Laser decoating of DLC films for tribological applications

Damaged DLC coatings usually require remanufacturing of the entire coated components starting from an industrial chemical de-coating step. Alternatively, a complete or local coating repair can be considered. To pursue this approach, however, a local coating removal is needed as first operation. In this context, controlled decoating based on laser sources can be a suitable and clean alternative to achieve a pre-fixed decoating depth with high accuracy. In the present study, we investigated a laser-based decoating process executed on multilayered DLC films for advanced tribological applications (deposited via a hybrid PVD/PE-CVD technique). The results were acquired via multifocal optical digital microscopy (MF-ODM), which allowed high-resolution 3D surface reconstruction as well as digital profilometry of the lasered and unlasered surface. The study identifies the most critical process parameters which influence the effective decoating depth and the post-decoating surface roughness. In particular, the role of pulse overlap (decomposed along orthogonal directions), laser fluence, number of lasing passes and assist gas is discussed in text. A first experimental campaign was designed to identify the best conditions to obtain full decoating of the DLC + DLC:Cr layers. It was observed that decreasing the marking speed to 200 mm/s was necessary to obtain a sufficient pulse overlap and a nearly planar ablation profile. By operating with microsecond pulses and 1 J/cm² (fairly above the ablation threshold), less than 10 passes were needed to obtain full decoating of the lasered area with an etching rate of 1.1 μm/loop. Further experiments were then executed in order to minimise the roughness of the rest surface with the best value found at around 0.2 μm. Limited oxidation but higher R _a values were observed in Ar atmosphere.     

TiN涂层刀具的抗热冲击性能

采用激光照射的方法研究了TiN涂层刀具的抗热冲击性能,并用有限元的方法计算了TiN涂层刀具在激光照射过程中产生的应力分布.结果表明:利用激光照射的方法研究涂层刀具的抗热冲击性能是可行的,将激光的临界功率密度作为评价涂层刀具抗热冲击性能的参数;涂层在激光照射过程中产生的压应力作用下发生失稳翘曲,进而导致裂纹的产生.试验结果和有限元计算结果吻合良好.     

Influence of laser heat treatment on microstructure and properties of surface layer of Waspaloy aimed for laser-assisted machining

In this study, a nickel-based superalloy, Waspaloy, was laser heat treated with diode laser. Single laser tracks were manufactured with different laser beam power densities between 63 and 331 kW/cm², and scanning laser beam speed ranged from 5 to 100 m/min. It was found that laser heat treatment of Waspaloy causes decrease in material hardness—the microhardness in laser tracks is about 300 HV0,1 while the microhardness of substrate is ranged from 300 to 600 HV0,1—which is a positive phenomenon for laser-assisted machining of investigated material. Impacts of laser heat treatment parameters on laser tracks properties were identified for obtaining multiple laser tracks with the most homogenous thickness. Moreover, roughness of heated layers was measured to specify surface quality after laser heat treatment. Multiple laser tracks were produced using different scanning laser beam speed and distances between laser tracks ranged from 0.125 to 1 mm. It was found that if scanning laser beam speed is 75 m/min and distance between laser tracks is equal to or lower than 0.25 mm, in microstructures of multiple laser tracks, cracks are occurring. The most suitable laser heat parameters for obtaining heated layers, and which can be used for laser-assisted machining, were identified as laser beam power density 178.3 kW/cm², scanning laser beam speed 5 m/min, and distance between laser tracks 0.125 mm.     

A fuzzy logic based model to predict surface hardness of thin film TiN coating on aerospace AL7075-T6 alloy

Aerospace applications and energy-saving strategies in general raised the interest and study in the field of lightweight materials, especially on aluminum alloys. Aluminum alloy itself does not have appropriate wear resistance. Therefore, improvement of surface properties is required in practical applications, especially when aluminum is in contact with other parts. In this work, first titanium nitride (TiN) is coated on aerospace Al7075-T6 in different conditions using PVD magnetron sputtering technique, and the surface hardness of TiN-coated specimens is measured using a micro hardness machine. Second, a fuzzy logic model is offered to predict the surface hardness of TiN coating on AL7075-T6 with respect to changes in input process parameters, direct current (DC) power, DC bias voltage, and nitrogen flow rate. Four membership functions are allocated to be connected with each input of the model. The predicted results achieved via fuzzy logic model are compared to the experimental result. The result demonstrated settlement between the fuzzy model and experimental results with 96.142 % accuracy. The hardness of titanium nitride-coated specimens is increased significantly up to 720 HV, while the hardness of uncoated specimens was 170 HV.     

Dry machining of aluminum for proper selection of cutting tool: tool performance and tool wear

Machining of aluminum and its alloy is very difficult due to the adhesion and diffusion of aluminum, thus the formation of built-up edge (BUE) on the surface. The BUE, which affects the surface integrity and tool life significantly, affects the service and performance of the workpiece. The minimization of BUE was carried out by selection of proper cutting speed, feed, depth of cut, and cutting tool material. This paper presents machining of rolled aluminum at cutting speeds of 336, 426, and 540 m/min, the feeds of 0.045, 0.06, and 0.09 mm/rev, and a constant depth of cut of 0.2 mm in dry condition. Five cutting tools WC SPUN grade, WC SPGN grade, WC + PVD (physical vapor deposition) TiN coating, WC + Ti (C, N) + Al₂O₃ PVD multilayer coatings, and PCD (polycrystalline diamond) were utilized for the experiments. The surface roughness produced, total flank wear, and cut chip thicknesses were measured. The characterization of the tool was carried out by a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) pattern. The chip underface was analyzed for the study of chip deformation produced after machining. The results indicated that the PCD tool provides better results in terms of roughness, tool wear, and smoother chip underface. It provides promising results in all aspects.     

An experimentally based thermo-kinetic phase transformation model for multi-pass laser heat treatment by using high power direct diode laser

Laser-based phase transformation hardening (LPTH), based on rapid heating and cooling cycles produces hard and wear-resistant layers only at the selective region of the components. However, the bulk mass of the material’s core property is retained. The advantages of high power direct diode laser in comparison with other high power lasers (CO₂ and Nd:YAG) have put this type of laser as a main heat source for localized heat treatment. However, a tempered zone is formed in overlapping regions of a large heat-treated area during multi-pass laser heat treatment (MPLHT) that affects the uniformity of heat-treated depth of material. This study is focused on the development of a uniform hardness distribution model to minimize the tempering effect during the MPLHT process. A tool steel AISI S7 is heat treated by using different levels of laser power (1,400–1,800 W) and scanning speeds (15–25 mm/s). An experimentally based finite element (FE) thermal model is developed to predict the cross-sectional as well as surface temperature history of the MPLHT process. The temperature-dependent material properties and phase change kinetics are taken into account in the model. The laser beam is considered as a moving rectangular-shaped heat source (12 mm?×?1 mm) with a uniform distribution (top-hat) of laser power. The temperature history acquired from the FE thermal model is coupled with thermo-kinetic (TK) equations to determine the corresponding phase transformations and hardness. The tempering effect of MPLHT is studied for different sizes of overlap (1 mm–3 mm) and lengths of scan (10 mm–35 mm). The TK model results are verified with experimental ones to optimize the processing parameters. The optimized processing parameters, including laser power, scanning speed, size of overlap, and the length of scan are used to achieve a uniform hardness distribution and an even depth of heat treatment in the MPLHT area.     

Evaluation on Effectiveness of CVD and PVD Coated Tools during Dry Machining of Incoloy 825

With wide applications of nickel-based superalloys in strategic fields, it has become increasingly necessary to evaluate the performance of different advanced cutting tools for machining such alloys. With a view to recommend a suitable cutting tool, the present work investigated various machinability characteristics of Incoloy 825 using an uncoated tool, chemical vapor deposition (CVD) of a bilayer of TiCN/Al₂O₃, and physical vapor deposition (PVD) of alternate layers of TiAlN/TiN-coated tools under varying machining conditions. The influence of cutting speed (51, 84, and 124 m/min) as well as feed (0.08, 0.14, and 0.2 mm/rev) was comparatively evaluated on surface roughness, cutting temperature, cutting force, coefficient of friction, chip thickness, and tool wear using different cutting tools. Although the CVD-coated tool was not useful in decreasing surface roughness and temperature, a significant reduction in cutting force and tool wear could be achieved with the same coated tool under a high cutting speed of 124 m/min. On the other hand, the PVD-coated tool outperformed the other tools in terms of machinability characteristics. This might be attributed to the excellent antifriction and antisticking property of TiN and good toughness due to the multilayer configuration in combination with a thermally resistant TiAlN phase. Adhesion, abrasion, edge chipping, and nose wear were the prominent wear mechanisms of the uncoated tool, followed by the CVD-coated tool. However, remarkable resistance to such wear was evident with the PVD TiAlN/TiN multilayer-coated tool.     

Surface quality improvement of EDMed Ti–6Al–4V alloy using plasma etching and TiN coating

This paper seeks to improve the surface quality of electrical discharge machining (EDM) Ti–6Al–4V using plasma etching treatment and TiN coating. The EDM parameter setting is optimized firstly based on grey-Taguchi method. Four EDM parameters, including current (A), voltage (V), pulse duration (μs), and duty factor (%), are selected for multiple performance of lower electrode wear rate (EWR), higher material removal rate (MRR), and better surface roughness (SR). An orthogonal array, signal-to-noise (S/N) ratios, and analysis of variance (ANOVA) are used to analyze the effects of these EDM parameters. Normality tests show that all the distributions fit normality assumption with p?=?0.276, 0.688, and 0.663, respectively. The EDM process is stable over time monitored by Shewhart control charts. It is observed that there is an EDM damaged layer on the surface consisting of debris, microcracks, molten drops, and solidified metals by scanning electron microscopy. The plasma etching and TiN coating are employed to improve surface quality of the EDMed Ti–6Al–4V alloys. The results demonstrate that using the oxygen plasma etching treatment, the damaged phenomena are decreased, and the mean SR value is reduced from Ra?=?2.91 to Ra?=?2.50 μm. In addition, when the plasma-treated alloy is coated with Ti buffer/TiN coating by physical vapor deposition, the surface morphology exhibits less defects and a better surface finish. The mean SR values are further reduced from Ra?=?2.50 μm to Ra?=?1.48 μm (for 740 nm TiN film) and Ra?=?0.61 μm (for 1450 nm TiN film), respectively.     

Effect of process parameters in nanosecond pulsed laser micromachining of PMMA-based microchannels at near-infrared and ultraviolet wavelengths

This paper presents investigations on the effects of nanosecond laser processing parameters on depth and width of microchannels fabricated from polymethylmethacrylate (PMMA) polymer. A neodymium-doped yttrium aluminium garnet pulsed laser with a fundamental wavelength of 1,064 nm and a third harmonic wavelength of 355 nm with pulse duration of 5 ns is utilized. Hence, experiments are conducted at near-infrared (NIR) and ultraviolet (UV) wavelengths. The laser processing parameters of pulse energy (402–415 mJ at NIR and 35–73 mJ at UV wavelengths), pulse frequency (8–11 Hz), focal spot size (140–190 μm at NIR and 75 μm at UV wavelengths) and scanning rate (400–800 pulse/mm at NIR and 101–263 pulse/mm at UV wavelengths) are varied to obtain a wide range of fluence and processing rate. Microchannel width and depth profile are measured, and main effects plots are obtained to identify the effects of process parameters on channel geometry (width and depth) and material removal rate. The relationship between process variables (width and depth of laser-ablated microchannels) and process parameters is investigated. It is observed that channel width (140–430 μm at NIR and 100–150 μm at UV wavelengths) and depth (30–120 μm at NIR and 35–75 μm at UV wavelengths) decreased linearly with increasing fluence and increased non-linearly with increasing scanning rate. It is also observed that laser processing at UV wavelength provided more consistent channel profiles at lower fluences due to higher laser absorption of PMMA at this wavelength. Mathematical modeling for predicting microchannel profile was developed and validated with experimental results obtained with pulsed laser micromachining at NIR and UV wavelengths.     

A prototyping and microfabrication CAD/CAM tool for the excimer laser micromachining process

A CAD/CAM tool for prototyping and small-scale production of micro-electro-mechanical systems (MEMS) devices based on the excimer laser ablation process has been developed. The system’s algorithms use the 3D geometry of a microstructure, defined as an STL file exported from a CAD model, and parameters that influence the process (laser fluence, pulse repetition frequency, number of shots per area, wall angle, stitching errors) to automatically generate a precise NC part program for the excimer laser machine. The performance of the system has been verified by NC part program generation for several 3D microstructures and subsequent machining trials. An initial stitching error of 23.4±2.2-μm wide and 3.4±1.5-μm high was observed when the overlap size between adjacent volumes was zero, when ablating 100×100-μm features in polycarbonate (PC) at a fluence of 0.5 J/cm² using a workpiece-dragging technique. When the size of the overlap was optimised by a system based on optimal process parameters determined by the Taguchi design of experiment method (DOE), and incorporated in the mask design, the maximum stitching error was reduced to 13.4±2.2-μm wide and 1.4±0.9-μm high under the same conditions. By employing a hexagonal-shaped mask with incorporated size of the image overlap, reduced horizontal-stitching errors of 2.4±0.2-μm wide and 1.4±0.2-μm high were observed. The system simplifies part program creation and is useful for excimer laser operators who currently use a tedious trial and error process to create programs and complex masks to generate microstructure parts.     

Residual stresses in TiN, DLC and MoS2 coated surfaces with regard to their tribological fracture behaviour

Thin hard coatings on components and tools are used increasingly due to the rapid development in deposition techniques, tribological performance and application skills. The residual stresses in a coated surface are crucial for its tribological performance. Compressive residual stresses in PVD deposited TiN and DLC coatings were measured to be in the range of 0.03-4 GPa on steel substrate and 0.1-1.3 GPa on silicon. MoS₂ coatings had tensional stresses in the range of 0.8-1.3 on steel and 0.16 GPa compressive stresses on silicon. The fracture pattern of coatings deposited on steel substrate were analysed both in bend testing and scratch testing. A micro-scale finite element method (FEM) modelling and stress simulation of a 2 μm TiN-coated steel surface was carried out and showed a reduction of the generated tensile buckling stresses in front of the sliding tip when compressive residual stresses of 1 GPa were included in the model. However, this reduction is not similarly observed in the scratch groove behind the tip, possibly due to sliding contact-induced stress relaxation. Scratch and bending tests allowed calculation of the fracture toughness of the three coated surfaces, based on both empirical crack pattern observations and FEM stress calculation, which resulted in highest values for TiN coating followed by MoS₂ and DLC coatings, being K_C = 4-11, about 2, and 1-2 MPa m^1/2, respectively. Higher compressive residual stresses in the coating and higher elastic modulus of the coating correlated to increased fracture toughness of the coated surface.     

EFFECT OF CUTTING SPEED AND SURFACE CHEMISTRY OF CUTTING TOOLS ON THE FORMATION OF BUL OR BUE AND SURFACE QUALITY OF THE GENERATED SURFACE IN DRY TURNING OF AA6005 ALUMINIUM ALLOY

In the present investigation, AA6005 (ISO: AlSiMg) alloy was machined in turning operation with different cutting tools, such as uncoated cemented carbide insert, PVD TiN coated, CVD diamond coated and PCD insert, under dry environment. Effect of cutting speed was studied for each of the cutting tools with regard to the formation of built-up layer (BUL) or built-up edge (BUE). The rake surface of the tools was characterized by optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopic microanalysis. Particular emphasis was given on wear mechanism of PVD TiN coated insert, conventionally used in machining ferrous alloys, during dry turning of AA6005 alloy. It has been observed that increase of cutting speed from 200 m/min to as high as 1000 m/min could not substantially reduce formation of BUL over tool rake surface during dry machining of AA6005 alloy with uncoated or PVD TiN coated cemented carbide inserts. The potential of diamond-based tools in dry machining of aluminium alloy was also studied. Finally, the effect of cutting speed on surface finish of the workpiece machined with different cutting tools was studied during dry turning of AA6005 alloy.     

TiCN涂层硬质合金刀具铣削性能研究

采用Kistler三向压电铣削测力仪测试了刀具切削45钢过程中的切削力,利用超景深显微镜、扫描电镜和能谱仪观察分析刀具切削后的磨痕宽度、形貌和成分,获得了未涂层刀具HSS、TiN和TiCN涂层刀具的切削时间与磨痕宽度关系图,探讨了刀具的切削失效机理。采用XRD分析了涂层刀具铣削前的相结构,结果表明:TiN与TiCN涂层均表现为fcc-TiN相结构,TiCN具有明显的(111)择优取向,TiN择优取向不明显。切削试验表明:在磨痕宽度达到0.3mm时,TiCN涂层刀具的切削时间比TiN涂层刀具切削时间约长2.5倍,同时整个切削过程中TiCN比TiN具有更低的切削力。这可能是因为TiCN涂层比TiN涂层具有更高的硬度和耐磨性,并且切削过程中TiCN涂层中固溶的C能析出至晶界处,起到润滑作用,降低刀具与工件材料之间的摩擦,减小切削力,延长刀具使用寿命。SEM和EDS分析表明:TiN涂层刀具磨损失效机理为磨料磨损和粘着磨损,而TiCN涂层刀具失效以磨料磨损为主。     

Wear behaviour of laser cladded and plasma sprayed WCCo coatings

The usefulness of WCCo cermets as wear resistant material for coatings is determined by the cladding technique employed. This paper compares the features of an 83% WCCo coating on an AISI 1043 steel substrate using two different application techniques: plasma spraying and laser cladding. Results show significantly less porosity, improved coating hardness and better layer-substrate adherence in laser cladded than in plasma sprayed coatings. This causes them to have different wear behaviour which was determined using a method developed on the basis of the PV factor theory using sliding linear contact of flat-cylinder type. The method proved that wear rate (V_d′) is directly proportional to the product of coefficient of friction (μ), load (C) and applied speed (V), V_d′ = KμCV, where proportionality constant, K, is different for every material and depends on conditions such as lubrication, temperature, etc. To study wear behaviour, laser cladded and plasma sprayed 83% WC-Co coatings, under extreme lubrication, were placed against a hardened and tempered AISI 1043 steel, at different load and sliding speed rates. As a result constant K was estimated for each coating. The tests also showed that wear rate in laser deposited coatings is approximately 34% lower than in plasma sprayed coatings.     

Effect of 10 wt% VC on the Friction and Sliding Wear of Spark Plasma–Sintered WC–12 wt% Co Cemented Carbides

The effect of 10 wt% VC addition on the friction and sliding wear response of WC–12 wt% Co cemented carbides produced by spark plasma sintering (SPS) was studied. The SPS of WC–12 wt% Co alloys with and without 10 wt% VC, at 1100 and 1130°C, respectively, yielded dense materials with minimal porosity. No eta phase was found in any of the alloys. The WC–12 wt% Co–10 wt% VC alloy showed the formation of a hard WV₄C₅ phase, which improved the alloy's hardness. Friction and dry sliding wear tests were done using a ball-on-disk configuration under an applied load of 10 N and sliding speed of 0.26 m.s^?1, and a 100Cr-steel ball was used as the counterface. A significant improvement in the sliding wear response of the harder and more fracture tough WC–12 wt% Co–10 wt% VC alloy compared to the WC–12 wt% Co alloy was found. Analysis of the worn surfaces by scanning electron microscopy showed that the wear mechanisms included plastic deformation, preferential binder removal, adhesion, and carbide grain cracking and fragmentation.     

Sliding-Wear Behavior of TiN- and CrN-Coated 2024 Aluminum Alloy Against an Al2O3 Ball

Dry sliding friction and wear behavior of TiN and CrN deposited on 2024 aluminum alloy by arc ion plating was investigated using the ball-on-disk wear test. The effects of normal load and ceramic coating on the friction coefficient and wear-resistance of 2024 aluminum alloy were studied. The worn surfaces were observed by scanning electron microscopy (SEM). The results show that wear volume increases while the friction coefficient decreases with an increase in normal load. The wear resistance of CrN is higher than that of TiN. The wear mechanism of TiN-coated 2024 Al is related to the oxidation of TiN coating and plastic deformation of 2024 Al. Conversely, the wear mechanism of CrN-coated 2024 Al is related to the fatigue fracture of the coating, which was affected by residual stress and plastic deformation of 2024 Al.     

Design of energy optimization for laser polymer joining process

Different laser heat inputs were applied on the gray-colored acrylonitrile butadiene styrene (ABS) plastic using fixed laser power and variable scanning speeds to join ABS- and polycarbonate (PC)-based polymers. Experiments with a laser power between 6 and 8 W and a scanning speed of 1,500, 3,000, and 4,500 mm/min were used for the joining. Heat-affected zone (HAZ) and melt zone measurements were performed to find the joining energy threshold, and the mechanical properties of welds were evaluated. At the low scanning speed, the total heat input at the given area resulted in carbonization damage on the surface. However, energy distributed laser beam joining process by galvanometers resulted in secure and sound weld joining quality. Damage threshold was calculated as 127 J/cm² with relatively less sensitivity of scanning speed. However, the ablation threshold was measured to be 215, 281, and 424 J/cm² for the scanning speed of 4,500, 3,000 and 1,500 mm/min, respectively.     

激光熔覆与激光-感应复合熔覆WC-Ni60A涂层的结构与性能特征

对单纯激光熔覆与激光-感应复合熔覆Ni60A+35%WC涂层的几何外形、稀释率、WC颗粒分布、显微组织与抗干滑动磨损性能进行对比分析。结果表明,单纯激光熔覆的最大激光扫描速度与最大送粉量仅为600 mm.min–1与25 g.min–1,当激光-感应复合熔覆采用相同的工艺参数时,复合熔覆层的宽度、热影响区、稀释率均大于单纯激光熔覆层,厚度却小于单纯激光熔覆层,WC颗粒与析出的碳化物不均匀地分布于复合熔覆层内,复合熔覆层的抗干滑动磨损性能比单纯激光熔覆层的差。但是,激光-感应复合熔覆的最大激光扫描速度可以提高到2 200 mm.min–1,最大送粉量可以提高到75.6 g.min–1,加工效率是单纯激光熔覆的3倍多,复合熔覆层内WC颗粒分布均匀,经检测无裂纹且稀释率仅为5.2%,抗干滑动磨损性能约是单纯激光熔覆层的1.42倍。     

DISCUSSION ON: A Fundamental Study of Synthetic Sapphire as a Bearing Material

Thermal reactive diffusion (TRD) coating on a DIN 1.2367 die steel substrate was performed in a powder mixture consisting of ferrovanadium, ferrochromium, ammonium chloride, alumina, and naphthalene at temperatures of 1000, 1050, and 1100°C for 2–4 h. The carbide layers were characterized using the microstructure, microhardness, X-ray diffraction, and chemical analysis. Wear scars were analyzed on scanning electron microscopy (SEM) micrographs with an energy-dispersive X-ray spectroscopy module. Depending on the coating process time and temperature, the thicknesses of the vanadium carbide and the chromium carbide layers formed on the substrate were obtained in a range from 7 to 30 μm and 5 to 17 μm, respectively. The maximum hardness values of vanadium carbide and chromium carbide layers were measured as 2537 and 1973 HV, respectively. The test samples coated using the TRD method were analyzed with regard to abrasive wear behavior using three different loads (1, 2, and 3 N) and speeds of 40, 80, and 160 rpm in fixed-ball micro-abrasion tests. Depending on the load and speed values applied, the grooving and rolling mechanisms were found to be predominant abrasion mechanisms on the worn surfaces.     

Fabrication of porous copper surfaces by laser micromilling and their wetting properties

Porous copper surfaces show their great merits in the applications of chemical reaction, sound absorption and heat transfer. In this study, a laser micromilling method is proposed to fabricate porous surfaces with homogeneous micro-holes and cavities of the size about 1–15 μm on pure copper plates in a one-step process. The laser micromilling was performed by a pulsed fiber laser via the multiple–pass reciprocating scanning strategy. Based on the measurement of scanning electron microscope (SEM) and 3D laser scanning confocal microscope, the formation of surface structures was investigated together with the laser ablation mechanisms. The effects of laser processing parameters, i.e., laser fluence, scanning speed, number of scanning cycles and scanning interval, on the formation and surface morphology of porous surfaces were systematically assessed. Furthermore, the wettability of the porous copper surfaces was also evaluated by measuring the static contact angle of water. The results showed that the laser fluence played the most significant role on the formation of porous copper surfaces. The average depth and surface roughness of porous copper surfaces increased with increasing the laser fluence and number of scanning cycles while decreased with the increase in scanning interval. The scanning speed played little influence on the formation of porous copper surfaces. These results can be closely related to the variation of energy density and re-melting process during the laser micromilling process. Moreover, all the copper porous surfaces were found to be hydrophobic. The contact angle of porous copper surfaces was significantly dependent on laser fluence, but weakly affected by the scanning speed and number of scanning cycles.