Preparation and Performance Study of Si-DLC Based on Ion Deposition of Different Multiple Gradient Transition Layers
Round 1
Reviewer 1 Report
The authors present an interesting paper on the use of different gradient transition layers for improved performance silicon-added diamond-like carbon films. The authors extensively analyze the coating roughness (SEM), composition (EDX), and structure (XRD, Raman), as well as hardness and wear. The conclusions are supported by the results, only the presentation of the results can be improved. Particularly, in fig.2 the text and numbers are illegible. Further, the authors should check the font sizes in fig. 3-5 and properly format superscripts (e.g. cm-1) i.a. in section 3.4.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The study addresses different transition layers (AlTiSiN, AlCrN and AlTiCrN) for silicon diamond-like carbon coatings on austenitic stainless steel substrates using multi-arc ion plating technique. The coatings were studied by means of SEM, XRD, nanoindentation, Rockwell hardness, Raman spectroscopy and tribo-testing. It was reported that the AlTiSiN transition layer resulted in the lowest surface roughness, highest hardness, highest adhesion and highest wear resistance.
The topic is of interest for the scientific community, the manuscript basically is well written and mostly scientifically sound. However, I have a couple of comments that should be addressed and implemented prior to further consideration (major and mandatory):
1. Substrate cleaning: Please provide more details on the procedure and the used
2. Specimen rotation on the rack during coating: Was it one-, two- or three-fold?
3. Information on the specimen geometry should be provided.
4. More detailed information on the employed measurement parameters of the different equipment used for the evaluation of the structural and mechanical properties (SEM, Raman, hardness, roughness) should be provided for reasons of reproducability. Also, please provide the exact type and manufacturer of the used equipment.
5. Fig. 6: What is the purpose of the black arrow in the upper left part of the figure? Also, the use of connected line graphs implies that there would be the possibility for a gradual transition between the different interlayers. I suggest to use a bar chart instead.
6. The specifications for the wear and scratch test are insufficient. Again, much more information is needed to reproduce the results, for example the loads etc. Also, how often were the tests performed for statistical validation?
7. My main point of critique is that the comparison of adhesion tendency and wear resistance is only qualitatively done, the authors failed to provide a quantitative comparison that is not subject to the influence of the operator of the tests (the test time is, for example). This would be, for example, the adhesion class (HF) in Rockwell testing, the critical loads at which characteristic damage occurs in scratch testing etc. There are also appropriately standardized test procedures that should be employed.
8. This is a subjective comment: I prefer when references to Figures or Tables are formulated passively ("something is shown in Figure X" instead of "Figure X shows something"), because the authors show something with the item and the Figure/Table itself cannot perform any active actions. The authors can feel free to consider this or not.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors did a good job in answering all my comments in detail and implementing the suggested changes in the revised version of the manuscript. I believe that quality has improved and suggest acceptance of the paper in its current form.
