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Optimization of Residual Stresses in Laser-Mixed WC(Co, Ni) Coatings
摘要： A ternary mixture of tungsten carbide (WC), cobalt (Co), and nickel (Ni) powders is prepared to form ceramic-metal composite coatings employed for laser cladding of 40Cr steel. This coating is investigated using the mixture design to evaluate the influence of its ratios on the residual stresses in the clads. The WC/Co/Ni ternary mixture exhibits higher residual stresses than those of the Co/Ni or WC/Ni binary mixtures, except for the WC/Co one. Single WC, Co, or Ni designs illustrate a high sensitivity of residual stresses, cracks pass through the interior of WC particles rather than around them, and the cracks mostly propagate along the eutectic phases at 50%Co–50%WC. A reduced special quartic model in the mixture design exhibits excellent fit, predicted and experimental values of residual stresses for these laser clads are in good agreement.
关键词： residual stress optimization,mixture,reduced special quartic model,tungsten carbide
更新于2025-11-28 14:24:20
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Highly efficient bio-based porous carbon hybridized with tungsten carbide as counter electrode for dye-sensitized solar cell
摘要： Bio-based porous carbon (CMA and CTA) are successfully prepared from waste carton via microwave-assisted activation (MA) and two-step chemical activation (TA) methods, respectively. The as-prepared CTA sample exhibits higher specific surface area (824.16 m2 g?1) and larger total pore volume (0.71 cm3 g?1), as compared with those of the CMA sample (655.36 m2 g?1 and 0.62 cm3 g?1, correspondingly). The higher specific surface area could provide more catalytic sites; thus, the dye-sensitized solar cell (DSSC) assembled with a CTA counter electrode (CE) deliver a power conversion efficiency (PCE) of 6.76%, surpass the CMA-based DSSC (6.19%). Further, tungsten carbide (WC) are introduced into CTA and CMA to form hybrid catalysts (WC/CTA and WC/CMA, respectively) in order to improve their catalytic activities. Benefitting from the synergistic effect of bio-based porous carbon and WC, the DSSCs with WC/CTA and WC/CMA CEs exhibit superior PCE values of 7.32% and 6.85%, respectively, close to Pt (7.51%). This work provides an effective strategy for synthesizing low-cost and high-performance hybrid catalysts from bio-based carbon to achieve resource utilization of biomass waste in new energy fields.
关键词： Electrocatalyst,Counter electrode,Bio-based carbon,Tungsten carbide,Dye-sensitized solar cell
更新于2025-09-23 15:19:57
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Polyoxometalate‐derived multi‐component X/W2C@X, N‐C (X=Co, Si, Ge, B and P) nanoelectrocatalysts for efficient triiodide reduction in dye‐sensitized solar cells
摘要： A series of multi-component X/W2C@X,N-C hybrid catalysts have been prepared to systematically investigate the electro-catalytic activity of triiodide reduction in DSSCs. Different components in catalyst promote photovoltaic performance by synergistic effect. The electronegativity of dopants can directly influence the catalytic activity of catalysts.
关键词： nanocomposite,dye-sensitized solar cells,counter electrode,tungsten carbide,polyoxometalate
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE/MTT-S International Microwave Symposium - IMS 2019 - Boston, MA, USA (2019.6.2-2019.6.7)] 2019 IEEE MTT-S International Microwave Symposium (IMS) - A Novel VHF Heating System to Aid Selective Laser Melting
摘要： A novel approach is proposed for penetrative heating of metal powders for component manufacture using selective laser melting (SLM). Large volumes of metal powders have been shown to have unusual properties at higher RF frequencies, whereby magnetic fields can penetrate into them almost completely, at depths much greater than the expected skin depth. A resonant structure at VHF (100-500MHz) and a medium power VHF source (delivering up to 75 W) are described, analyzed and demonstrated, to efficiently heat tungsten carbide powdered samples of volumes of 40cm3 to above 7000C. Further development of this technique will help alleviate the thermal instability problems widely encountered in SLM which lead to large thermal stresses and mis-shaped components.
关键词： additive manufacturing,tungsten carbide,VHF heating,selective laser melting
更新于2025-09-12 10:27:22
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Improving the R&D process efficiency of the selective laser sintering industry through numerical thermal modeling
摘要： The selective laser melting (SLS) industry is a relatively novel industry within the broad spectrum of available additive manufacturing (AM) technologies. As with most developing industries, the primary aim is to develop better quality components at reduced costs, often with a disregard towards efficiency. Resource efficiency is a key component of waste management and ties directly to sustainable manufacturing. In the SLS industry, large quantities of raw material are wasted during the machine calibration stage. Each time a new material is developed for SLS manufacturing a specific set of processing parameters need to be developed in order to ensure that high density, high strength components are produced. This paper investigates the possibility of replacing the current inefficient research and development (R&D) methods with numerical modeling. The fusion process can be simulated in a numerical thermal model using a combination of temperature dependent material properties and heat transfer principles.
关键词： tungsten carbide,powder bed fusion,numerical modeling,Additive manufacturing,process chain
更新于2025-09-12 10:27:22
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Effect of tungsten carbide partial dissolution on the microstructure evolution of a laser clad surface
摘要： Laser surface modification has been a way to promote wear resistance in dies and molds application. Previously, researchers have succeeded in enhancing surface properties through laser surface modification. The addition of particles in laser cladding process enhanced the surface properties by strengthening the modified AISI H13 tool steel structure. Controlled parameter was laser power, pulse repetition frequency (PRF) and scanning speed with a range of 1.7–2.5 kW, 30–70 Hz and 10.5–24.5 mm s?1 respectively. The powder addition executed by a preplaced method. The grain size and hardness properties of treated samples were characterized using scanning electron microscope (SEM) and hardness Vickers indenter respectively. Surface roughness was characterized using roughness tester. From the findings, tungsten carbide (WC) particles were dissolved homogenously within refined substrate grain structure at higher laser energy. Higher laser scanning speed contributed in uniform particles distribution. The grain refinement with W element in modified layer resulted in maximum hardness of 660 HV. Rapid solidification during laser processing produced metastable phase formation grain refinement, and a higher fraction of grain boundary which resulted in grain boundary strengthening, grain refinement and metastable phase formation. In this paper laser cladding of AISI H13 tool steel with micron size WC particles addition for enhanced surface properties was investigated. These findings are important to design high precision modification of die surface for high temperature forming process.
关键词： Laser cladding,Nd:YAG laser,Grain refinement,Phase transformation,Carbide dissolution,Tungsten carbide particle
更新于2025-09-11 14:15:04