Wetting of Cu-SiC Composite Material Modified by Nanosecond Laser Radiation and Liquid Spreading over It

Round 1

Reviewer 1 Report

In this work, Orlova et al. introduce the very first results on the near-surface characterization of metal-composites materials subjected to laser processing.

In particular, they analyzed the properties of a Cu-SiC surface subjected to ultrafast laser pulses in the nanosecond regime.

The topic is of primary interest to researchers working in the general field of functionalization of materials by laser processing, and it is definitely worth to be investigated.

As regards the manuscript, it is well-written, the used methodology is rigorous, and results are well-presented and exhaustively discussed.

I only have some suggestions for authors to improve their paper:

1) The abstract is too long in my opinion, and it risks to defocus the reader. I suggest to reduce its length, limiting to enlist the topic, what has been done in practice (in this case the laser treatment and the surface characterizations) and main results. For instance, the motivation of the study (lines 10-14) should be described in the introduction, and comments on the results (lines 30-33) should be left to the related section.

2) In the introductory section, authors should mention two of the most important reasons for using laser-induced surface texturing, that is: 1) the change of the electrical properties; for instance, some insulators like diamond may become conductive after laser processing (see M. Komlenok et al., "Diamond detectors with laser induced surface graphite electrodes" Nucl. Instrum. Meth. A 837, pp. 136-142 (2016)). 2) thermal properties can also be modified by laser texturing (see Jiang et al. "Laser texturing at interface for improved strain tolerance and thermal insulation performance of thermal barrier coatings", Surf. Coatings Technol. 459, 129385 (2023)). I suggest to add this info when enlisting the applications of laser texturing.

3) Line 152. For consistency with the terms used in the literature, please replace "frequency" with "repetition rate". Also, specify that it is the "pulse duration", not simply "duration".

4) Some words should be added on the possible effect of pulse duration on the surface properties. Authors used 120 ns pulses, which are relatively "long": in this case, a consistent heat transfer in the region surrounding the laser spot occurs. When using faster pulses (i.e., 100 fs) heat spreading can be neglected, and the treated volume is limited to the focal plane and to the laser spot. Do authors think that pulse duration can affect wetting and/or the dynamic characteristics of spreading?

 

Very good English. Just a few typos to correct.

Author Response

Responses to the Reviewer's comments are attached. 

Author Response File: Author Response.docx

Reviewer 2 Report

(1) The title of this paper is "Surface properties", but this paper investigated about the wetting properties. Therefore, the title should be modified to that surface properties is the wetting properties.

(2)Table 1. Composition, sintering temperature and hardness of final bulk Cu-SiC samples.  Cu 100%  9±2

Is this a wrong about the 90±2?

(3)Table 2. SEM images of surface and elemental composition of the near surface layer of Cu-SiC material.

Examine not only the composition of a narrow region, but also the average composition over a large region at low magnification.Check to see if the laser radiation has changed the overall composition of the sample surface.

(4)The wetting properties are greatly influenced by the surface texture.　Then, surface roughness measurement results should also be graphed so that they can be compared.

(5) In conclusion of 3."the reason for the spontaneous hydrophobization of the Cu-SiC composite materials modified by nanosecond laser radiation are due  to the adsorption of airborne hydrocarbon contami-nants, similarly to the known wetting  inversion of metal surfaces."

" the adsorption of airborne hydrocarbon contami-nants" is likely to be present, but there is no experimental data in this paper to support its presence; it is recommended to add the results of surface analysis by XPS, etc.

Author Response

Responses to the Reviewer's comments are attached. 

Author Response File: Author Response.docx