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Improvement of nickel nanocomposite coatings by combining zinc-doped TiO2 nanoparticles
摘要： Pure nickel and compound of nickel coatings (Ni-TiO2 and Ni-Zn/TiO2) were coated on the steel material using Watts bath with the electrodeposition conditions. Effect of the nanoparticle type and current density on the coating structure, surface morphology of the coating, hardness of the coating, and the corrosion properties of the coatings are presented. Phase and elemental analysis of the coatings were carried out by XRD and EDS techniques, respectively. SEM was used to investigate the surface morphology of the coatings, and Vickers microhardness values were measured to determine the hardness variation of the coatings. NaCl solution (3.5 wt%) was used to evaluate the corrosion properties of the coatings by the potentiodynamic polarization tests. Corrosion current density of 2.890 μA/cm2 for pure nickel coating was improved to 0.379 μA/cm2 by the coating of Zn-doped TiO2 nanoparticles at the 7A/dm2 current density. Microhardness of the Zn-doped TiO2 coating was improved compared to the pure Ni coating.
关键词： Sol-gel processes,Metal matrix composites,Nanoparticles,Composite coatings
更新于2025-09-23 15:23:52
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Cladding of Stellite-6/WC Composites Coatings by Laser Metal Deposition
摘要： This study aims to investigate the microstructure and hardness of multi-layered Stellite-6/WC metal-matrix composites coatings on metallic substrates cladded by laser metal deposition (LMD) for improvement of wear and corrosion resistances. As coating materials, Stellite-6 and WC-12wt.%Co powders were selected. Powder mixtures having various mixing-ratios of Stellite-6 and WC-12wt.%Co were provided vertically on S45C substrates by controlling powder feeding rates of the two powder feeders, individually. Stellite-6/WC composites which consist of three layers with different compositions were cladded on the S45C substrates by laser melting. Cross-sectional microstructure observation was carried out by using an optical microscope (OM). Vickers microhardness tests were conducted to evaluate hardness of the cladding layers and substrates. The experimental results demonstrate that hard multi-layered Stellite-6/WC metal-matrix composites coatings were successfully cladded on the S45C substrates. Property gradients in the Stellite-6/WC composites could be made due to the position-dependent chemical composition and microstructure made by controlling powder feeding rates of an LMD system.
关键词： Cladding,Additive Manufacturing (AM),Metal Matrix Composites (MMC),Laser Metal Deposition (LMD),Hard Materials
更新于2025-09-23 15:22:29
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Development of metal matrix composites by laser-assisted additive manufacturing technologies: a review
摘要： Metal matrix composites (MMCs) generally possess superior properties than the monotonic matrix alloys, and thus, they have become excellent candidate materials in various applications. Also, the ability of property tailoring at an affordable cost is of particular importance to industries. Among the many manufacturing techniques for MMCs, laser-assisted additive manufacturing (AM) techniques have emerged and drawn increasing attention in the past decade. In the literature, a wealth of studies have been carried out on the synthesis of MMCs via laser-assisted AM techniques, as well as the property evaluation of the obtained MMCs. In this paper, we review and analyze the relevant literature and summarize the material preparation, optimization of process parameters, resultant improvements, and corresponding strengthening mechanisms for each major category of MMCs. Moreover, the limitations and challenges related to MMC synthesis using the laser-assisted AM techniques are discussed, and the future research directions are suggested to address those issues.
关键词： Laser-assisted additive manufacturing,Process parameters,Material preparation,Strengthening mechanisms,Metal matrix composites
更新于2025-09-23 15:21:01
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In-situ formation of ceramic layer on Mo-based composites via laser powder bed fusion
摘要： Poor oxidation resistance is a longstanding disadvantage of Mo-based materials for ultrahigh-temperature applications. In this study, we developed a facile strategy for depositing an in-situ ceramic layer on the surface of Mo-based composites via laser powder bed fusion (L-PBF) using Mo-based alloy powders covered with uniform Al2O3 nanoparticles and bridged by functionalized carbon nanotubes. The surface layer consisted of an α-Al2O3 matrix with a dispersed TiC phase and had a controllable thickness. The formation mechanism of this layer was investigated systematically through single-track observations and finite-element simulation. Moreover, the increased nanohardness can be attributed to the uniformly dispersed, intimately contacted ceramic nanoparticles in the matrix. The results indicated the multifunctionality of L-PBF-processed metallic parts, introducing the possibility of fabricating advanced ultrahigh-temperature materials.
关键词： carbon nanotubes,metal matrix composites,molybdenum,oxidation resistance,laser powder bed fusion
更新于2025-09-23 15:19:57
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Atomic structure revolution and excellent performance improvement of composites induced by laser ultrafine-nano technology
摘要： Carbon nanotubes (CNTs) reinforced high-entropy alloy composites (HEACs) were fabricated on a TA2 titanium alloy by mean of a laser melting deposition (LMD) of the FeCoCrAlCu-(nano-SiB6)-(Ni/Ag-coated CNTs) mixed powders, noting that large quantities of the ultrafine nanocrystals (UNs) were formed, portion of them were able to obtain the enormous energy from laser beam, which were able to permeate into the original ordered atom arrangement due to the high diffusion rates and their ultrafine microstructure. In substance, partial UNs can destroy the balanced state of atoms, increasing significantly the free energy of the crystal boundaries. Such CNTs/UNs modified LMD composites showed the better corrosion/high-temperature oxidation resistance properties than those of the TA2 alloy. Identification of the synthetic UNs in such LMD HEACs, more importantly the UNs transition effect, contributes theoretical/experimental basis to upgrade the quality of the industrial light alloy.
关键词： Metal-matrix composites (MMCs),Surface treatments,Laser melting deposition,Nanocomposites,Powder processing
更新于2025-09-16 10:30:52
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Surface Micro patterning of Aluminium Reinforced Composite for Aerospace Applications through High Energy Pulse Laser Peening
摘要： Aluminium (Al) Composites have universal engineering applications because of their higher strength to weight ratio, ductility, and formability. However, in diverse applications, mechanical properties such as hardness, corrosion, wear, and fatigue resistance are the prerequisite at closer surface regions. Such localised changes without impacting various surface treatment approaches can attempt the bulk phase. Laser shock peening is an advanced surface engineering technique, which has been successfully applied to improve the surface morphology and microstructure of the material. In this work, we are focusing on improving the surface properties of Al7075 reinforced with SiC and Zirconia through laser peening technique. The hardened layer was evaluated using surface integrity with optical microscopy, energy dispersive spectroscopy, scanning electron microscope (SEM) and analysis of microhardness. Process parameters and resulting microstructures of Aluminium composite are summarised, along with the impact of laser peening on surface properties. Research results indicated that laser peening shows a significant influence on the final condition of the surface layer of Aluminium composite.
关键词： Zirconia,Aluminium Metal Matrix Composites,SiC,SEM,Laser peening
更新于2025-09-12 10:27:22
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Effect of powder characteristics on production of oxide dispersion strengthened Fe 14Cr steel by laser powder bed fusion
摘要： In order to assess the potentialities of additive manufacturing in nuclear industry, Oxide Dispersion Strengthened (ODS) Fe\14Cr steels are produced by laser powder bed fusion (L-PBF). Such materials are currently manufactured by milling a Fe\14Cr atomized powder with Y2O3 and TiH2 powders. The resulting powder has a non-spherical shape being coarser than powders typically used in L-PBF equipment. The influence of powder characteristics on the processability of ODS Fe\14Cr by L-PBF are studied in details. Four different powders are used. These powders differ from size, morphology and chemical composition. Finer is the powder; wider is the process range to obtain dense samples. This phenomenon could be mitigated by transferring an amount of energy superior to 110 J.mm?3. The presence of yttrium and titanium gives columnar microstructure for ODS samples, whereas Fe\14Cr samples have stirred microstructure. Titanium and yttrium form oxides, which enlarge the melt pool and induce columnar growth.
关键词： Additive manufacturing,Powder flowability,Metal Matrix Composites (MMCs),Chemical composition,Laser Powder Bed Fusion (L-PBF),Particle size distribution
更新于2025-09-11 14:15:04
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Laser powder deposition of WC particle reinforced metal matrix composites
摘要： Laser Powder Deposition (LPD) is an additive layered manufacturing process that can deposit near-net shape parts directly from metal powder. Metal Matrix Composites (MMCs) combine the merits of ductile metal matrix and hard ceramic reinforcement, providing enhanced properties including hardness and wear resistance. MMCs can be easily implemented in LPD process via blending the powders during deposition of coatings and 3-D parts. However, cracks induced by thermal stress and material embrittlement limit the application of MMCs in direct LPD processes. This study experimentally investigated the mechanical properties of MMCs deposited via LPD. Hardfacing alloy Stellite 6 and ductile alloy Inconel 718 were chosen as the matrix material, respectively, with spherical Tungsten carbide (WC) particles as the reinforcement. According to the experiment results, Inconel 718 was found to be a better choice for matrix material as it presented better compatibility with WC particles with acceptable wear resistance. Influence of direct age heat treatment of Inconel 718 matrix on mechanical properties was also investigated. Tensile tests showed that addition of WC particles in the matrix reduces both the ultimate strength and elongation. Microstructural observation of the tensile specimens indicated that WC particles are the preferable crack initiation sites, which significantly reduces the load-carrying capacity and ductility of the composite. Dissolution of WC into the matrix, which embrittles the matrix and further reduces the ductility of the composite, was proven by micro-hardness test and elemental analysis. Last, dry sliding test is conducted to evaluate the wear resistance of the MMCs. It was found that a small addition of WC particles can significantly increase the wear resistance.
关键词： Inconel 718,wear resistance,Laser Powder Deposition,Stellite 6,WC particles,Metal Matrix Composites
更新于2025-09-11 14:15:04
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Laser additive manufacturing of nano-TiC reinforced Ni-based nanocomposites with tailored microstructure and performance
摘要： Laser additive manufacturing has demonstrated a promising capability in the simultaneous formation of high-performance nanocomposites with unique microstructure characteristics. The present work studied the densification, microstructure and mechanical properties of nano-TiC reinforced Inconel 718 composites processed by selective laser melting (SLM) with variation of laser energy linear density (E). It revealed that a fully dense TiC/Inconel 718 part was fabricated at a proper E of 300 J/m. On increasing E from 225 to 300 J/m, the nano-TiC reinforcement experienced severe agglomeration to uniform distribution along the grain boundaries and inside the grains of matrix. The morphologies of nano-particles transferred from irregular polygonal to near-spherical shape. The presence of nano-TiC could also accelerate the refinement of columnar dendrites spacing of γ matrix. A high nanohardness of 4.48 GPa, a low coefficient of friction of 0.36 and resultant low wear rate of 3.83 × 10?4 mm3/N?m were obtained at E of 300 J/m, showing a significantly improved mechanical performance compared to the SLM-processed unreinforced nickel-based alloys.
关键词： Nano-TiC,Metal-matrix composites (MMCs),Selective laser melting,Microstructures,Mechanical properties
更新于2025-09-11 14:15:04