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In this study, a laser-assisted electrodeposition method is used to prepare Ni–Co–W and amorphous Ni–P coatings for different laser scanning rates. The laser scanning rate is an important parameter as it can be used to adjust the laser spot overlap (ε) and energy distribution of the laser pulse, thereby affecting the properties and performance of the coatings. The effect of ε on the various properties of the Ni–Co–W and Ni–P coatings is explored. The experimental results show that a change in ε influences the surface morphology, mechanical properties, and corrosion resistance of the coatings. For ε = 85%, the Ni–Co–W and Ni–P coatings exhibit the best surface morphology. The Ni content of both the Ni–Co–W and Ni–P coatings is found to decrease with an increasing ε , whereas the Co and P contents are found to increase with ε. However, the residual tensile stress of the Ni–P coating fails to improve with an increasing ε. The wear and corrosion resistances of the Ni–Co–W coating increase with ε. Moreover, a change in ε affects the intensities of the (111) and (220) diffraction peaks of Ni–Co–W. For ε = 85%, both the Ni–Co–W and Ni–P coatings exhibit good wear and corrosion resistances. • Creatively studying the effect of laser spot overlap (ε) on Ni-based coatings. • With the ε increase, the surface morphology, and elemental content change. • The ε affects the corrosion resistance and mechanical properties of coatings. • Providing a new idea for preparing Ni-based coating. [ABSTRACT FROM AUTHOR]

[Display omitted] • Laser irradiation realizes ultra-thin localized Au Coating. • Laser irradiation increases the electrodeposition efficiency. • Laser irradiation improves the surface quality of Au coating. • Laser irradiation achieves precise regulation of dimensional accuracy. • Laser irradiation improves corrosion resistance of Au coating. Traditional electrodeposition requires auxiliary technologies such as mask to realize localized deposited layer. In this paper, ultra-thin Au coating can be obtained selectively by laser-induced electrodeposition without mask, which has advantages in dimensional accuracy, brightness, good compactness. The deposition rate, dimensional accuracy, density, roughness, and corrosion resistance were evaluated under different laser single pulse energy (4.5, 5, 5.5, 6, 6.5, 7, 7.5, and 8 μJ). Furthermore, the spatial distribution of the transient temperature field and the change law of the cathode substrate current under laser irradiation were detected to explore the mechanism induced by laser thermal effect. The results show that laser irradiation can increase the cathode limit current density to reach the Au precipitation potential. Besides, the electrodeposition rate increases with the increase of laser single pulse energy. When the laser single pulse energy is 6 µJ, the electrodeposition rate reaches 0.167 mg/min. Meanwhile, the electrodeposition accuracy and surface density are better, and surface roughness (Sa) is 0.98 μm. Moreover, compared with the Au coating product provided by an electroplating enterprise, the coating prepared by laser-induced electrodeposition has better corrosion resistance. When the laser single pulse energy is 6 µJ, self-corrosion potential (φ corr) is −0.3059 V, and self-corrosion current density (j corr) is 5.066 × 10−5 A/cm2. [ABSTRACT FROM AUTHOR]

Amorphous Ni-P alloys crystallize at high temperatures, which leads to the deterioration of resistivity and corrosion resistance. In this study, the use of laser irradiation with the electrodeposition (ECD) process for preparing amorphous Ni-P coatings was investigated; and the resistivity and corrosion resistance were analyzed, which is related to crystallization process, surface morphology, residual internal stress, and oxidation layer. The results indicates that the crystallization rate of Ni-P coating prepared by laser-assisted electrodeposition (LECD) was slower than that of ECD coating. With increasing ambient temperature, the internal tensile stress first decreased and then increased. The LECD coating has better oxidation resistance, with XPS indicating the oxide layer mainly comprised Ni-O compounds. At the same ambient temperature, the resistivity of the LECD coating was higher than that of the ECD coating. The Ni-P coating had better corrosion resistance after heating, and the corrosion mechanism changes from stress corrosion to pitting corrosion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic field is introduced into ECD based on laser irradiation. • Transverse magnetic field has a better impact on properties of Fe-Ni coating. • The magnetic field affects the grain growth orientation and forms flow pattern. • The Fe content is affected due to the MHD effect on the diffusion degree. • Magnetic field can improve the properties of Fe-Ni coating. A steady-state magnetic field is introduced to prepare Fe-Ni coating based on laser-assisted electrodeposition (LECD) to control the change of element content and improve the surface quality. The internal structure, surface quality, and properties are tested to discuss under different magnetic field intensities. The results indicate that the comprehensive performance of Fe-Ni coating with a transverse magnetic field is better. The magnetohydrodynamic (MHD) and magnetization effect make the grain refinement and improve the surface quality of Fe-Ni coating. The surface morphology shows that the laser makes the surface denser, while the magnetic field causes the ions to magnetize so that the clusters form on the surface. The addition of the magnetic field does not change the grain structure, but the Fe content is increased because of the MHD effect on the diffusion degree. Besides, when the magnetic field intensity is 15 mT, the residual internal stress reaches 587 MPa in the form of compressive stress. Meanwhile, the test of micro-hardness, tensile strength, wear, and corrosion resistance indicates that the comprehensive performance of Fe-Ni coating by the magnetic field and laser-assisted electrodeposition (MLECD) is better than that of electrodeposition (ECD) and LECD. [ABSTRACT FROM AUTHOR]

Electrodeposited amorphous alloys require numerous nuclei and irregular atomic arrangements. In this study, the impact of processing parameters (e.g., a nanosecond laser) on the current density in the electroplating solution for an electrodeposited Ni P coating was tested using an electrochemical workstation. In addition, the effect of the laser on the temperature and micro-stirring caused by cavitation was simulated using COMSOL (version 5.4). The surface quality, wear, and corrosion resistance of the Ni P coating prepared by laser-assisted electrodeposition (LECD) at different laser repetition frequencies (picosecond laser, 0.5, 1, 1.5, 2, and 2.5 MHz) were evaluated. The results showed that the stability of current change was best when the laser frequency, pulse width, scanning line spacing, and irradiation area were 1 MHz, 200 ns, 20 μm, 1 mm2, respectively. Excessive laser energy destroys the balance of electrochemical deposition process. The simulation results showed that the maximum instantaneous temperature of the laser-irradiated solution was 123 °C. Cavitation increases the flow rate of the solution and produces a jet impact on the substrate. The maximum velocity and instantaneous pressure were 0.13 m/s and 7.26 × 108 Pa at 0.1 ns, respectively. At the laser frequency of 0.5 MHz, the P content increases by approximately 2% compared to that of the coating prepared by LECD (1–2.5 MHz). The residual internal stress decreased with increasing frequency, and it existed in the form of tensile stress. The wear and corrosion resistances of the Ni P coating were the best when the laser frequency was 1 MHz. [Display omitted] • Laser irradiation increases the current density of ECD. • Laser irradiation has a force impact on the solution. • Cavitation accelerates the flow velocity of solution and form jet impact. • Laser frequency affects the quality of electrodeposited layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Laser irradiation realizes maskless localized electrodeposition. • Laser irradiation increases the limiting current density. • Laser irradiation improves the surface quality of Ni-P coating. • Laser irradiation increases the amorphous degree of Ni-P coating. • Laser irradiation improves corrosion resistance of Ni-P coating. To obtain electrodeposited layers with different patterns, the additional auxiliary measures such as mask prepared by photoresist are usually required for traditional electrodeposition (ECD) technology, which may reduce the flexibility and convenience of this method. Meanwhile, the ultrashort pulsed laser can be introduced into ECD process and increase current density in the selected area on cathode, and has potential in helping achieve maskless localized ECD. In this paper, the picosecond (ps) laser-assisted ECD (LECD) method is studied, in which a cyclic laser scanning scheme is used to produce different electrodeposited layers on the cathode substrate. In addition, the realizing mechanism of localized ECD is discussed, and the surface quality of Ni-P coating prepared by LECD is evaluated. The results show that the electrodeposited layers with different sizes (1 × 1 mm, 2 × 2 mm and 3 × 3 mm) can be obtained by laser selective irradiation on the copper substrate (10 × 10 mm), demonstrating that the critical current can be increased to reach the reaction conditions in the irradiated zone by the laser-caused thermal effects. Analysis also shows that the theoretical diameter of zigzag edge can be calculated, which is consistent with that of actual electrodeposited layer, indicating that the precision and localization of electrodeposited layer is controllable by adjusting laser processing parameters. Furthermore, measurement shows that a surface roughness of 0.012 μm and better surface flatness can be obtained by LECD under a pulse energy of 16 μJ, and the amorphous degree Ni-P can be increased by the thermal and photoelectric effects of ps laser irradiation. Besides, the corrosion potential and current density are −0.19 V and 3.83 × 10−6 A/cm2, respectively, and the AC impedance spectrum also indicates a higher electron transfer resistance, illustrating better corrosion resistance can be achieved by LECD (16 μJ). [ABSTRACT FROM AUTHOR]

This study developed a new electrodeposited Fe–Ni coatings using the laser-induced current waveform. This process refined grains accomponied with a mixed nanocrystalline size and alternate element content. The electrochemical and immersion corrosion performance at 3.5 wt% NaCl was improved, which is still pitting corrosion. The corrosion pits are more likely to spread around rather than in the depth direction. The enhancement mechanism is mainly attributed to the richer grain boundaries. This microstructure increases the interface transfer resistance and makes the corrosion more uniform. This study provides a potential process for preparing nanocrystalline coatings with better performance. [Display omitted] • Laser-induced current waveform refines grains with a mixed size. • The element content is distributed alternately along the cross-section. • The electrochemical and immersion corrosion properties are improved. • The enhance mechanism is mainly attributed to the rich grain boundaries. [ABSTRACT FROM AUTHOR]

Electrodeposited amorphous Ni-P alloys have enormous internal stress and high brittleness, resulting in cracks and poor wear resistance. In this study, the surface cracks of an amorphous Ni-P coating, prepared by laser-assisted electrodeposition were removed by laser remelting. The surface quality was characterized and the wear mechanism was analyzed by evaluating its microhardness and wear resistance. The results showed that the remelted layer had a corrugated structure, and the surface roughness increased. The remelted layer is transformed from amorphous to crystalline, consisting of stable phases of Ni, and Ni-P compounds. Compared with the non-remelted coating, the microhardness and wear resistance of remelted coating are improved. The main wear mechanisms of remelted coatings include abrasive wear, oxidation wear, and plastic deformation. [Display omitted] [ABSTRACT FROM AUTHOR]

Icing has adverse effects on human daily life and industrial production. The superhydrophobic surfaces have enormous potential for anti-icing applications because of the excellent water repellent effect. To enhance the anti-icing properties of metal surfaces, a hybrid method was employed, which combined laser processing, electrodeposition, and chemical soaking. This method was used to create a superhydrophobic surface with regular micro-nano composite concave corner structures on the surfaces of 7075 aluminum alloy. The morphology and wetting performance of samples under different current densities and deposition times were characterized. Under the current density of 40 mA/cm2 and the deposition time of 300 s, the hydrophobic performance of the prepared Zn Ni alloy superhydrophobic coating was optimal. During the anti-frost testing, the prepared superhydrophobic surface only experienced water droplet aggregation, while frost never appeared. Compared to unprocessed surfaces, the prepared superhydrophobic surfaces showed a significant increase in anti-icing performance. Finally, the mechanism of the delayed icing on the surface of the prepared Zn Ni alloy superhydrophobic coating was analyzed. This research provided a feasible approach for the manufacturing of superhydrophobic anti-icing surfaces. [Display omitted] • A hybrid method was applied to prepare superhydrophobic surfaces. • Current density and deposition time controlled the morphology of Zn Ni coatings. • The prepared surface greatly improved the anti-icing performance of the substrate. [ABSTRACT FROM AUTHOR]

The laser thermal effect effectively reduces the internal stress of Ni-Fe-P coating, but it still exists in the form of tensile stress. In this paper, a steady-state magnetic field is introduced into laser-assisted electrodeposition (LECD). Whether the magnetohydrodynamic (MHD), magnetic, and magnetization effect can alleviate the residual tensile stress of amorphous Ni-Fe-P coating was discussed. The results indicate that magnetic field impacts the formation of particle clusters and the reduction of the number of micro-cracks. When the magnetic field strength is 15 mT, the internal stress exists in compressive stress (150 MPa). When the magnetic field strength is 25 mT, the surface micro-cracks formed directionality. Based on LECD, the influence of magnetic field on ECD rate is not significant, while the Fe content increases because of the MHD effect. In addition, when a magnetic field is added, the amorphous structure does not change. When the magnetic field intensity is 15 mT, the diffraction peak of XRD is broader and smoother, indicating that the size of the crystal nucleus is smaller. Moreover, compared with LECD, magnetic field and laser assisted ECD (MLECD) improves corrosion resistance, but decreases wear resistance. [Display omitted] • MLECD makes Ni-Fe-P coating manifested with particle clusters. • MLECD reduces the residual internal stress existing in compressive stress. • MLECD makes the reduction of Fe preferentially because of the MHD effect. • MLECD improves corrosion resistance, but decreases wear resistance. [ABSTRACT FROM AUTHOR]

• Laser irradiation improves grain size and degree of amorphous. • Laser irradiation removes the bubbles and improves the surface quality. • The laser energy offsets part of the residual tensile stress. • Laser irradiation improves the hardness, corrosion and wear resistance. The formation of electrodeposited amorphous Ni-P alloy requires numerous tiny crystal nuclei and disorderly arranged atoms. In this paper, laser irradiation is introduced into the electrodeposition process by a cyclic reciprocating scanning manner. The laser thermal effect not only enhances the formation of amorphous Ni-P alloy with smaller nucleus and better density, but also accelerates the reduction of ions and hence hydrogen evolution at the cathode. The transient high-temperature zone occurs under laser irradiation, leading to micro-area agitation formation, so that the gas deposited in the cathode can be eliminated in time, and the pore defects generated in the deposited layer can be reduced. In addition, part of the heat generated by laser irradiation is absorbed by the reducing ions and deposited on the substrate in the form of compressive stress, which may reduce the overall residual tensile stress of the coating. Amorphous Ni-P alloy heat treatment will increase the hardness but decrease the corrosion resistance. However, the results show that laser irradiation can improve the corrosion and wear resistance of the coating simultaneously. [ABSTRACT FROM AUTHOR]

[Display omitted] • Laser remelting can remove surface cracks. • The remelted layer changes from amorphous to crystalline. • There are many pores in the remelted layer due to cracks. • The crack size affects the corrosion resistance of the remelted coating. The amorphous Ni-P coating crack may further propagate with an increase in electrodeposition (ECD) time, and hence decreases the corrosion resistance. In this study, the Ni-P coating was firstly prepared by picosecond (ps) laser-assisted ECD (LECD), followed by a nanosecond (ns) laser remelting step to remove cracks. The corrosion behavior was detailed evaluated under different LECD time and processing sequence. The results show that the ns laser remelting step results in an increase in surface roughness (Sa) by about one order of magnitude, as well as phase transition from amorphous to crystalline. The LECD time length significantly affect the corrosion behavior after the remelting step, as obvious decrease in corrosion resistance compared with the non-melted surface can be observed for 40 min and 90 min LECD. In contrast, for 180 min case, the corrosion behavior has been significant improved. Longer LECD time may reduce the surface corrosion defects on the remelted coating, and hence decrease the probability of solution-defect contact and hence cracks development, thus improving corrosion resistance. [ABSTRACT FROM AUTHOR]