Formation of Layered Structure in Ceramics Based on Alumina Nanopowder Under Effect of Induction Heating
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Report on manuscript: powders-2935469
Title: “ Formation of Layered Structure in Ceramics Based on Alumina 2 Nanopowder under Effect of Induction Heating”
By Lina L.Sartinska.
In the manuscript, the author reports on results of exploring the effect of induction heating on alumina ceramics and alumina ceramic composites which are based on α-Al2O3 nanopowders with SiC, Si3N4, SiO2, and ZrO2 additives. The influence of different factors on properties of the seramics are considered. Among them are structure type, grain size, hardness, fracture toughness, wear resistence, and distribution of chemical elements. Tharticle can be of interest for potential readers of the journal “Powders”. However, some revision should be made as reported just below:
1) Page 1: The authors report “For example, hot pressing, when carried out under the correct conditions, have all been shown to be capable of producing nanocrystalline ceramics.” The term “under the correct conditions” is not clear in this sentence and should be specified.
2) Page 2: “Composition can greatly influence on the mechanical properties of ceramic materials [5].” => “Composition of ceramic materials can greatly influence their mechanical properties [5].”
3) Page 2: The author reports “5 wt. % of silicon carbide (SiC), silicon 84 nitride (Si3N4), silica (SiO2) and zirconia (ZrO2) powders of mean particle size <1 μm were 85 incorporated into alumina powder.” What about the purities of these additives? What about companies where the author purchased these silicon-based additives?
4) Page 2: The author reports Then samples were cleaned, ground and polished by 1 μm diamond using special machine”. What kind of machine was employed in the present work to clean the samples under study?
5) Pages 2-3 “Hardness and fracture toughness (K1c) measured by a standard microindentation technique, under a load of 98 N.” => “Hardness and fracture toughness (K1c) were measured by a standard microindentation technique, under a load of 98 N.”
6) Page 3: “However, at a hot-pressing temperature above 1600 0C the average grain size of alumina ceramics increases to 9.2 μm and the properties decrease sharply (Table 1).” What properties are sharply reduced?
7) Page 4: “Figure 2. Porosity (a), hardness and fracture toughness (b) vs hot-pressing temperature. The dwell time was chosen randomly.” => “Figure 2. (a) Porosity (a) and (b) hardness and fracture toughness vs hot-pressing temperature. The dwell time was chosen randomly.” Comas should be replaced by points in this figure. The uncertainties of measurements of the porosity, hardness and fracture toughness should be indicated by uncertainty bars. The same concerns data presented in Fig. 3.
8) Figure 5 is of poor quality and should be revised.
9) Did the authors test the present alumina ceramics and alumina ceramic composites with XRD to explore the phase purity of the materials?
10) What about implication/suggestion of the present study in future?
11) The text contains some grammar and syntax errors. They should be verified and corrected.
Comments on the Quality of English Language
The text contains some grammar and syntax errors. They should be verified and corrected.
Author Response
Reply to Reviewer 1
In the manuscript, the author reports on results of exploring the effect of induction heating on alumina ceramics and alumina ceramic composites which are based on α-Al2O3 nanopowders with SiC, Si3N4, SiO2, and ZrO2 additives. The influence of different factors on properties of the ceramics are considered. Among them are structure type, grain size, hardness, fracture toughness, wear resistance, and distribution of chemical elements. The Article can be of interest for potential readers of the journal “Powders”. However, some revision should be made as reported just below:
Dear Reviewer,
I really appreciate your opinion. Thank you very much for your valuable comments. I have changed my manuscript according to your suggestions.
1) Page 1: The authors report “For example, hot pressing, when carried out under the correct conditions, have all been shown to be capable of producing nanocrystalline ceramics.” The term “under the correct conditions” is not clear in this sentence and should be specified.
changed
2) Page 2: “Composition can greatly influence on the mechanical properties of ceramic materials [5].” => “Composition of ceramic materials can greatly influence their mechanical properties [5].”
changed
3) Page 2: The author reports “5 wt. % of silicon carbide (SiC), silicon nitride (Si3N4), silica (SiO2) and zirconia (ZrO2) powders of mean particle size <1 μm were incorporated into alumina powder.” What about the purities of these additives? What about companies where the author purchased these silicon-based additives?
changed
4) Page 2: The author reports Then
samples were cleaned, ground and polished by 1 μm diamond using special machine”. What kind of machine was employed in the present work to clean the samples under study?
Automatic Grinder and Polisher machine (Verder company). Added.
5) Pages 2-3 “Hardness and fracture toughness (K1c) measured by a standard microindentation technique, under a load of 98 N.” => “Hardness and fracture toughness (K1c) were measured by a standard microindentation technique, under a load of 98 N.”
changed
6) Page 3: “However, at a hot-pressing temperature above 1600 0C the average grain size of alumina ceramics increases to 9.2 μm and the properties decrease sharply (Table 1).” What properties are sharply reduced?
changed. All properties.
7) Page 4: “Figure 2. Porosity (a), hardness and fracture toughness (b) vs hot-pressing temperature. The dwell time was chosen randomly.” => “Figure 2. (a) Porosity (a) and (b) hardness and fracture toughness vs hot-pressing temperature. The dwell time was chosen randomly.” Comas should be replaced by points in this figure. The uncertainties of measurements of the porosity, hardness and fracture toughness should be indicated by uncertainty bars. The same concerns data presented in Fig. 3.
I agree with the comment about measurement uncertainty. Unfortunately, experimental data in this field always have such large uncertainties, however the trend was clear and was then confirmed by wear rate measurements.
8) Figure 5 is of poor quality and should be revised.
I agree with this comment, but there is no way to change this picture.
9) Did the authors test the present alumina ceramics and alumina ceramic composites with XRD to explore the phase purity of the materials?
Unfortunately, this work was devoted only to mechanical properties, and the addition of 5 wt.% of various additives supposedly should not have affected the properties. The effect of additives was revealed only in the process of analyzing the results.
10) What about the implication/suggestion of the present study in future?
This manuscript states that hot pressing under induction heating must take into account the interaction of the electromagnetic field with nanopowders. Large-sized powders will not exhibit this effect.
11) The text contains some grammar and syntax errors. They should be verified and corrected.
Changed
Sincerely yours,
Lina L. Sartinska
Reviewer 2 Report
Comments and Suggestions for Authors
The paper presents important results of sintering and formation of layered structure in Al2O3 ceramics using induction heating. The presented results on sintering, microstructure and mechanical properties of Al2O3 with different additives, such as SiC, Si3N4, SiO2, and ZrO2 clearly show the improvements of the Al2O3 ceramics both for hardness, fracture toughness and wear resistance. The lowest wear rate was determined to occur when 5wt% SiC was added to Al2O3 to strengthen it and improve wear resistance because of the smooth surface formation with a special grain structure. Overall, it is important conclusion and could be further use to develop high tech ceramics for numerous industrial applications such as cutting tools for example.
Author Response
The paper presents important results of sintering and formation of layered structure in Al2O3 ceramics using induction heating. The presented results on sintering, microstructure and mechanical properties of Al2O3 with different additives, such as SiC, Si3N4, SiO2, and ZrO2 clearly show the improvements of the Al2O3 ceramics both for hardness, fracture toughness and wear resistance. The lowest wear rate was determined to occur when 5wt% SiC was added to Al2O3 to strengthen it and improve wear resistance because of the smooth surface formation with a special grain structure. Overall, it is important conclusion and could be further use to develop high tech ceramics for numerous industrial applications such as cutting tools for example.
Dear rewiever,
Many thanks for your responce. Especially I am greatfull for your insight into the essence of the article and its importance. As an expert in the field of ceramics, layered materials, and hot pressing under the effect of induction heating, you have understood the need of considering of the interaction of ceramic nanopowders with the electromagnetic field to obtain the best material properties.
With best wishes,
Dr. Lina L. Sartinska
