Search Results (978)

Ni-based WC composite coatings are widely used to protect hydraulic components, yet the role of WC particle morphology in binder-phase strengthening remains unclear. In this study, two Ni40-based coatings containing 55 wt.% WC were laser-cladded on 0Cr13Ni5Mo steel under identical conditions using either rough spherical WC coating (RWC) or smooth spherical WC coating (SWC). Both coatings were mainly composed of γ-Ni, residual WC, W₂C, carbides, and borides. Although the rough WC particles showed about 38% lower intrinsic hardness than the smooth WC particles, the RWC exhibited a 25% higher binder-phase hardness and a 47% higher overall coating hardness. Accordingly, compared with the SWC, the RWC reduced the specific wear rate by about 33% under water-lubricated sliding. In slurry erosion, the RWC consistently showed lower erosion rates and less severe surface damage. The improved performance is attributed to the greater dissolution of rough WC during laser cladding, which strengthened the Ni-based binder and provided more stable support for the hard phases. These results demonstrate that tailoring WC particle morphology is an effective strategy for designing wear- and slurry erosion-resistant Ni-based laser-cladded coatings. Full article

Salt cavern Compressed Air Energy Storage (CAES) is one of the critical technologies for energy storage and an important infrastructure supporting the construction of new power systems and facilitating the achievement of the dual carbon goals. The salt rock resources in China are primarily composed of continental strata salt rocks, characterized by high heterogeneity, well-developed thin-layer interbedding, dissolution resistance among different lithologies, and significant creep variations. These features, to some extent, limit the improvement of wellbore construction accuracy, the reliability of abandoned well sealing, the safety of natural gas storage operations, and enhancements in gas injection–brine displacement efficiency. This study takes the continental bedded salt rock in the Dawenkou Basin as the research object and adopts a method combining theoretical analysis and field engineering verification to improve the systematic construction technology system, covering the whole process of drilling engineering, abandoned well plugging, the design of an injection and brine extraction device, and gas injection and brine drainage. The research results optimize four key technologies, including precise wellbore trajectory control, dual-section milling, and multi-stage redundant plugging of abandoned wells and long-term anti-corrosion completion with laser cladding, and dual-mode adaptive gas injection and brine drainage, and improve the technical system from wellbore construction to salt cavity formation. This study can provide valuable theoretical references and engineering demonstration guidance for underground space development projects in similar salt basins in China. Full article

This study proposes a novel synergistic design strategy to enhance the oxidation resistance of FeNiCuAl-based high-entropy alloys by integrating multi-element alloying (Cr-Co-Mn), trace Y modification, and laser-cladding-induced nanocrystallization. While the Base Alloy exhibited a mass gain of approximately 15 mg/cm² after oxidation at 900 °C for 120 h, the addition of Cr_2.5Co_2.5Mn_2.5 promoted the formation of a multilayered oxide scale (outer MnCr₂O₄/inner Al₂O₃), reducing the parabolic oxidation rate constant to 1.7 × 10⁻⁵ mg²·cm⁻⁴·s⁻¹. The originality of this work lies in the coupling of compositional and microstructural engineering; further addition of 0.5 at.% Y decreased this constant to 1.7 × 10⁻⁶ mg²·cm⁻⁴·s⁻¹—a three-order-of-magnitude reduction relative to the Base Alloy, while increasing the apparent oxidation activation energy to ~350 kJ/mol. After 100 thermal cycles at 1000 °C, the designed alloy showed a mass change of only 0.05 ± 0.02 mg/cm², with its critical load and interfacial fracture energy reaching 78 N and 14.8 J/m², respectively. Furthermore, the alloy retained a hardness of 310 HV, an elastic modulus of 135 GPa, and a tensile strength of 240 MPa at elevated temperature. These results demonstrate that the synergistic integration of chemical and structural optimization provides a new paradigm for designing low-cost, high-performance FeNiCuAl-based protective coatings. Full article

Additive manufacturing through a laser cladding has been shown to be an effective technology for the mitigation of wear and rolling contact fatigue (RCF) of railway track. Small-scale tests have consistently shown that creating a thin layer of premium material on the tribo-active surface of the railhead vastly reduces wear and suppresses the onset of RCF due to the ratcheting mechanism being almost eliminated in comparison to standard rail material. Cladding reduces material plastic flow by 60% which is a cause of insulated track joint failure. This paper reports results from the first full-scale trials of additively manufactured laser clad layers on railway rails by studying their mechanical properties and microstructure. This is a vital step in safely progressing this technology from lab scale to network application. Tested full-scale insulated block joint (IBJ) specimens, clad with martensitic stainless steel (MSS) and Stellite 6, were sectioned, polished and etched and the microstructures of the clad, heat-affected zone and parent rail materials were inspected using optical and scanning electron microscopy (SEM) (Hitachi TM3030 plus, Tokyo, Japan). Residual stress was also measured. Cladding with MSS and Stellite 6 showed high wear and RCF resistance after the tests. Material flow was reduced with the clad layer applied. No defects such as porosity or large precipitates were observed in the heat-affected zone (HAZ), particularly close to the rail surface at the clad end which could act as a point of weakness. Residual stress states varied between materials, MSS being compressive (−344 MPa average) and Stellite 6 being tensile (+391 MPa average) which could have an impact on the fatigue life of the clad. This finding matches previous work, indicating that MSS may be preferable in the field, where bending of rails can occur. Overall, the work showed that laser cladding can provide a good solution to lipping issues and wear problems of rail in IBJs. Analysis in this work confirmed that the HAZ where clad meets the bulk rail at the surface has good structural integrity; however, this needs to be a focus of attention in field application of these layers. Full article

Wire laser cladding (WLC) of bronze on stainless steel offers a promising approach for combining the structural strength of steel with the superior tribological and corrosion properties of copper alloys. In this study, the influence of key process parameters, including wire preheating current, deposition speed, laser power, and wire feed speed on melt pool temperature and clad geometry was investigated using response surface methodology (RSM). Experiments were performed using a robot-assisted coaxial wire feeding laser cladding system, and real-time thermal monitoring was conducted using an infrared camera. The results showed that defect-free bronze clads with good metallurgical bonding and limited dilution were achieved across the investigated parameter range. Statistical analysis revealed that melt pool temperature is primarily governed by laser power and deposition speed, with a significant interaction between these parameters. Clad height was mainly influenced by wire feed speed and deposition speed, whereas clad width was controlled by laser power and deposition speed. The side angle was affected by deposition speed, laser power, and wire feed speed, reflecting the balance between vertical buildup and lateral spreading. Overall, the study demonstrates that stable and high-quality clads can be achieved by properly balancing energy input and material supply. The developed models provide valuable insight for optimizing process parameters in wire laser cladding of bronze on stainless steel. Full article

FeCoCrNi coating and FeCoCrNiNb_0.5 HEA coatings were deposited onto the surface of a stainless-steel motor main shaft using laser cladding technology. This study investigated the effect of Nb addition on the microstructure, phase composition, crystallographic properties, nanoindentation response, and wear behavior of the FeCoCrNi coating. The results indicated that the FeCoCrNiNb_0.5 coating consisted of an FCC phase and a Laves phase. Furthermore, the solid solution of Nb increased the lattice distortion of the FCC phase and enhanced its solute strengthening effect. The addition of Nb significantly improved the nanohardness of the coating. The nanohardness of the FeCoCrNiNb_0.5 coating reached 6.47 ± 0.23 GPa, markedly higher than that of the Nb-free FeCoCrNi coating. In addition, the FeCoCrNiNb_0.5 coating exhibited higher H/E and H³/E² ratios, suggesting improved resistance to plastic deformation. Owing to the increased nanohardness, the FeCoCrNiNb_0.5 coating demonstrated superior wear resistance, with an average friction coefficient of 0.52 and a wear volume of 5.49 × 10⁵ μm³. The dominant wear mechanisms were identified as abrasive wear, adhesive wear, and oxidative wear. Full article

High-speed laser cladding shows significant potential for application in the field of high-performance surface hardening due to its low heat input and high cladding efficiency. However, the pool solidification time is significantly reduced at high scanning speeds, resulting in a narrower process window and making it more difficult to ensure coating formation stability and control performance. Therefore, this study employed high-speed laser cladding technology to prepare FeCrNiB alloy coatings, and systematically conducted research on process parameter optimization and friction properties. Firstly, the response surface method (RSM) was used to establish quantitative relationship models between laser power, scanning speed, and powder feed rate and the dilution ratio, forming coefficient, and microhardness. Then, the hybrid differential evolution and NSGA-II algorithm (DE-NSGA-II) was employed for multi-objective optimization. Finally, a systematic analysis was conducted on the friction and wear properties of the coatings produced under the optimal process parameters. The results indicate that the interaction between laser power and scanning speed has a significant impact on the dilution behavior of the coating, while the coupling between scanning speed and powder feed rate governs the formation characteristics and microhardness evolution of the coating. The experiment verified that the prediction error for the optimal parameters is controlled within 5%, demonstrating good engineering applicability. Further analysis indicates that grain refinement and the formation of strengthening phases in the optimal coating are the key mechanisms behind the significant improvement in hardness and wear resistance, and the coating primarily exhibits a mild abrasive wear mechanism. This work realizes the multi-objective optimization of the high-speed laser cladding process via RSM and DE-NSGA-II algorithm, which provides a novel and efficient method for parameter optimization and engineering application of high-speed laser cladding. Full article

The research investigates the influence of laser-cladding parameters in WC9 steel-surface multi-track Stellite 12 alloy coatings. Mathematical models of penetration depth, grain size, and microhardness in the coating were developed by Central Composite Design with altering of the input laser power, scanning speed, powder feed rate, and overlapping rate. Response Surface Methodology was used to analyze the correlation of different processing parameters affecting the selected responses. A coating with penetration depth was achieved by significantly reducing the laser power and overlap ratio while increasing the powder feed rate. Appropriately reducing the laser power while increasing the powder feed rate effectively refined the grain size of the Stellite 12 alloy coating. Higher microhardness in the coating was obtained by appropriately increasing the powder feed rate and scanning speed while reducing the laser power. Afterwards, a desired processing parameters set was obtained through optimization with the target of minimizing the penetration depth and grain size and maximizing the microhardness. Experimental validation with this processing parameter setup provided satisfactory coating, and the error rate for the penetration depth, grain size, and microhardness was 9.66%, 7.36%, and 5.46%, respectively. This paper provides the theoretical guidance for the prediction and control of the penetration depth, grain size, and microhardness in WC9 steel-surface multi-track laser cladding with the Stellite 12 alloy. Full article

CoNiV medium-entropy alloy (MEA) composite coatings reinforced with 40 wt.% tungsten carbide (WC/W₂C) particles were fabricated on carbon steel via laser cladding under nominal heat inputs ranging from 75 to 150 J/mm. The phase constituents and microstructural evolution were investigated, revealing that the coatings were primarily composed of an FCC matrix, retained WC/W₂C particles, and in situ formed V-rich and VWC₂ carbides. While the phase compositions remained generally consistent, the features of the reinforcement architecture varied with the extent of WC/W₂C dissolution governed by laser heat inputs. At low heat inputs, limited particle dissolution yielded sparsely distributed in situ carbides, whereas excessive dissolution at high heat inputs promoted the agglomeration of dense and coarse carbides, driving the microhardness to peak at 570.5 HV_0.5. However, the coating deposited at 150 J/mm exhibited compromised wear resistance due to the fragmentation and detachment of these coarse carbides, which intensified abrasive wear. In contrast, moderate dissolution at intermediate heat input (100 J/mm) facilitated the formation of fine in situ carbides in interparticle regions. This resulted in a homogeneous multiscale synergistic reinforcement microstructure that endowed the coating with optimal wear performance. By precisely controlling heat input to regulate in-situ precipitation, this study established a solid foundation for tailoring wear resistance and expanding the application of composite coatings. Full article

Laser cladding processing efficiency is often limited by low powder utilization. To address this, our study elucidates the mechanism by which powder feeding parameters influence powder stream convergence, aiming to optimize these parameters. A three-dimensional model of a wide-band symmetrical nozzle was developed using a Computational Fluid Dynamics—Discrete Element Method (CFD-DEM) coupling method to simulate the gas–solid flow. Single-factor tests and experimental validation confirmed the model’s reliability. The results identify carrier gas flow as the key parameter controlling the focal length and powder concentration, while the powder feed rate primarily governs the concentration on the focal plane. These findings provide a theoretical foundation for optimizing laser cladding parameters to enhance powder utilization. Full article

This study investigates the influence of design factors and key process parameters—including explosive welding (EXW), rolling, and laser processing—on the formation, microstructure, and tribological properties of Ti–Cu–Ni intermetallic coatings. A combined manufacturing approach was employed, starting with the EXW of an MN19 cupronickel alloy to a VT1-0 titanium substrate, followed by multi-pass rolling to achieve a cladding thickness of approximately 0.3 mm. Subsequently, laser surface remelting was performed to facilitate controlled mass transfer and homogenization within the reaction zone. Numerical simulation using COMSOL Multiphysics v. 5.4 was utilized to optimize the thermal cycles and determine the ideal energy density (42 J/mm²) for phase formation. The results demonstrate that the primary structural components of the coatings produced under optimal conditions are solid solutions based on the ternary-modified titanium cuprides Ti₂Cu(Ni) and TiCu(Ni). The transition from a layered bimetal to a finely dispersed intermetallic structure significantly enhances the surface characteristics. This specific phase composition provides a sustained microhardness of ~5 GPa across the coating cross-section. Comparative wear tests against fixed abrasive revealed that the wear resistance of the Ti–Cu–Ni coatings is 2.5 times higher at room temperature and 1.5 times higher at 600 °C than that of the base VT1-0 titanium. Full article

Three Ni-based composite coatings with varying TiCN/h-BN contents were fabricated on the surface of Ti-6Al-4V (TC4) alloy by laser cladding. The coatings were formulated with a fixed 15% TiCN and 0%, 2% and 5% h-BN, corresponding to L1–L3 coatings. The microstructure and phase composition were fully characterized and investigated. In addition, the microhardness and wear resistance of the coating were evaluated too. The analysis revealed that the L1–L3 coatings primarily consisted of Ti, TiNi, Ti(C, N) and TiAl₃ phases. Microstructural analysis indicated that the top region of the coating was predominantly composed of granular crystals, while the middle and bonding regions featured a combination of dendrites and white granular crystals. The average microhardness values for the L1–L3 coatings were measured at 1203.8, 1216.8 and 1235.5 HV_0.2, respectively, while the corresponding wear volumes were 0.098, 0.094 and 0.086 mm³. As the h-BN content increased, the microstructure of the Ni-based composite coating became finer and finer. Some TiB particles were also generated in the coating, which made the average microhardness and wear resistance increase gradually. Notably, the coating with 5% h-BN demonstrated the highest average microhardness and optimal wear resistance. Compared with the substrate, 5% h-BN increased the wear resistance of the substrate by 47.6%. The primary wear mechanism observed was abrasive wear. Full article

To improve the surface properties of 40Cr steel, Ni45/Y₂O₃ laser-cladded coatings (L-CCs) were fabricated on the surface of 40Cr steel. The effects of Y₂O₃ addition (0.5%, 1.0%, and 1.5%) on the microstructure, microhardness, residual stress, wear resistance, and corrosion resistance of the L-CCs were systematically investigated. The results indicate that Y₂O₃ has a significant effect on enhancing the corrosion resistance and suppressing the residual stress of the L-CCs, whereas its contribution to the improvement of microhardness and wear resistance is relatively limited. Compared with the single Ni45 L-CC, the L-CC containing 1.0% Y₂O₃ exhibited a 45.9% reduction in corrosion current density and a 79.3% reduction in residual stress. At a Y₂O₃ addition of 0.5%, the microhardness increased by 4.0%, while the average friction coefficient and wear mass loss decreased by 4.8% and 2.6%, respectively, relative to the single Ni45 L-CC. Excessive Y₂O₃ addition reduces the fluidity of materials in the molten pool and deteriorates the microstructural uniformity, thereby weakening or even impairing the surface properties of the L-CCs. Full article

To address the surface wear issues of tungsten alloys in die-casting mold applications—where low hardness coupled with severe service conditions involving high-pressure impact from molten metal, thermal cycling, and component counter-friction—this study employed three techniques: laser cladding, plasma spraying, and vacuum surface carburization. Three distinct strengthening coatings were prepared on a tungsten heavy alloy (WHA) substrate. X-ray diffraction (XRD), scanning electron microscopy (SEM), a Vickers hardness tester, and block-on-ring friction and wear tests were employed to characterize the phase composition, microstructure, hardness, and wear resistance of the coatings. The results indicate that all three coatings significantly enhanced the hardness of the substrate, albeit through different strengthening mechanisms. The hardness increase in the laser-clad coating is attributed to the combined strengthening effect of rapid solidification-induced fine grains and dispersed WC particles. The enhanced hardness of the plasma-sprayed coating is due to the intrinsic hardness of WC and its dense layered structure. The carburized layer exhibits the highest hardness, resulting from the continuous WC phase formed via in situ reaction and an interface-free gradient transition with the substrate, which eliminates interfacial weak zones. Under loads of 50 N and 100 N, the plasma-sprayed coating demonstrated the best wear resistance, with wear volumes of 0.16% and 0.18% of that of the substrate, and wear depths of 4.57% and 3.50% of that of the substrate, respectively. It also exhibited the optimal load adaptability, making it a preferred solution for surface strengthening of tungsten alloy die-casting molds. Full article

The efficient fabrication of high-quality Ni60-WC composite coatings with low dilution and defect density remains a challenge for wear-critical tunneling cutters. In this study, a plasma–laser hybrid cladding (PLHC) strategy was developed to fabricate Ni60-40 wt% WC composite coatings, and their microstructures and properties were systematically compared with those produced by plasma cladding (PC) and laser cladding (LC). The PLHC coatings exhibit a low dilution rate of 10.7% and an ultra-low porosity of 0.2%, indicating improved metallurgical integrity. Microstructural analysis reveals that the hybrid energy input effectively suppresses WC dissolution and promotes a refined, uniformly distributed hard-phase network within the Ni-based matrix. As a result, the PLHC coatings achieve a high average microhardness of 1187.83 HV_1.0 and superior wear resistance, with a wear volume of 24.69 × 10⁻³ mm³ under a 200 N load, representing reductions of 53.6% and 20.9% compared with PC and LC coatings, respectively. These results demonstrate the effectiveness of plasma–laser hybrid cladding in tailoring the microstructure–property relationship of WC-reinforced composite coatings. Full article