Cladding high-hardness In718 alloy onto ductile iron emerges as an effective solution to mitigate interfacial degradation, owing to the alloy’s superior resistance to corrosion, oxidation, wear and thermal fatigue. Herein, the effects of laser cladding parameters on the tribological performance of laser-cladded In718 coatings were investigated. Simulation results demonstrated that optimized cladding parameters effectively homogenize the molten pool’s temperature gradient and significantly reduce the residual stress within the cladding layer, thereby enhancing the cladding quality. In718 alloy coatings were cladded on ductile iron substrates using simulation-optimized cladding parameters, achieving a microcrack-free morphology with minimal powder inclusions, negligible pores, and refined metallographic structures. The coatings demonstrate a substantial hardness enhancement of 46.7%–58.9% compared to the substrate, attributed to hard carbide formation and metallurgical grain refinement. The coatings generate a stable coefficient of friction across varying loads, with values of 0.63–0.77 (10N), 0.58–0.77 (12N) and 0.63–0.72 (15N), demonstrating enhanced hardness and wear resistance. The wear severity of the coatings exhibits minimal variation, but intensifies remarkably with increasing loads. The dominant wear mechanisms include abrasive wear, fatigue wear and plastic deformation, with oxidative wear becoming a significant factor under higher loads. This study provides a technical foundation for developing high-hardness In718 alloy coatings with enhanced tribological performance.

Nickel-based superalloys are widely employed in critical service scenarios of mechanical engineering, owing to their excellent creep strength and superior high-temperature corrosion resistance. However, their intrinsically low microhardness easily causes abnormal wear and fatigue cracking, threatening service safety. Herein, WC-reinforced In718 composite coatings were laser-cladded on In718 substrates, and their tribological enhancement mechanisms were systematically elucidated. Localized critical melting occurs at WC particle peripheries, promoting complex multiphase metallurgical microstructures that enhance interfacial bonding strength. The coatings consist of face-centered cubic γ-Ni, (Ni, Cr) and (Ni, Fe) solid solutions, with in-situ precipitated hard phases and precipitation-strengthening phases. Due to the synergistic strengthening from WC dispersion, grain refinement, and multiphase in-situ precipitation, the coatings exhibit 49.3%–70.7% higher microhardness, stable 0.66–0.72 coefficient of friction, and 38.2%–70.4% lower wear mass loss. In-situ precipitated Fe3W3C hard phases and WO3 oxides induced by frictional heat further enhance wear resistance. Dominant wear mechanisms include abrasive wear, adhesive wear, and fatigue wear, with oxidative wear increasing remarkably under high loads. Progressively enhanced dispersion and grain refinement strengthening from higher WC content, coupled with in-situ precipitated hard phases, synergistically improve tribological performance. This study provides a new technical reference for fabricating high-tribological-performance In718/WC coatings, addressing the poor wear resistance of nickel-based superalloys.

Laser cladding uses a high-energy laser to rapidly melt cladding materials with the substrate surface， forming a metallurgically bonded coating upon solidification. It is a key technology for producing high-performance surface coatings and remanufacturing metallic components. Recently， laser cladding has evolved from a surface coating technique into a comprehensive process integrating coating fabrication， repair of damaged parts， and additive manufacturing， showing great potential in new material development. This review first elaborates the metallurgical characteristics of laser cladding metals， then highlights process innovations in four directions： high efficiency， hybridization， specialization， and intellectualization. It further addresses the role of laser cladding in material development and fabrication， systematically reviewing research progress on conventional alloys， high-entropy alloys， amorphous alloys， metal matrix composites， and functionally graded materials， and summarizing their strengthening mechanisms and typical applications. However， challenges remain for laser cladding fabricating materials， including incomplete non-equilibrium solidification theories， lack of quantitative process-microstructure-property models， and inadequate monitoring and evaluation techniques. Future efforts should prioritize data-driven intelligent optimization， novel material system design， extreme-environment adaptability， and integration of multi-energy-field hybrid processes and combined process chains.

To address the problem of protective oxide film failure of FeCrAl coating in chloride molten salts due to longterm exposure. In this study, Al2O3 and TiC-reinforced FeCrAl coatings were individually fabricated by laser cladding technology and compared for their corrosion resistance. The hot corrosion behavior and corrosion mechanisms of the composite coatings in molten salts of 50 wt% NaCl + 50 wt% KCl salt at 650 degrees C were systematically investigated using weight change kinetics, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The results indicated that, compared to pure FeCrAl coating, the FeCrAl/TiC (20 wt%) and FeCrAl/Al2O3 (20 wt%) composite coatings exhibit significant reductions in corrosion rates of 42.5 % and 32.7 %, respectively. The incorporation of TiC particles suppresses molten salt penetration while simultaneously facilitating in-situ oxidation to form a TiO2 nanolayer at elevated temperatures. These synergistic effects promote the formation of a denser, Cr/Al-rich protective oxide film. In contrast, Al2O3 particles primarily inhibit molten salt infiltration through a physical barrier effect while simultaneously serving as an aluminum reservoir to promote Al enrichment at the interface, thereby enhancing the protective properties of the oxide layer. However, the FeCrAl/TiC (40 wt%) and FeCrAl/ Al2O3 (40 wt%) composite coatings exhibited coating interface defects due to excess ceramic phases, which promotes rapid penetration of molten salts along the pores, leading to a decrease in corrosion resistance.

Additive friction stir deposition (AFSD) presents an attractive manufacturing approach for producing fully dense structures without undergoing melting-solidification phase transformations. In this study, 6061 aluminum alloy was deposited using AFSD technique. The microstructural evolution, hardness, modulus of elasticity, electrochemical corrosion, and tensile properties of the deposited and heat-treated specimens were investigated in detail. The findings indicate that there was no notable expansion of grains in the substrate and the deposition bonding surface after heat treatment. EBSD analysis indicates that following heat treatment, the average grain size increased by 65.7

As an emerging solid-state additive manufacturing technology, friction extrusion additive manufacturing (FEAM) can effectively inhibit melt defects such as porosity and thermal cracks by virtue of its non-melt properties. However, significant strength degradation occurs in the as-deposited material due to incomplete dynamic recovery during solid-state deposition. In this study, an innovative FEAM synergistic reinforcement process for TiCreinforced AA6061 aluminum matrix composites (TiC/AA6061 AMCs) was developed to achieve the micro-structural densification and mechanical properties enhancement of the deposited layer through the composite strategy. The microscopic characterization showed that the grain size of as-deposited TiC/AA6061 AMCs was refined by 58 % compared with the as-deposited AA6061, and showed a uniform gradient distribution. Mechanical tests showed that the as-deposited TiC/AA6061 AMCs exhibited a micro-hardness of 76.5 HV and an ultimate tensile strength (UTS) of 244.2 MPa, corresponding to an increase of 24 % and 59.1 %, respectively, compared to the as-deposited AA6061, evidencing a significant improvement in mechanical properties. Heat treatment effectively eliminated the grain size gradient and mechanical properties inhomogeneity in TiC/ AA6061 AMCs, resulting in a homogenized microstructure. Consequently, the microhardness and ultimate tensile strength (UTS) reached 109.1 % (114.6 HV) and 104 % (313 MPa) of the substrate, respectively. The study shows that TiC particles provide a new process paradigm for the additive manufacturing of high-performance AMCs by promoting dynamic recrystallization to refine the grain structure, pinning dislocation motion to achieve load transfer and other multiple strengthening mechanisms.

Laser additive manufacturing is a revolutionary advanced manufacturing technology that has rapidly developed and been applied in fields such as aerospace, automotive, and medical. However, when using LAM to form metals, it is easy to form defects such as pores and cracks, as well as microstructural issues such as coarse columnar crystals and composition segregation, affecting the performance of the metal. The addition of nano-ceramic particles can effectively improve alloy formability, refine microstructure, and thereby enhance mechanical properties of the metal. This research discussed the addition method of nano-ceramic particles during laser additive manufacturing of metals, the evolution behavior of nano-ceramic particles in the molten pool, and the impact of nano-ceramic particles on formability, microstructure, and mechanical properties. The existing problems and future research in this field were also summarized and prospected.

The adhesion force of water-droplet sliding on superhydrophobic surface is essential for the wettability characterization. Direct measurement causes the deformation of water-droplet and other unfavorable factors to decrease the accuracy, and the published simulation method is generally used for qualitative characterization. Herein, we proposed a simulation method to characterize the adhesion force. Three types of superhydrophobic surfaces were designed and fabricated with femtosecond laser ablation and chemical fluorination. Wettability and structure were quantitatively characterized for establishing the simulation model. Wettability data were accurately acquired by analyzing the morphology characteristics of sliding water-droplet and superhydrophobic structures, and six types of adhesion forces were calculated. Sliding angle of simulation and measurement was adopted to analyze the availability of simulation method, and exhibited an unignorable difference (1.02 degrees - 1.85 degrees), which results from the simplification of structure model. The simplification decreases the super- hydrophobicity and accordingly increases the sliding angle, causing the deviation of adhesion force with its real value. Improving the accuracy of structure model can reduce the deviation. This study offers a novelty and available method to characterize the adhesion force of water-droplet sliding on superhydrophobic surface, and greatly promotes the development of superhydrophobic surfaces with controllable adhesion properties.

During the braking process, temperature of brake disc in high-speed light-load vehicles sharply increases, causing the thermal fatigue crack. Therefore, it is necessary to design new brake disc and study its thermomechanical and friction properties. Here, authors designed new brake discs by way of constructing biomimetic nonsmooth structures in contact surface, then conducted simulation and experiment to quantify their effect on thermomechanical and friction properties. Compared with the smooth brake disc and under the initial velocity 120/160/200 km/h, the brake disc with straight grooves reduces the friction temperature that exhibits the reduction rate of 27.16%, 36.25% and 31.20%. Equivalent stress shows the increase rate of 61.64%, 46.92% and 71.58%, but these values are within the material yield strength. Experiment results showed the biomimetic brake discs have slightly smaller friction coefficient (0.32-0.48) but significantly lower friction temperature (41.7 degrees C-77.9 degrees C) than the smooth brake disc (0.56, 96.7 degrees C). The biomimetic brake disc with straight grooves and air inlets exhibit relatively better performance, resulting from the superior capability in dissipating heat. This study demonstrates biomimetic nonsmooth structures can improve brake disc's thermomechanical properties, which provides an available design approach for brake discs in high-speed light-load vehicles.

Titanium alloys have great applications in the fields of medical devices, orthopedic implants and aerospace components due to their excellent physicochemical properties, and endowing their surface with superhydrophobic properties is very necessary. Inspired by the wax crystals of Nepenthes, superhydrophobic microstructures on titanium alloy were designed and then fabricated via femtosecond laser ablation and chemical fluorination. This innovative method attributes a programmable laser micro-processing technique that realizes the facile fabrication of superhydrophobic microstructures with the advantages of simple design and multiple functions. The fabricated superhydrophobic surfaces achieved the contact angle of 163.45° and the sliding angle of 5.13°, and exhibited ultralow adhesion, good bouncing behaviors, excellent anti-icing capability and strong functional durability. Moreover, analyses based on experiment results demonstrated that the microstructure characteristics have a significant effect on the superhydrophobicity, and appropriate parameters can improve the superhydrophobic properties. Additionally, due to the insufficient accuracy and uncontrollability of femtosecond laser ablation, irregular pores resembled the wax crystals were fabricated which can cause the formation of stable air-film and accordingly enhances the superhydrophobicity, therefore becomes the crucial technique of this study. This study offers an innovative method for the fabrication of multi-functional superhydrophobic surfaces on titanium alloys, and promotes their applications in engineering fields.

The damage to brake discs in heavy-duty vehicles caused by uneven wear is usually repaired with milling method, which reduces their radius and accordingly shortens their service life. Laser cladding repair can maintain the radius, thereby gradually becoming a promising method for brake disc repair, but the complexity of the laser cladding process causes the cladding layer to generate defects that decrease the repair quality. Here, we studied the regulation mechanism of laser power, beam diameter and scanning speed in the cladding layer’s quality via simulation and experiment. Simulation results showed that with the increase of laser power and the decrease of beam diameter or scanning speed, the molten pool’s temperature and flow rate, and the cladding layer’s residual stress have varying degrees of increase. We then fabricated laser cladding samples (Ni60/WC on ductile iron) and acquired their micromorphology, dilution rate and microhardness, and analyzed their regulation mechanism. Experiment results exhibited that the cladding process with laser power 1400 W, beam diameter 3 mm and scanning speed 10 mm/s can make the cladding layer have a better quality. This study provides an available reference for the laser cladding repair of uneven wear in brake discs from heavy-duty vehicles.

Selective laser melting (SLM) is a promising technique for achieving function-driven design as well as unique performances of parts. This article focuses on the frictional behavior of the SLMed brake disc under high-speed conditions, aiming to reveal the inherent wear mechanisms. A bench test of the SLMed disc was conducted using a full-scale flywheel brake dynamometer. The initial braking speed ranged from 50km/h to 380km/h, and the clamping force was from 18 kN to 37 kN. The relationship between instantaneous friction coefficient and multiple variables was explored, including clamping force, initial braking speed, and temperature. With rising temperature, the wear mechanism shifted from abrasive wear to adhesive wear. Compared to a cast disc, SLMed disc is better for high-speed conditions, as it exhibits a more stable friction coefficient, shorter braking distance, and higher braking energy efficiency. The average friction coefficient distribution of the SLMed disc is relatively more concentrated, ranging from 0.333 to 0.417, while it is from 0.277 to 0.426 for cast disc. The braking distance of the SLMed disc is 20% shorter when clamping force is 37 kN. Moreover, the braking amplification factor is proposed to enhance the accuracy of brake performance evaluation. Additionally, a preliminary utilization principle is established for SLMed discs.

Femtosecond laser has been an important processing technique for micro/nano structures in recent years. It can modify and ablate materials, and is capable of machining high-precision three-dimensional structures in specific areas. Femtosecond laser machining has broad application prospects in micro/nano processing. In this paper, the general interaction process between femtosecond laser and metals is described, and the methods for the preparation of micro/nano structures are introduced, such as femtosecond laser direct writing, femtosecond laser induced surface periodic structure, and femtosecond laser composite chemistry method. Then, the applications of femtosecond laser for the preparation of micro/nano structures on metal surfaces in environmental engineering, aerospace, and biomedicine are discussed. Finally, the shortcomings and future research directions of preparation of micro/nano structures by femtosecond laser are summarized and prospected.

Preparation of ceramic reinforced coating on aluminum alloy surface is a common method to improve the wear resistance. Traditional methods usually have some drawbacks such as low adhesion and obvious element dilution. In this paper, TiC and WC reinforced coatings were prepared in situ on aluminum alloy surface using laser melt injection melted, and different times of remelting treatment were attempted to increase the wear resistance of the coatings. Optical microscopy (OM) and Scanning electron microscopy (SEM) were used to identify the microstructure and phase composition of the coatings. The results showed that the coatings without remelting treatment illustrated good wear resistance. After remelting treatment, WC particles gathered at the bottom of the coating. Even though new fine WC ceramic particles formed in the coating, the hardness of the coating was not significantly improved. For WC reinforced coating, there are obvious cracks in the coating after remelting. However, aggregation and cracking were not happened in TiC reinforced coatings. Wear resistance could not be increased obviously using remelting treatment.

A facile and flexible method was introduced to fabricate a multifunctional surface with various micro/nanostructures. Ripples and hierarchical micro/nano conical structure arrays were patterned on titanium alloy sheets by adjusting the parameters of femtosecond laser, realizing the controllable processing of surface micro/nanostructures. After further chemical modification to lower surface free energy, the titanium alloy sheets covered with hierarchical micro/nano conical structure arrays and ripples were superhydrophobic and hydrophobic. The surfaces processed by femtosecond laser showed excellent durability and stability after a 15-day contact angle test and sandpaper friction measurement. Finally, three-dimensional macro devices with hierarchical micro/ nanostructures were prepared by femtosecond laser, which has excellent self-cleaning performance. In addition, the light absorption efficiency of the fabricated titanium alloy sheets was much higher than that of the bare sheet at a wavelength range of 200-2500 nm, indicating the excellent light trapping ability of the fabricated surfaces. These results imply the potential applications of the fabricated hierarchical micro/nanostructures in self-cleaning and light absorption.

At present, obvious difference in maneuverability exists between the micro biomimetic flying aerocraft and its biomimetic prototype in the landing/take-off process, which reduces the safety of its operation process and the universality of its application scope.Accurate characterization of contact force of biomimetic prototype in the landing/take-off process without interference is a necessary prerequisite to solve this problem. A micro-Newton scale contact force measurement system for small flying insects during landing/take-off was designed. The carbon fiber spring T300 was selected as the sensing device of contact force and calibrated to obtain the mathematical equation involved contact force-deflection-contact point position（goodness of fit R~2=0.979）. A high frame camera was selected to record the image information of small flying insects during landing on and take-off from the carbon fiber spring. Taking the fly（Musca domestica） as the small flying insect, the operation debugging of the contact force measurement system was conducted. The image analysis and processing program based on the Matlab software was used to accurately obtain the deflection of carbon fiber spring and the position of landing/take-off contact point. According to the mathematical equation, the contact force was calculated and corrected to eliminate the influence of carbon fiber spring’s gravity. Result shows that the contact force of flies during landing/take-off process ranges from 0.121 m N to 0.772 m N, which is about 0.71 to 4.53 times of their body weight（17.38 mg）. Four the designed contact force measurement system, its resolution is 0.001 mN and its accuracy is improved by four aspects: simulation/actual calibration, accurate acquisition of deflection, contact force correction and no interference in landing/take-off process. Our result provides a reference technology/method for the quantitative and accurate characterization of the biomimetic prototype’s movement behavior for developing micro flying aerocraft.