Dispersed CeO₂ Nanorods with Low-Speed Mixing for Mechanical Properties Promotion of PTA Steel Coatings

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Title: Dispersed CeO2 Nanorods with low-speed mixing for Mechanical Properties Promotion of PTA Steel Coatings

Manuscript ID: coatings-3005403

Recommendation and Comments

 

In this manuscript, the authors aimed to successfully develop a uniform coating of 14Cr2NiSiVMn alloy powder by utilizing low-speed mixing to enable electrostatic adsorption of CeO2 nanorods (CNRs) on the powder surface. The authors studied that the use of dispersed Ce-based heterogeneous nucleation in the rapid solidification process of PTA fabrication of high-strength steel coatings promotes the formation of equiaxed crystals and reduces preferred orientation in different deposition directions. Also, the microhardness, tensile strength, and wear resistance of the Fe alloy coating have been investigated.

More details in this manuscript need to be corrected, and I suggest that the manuscript needs major revision.

 

1. In section 1;

·         There are thirty-six references in all the paper. There are six references in the results and discussion section. The references should be increased in the paper.

2. In section 3.1;

·         Figure 3 should be explained to understand the difference between images and enlarged images. “…the addition of 0.5 wt.% CNRs lead to Grain Orientation Reduce.” Which image do you mention? Please remark.

·         Figure 4 has the same issue as Figure 3. It should be explained to understand the difference between images and enlarged images.

·         Could you cite current references (last five years) for Figure 3 and Figure 4?

3. In section 3.2;

·         “The solubility of CeO2 in Fe alloys is low, and its concentration in the alloy is also limited, which does not have a significant impact on the phase composition.” Could you cite a reference?

·         Could you explain the difference between Figure 5a and Figure 5b? What did you want to see with XRD spectra (range 20^o – 30^o). Please clarify.

4. In section 3.3;

·         “In the traditional CeO2 addition mechanism, the Ce element tends to form impurities with other elements and aggregate at the boundary positions, resulting in the creation of micro cracks in the specimen and subsequently reducing its performance.” Could you cite a reference?

·         Figure 6 should be redrawn due to inconsistency. There is no Figure d in Figure 6. All the images should be the same size.

·         Figure 7 should be clarified in the paper. For example, what does mean a1, a2…?

5. In section 3.4;

·         The red colors of the arrows in Figure 10 should be changed to a different color for visibility.

6. In section 3.5;

·         The red colors in Figure 11 should be replaced with a different color.

·         The arrows and text in Figure 12 should be replaced with a different color.

·         “The exist of fish scale-like friction patterns on the sample surface indicates the friction mechanism to be plastic deformation and adhesive wear caused by delamination.” Could you cite a reference? I can suggest this reference; https://doi.org/10.1007/s11837-021-05070-6

7. In section conclusions;

·         Conclusion should be involved highlight sentences. There are only experimental results in the conclusions section. It should be indicated prospectus regarding test results.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents new experimental results investigating the grain orientation in multiple directions and nonuniform grain growth within the coating obtained by plasma transferred arc (PTA) technology using 14Cr2NiSiVMn alloy powder. The influence of dispersed 0.5 -1 wt.% CeO2 nanorods (CNRs) covered onto the surface of this 14Cr2NiSiVMn alloy powder particles on the grain growth orientation and heterogeneous nucleation effect of CNRs additives in the PTA coatings were studied.

The novelty of the  obtained results is associated with the establishment of the possibility, using the addition of CeO2 nanorods, to ensure the refinement of dendritic grains in a FTA coating based on 14Cr2NiSiVMn powders in both perpendicular and parallel directions, as well as to obtain coatings with more equiaxed grains.

Previous studies have shown the possibility of grain refinement and increasing the solubility of solute elements in the Fe matrix by adding CeO2 nanoparticles to the coating.

In this study, the resulting coatings were shown to provide noticeable improvements in microhardness, tensile strength, and elongation to failure. An important result of the use of this coating was the establishment of a reduction in wear mass by 44.2% and an increase in relative wear resistance by 79.3%.

Comments:

1) It is necessary to supplement the manuscript with information on the manufactoring of dog-bone samples for tensile testing of the coating material.

Subsection 2.2 (Line 109) states that the coating thickness was approximately 5 mm. Figure 2(b) indicates that the thickness of the samples was 1 mm. Figure 1(a) shows a diagram of the fabrication of test specimens. From this information it follows that the samples were made by cutting the coating into layers. In this regard, the question arises: whether the thickness of the samples was monitored and how the location of the material layer in the coating affected mechanical characteristics.

2) It is necessary to supplement the manuscript with information explaining why Fig. 8 shows the dependence of microhardness for a coating thickness of only up to 2 mm, while the authors indicate a coating thickness of about 5 mm.

3) It is necessary to supplement the manuscript with an indication of the confidence intervals of the experimental data given in Table 3. The feasibility of indicating the value of the elastic modulus with an accuracy of tenths of GPa is questionable.

4) It is necessary to supplement the manuscript with an indication of the confidence intervals of the experimental data o weight loss given in Table 4.

5) Figure 9 caption (b) and (d) should be checked. Specified subfigures do not contain elastic moduli data

6) Methodologies for determination of stress-strain curves and elastic modulus data are unclear. For such relatively low elongation to fracture (several % of elongation), application of extensometer is necessary because of sufficient error associated with elastic deformation of specimen outside the gauge section. Elastic deformation of specimen outside the gauge section makes it difficult to determine the Young modulus. Analytical solution of a theory of elasticity problem is required in this case. Furthermore, deformation of device parts will produce error too. Why ultrasound method was not employed for determination of the Young modulus?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The necessary corrections have been made by the authors. I accept this paper. 

Reviewer 2 Report

Comments and Suggestions for Authors

Authors addressed previous comments. Therefore, the reviewer suggests acceptance in present form.