Review of Laser Texturing Technology for Surface Protection and Functional Regulation of Aluminum Alloys: Wettability, Anti-Icing, Corrosion Resistance, and Wear Resistance

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I have no significant comments. I liked this review; it contains quite a lot of references to modern research in the areas under consideration.

Indeed, the article submitted for review is not just a scientific article, but a review of scientific articles, which requires more time for its consideration. Nevertheless, after reading the submitted work, I got the feeling that this is a high-quality work in which a fairly meaningful literature search and review was carried out.

The presented review is devoted to the technology of laser texturing, its progress in development, its latest technical capabilities. The methods and limits of application of the LST method to aluminum alloys are separately covered for the possibility of using this method as a surface protection and regulation of the functional characteristics of aluminum alloys. 

I think the topic chosen by the authors is original and relevant to the field. I also think that this review fills a certain gap in the literature on the LST method. This gap is due to the small number of articles that combine the description of the surface treatment technology and its consequences with the specific functional properties that are deteriorated as a result of this treatment. It is known that the LST method consists of rapid interaction between high-energy laser beams and the surface of the material, which inevitably leads to the creation of micro- and nanoscale features. At the same time, it is the LST method that attracts attention due to its accuracy, ease of control and flexibility of process adjustment. In this regard, it is reviews that include both the technological parameters of alloy processing and real properties with a quantitative value that are useful for improving surface treatment technology. This review brings it all together. 

This review is thoughtful and covers a wide range of articles on the topic chosen, so I have no suggestions for improving the methodology of the article; in my opinion, the methodology was chosen correctly.

This work is a review of existing scientific articles, so it does not and cannot contain a conclusion. It contains a section "Summary and Prospects" that corresponds to the type of article submitted for review. 

For the considered modern method, which is LST, the authors have chosen modern research. Many links lead to the research of groups of authors known in the scientific community for their research on processing alloys and aluminum-based alloys using the LST method. These links correspond to the subject and logic of the presented work. 

Author Response

Response to Reviewer 1 Comments

Point 1: I have no significant comments. I liked this review; it contains quite a lot of references to modern research in the areas under consideration.

Indeed, the article submitted for review is not just a scientific article, but a review of scientific articles, which requires more time for its consideration. Nevertheless, after reading the submitted work, I got the feeling that this is a high-quality work in which a fairly meaningful literature search and review was carried out.

The presented review is devoted to the technology of laser texturing, its progress in development, its latest technical capabilities. The methods and limits of application of the LST method to aluminum alloys are separately covered for the possibility of using this method as a surface protection and regulation of the functional characteristics of aluminum alloys.

I think the topic chosen by the authors is original and relevant to the field. I also think that this review fills a certain gap in the literature on the LST method. This gap is due to the small number of articles that combine the description of the surface treatment technology and its consequences with the specific functional properties that are deteriorated as a result of this treatment. It is known that the LST method consists of rapid interaction between high-energy laser beams and the surface of the material, which inevitably leads to the creation of micro- and nanoscale features. At the same time, it is the LST method that attracts attention due to its accuracy, ease of control and flexibility of process adjustment. In this regard, it is reviews that include both the technological parameters of alloy processing and real properties with a quantitative value that are useful for improving surface treatment technology. This review brings it all together.

This review is thoughtful and covers a wide range of articles on the topic chosen, so I have no suggestions for improving the methodology of the article; in my opinion, the methodology was chosen correctly.

This work is a review of existing scientific articles, so it does not and cannot contain a conclusion. It contains a section "Summary and Prospects" that corresponds to the type of article submitted for review.

or the considered modern method, which is LST, the authors have chosen modern research. Many links lead to the research of groups of authors known in the scientific community for their research on processing alloys and aluminum-based alloys using the LST method. These links correspond to the subject and logic of the presented work.

Response 1: Thank you for your valuable time and professional review. We are particularly grateful for your acknowledgment of our research’s relevance and the rigor of our literature synthesis.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please see the attached PDF file

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 Comments

Overall, this is a good manuscript that covers key literature of the Laser Texturing forsurface modification of alloys. I have the following minor comments for authors which are rather easy to address.

Point 1: The introduction section is written well with sound motivation for different micromanufacturing techniques such as LST, ECM etc. However, it would be a good idea to include a figure to help the reader visually glance at different techniques in a consolidated manner. Additionally, another figure that exhibits different applications of LST i.e. low-friction sliding films, corrosion resistant films, anti-icing films can also be added.

Response 1: Thank you for the reviewer’s valuable suggestion. Following the reviewer’s suggestion, we have added Table 1 to summarize different micromanufacturing techniques, processing methods, and main functions.We have also added Figure 1 to present the various functional applications of LST.The added content is as follows:

Recently, a variety of micro-manufacturing techniques have been utilized to create patterned surfaces on metals, including laser surface texturing (LST)[60,61], electrochemi-cal machining (ECM)[62,63], chemical milling (CM)[64], spark erosion machining(EMD)[65], photolithographic etching (PLE)[66,67], and ultrasonic-assisted machining (UAM)[68]. Among these, LST has attracted considerable interest due to its precision, control, and process flexibility[51,69]. The main processing methods and functions of these techniques are summarized in Table 1.

Table 1. Micromanufacturing Techniques, Processing Methods, and Main Functions

Technique	Abbreviation	Processing Method	Main Function
Laser Surface Texturing	LST	Using laser to engrave micro-textures on surfaces.	Improves wear resistance, corrosion resistance, anti-icing, and surface wettability.
Electrochemical Machining	ECM	Dissolving material in an electrolyte with electric current.	Enables precision shaping of hard materials without thermal damage.
Chemical Milling	CM	Selectively etching surface areas with chemical solutions.	Reduces material thickness and weight.
Spark Erosion Machining	EDM	Removing material with electrical sparks in liquid.	Processes complex shapes in hard and brittle materials.
Photolithographic Etching	PLE	Creating fine patterns using photolithography and etching.	Fabricates micro- and nano-structures for microelectronics.
Ultrasonic-Assisted Machining	UAM	Applying ultrasonic vibration during cutting or drilling.	Reduces cutting force and improves surface quality.

Furthermore, in composite material bonding applications[75-77], the micro/nano-scale surface patterns promote mechanical interlocking with other materials, thereby enhancing the adhesive bond strength at the interface. Some research[78-80] has integrated patterned surfaces with functional coatings, dry lubricants, or ceramic coatings, resulting in combined enhancements in friction reduction, corrosion resistance, and wear durability, highlighting potential applications in marine, aerospace, and other high-demand industrial settings. The different surface functional applications enabled by LST are summarized in Figure 1.

 

Figure 1. Overview of the functional applications of LST.

Point 2: The DLW method in line 159 is not defined or discussed previously. Please add that

discussion or clarify what the DLW method is.

Response 2: I have completed the revisions, as detailed below：

Milles et al.[89] compared the microstructure fabrication capabilities of direct laser writing (DLW) and DLIP. DLW is a technique that uses a focused laser beam to directly write patterns onto material surfaces. It can produce relatively large structures, ranging from approximately 50 to 500 micrometers in size, with depths reaching up to 36.8 mi-crometers and a maximum Sq value of about 13 micrometers, but it offers relatively low resolution.

Point 3: There is more to what was done in ref 91 than what is discussed in lines 191-199. Simple use of LSP does not lead to improvement in tensile strength, generally. In that study, authors actually achieved interlocking of aluminum and graphene and dislocation accumulation. Currently the discussion presented by the authors is rather vague without any visual aids that does not clearly explain how texture strengthening can be achieved using LSP.

Response 3: Thank you very much for your valuable guidance. I have carefully reviewed and studied the original text again. The modifications have been made according to the suggestions, and the revised content is presented below.

The superior strength of natural nacre primarily originates from its interlocked lamellar structure. Inspired by this, Kumar et al. [91] developed a bioinspired nano-laminate graphene-aluminum alloy composite (AA-Gr). Initially, AA6061 aluminum alloy and graphene composite powders were prepared using ultrasonic dispersion and ball milling techniques, followed by cold pressing, sintering, and hot extrusion. Subse-quently, the samples were subjected to LSP. After LSP treatment, the lamellar grains of the AA-Gr composites were further refined, forming an interlocked brick-and-mortar-like nanostructure similar to that of nacre, where graphene was posi-tioned at the grain boundaries, effectively inhibiting grain growth and promoting la-mellar arrangement. LSP also induced a high density of dislocations, leading to the formation of nanoscale stacking faults, micro shear cells, and other microstructural features, which significantly contributed to grain refinement.

Figure 3 illustrates the typical microstructural evolution of the AA-Gr nanocom-posites after LSP treatment. Figure 3a shows the formation of interlocked lamellar structures, indicating the effective bonding and strengthening role of graphene at the grain boundaries. Figure 3b reveals a dense and uniform distribution of dislocation structures within the interlocked laminates. Figure 3c presents the SAED pattern of the dislocation region, confirming local lattice misorientations induced by high-density dislocations. Figure 3d displays the inhibition of large dislocation loop formation by graphene, effectively preventing the expansion of Frank-Read dislocation sources and reducing dislocation accumulation. Figures 3e and 3f respectively show the emergence of multiple deformation twins and stacking faults within the composites after LSP treatment. Figures 3g and 3h further reveal features of grain refinement, including the formation of small grains, dense dislocation walls, and low-angle grain boundaries.

 

Figure 3. TEM nanostructure of (a) Interlocked laminates (b) dislocation nanostructure with cor-responding (c) diffraction pattern showing steaks on spots (d) grapheneinhibited dislocation loops (e & f) multiple deformations twins and stacking faults of LSP treated AA-Gr laminate nano-composites and (g & h) grain refinement features of nanocomposites after LSP treatment.

Mechanical testing results demonstrated that LSP treatment led to a 24.55% in-crease in ultimate tensile strength, reaching 439 MPa, a 29.56% improvement in micro-hardness, and more than a twofold enhancement in fatigue life compared to the un-treated samples. These findings confirm the synergistic effect of graphene reinforce-ment and laser shock processing in significantly enhancing the comprehensive perfor-mance of the composites.

Point 4: Are there examples from nature where surface texturing is actually exploited to

improve the frictional properties? Authors may want to discuss it in section 5

Response 4: Thank you for the valuable suggestion. I have reviewed extensive literature and found examples where surface texturing inspired by biological structures, such as the scales of pangolins, is exploited to improve frictional properties. The corresponding discussion has been added to Section 5. The modifications are as follows:

Zhang et al. [109]investigated a dual surface modification strategy combining bio-mimetic texturing and TiN coating to enhance the wear resistance of 20Mn cast steel. In this study, microstructures mimicking the morphology of pangolin scales were first fabricated on the substrate surface using laser surface processing. Subsequently, a TiN coating was deposited on the surface via physical vapor deposition. The biomimetic texture effectively reduced the frictional contact area, dispersed frictional stress, and captured wear debris generated during the wear process, thereby suppressing local stress concentration and mitigating three-body wear. The TiN coating provided a hard and dense protective layer on the material surface, further enhancing scratch resistance and overall wear performance.Experimental results showed that the application of bi-omimetic texture alone reduced the friction coefficient by approximately 20%, while the TiN coating alone resulted in a reduction of about 30.9%. When both modifications were applied together, the friction coefficient decreased by 38.09%. The synergistic effect of biomimetic texturing and TiN coating significantly enhanced the wear re-sistance and service stability of 20Mn cast steel under dry friction conditions.

 

Point 5: Summary and outlook section can be substantially improved. For instance, in lines 837-838 authors mention that long-term tribological performance of laser textured surfaces have not been investigated. What have been the roadblocks to such investigations? Is it the scalability of such samples? Cost of laser treatments? Or something else? It’s not obvious why despite such benefits these treatments would not be applied in actual products or technologies.

Response 5: Thank you for the expert’s insights. Based on the suggestions, I have made detailed revisions to the Summary and Outlook section as follows:

1. Durability and environmental adaptability: Although laboratory studies confirm excellent anti-icing, corrosion resistance, and tribological performance, the long-term performance of laser-textured surfaces in various performance domains remains inad-equately investigated. Roadblocks to these investigations primarily include the com-plexity and cost associated with long-duration testing under realistic operating condi-tions. Additionally, the inability to replicate exact industrial environments in laborato-ry settings further complicates obtaining representative long-term data. Addressing these issues requires collaborative efforts to establish standardized, scalable, and eco-nomically feasible testing methodologies.
2. Scalability for industrial applications: Current studies mostly focus on small-area samples. Scaling laser texturing technologies for large-scale industrial surfaces effi-ciently and cost-effectively remains challenging. Future research should focus on de-veloping automated and high-speed laser processing systems to facilitate broader in-dustrial applications.

3.Developing multifunctional composite surface structures: Future advancements require combining laser surface texturing with other surface treatment methods, such as plasma electrolytic oxidation, chemical modifications, and nano-coating deposition, to create composite protective layers. Integrating multiple functionalities like an-ti-corrosion and tribological performance on a single surface significantly enhances material performance under complex operating conditions. Additionally, developing intelligent, responsive textures that dynamically adapt surface properties to environ-mental changes will cater to diverse application requirements.

4.Advanced characterization and theoretical modeling: Fully understanding the intrinsic relationships between laser texturing and resultant material performance is crucial. Future research should employ advanced characterization techniques alongside multi-scale theoretical modeling methods such as molecular dynamics simulations and finite element analyses to elucidate structure-performance relationships. Applying machine learning and artificial intelligence to analyze extensive datasets can further identify complex interdependencies between processing parameters and performance outcomes, enabling intelligent and optimized texture designs.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The presented review thoroughly investigates the application of laser texturing technology for the enhancement of surface protection and functional control of aluminium alloys, with a specific emphasis on properties such as wettability, anti-icing capabilities, corrosion resistance, and wear resistance. Furthermore, the review explores advancements in laser surface patterning techniques while also considering the impact of relevant physical parameters on these processes. 
The organization and comprehensiveness of the review are commendable, and it includes a substantial number of relevant citations. However, a notable concern arises from the age of many cited sources, which exceeds a decade. This aspect necessitates revision to ensure the inclusion of more contemporary research. Additionally, there are instances of invalid sources that require rectification. 
Despite these shortcomings, I assess the article positively and recommend its publication after the mentioned shortcomings are corrected.

Author Response

Response to Reviewer 2 Comments

Overall, this is a good manuscript that covers key literature of the Laser Texturing forsurface modification of alloys. I have the following minor comments for authors which are rather easy to address.

Point 1: The introduction section is written well with sound motivation for different micromanufacturing techniques such as LST, ECM etc. However, it would be a good idea to include a figure to help the reader visually glance at different techniques in a consolidated manner. Additionally, another figure that exhibits different applications of LST i.e. low-friction sliding films, corrosion resistant films, anti-icing films can also be added.

Response 1: Thank you for the reviewer’s valuable suggestion. Following the reviewer’s suggestion, we have added Table 1 to summarize different micromanufacturing techniques, processing methods, and main functions.We have also added Figure 1 to present the various functional applications of LST.The added content is as follows:

Recently, a variety of micro-manufacturing techniques have been utilized to create patterned surfaces on metals, including laser surface texturing (LST)[60,61], electrochemi-cal machining (ECM)[62,63], chemical milling (CM)[64], spark erosion machining(EMD)[65], photolithographic etching (PLE)[66,67], and ultrasonic-assisted machining (UAM)[68]. Among these, LST has attracted considerable interest due to its precision, control, and process flexibility[51,69]. The main processing methods and functions of these techniques are summarized in Table 1.

Table 1. Micromanufacturing Techniques, Processing Methods, and Main Functions

Technique	Abbreviation	Processing Method	Main Function
Laser Surface Texturing	LST	Using laser to engrave micro-textures on surfaces.	Improves wear resistance, corrosion resistance, anti-icing, and surface wettability.
Electrochemical Machining	ECM	Dissolving material in an electrolyte with electric current.	Enables precision shaping of hard materials without thermal damage.
Chemical Milling	CM	Selectively etching surface areas with chemical solutions.	Reduces material thickness and weight.
Spark Erosion Machining	EDM	Removing material with electrical sparks in liquid.	Processes complex shapes in hard and brittle materials.
Photolithographic Etching	PLE	Creating fine patterns using photolithography and etching.	Fabricates micro- and nano-structures for microelectronics.
Ultrasonic-Assisted Machining	UAM	Applying ultrasonic vibration during cutting or drilling.	Reduces cutting force and improves surface quality.

Furthermore, in composite material bonding applications[75-77], the micro/nano-scale surface patterns promote mechanical interlocking with other materials, thereby enhancing the adhesive bond strength at the interface. Some research[78-80] has integrated patterned surfaces with functional coatings, dry lubricants, or ceramic coatings, resulting in combined enhancements in friction reduction, corrosion resistance, and wear durability, highlighting potential applications in marine, aerospace, and other high-demand industrial settings. The different surface functional applications enabled by LST are summarized in Figure 1.

 

Figure 1. Overview of the functional applications of LST.

Point 2: The DLW method in line 159 is not defined or discussed previously. Please add that

discussion or clarify what the DLW method is.

Response 2: I have completed the revisions, as detailed below：

Milles et al.[89] compared the microstructure fabrication capabilities of direct laser writing (DLW) and DLIP. DLW is a technique that uses a focused laser beam to directly write patterns onto material surfaces. It can produce relatively large structures, ranging from approximately 50 to 500 micrometers in size, with depths reaching up to 36.8 mi-crometers and a maximum Sq value of about 13 micrometers, but it offers relatively low resolution.

Point 3: There is more to what was done in ref 91 than what is discussed in lines 191-199. Simple use of LSP does not lead to improvement in tensile strength, generally. In that study, authors actually achieved interlocking of aluminum and graphene and dislocation accumulation. Currently the discussion presented by the authors is rather vague without any visual aids that does not clearly explain how texture strengthening can be achieved using LSP.

Response 3: Thank you very much for your valuable guidance. I have carefully reviewed and studied the original text again. The modifications have been made according to the suggestions, and the revised content is presented below.

The superior strength of natural nacre primarily originates from its interlocked lamellar structure. Inspired by this, Kumar et al. [91] developed a bioinspired nano-laminate graphene-aluminum alloy composite (AA-Gr). Initially, AA6061 aluminum alloy and graphene composite powders were prepared using ultrasonic dispersion and ball milling techniques, followed by cold pressing, sintering, and hot extrusion. Subse-quently, the samples were subjected to LSP. After LSP treatment, the lamellar grains of the AA-Gr composites were further refined, forming an interlocked brick-and-mortar-like nanostructure similar to that of nacre, where graphene was posi-tioned at the grain boundaries, effectively inhibiting grain growth and promoting la-mellar arrangement. LSP also induced a high density of dislocations, leading to the formation of nanoscale stacking faults, micro shear cells, and other microstructural features, which significantly contributed to grain refinement.

Figure 3 illustrates the typical microstructural evolution of the AA-Gr nanocom-posites after LSP treatment. Figure 3a shows the formation of interlocked lamellar structures, indicating the effective bonding and strengthening role of graphene at the grain boundaries. Figure 3b reveals a dense and uniform distribution of dislocation structures within the interlocked laminates. Figure 3c presents the SAED pattern of the dislocation region, confirming local lattice misorientations induced by high-density dislocations. Figure 3d displays the inhibition of large dislocation loop formation by graphene, effectively preventing the expansion of Frank-Read dislocation sources and reducing dislocation accumulation. Figures 3e and 3f respectively show the emergence of multiple deformation twins and stacking faults within the composites after LSP treatment. Figures 3g and 3h further reveal features of grain refinement, including the formation of small grains, dense dislocation walls, and low-angle grain boundaries.

 

Figure 3. TEM nanostructure of (a) Interlocked laminates (b) dislocation nanostructure with cor-responding (c) diffraction pattern showing steaks on spots (d) grapheneinhibited dislocation loops (e & f) multiple deformations twins and stacking faults of LSP treated AA-Gr laminate nano-composites and (g & h) grain refinement features of nanocomposites after LSP treatment.

Mechanical testing results demonstrated that LSP treatment led to a 24.55% in-crease in ultimate tensile strength, reaching 439 MPa, a 29.56% improvement in micro-hardness, and more than a twofold enhancement in fatigue life compared to the un-treated samples. These findings confirm the synergistic effect of graphene reinforce-ment and laser shock processing in significantly enhancing the comprehensive perfor-mance of the composites.

Point 4: Are there examples from nature where surface texturing is actually exploited to

improve the frictional properties? Authors may want to discuss it in section 5

Response 4: Thank you for the valuable suggestion. I have reviewed extensive literature and found examples where surface texturing inspired by biological structures, such as the scales of pangolins, is exploited to improve frictional properties. The corresponding discussion has been added to Section 5. The modifications are as follows:

Zhang et al. [109]investigated a dual surface modification strategy combining bio-mimetic texturing and TiN coating to enhance the wear resistance of 20Mn cast steel. In this study, microstructures mimicking the morphology of pangolin scales were first fabricated on the substrate surface using laser surface processing. Subsequently, a TiN coating was deposited on the surface via physical vapor deposition. The biomimetic texture effectively reduced the frictional contact area, dispersed frictional stress, and captured wear debris generated during the wear process, thereby suppressing local stress concentration and mitigating three-body wear. The TiN coating provided a hard and dense protective layer on the material surface, further enhancing scratch resistance and overall wear performance.Experimental results showed that the application of bi-omimetic texture alone reduced the friction coefficient by approximately 20%, while the TiN coating alone resulted in a reduction of about 30.9%. When both modifications were applied together, the friction coefficient decreased by 38.09%. The synergistic effect of biomimetic texturing and TiN coating significantly enhanced the wear re-sistance and service stability of 20Mn cast steel under dry friction conditions.

 

Point 5: Summary and outlook section can be substantially improved. For instance, in lines 837-838 authors mention that long-term tribological performance of laser textured surfaces have not been investigated. What have been the roadblocks to such investigations? Is it the scalability of such samples? Cost of laser treatments? Or something else? It’s not obvious why despite such benefits these treatments would not be applied in actual products or technologies.

Response 5: Thank you for the expert’s insights. Based on the suggestions, I have made detailed revisions to the Summary and Outlook section as follows:

1. Durability and environmental adaptability: Although laboratory studies confirm excellent anti-icing, corrosion resistance, and tribological performance, the long-term performance of laser-textured surfaces in various performance domains remains inad-equately investigated. Roadblocks to these investigations primarily include the com-plexity and cost associated with long-duration testing under realistic operating condi-tions. Additionally, the inability to replicate exact industrial environments in laborato-ry settings further complicates obtaining representative long-term data. Addressing these issues requires collaborative efforts to establish standardized, scalable, and eco-nomically feasible testing methodologies.
2. Scalability for industrial applications: Current studies mostly focus on small-area samples. Scaling laser texturing technologies for large-scale industrial surfaces effi-ciently and cost-effectively remains challenging. Future research should focus on de-veloping automated and high-speed laser processing systems to facilitate broader in-dustrial applications.

3.Developing multifunctional composite surface structures: Future advancements require combining laser surface texturing with other surface treatment methods, such as plasma electrolytic oxidation, chemical modifications, and nano-coating deposition, to create composite protective layers. Integrating multiple functionalities like an-ti-corrosion and tribological performance on a single surface significantly enhances material performance under complex operating conditions. Additionally, developing intelligent, responsive textures that dynamically adapt surface properties to environ-mental changes will cater to diverse application requirements.

4.Advanced characterization and theoretical modeling: Fully understanding the intrinsic relationships between laser texturing and resultant material performance is crucial. Future research should employ advanced characterization techniques alongside multi-scale theoretical modeling methods such as molecular dynamics simulations and finite element analyses to elucidate structure-performance relationships. Applying machine learning and artificial intelligence to analyze extensive datasets can further identify complex interdependencies between processing parameters and performance outcomes, enabling intelligent and optimized texture designs.

Author Response File: Author Response.pdf