of the figure (the sentence starting with ”projection (Liq-Oxyfluoride)…..”).
Response 4: Projection represents the projection of the plane of the ternary system, and depends on the properties of matter in Liq-Oxyfluoride to construct lines.
Thank you for your advice!
Point 5: Page 3, Table 1: It is not clear which component is replaced by CaF2 when the CaF2 amount is changed.
Response 5: When the CaF2 amount was changed, the content of CaO and SiO2 changed in a constant basicity. The contents of the form have been modified.
Thank you for your advice!
Point 6: Page 3, Line 113: “Brookfield rotational viscometer test device (Chongqing, China)” Brookfield is located in the US.
Response 6: I’m very sorry, I’ll correct this mistake.
The description of “Brookfield rotational viscometer test device” was not accurate enough and has been changed to “The rotating viscometer”. The equipment was designed by Chongqing University according to the standard of China's metallurgical slag viscosity test (YB/T 185-2001). The manuscript introduced its principle of operation and construction is different from that of Brookfield viscometer.
Thank you for your advice!
Point 7: Page 4, Fig. 2: The schematic illustration of the viscometer part is not for the Brookfield viscometer.
Response 7: The description of Fig.2 is not accurate enough and have been changed to “Schematic diagram of apparatus viscosity measurement”.
Thank you for your advice!
Point 8: Page 5, Fig. 4: Why it does not have the data at 1300 C, which is shown in Fig. 3?
Response 8:
The constant temperature viscosity is a series of data which are measured at 1300 ℃, and the average value is obtained. The measured value is a criterion for evaluating the performance of the flux from meniscus to mould in the metallurgical industry of China.
Academically speaking, the viscosity-temperature curve can better represent the real situation of flux flow when the slab temperature changes. Variable temperature viscosimetry is to measure the temperature directly from 1400℃ and constant temperature viscosity is to measure the temperature at 1300℃ because of the different test conditions, there is a certain gap in the viscosity.
Thank you for your advice!
Point 9: Page 5, Table 2: Consider the significant figures. It should be at most 4 or 5 digits.
Response 9: Because the manuscript structure was modified. It had been changed in Page 7, Table 5.
Thank you for your advice!
Point 10: Page 6, Line 176: “dynamic and stable” How can it be dynamic and stable?
Response 10: Stability represents a state of the system under this condition, which satisfies the limitation of the condition and is actually independent of time. Dynamic state change is not unchanged, it is a 'stable' static state. It will change into another 'steady state' at the next 'moment', so it is called dynamic stability.
Thank you for your advice!
Point 11: Page 6, Line 177: The sentence starts with “Since the interaction …”. It is difficult to understand.
Response 11: It had been changed to “Because the interation force between particles is the result of mathematical fitting by researches, it is not easy if too many elements appear in the same system”.
Thank you for your advice!
Point 12: Page 6, Table 3: The information of the liquidus and/or solidus temperatures in the table will help to interpret the experimental results.
Response 12: I am sorry, you may have been misled by my mistake. In the original manuscript, Table 3 interprets the data needed for molecular dynamics simulations. The transition temperature in Table 2 is that the mold flux has no fixed melting point, but only in the process of viscosity change. We think that the sudden increase of viscosity is the transition temperature, and the flux can keep liquid lubrication between the mould and the shell when it is lower than the transition temperature.
Thank you for your advice!
Point 13:
Overall:
It is difficult to read through the manuscript due to the bad structure. I suggest restructuring the manuscript based on the basic structure, i.e.
1. Introduction
2. Experimental
Materials (Tables 1 and 3, Fig. 1)
Procedure (Fig. 2)
3. Results (Figs. 3, 4, Table 2)
4. Discussion (The rest of the figs and tables)
5. Conclusion
Response 13: The structure of the manuscript has been modified.
Thank you for your advice!
According to the revision opinions of reviewers 2 and 3, the structure of manuscripts was adjusted, and the statement errors were modified.
All the changes in this article adopted "track chages" fuction, and all the changes were marked and displayed in red font.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Within this paper the influence of CaF2 on viscosity as well as melt structure is shown in detail after extensive investigation of these slags.
Revise grammar thoroughly throughout the whole paper, otherwise reader are not able to understand the paper, e.g. line 31-32, or are incomplete, e.g., line 227-228. This may also be the reason, why the main massage of the paper as well as the details are not clear. Additionally, some statements are wrong, probably due to the poor English, e.g. line 107-110. What do you mean with composition range of CaF2?
Arrhenius equation is not valid for the total viscosity curve, but probably for the linearized curve progression related to temperatures above the break temperature. Thus, the temperature range has to be given for the calculated activation energy given in table 2.
The novelty of the paper cannot be seen, as far as the influence of CaF2 on viscosity as well as its influence on the melt structure has already been published.
Figures cannot be understood without reading the text. Especially, axis labelling is not clear.
The message of Figure 6 is not clear. What do you want to show?
Author Response
Dear Metals Editors and Reviewer 2:
Thank you for your useful comments and suggestions on the report of our manuscript. We have revised the paper, and would like to re-submit it for your consideration. We have modified the manuscript accordingly, and detailed corrections are listed below point by point:
Response to Reviewer 2 Comments
Point 1: Revise grammar thoroughly throughout the whole paper, otherwise reader are not able to understand the paper, e.g. line 31-32, or are incomplete, e.g., line 227-228. This may also be the reason, why the main massage of the paper as well as the details are not clear. Additionally, some statements are wrong, probably due to the poor English, e.g. line 107-110. What do you mean with composition range of CaF2?
Response 1: Line 31, “about” was changed to “spproximately”.
Line 32, “Fluoride” was changed to “It”.
Line 227-228, “The accuracy of the simulation” was removed. “The bond length of Si-O is 1.6Å, and the bond length of Al-O is 1.7 Å” was changed to “ The bond lengths of Si-O and Al-O are 1.6Å and 1.7 Å, respectively.”
Line 107-110, “ At the same time, the cement” was changed to “Cement”. “examine different slag”was changed to “propare different slags”. Line 110, “the flux” was changed to “the mold flux”
Thank you for your advice!
Point 2: Arrhenius equation is not valid for the total viscosity curve, but probably for the linearized curve progression related to temperatures above the break temperature. Thus, the temperature range has to be given for the calculated activation energy given in table 2.
Response 2: The temperature range of activation energy was given in the manuscript, which was set to be larger than the transition temperature.
Thank you for your advice!
Point 3: The novelty of the paper cannot be seen, as far as the influence of CaF2 on viscosity as well as its influence on the melt structure has already been published.
Response 3:
First of all, I must clear the real role of CaF2 in mold flux, and to find a substitute for it (for viscosity, structure) new substances to replace it, find fluoride-free mold flux.
Second, in manuscript had pointed out “Wang et al. [16] studied the crystallization behavior of the protective slag in the CaO-SiO2-Al2O3 slag system in CaF2 and pointed out that after the mass fraction of CaF2 was increased to a specific amount, the fluoride ion was converted to a certain degree owing to the netting effect”. However, according to my research, the increase of CaF2 can reduce the degree of polymerization and viscosity of mold flux.
Finally, Previous studies on the influence of fluoride on the metallurgical properties of mold flux have been conducted, but the state on the occurrence and microstructures visible of fluorine in the high temperature mold flux is still unclear.
Thank you for your advice!
Point 4: Figures cannot be understood without reading the text. Especially, axis labelling is not clear.
Response 4: I’m very sorry. Figures and axis labelling have been modified.
Thank you for your advice!
Point 5: The message of Figure 6 is not clear. What do you want to show?
Response 5: Figure 6 shows the macro-bonding model after calculation. And figure 7 shows the micro-bonding model.
The model was built by converting the existing components into specific atomic numbers and adding them randomly to a box of three-dimensional periodic boundaries. The total number of particles set by the simulation was approximately 6000, and the number of particles corresponding to each element in the simulated system was calculated from the ratio of the number of moles of each ion.
“CaF2 content is equal to 9% simulation effect diagram” was changed to “The model of ions in mold flux with 9% CaF2 accrued by simulation in Scigress.”
Thank you for your advice!
The structure of manuscripts has been adjusted and some errors in statement have been amended.
All the changes in this article adopted "track chages" fuction, and all the changes were marked and displayed in red font.
Sincerely,
Xingjuan Wang.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors,
thank you very much for your interesting paper.
As reviewer, I have few recommendations:
1. Please, review the manuscript scan with marked blue notes.
2. Please, modify some titles of figures to be more accurate of description.
3. In introduction, you are writing about the harmful effect of CaF2 on environment. At the end of the first paragraph of the Introduction you state, that the aim of the paper is also to develop the fluorine-free mold flux. But in the paper, there is missing the explanation, for example in Conclusion, how your results can lead to minimization of the CaF2 content in mould flux. Please, add this information more precisely and clearly.
Thank you
Reviewe
Comments for author File: Comments.pdf
Author Response
Dear Metals Editors and Reviewer 3:
Thank you for your useful comments and suggestions on the report of our manuscript. We have revised the paper, and would like to re-submit it for your consideration. We have modified the manuscript accordingly, and detailed corrections are listed below point by point:
Response to Reviewer 3 Comments
Point 1: Please, review the manuscript scan with marked blue notes.
Response 1:
Line 14, ”powder slag” was changed to “mold flux”.
Line 15, “Factsage” was changed to “FactSage”.
Line 26, inserted keywords “ continuous casting”.
Line 30, inserted “steel”.
Line 38-41, “Therefore, in order to reduce the consumption of fluorite, study the occurrence of fluorine in the continuous casting mold flux and guide the development of fluorine-free mold flux, which plays an important role in resource control.” was changed to “Therefore, to reduce the consumption of fluorite, it is necessary to study the occurrence of fluorine in the continuous casting mold flux, and carry out the development of a fluorine-free mold flux, which plays an important role in resource control.”.
Line 44, "[SiOF]3-" was changed to “ [SiO3F]3-”.
Line 51, “casting flux” was changed to “casting mold flux”.
Line 76, “Factsage” was changed to “FactSage”.
Line 80, “casting flux” was changed to “casting mold flux”.
Line 86, “Factsage” was changed to “FactSage”.
Line 87, “FactSage (FactSage 7.2, Thermfact/CRCT and Technologies, Canada and Germany) thermodynamics software.”was changed to “FactSage thermodynamics software (FactSage 7.2, Thermfact/CRCT and Technologies, Canada and Germany).”.
Line 88-89,” The closer to a certain component in the phase diagram, the greater the proportion of the component. The calculation results are shown in Fig.1” was changed to “The closer a certain component is to the phase diagram, the greater the proportion of that component. The calculation results are shown in Figure 1”.
Line 96, “pouring” was changed to “casting”.
Line 105, “Fig.1” was changed to “Figure 1”.
Line 106, “is 1000℃” was changed to “1000℃”.
Line 257, “flux” was changed to “slag”.
Thank you for your advice!
Point 2: Please, modify some titles of figures to be more accurate of description.
Response 2: Thank you very much for pointing out my mistake, and they've been corrected.
Table 1, the title was changed to “Chemical composition of fluorine-containing mold flux /%”.
Figure 2 , the title was changed to “Schematic diagram of apparatus viscosity measurement”
Because of the structural adjustment, Figure 3 was adjusted to Figure 4. Figure 4, the title was changed to “The influence of CaF2 calaulate on the measured fixed temperature viscosity of 1300 ℃” .
Because of the structural adjustment, Figure 4 was adjusted to Figure 5. I'm sorry for your question in Figure 5. I don't quite understand what you mean and I can't read your manuscript clearly.
Figure 6, the title was changed to “The model of ions in mold flux with 9% CaF2 accrued by simulation in Scigress”.
Figure 8, the title was changed to “Radial distribution function and coordination number function of CaF2 content of 9%”.
Figure 10, the title was changed to “Number of atoms coordinated to (a) Si and (b) O with different CaF2 content“.
Figure 11, the title was changed to “(a) Number of non-bridging fluorine and (b) number of bridging fluorine”.
Thank you for your advice!
Point 3: In introduction, you are writing about the harmful effect of CaF2 on environment. At the end of the first paragraph of the Introduction you state, that the aim of the paper is also to develop the fluorine-free mold flux. But in the paper, there is missing the explanation, for example in Conclusion, how your results can lead to minimization of the CaF2 content in mould flux. Please, add this information more precisely and clearly.
Response 3: The purpose of studying the effect of CaF2 on the viscosity and structure of mold fluxes is not to reduce CaF2 to a certain range to achieve some properties, but to search for similar substances with similar properties to CaF2 in the future to change the viscosity and structure of mold fluxes.
Thank you for your advice!
The structure of manuscripts has been adjusted and some errors in statement have been amended.
All the changes in this article adopted "track chages" fuction, and all the changes were marked and displayed in red font.
Sincerely,
Xingjuan Wang.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear authors,
thank you for your corrections. But there are still improvements necessary.
1.) Revise grammar thoroughly throughout the whole paper. Following, some selected examples are given:
Only corrections of some words have been done, but the English language has not been improved, e.g. line 33. Here you may mean the evaporation of fluorine to the environment. Otherwise I do not know, what you want to say with "overflow". Nevertheless, the element "F" is called fluorine, not fluoride.
There are also sentences within the paper, which are still obviously wrong: E.g. lines 119-121; here the reader may think you mean CaF2 is made from cement clinker and wollastonite, which is not correct. Probably, you wanted to say, that the basicity of the slag was kept constant and only the CaF2 content was varied. Therefore, revision of this sentence is necessary.
Line 96-97: What do you want to say with this sentence? Nevertheless, basics of how to deal with phase diagrams are not necessary to be discribed in this paper.
Line 360°: Do you mean Break temperature instead of turning temperature?
2.) As far as I can tell from the abstract of paper [16], the authors investigated the crystallization behaviour of the slag. Thus, I am not sure if the influence on slag structure was also investigated in this paper, or only its effect on cuspine crystallization. Probably, "netting effect" does not refer to melt structure in this case. Nevertheless, if an element acts the same as silica it is a network former. Thus, network forming effect may be more precise, if this is what you want to say.
3.) The use of another element instead of fluorine will most probably not work, as far as any other ion does not behave as fluorine in all cases (e.g. decreasing of viscosity, formation of cuspidine,..).
4.) It is known, that decrease in viscosity is related with the increase of fluorine in mold slag systems (see e.g. K. Mills). Thus, I am sorry, but I do not see the novelty of this paper, except for the simulation of slag structure.
5.) The authors do not really come to the point of their findings (1)-(2). Line 356-357 is not really applicable for mold slags.
Best regards,
Reviewer 2
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
