Effect of Nano-La2O3 and Mo on Wear Resistance of Ni60a/SiC Coatings by Laser Cladding
Alexey G. Kolmakov
Round 1
Reviewer 1 Report
The paper “processes-2263185-Laser Cladding” related to laser cladding was reviewed. Please follow the comments carefully and resubmit your paper for the next consideration and reviewing process.
1. Please add a brief statement on your methodology in the abstract.
2. Add brief quantitative results to the abstract
3. The size of the error bars in Figure 2 is too small.
4. Please highlight the novelty of using Nano-La2O3.
5. The explanation in Figure 4 “Three-dimensional morphology” needs to be expanded.
6. Laser absorptivity in AM is important which shows the quality of the parts and transition from keyhole to conduction mode. Please read and add the following ref in this area. “The effect of absorption ratio on meltpool features in laser-based powder bed fusion of IN718”.
7. Laser has many advantages over the conventional manufacturing method which can be highlighted in your paper. Please read the following manuscript and add it to the literature to show how the laser is comparable with conventional manufacturing.
· Laser subtractive and laser powder bed fusion of metals: review of process and production features
Author Response
- Please add a brief statement on your methodology in the abstract.
Answer: Thank you very much. We have revised them in the manuscript as follows：
To improve the wear resistance of TMR blade and investigate the effect of nano- La2O3 and Mo on the wear resistance of laser cladding coating. 65Mn blade as the substrate, La2O3, Mo and Mo-La2O3 composite powders were added into Ni60a/SiC composite powder. By using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and the CFT-I surface synthesizer, the phase composition, element distribution and friction and wear properties of the coating were analyzed to obtain the best composition of the composite coating. The results showed that the wear resistance of Mo-La2O3-Ni60a/SiC composite coating was the best. The coating was analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The coating contained hard phases such as CrB, CrC and Cr7C3, and the element distribution was uniform. It can be seen from the scanning electron microscope that the addition of nano-Mo and La2O3 improves the toughness and compactness of Ni60a/SiC composite coating, and the microstructure is refined. The friction coefficient of Mo-La2O3-Ni60a/SiC composite coating is 0.5, and the wear depth is 12.35 μm, which is 23% and 89% lower than that of 65Mn substrate, respectively. The wear mechanism of the coating is mainly adhesive wear, abrasive wear and oxidation wear. The wear surface of the Mo-La2O3-Ni60a/SiC composite coating is mainly composed of micro furrows, accompanied by the generation of new wear resistant layers.
- Add brief quantitative results to the abstract
Answer: Thank you very much. We have revised them in the manuscript as follows：
To improve the wear resistance of TMR blade and investigate the effect of nano- La2O3 and Mo on the wear resistance of laser cladding coating. 65Mn blade as the substrate, La2O3, Mo and Mo-La2O3 composite powders were added into Ni60a/SiC composite powder. By using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and the CFT-I surface synthesizer, the phase composition, element distribution and friction and wear properties of the coating were analyzed to obtain the best composition of the composite coating. The results showed that the wear resistance of Mo-La2O3-Ni60a/SiC composite coating was the best. The coating was analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The coating contained hard phases such as CrB, CrC and Cr7C3, and the element distribution was uniform. It can be seen from the scanning electron microscope that the addition of nano-Mo and La2O3 improves the toughness and compactness of Ni60a/SiC composite coating, and the microstructure is refined. The friction coefficient of Mo-La2O3-Ni60a/SiC composite coating is 0.5, and the wear depth is 12.35 μm, which is 23% and 89% lower than that of 65Mn substrate, respectively. The surface roughness of the Mo-La2O3-Ni60a/SiC coating after wear is 2.06 μm, and the wear amount is 0.001 g, The wear mechanism of the coating is mainly adhesive wear, abrasive wear and oxidation wear. The wear surface of the Mo-La2O3-Ni60a/SiC composite coating is mainly composed of micro furrows, accompanied by the generation of new wear resistant layers.
- The size of the error bars in Figure 2 is too small.
Answer: Thank you very much. We have revised them in the manuscript as follows：
Figure 2. Micro-hardness and XRD pattern of composite coating
- Please highlight the novelty of using Nano-La2O3.
Answer: Thank you very much. The appropriate amount of rare earth La2O3 can effectively improve the microstructure of the laser clad composite layer, reduce the cracks, holes and inclusions in the composite layer; accelerate the dissolution of Ni60a/SiC particles in the composite layer and improve the shape change of Ni60a/SiC particles, and make the wear resistance and corrosion resistance of the clad composite layer significantly improved. And the research on rare earth La2O3 mainly involves the comparison of several rare earth oxides, and there is less research on the analysis of Ni60a/SiC composite melt clad layer with 65Mn steel as the substrate.
- The explanation in Figure 4 “Three-dimensional morphology” needs to be expanded.
Answer: Thank you very much. We have added related content to 2 Materials and methods - 2.4. Microscopic morphology characterization:
three-dimensional surface topography (Nanovea ST400, NANOVEA, USA) were used to in-vestigate the wear scar and polished sections of the coating, It enables the testing of material surfaces from nanometres to millimetres in terms of roughness, depth and other indicators, with high measurement accuracy.
- Laser absorptivity in AM is important which shows the quality of the parts and transition from keyhole to conduction mode. Please read and add the following ref in this area. “The effect of absorption ratio on meltpool features in laser-based powder bed fusion of IN718”.
Answer: Thank you very much. We have added relevant content to the introductory section of the manuscript:
Laser-cladding technology uses a high-energy-density laser beam to melt the cladding material and solidify it on the substrate surface [5]. Laser absorption and other indicators have a large influence on the quality of the cladding[6-7].
- Laser has many advantages over the conventional manufacturing method which can be highlighted in your paper. Please read the following manuscript and add it to the literature to show how the laser is comparable with conventional manufacturing: Laser subtractive and laser powder bed fusion of metals: review of process and production features
Answer: Thank you very much. We have added relevant content to the introductory section of the manuscript:
Laser-cladding technology uses a high-energy-density laser beam to melt the cladding material and solidify it on the substrate surface [5]. Laser absorption and other indicators have a large influence on the quality of the cladding[6-7]. Laser-cladding coated substrates offer significant improvements in material savings, processing accuracy, surface quality and mechanical properties compared to conventional manufacturing [8]
Author Response File: 
Author Response.docx
Reviewer 2 Report
Remarks: There are no principal essential remarks to the article. However, there are a number of comments on the presentation and design of the material:
1. Throughout the text, it is desirable to replace the term "65Mn material" with the more accurate "steel 65Mn"
2. In section “3. Results and discussion" lines 116-118 can be removed.
3. The authors are absolutely correct that CeO2 particles can be retained at the interface and reduce wear and friction coefficient. However, the term "solid lubrication" should not be applied to them. Solid lubricants include, for example, materials such as graphite, molybdenum disulfide, low-modulus metals (Cu, Zn), and not solid high-modulus oxides. Therefore, the term "solid lubrication" is better removed (lines 210-212 in section 3.3 and line 296 in section "4. Conclusions").
4. In the phrase "Si3N4 and SiC gradually transformed into CeO2" (line 289 in section 3.4), the term "transformed" should be corrected for the term "replaced".
Author Response
- Throughout the text, it is desirable to replace the term "65Mn material" with the more accurate "steel 65Mn"
Answer: Thank you very much. We have replaced "65Mn material" with "steel 65Mn" in the manuscript.
- In section “3. Results and discussion" lines 116-118 can be removed.
Answer: Thank you very much. We have removed from the manuscript.
- The authors are absolutely correct that CeO2 particles can be retained at the interface and reduce wear and friction coefficient. However, the term "solid lubrication" should not be applied to them. Solid lubricants include, for example, materials such as graphite, molybdenum disulfide, low-modulus metals (Cu, Zn), and not solid high-modulus oxides. Therefore, the term "solid lubrication" is better removed (lines 210-212 in section 3.3 and line 296 in section "4. Conclusions").
Answer: Thank you very much. We have made revisions in the appropriate places.
- In the phrase "Si3N4 and SiC gradually transformed into CeO2" (line 289 in section 3.4), the term "transformed" should be corrected for the term "replaced".
Answer: Thank you very much. We have made revisions in the appropriate places:
The binding energies of Y5 at 101.9 eV and 99.7 eV correspond to the orbits of CeO2 and Si2p3/2, respectively. Compared with Y3, Y4 and Y5, Si3N4 and SiC were not found in Y5, indicating that Si3N4 and SiC gradually replaced into CeO2, which promoted the anti-wear performance of Y5 coating.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The paper is ready to publish.
