Effect of Al2O3 on the Formation of Calcium Ferrite in the Solid State
Round 1
Reviewer 1 Report
In the paper it is studied the transformation of Ca(OH)2, Fe2O3 in calcium ferrite in the presence of Al2O3. Albeit there are many results and globally well presented, some improvements are necessary especially in the experimental part and in the discussion of the results. My comments are reported as follows:
- How the homogeneity of samples reported in Table 1 was verified?
- It is well known that Rietveld method is based on complex calculation but this is not a good reason to do not use that method; with modern pc that calculations are carried out very quickly and several softwares (MAUD, GSAS, FullProf just as examples) are freely available. Therefore more convincing reasons should be indicated
- In my opinion there is a possible problem concerning the homogeneity of samples in Table 2. In fact two ceramic products, with low density, are mixed with a metal with very high density, and furthermore no data concerning the particles size of that phases are reported. So some evidence of the very good homogeneity of that samples should be shown. Obviously the homogeneity of the samples is crucial and also in the original paper of Chung on the matrix-flushing method (Chung, J Appl Crystallogr, 1974, 7, 519) that point was clearly stated, in addition to necessary optimal particles size (see page 525 of the paper).
- Page 6, line 210 please indicate that third endothermic peak is the one located at about 1220°C
- It is not clear for me why the total weight loss in figure 1-(2) is markedly different from the other weight losses. Please explain this point
- Page 8, line 224; please explain clearly why in Fig.4 is shown that CF begins to form at 700-800 °C
- What is the difference between the two sub-figures of Figure 10? Delete one of them
- Please explain clearly the meaning of converation (maybe conversion?) rate of CF (in Figure 10) and also its unit; then explain clearly what is the generation rate (I suppose that is the slope of the lines in Figure 10). Furthermore for some data the linear regression appears questionable (see data for Al2O3 = 2.8 %).
- Since the focus of the paper is the effect of Al2O3 on the formation of CF, in my opinion the discussion of the effect of Al2O3 should be improved, highlighting the mechanisms by which Al2O3 influences the transformation especially for explaining its non-monotonic role in the generation rate (see data in Page 12, line 310).
Author Response
1. How the homogeneity of samples reported in Table 1 was verified?
Response: Yes, I have explained the homogeneity of the mixture samples in Line 105.
2. It is well known that Rietveld method is based on complex calculation but this is not a good reason to do not use that method; with modern pc that calculations are carried out very quickly and several softwares (MAUD, GSAS, FullProf just as examples) are freely available. Therefore more convincing reasons should be indicated.
Response: Thank the reviewer for the worthy comment, Rietveld full-pattern fitting method is suitable for quantitative analysis of complex samples. The K-value method is easy to understand and operate. Each method has clear physical interpretation and operation steps, and it is suitable for samples with few phase types. Therefore, for the case where there are not many components and phases in our experiment, it is more appropriate to choose the K value method.
3. In my opinion there is a possible problem concerning the homogeneity of samples in Table 2. In fact two ceramic products, with low density, are mixed with a metal with very high density, and furthermore no data concerning the particles size of that phases are reported. So some evidence of the very good homogeneity of that samples should be shown. Obviously the homogeneity of the samples is crucial and also in the original paper of Chung on the matrix-flushing method (Chung, J Appl Crystallogr, 1974, 7, 519) that point was clearly stated, in addition to necessary optimal particles size (see page 525 of the paper).
Response: Thanks, I have read the paper of Chung. My research method of this experiment is based on the paper Phase Formation in Iron Ore Sintering design. By verification, I have determined the particle size of the mixture and explained it in line 106.
4. Page 6, line 210 please indicate that third endothermic peak is the one located at about 1220°C.
Response: Thank the reviewer for the careful review, I have indicated the third endothermic peak.
5. It is not clear for me why the total weight loss in figure 1-(2) is markedly different from the other weight losses. Please explain this point.
Response: Maybe due to the different purity of Ca(OH)2 used each time, resulting in different weight loss of the mixture. Because at 400℃, only the decomposition of Ca (OH)2 occurs weight loss.
6. Page 8, line 224; please explain clearly why in Fig.4 is shown that CF begins to form at 700℃-800℃.
Response: Sorry, This should be described in Fig. 9, not Fig. 4, and I have deleted it. According to reference [11], it has indicated that CF begins to form at 700℃-800℃.
7. What is the difference between the two sub-figures of Figure 10? Delete one of them.
Response: Thanks, I have deleted one figure of Figure 10.
8. Please explain clearly the meaning of converation (maybe conversion?) rate of CF (in Figure 10) and also its unit; then explain clearly what is the generation rate (I suppose that is the slope of the lines in Figure 10). Furthermore for some data the linear regression appears questionable (see data for Al2O3 = 2.8 %).
Response: Thank the reviewer for the careful review, I have modified “converation” as “conversion”. The generation rate is the slope of the lines in Figure 10. Each set of data is verified by three experiments.
9. Since the focus of the paper is the effect of Al2O3 on the formation of CF, in my opinion the discussion of the effect of Al2O3 should be improved, highlighting the mechanisms by which Al2O3 influences the transformation especially for explaining its non-monotonic role in the generation rate (see data in Page 12, line 310).
Response: Thanks, I have added some discussion about the effect of Al2O3 on the formation of CF in line307-313.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Authors,
I have to read your manuscript with great attention and interest. The material is consistent and valuable
The submission falls within the scope of the journal and is sufficiently original, and I have a remark, so I publish it after MINOR REVISIONS.
The paper includes an analysis of the possibility of using lower quality ores containing aluminum ore and the recognition of the mechanism of action of aluminum oxide.
Minor points:
105- determine the particle size of the powders
174- homogenize the description of the Xa xis, call the diagrams as a), b)….
180- Curves
210- Fig.2 call the diagrams as a), b) .. or with amount of Al2O3… check the Fig. 1.
227- put the arrows in the reaction
233- improve the quality Fig. 4,
281- improve the quality Fig. 6
319- arrows in the reactions
404- change the letters
Author Response
1. 105- determine the particle size of the powders.
Response: Yes, I have explained the particle size of the mixture in Line 106.
2. 174- homogenize the description of the Xa xis, call the diagrams as a), b)….
Response: Thanks, I have modified the diagrams as a), b)…in the Fig.1.
3. 180- Curves
Response: Thanks, I have modified “curves” as “Curves”.
4. 210- Fig.2 call the diagrams as a), b) .. or with amount of Al2O3… check the Fig. 1.
Response: Thanks, I have modified the diagrams as a), b)…in the Fig.2.
5. 227- put the arrows in the reaction.
Response: Thanks, I have modified “=” as “→”.
6. 233- improve the quality Fig. 4.
Response: Thanks, I have improve the quality Fig. 6.
7. 281- improve the quality Fig. 6.
Response: Thanks, I have improve the quality Fig. 6.
8. 319- arrows in the reactions.
Response: Thanks, I have modified “=” as “→”.
9. 404- change the letters.
Response: Thank the reviewer for the careful review, I have changed the letters.
Author Response File: Author Response.pdf
Reviewer 3 Report
-The authors need to specify why they have selected the aluminium oxide? The fine powder of aluminium oxide is rather expensive, is it possible to replace it with something cheaper?
-It is good to add some references related to previous researches done on using aluminium oxide.
-Remove the table in figure 7 and figure 8 and mention the obtained value as a text on the red line.
-In figure 9, all the peaks should be identified.
-Figure 10, remove the Chinese text.
-Conclusion have to be expanded.
Author Response
1. The authors need to specify why they have selected the aluminium oxide? The fine powder of aluminium oxide is rather expensive, is it possible to replace it with something cheaper?
Response: Thank the reviewer for the comment. Maybe there is something cheaper alternative to Al2O3. But because Al2O3 is a substance inherent in sinter, Al2O3 is selected as the research object.
2. It is good to add some references related to previous researches done on using aluminium oxide.
Response: Thanks, There has been many references related to previous researches done on using aluminium oxide in the introduction.
3. Remove the table in figure 7 and figure 8 and mention the obtained value as a text on the red line.
Response: Yes, I have modified the table in figure 7 and figure 8.
4. In figure 9, all the peaks should be identified.
Response: I have identified all the peaks in figure 9.
5. Figure 10, remove the Chinese text.
Response: Yes, I have removed the Chinese text in the Figure 10 and modified it to English.
6. Conclusion have to be expanded.
Response:Yes, I have expanded conclusion.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Globally speaking I am pleased with the responses of the authors to my comments, even if in my opinion it should be better to show clearly the homogeneity of the mixtures analysed by x-ray diffraction. So, I can recommend the publication of the manuscript
