Articoli di riviste: "WC-W2C"

1

Li, Lian Jie, e Chi Bin Gui. "Effect of Dissolving of WC/W₂C on the Interface Microstructure of Iron Matrix Hardfacing Alloys". Advanced Materials Research 306-307 (agosto 2011): 819–22. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.819.

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Hardfacing alloys reinforced with WC/W2C on Q235 steel plates were prepared by the method of flux-cored wire TIG and MIG welding. The interface microstructure and carbide morphology were investigated using optical microscopy and scanning electron microscopy (SEM). The effect of dissolving of WC/W2C on the interface microstructure was discussed. It indicated that the C-W-Fe ternary brittle compound has formed on the interface due to dissolving of WC/W2C and the dissolving degree of the particles by TIG is less than by MIG. Abrasion resistance was evaluated by wet sand rubber wear tests and the wear mechanism was studied. The results show that WC/W2C particles play a key role in improving abrasion resistance.

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NAPIÓRKOWSKI, Jerzy, e Krzysztof LIGIER. "THE ANALYSIS OF WEAR OF THE LAYERS CONTAINING WC/W2C IN ABRASIVE SOIL". Tribologia 269, n. 5 (31 ottobre 2016): 121–32. http://dx.doi.org/10.5604/01.3001.0010.6612.

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The paper presents the results of research involving the resistance of hardfacing materials containing WC/W2C carbides to abrasive wear. The tested hardfacing materials were made using PJ5D and El-Tung FeA rods. The WC/W2C carbide contents of the examined materials amounted to 90% and 60%. These materials are meant to be used in mining tools subject to intense abrasive wear. In spite of its higher WC/W2C carbide content, the intensity of wear of the hardfacing material made using the PJ5D rod was higher than that of the hardfacing material made using the El-Tung FeA rod. Wear resistance tests were conducted by means of the “spinning bowl” method, using real (natural) soil masses. Light and heavy soil masses were used.

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Chi, Jing, Hui Qi Li, Shu Feng Wang, Min Li e Jian Nan Li. "Fabrication and Microstructures of WC-Based Composites by Plasma Jet Metallurgy". Advanced Materials Research 652-654 (gennaio 2013): 60–63. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.60.

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The WC-Fe bulk composites were prepared by means of the plasma jet metallurgy using WO3, C and Fe-based alloy powder as raw materials. Phases of the composites were mainly WC, W2C, M6C, M7C3and (Fe, Ni).The WC grains formed in situ had rectangular or triangular shapes with size of 30-70μm. The growth morphology of Fe3W3C was faceted polygon and herringbone. The formation of the unique composite microstructure was attributed to the incomplete peritectic reaction between W2C and Fe3W3C.

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Itagaki, Hirotomo, Taisei Yachi, Hisato Ogiso, Harumichi Sato, Yorihiro Yamashita, Junichi Yasuoka e Yoshinori Funada. "DC Arc Plasma Treatment for Defect Reduction in WC-Co Granulated Powder". Metals 10, n. 7 (20 luglio 2020): 975. http://dx.doi.org/10.3390/met10070975.

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Tungsten carbide–cobalt (WC–Co) agglomerated powder is widely used for additive manufacturing and spray coating, and a reduction in internal gaps in the powder is required to obtain a product of high quality. In this paper, we investigate plasma effects on agglomerated powder when WC–12%Co powder is directly subjected to direct current (DC) arc plasma treatment to reduce gaps in the WC–Co powder. We obtain a plasma-treated powder with reduced gaps among WC particles. Furthermore, plasma-treatment improves the sphericity of the powder particles, due to the spheroidization effect, so that the percentage of plasma-treated particles exceeding 95% sphericity is 50%, which is 1.7 times that of raw powder. Concern regarding the possible generation of W2C by plasma treatment is unfounded, with W2C levels kept very low according to X-ray diffraction (XRD) analysis, showing a value of 0.0075 for the area ratio W2C(002)/WC(100). XRD analysis also reveals that plasma treatment relaxes residual strains in the powder. From these results, the DC plasma treatment of WC agglomerated powder produces a spherical powder with fewer gaps and strains in the powder, making it more suitable for additive manufacturing while suppressing decarburization.

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Razavi, Mansour, Mohammad Reza Rahimipour e Rahim Yazdani-Rad. "Synthesis of Nanocrystalline WC Single-Phase Refractory via Mechanical Milling". Journal of Nanomaterials 2011 (2011): 1–5. http://dx.doi.org/10.1155/2011/540540.

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In this paper the possibility of production of nanocrystalline WC single-phase by mechanical milling has been investigated. The raw materials containing tungsten and carbon with WC as nucleation were milled in a planetary ball mill and sampled in different times. Studies showed that after 75 hours of milling the WC with W2C was produced and remained constant in higher milling time. Adding WC to raw materials at the beginning process leads to the fact that after 50 hours of milling only WC was synthesized without undesirable W2C phase. This material remained stable until higher times of milling too. From broadening of XRD peaks, the crystalline size in synthesized WC was estimated in nanometer scale which lower than the system containing primary WC, and it means that the strain in this system was lower than first system.

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Jonda, Ewa, Leszek Łatka, Anna Tomiczek, Marcin Godzierz, Wojciech Pakieła e Paweł Nuckowski. "Microstructure Investigation of WC-Based Coatings Prepared by HVOF onto AZ31 Substrate". Materials 15, n. 1 (22 dicembre 2021): 40. http://dx.doi.org/10.3390/ma15010040.

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In this paper, three commercial cermet powders, WC-Co-Cr, WC-Co and WC-Cr3C2-Ni, were sprayed by the High Velocity Oxy Fuel (HVOF) method onto magnesium alloy AZ31 substrate. The coatings were investigated in terms of their microstructure, phase analysis and residual stress. The manufactured coatings were analyzed extensively using optical microscopy (OM), X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM). Based on microstructure studies, it was noted that the coatings show satisfactory homogeneity. XRD analysis shows that in WC-Co, WC-Co-Cr and WC-Cr3C2-Ni coatings, main peaks are related to WC. Weaker peaks such as W2C, Co0.9W0.1, Co and W for WC-Co and W2C, Cr3C2 and Cr7C3 for WC-Cr3C2-Ni also occur. In all cermet coatings, linear stress showed compressive nature. In WC-Co and WC-Cr3C2-Ni, residual stress had a similar value, while in WC-Co-Cr, linear stress was lower. It was also proved that spraying onto magnesium substrate causes shear stress in the WC phase, most likely due to the low elastic modulus of magnesium alloy substrate.

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Tan, Guo Long. "Synthesis of Metastable Tungsten Carbide Nanoparticles by Mechanochemical Alloying Process". Advanced Materials Research 66 (aprile 2009): 135–38. http://dx.doi.org/10.4028/www.scientific.net/amr.66.135.

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Thermodynamically metastable tungsten carbide (W2C) nanoparticles have been synthesized by mechanochemical alloying (MCA) process. Mg was used as reductive agent and graphite as carbon source. The reduction reaction of WO3 and Mg gave nanometer W powders. Subsequent diffusion reaction of fresh W with carbon produced metastable W2C and a small amount of WC nanoparticles in a W rich environment. WC was then transferred to W2C during the prolonged MCA process. The mechanism of such a chemical transformation has been discussed from a point of view of thermodynamics. The subsequent self-propagation diffusion reaction of fresh W with C source controlled the rate of the whole reaction process due to its slow reaction speed. The final product of the MCA process mainly depends on the composition ratio of W to C in the raw materials. W2C nanoparticles in single phase have been finally fabricated by MCA process at a W rich environment. The structure of the final product has been determined by x-ray diffraction, while the morphology and microstructure of the as-milled W2C nanoparticles have been demonstrated by transmission electron microscopy images.

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Oliphant, Clive J., Christopher J. Arendse, Sigqibo T. Camagu e Hendrik Swart. "EBSD Analysis of Tungsten-Filament Carburization During the Hot-Wire CVD of Multi-Walled Carbon Nanotubes". Microscopy and Microanalysis 20, n. 1 (15 gennaio 2014): 4–13. http://dx.doi.org/10.1017/s1431927613014001.

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AbstractFilament condition during hot-wire chemical vapor deposition conditions of multi-walled carbon nanotubes is a major concern for a stable deposition process. We report on the novel application of electron backscatter diffraction to characterize the carburization of tungsten filaments. During the synthesis, the W-filaments transform to W2C and WC. W-carbide growth followed a parabolic behavior corresponding to the diffusion of C as the rate-determining step. The grain size of W, W2C, and WC increases with longer exposure time and increasing filament temperature. The grain size of the recrystallizing W-core and W2C phase grows from the perimeter inwardly and this phenomenon is enhanced at filament temperatures in excess of 1,400°C. Cracks appear at filament temperatures >1,600°C, accompanied by a reduction in the filament operational lifetime. The increase of the W2C and recrystallized W-core grain size from the perimeter inwardly is ascribed to a thermal gradient within the filament, which in turn influences the hardness measurements and crack formation.

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Sha, Jin, Liang-Yu Chen, Yi-Tong Liu, Zeng-Jian Yao, Sheng Lu, Ze-Xin Wang, Qian-Hao Zang, Shu-Hua Mao e Lai-Chang Zhang. "Phase Transformation-Induced Improvement in Hardness and High-Temperature Wear Resistance of Plasma-Sprayed and Remelted NiCrBSi/WC Coatings". Metals 10, n. 12 (17 dicembre 2020): 1688. http://dx.doi.org/10.3390/met10121688.

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The remelting method is introduced to improve the properties of the as-sprayed NiCrBSi coatings. In this work, tungsten carbide (WC) was selected as reinforcement and the as-sprayed and remelted NiCrBSi/WC composite coatings were investigated by X-ray diffraction, scanning electron microscopy, hardness test and tribology test. After spraying, WC particles are evenly distributed in the coating. The remelting process induced the decarburizing reaction of WC, resulting in the formation of dispersed W2C. The dispersed W2C particles play an important role in the dispersion strengthening. Meanwhile, the pores and lamellar structures are eliminated in the remelted NiCrBSi/WC composite coating. Due to these two advantages, the hardness and the high-temperature wear resistance of the remelted NiCrBSi/WC composite coating are significantly improved compared with those with an as-sprayed NiCrBSi coating; the as-sprayed NiCrBSi coating, as-sprayed NiCrBSi/WC composite coating and remelted NiCrBSi/WC composite coating have average hardness of 673.82, 785.14, 1061.23 HV, and their friction coefficients are 0.3418, 0.3261, 0.2431, respectively. The wear volume of the remelted NiCrBSi/WC composite coating is only one-third of that of the as-sprayed NiCrBSi coating.

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Zhou, Keyao, Xiangze Du, Linyuan Zhou, Huiru Yang, Xiaomei Lei, Yan Zeng, Dan Li e Changwei Hu. "The Deoxygenation of Jatropha Oil to High Quality Fuel via the Synergistic Catalytic Effect of Ni, W2C and WC Species". Catalysts 11, n. 4 (3 aprile 2021): 469. http://dx.doi.org/10.3390/catal11040469.

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Tungsten carbide-based materials have good deoxygenation activity in the conversion of biomass. In this paper, catalysts with different nickel–tungsten carbide species were prepared by tuning the reduction temperature and Ni loading, and the effects of these different tungsten carbide species in the conversion of jatropha oil were studied. XRD, XPS, TEM, HRTEM, Raman, H2-TPR, ICP-AES were used to characterize the catalysts. The results suggested that metallic W was gradually carburized to W2C species, and W2C species was further carburized to WC species with the increase in reduction temperature and Ni loading. The obtained 10Ni10W/AC-700 catalyst exhibited outstanding catalytic performance with 99.7% deoxygenation rate and 94.5% C15-18 selectivity, which were attributed to the smallest particle size, the best dispersion, the most exposed active sites, and the synergistic effect of Ni, W2C and WC species.

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Lyu, Xingxing, Xiaosong Jiang, Hongliang Sun e Zhenyi Shao. "Microstructure and mechanical properties of WC–Ni multiphase ceramic materials with NiCl2·6H2O as a binder". Nanotechnology Reviews 9, n. 1 (13 giugno 2020): 543–57. http://dx.doi.org/10.1515/ntrev-2020-0044.

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AbstractHigh-density WC–Ni composite ceramics were prepared by cold isostatic pressing–vacuum pressureless sintering–hot isostatic pressing with tungsten carbide (WC) powder and NiCl2·6H2O as a binder. Results show that with an increase in the contents of Ni in the metal binder phase, the relative density of WC–Ni composite ceramics is improved, and the formation of the carbon-deficient W2C phase is reduced. There is no W2C generated in the WC–1 wt% Ni material. At high temperatures, the Ni phase changes into the liquid phase and enters between the WC particles, thereby promoting the close alignment of the WC particles. Moreover, the WC particles will be more closely aligned under their own surface tension and capillary action, thereby promoting the densification of WC–Ni composite ceramics. The WC–0.5 wt% Ni composite ceramics are fully dense and show the best comprehensive performance with a microhardness of 23.0 GPa, a fracture toughness of 5.28 MPa m1/2, and a flexural strength of 1,396.58 MPa. WC–Ni composite ceramics are mainly composed of elongated triangular prism WC particles and Ni phase. Transgranular fracture was the main fracture mode of WC–Ni multiphase ceramic materials with a small amount of intergranular fracture due to the existence of the Ni phase. Such a fracture mode can increase the flexural strength of the composite material.

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Gassmann, R. C. "Laser cladding with (WC+W2C)/Co–Cr–C and (WC+W2C)/Ni–B–Si composites for enhanced abrasive wear resistance". Materials Science and Technology 12, n. 8 (agosto 1996): 691–96. http://dx.doi.org/10.1179/mst.1996.12.8.691.

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Oliveira, Fernando A. Costa, Bernard Granier, J. M. Badie, Jorge Cruz Fernandes, Luís Guerra Rosa e Nobumitsu Shohoji. "Surface Singularity Upon Solar Radiation Heating of Graphite/Tungsten Powder Mixture Compacts to Temperatures in Excess of 1600°C". Materials Science Forum 587-588 (giugno 2008): 993–97. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.993.

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Synthesis of single-phase tungsten sub-carbide W2C was attempted by heating pellets made out of a source of carbon (graphite-G) and W powders with G/W atom ratio between 0.35 and 0.50 to two target temperatures, namely 1600°C and 1900°C in an argon atmosphere using a solar furnace at PROMES-CNRS in Odeillo (France). The results showed that synthesis of single-phase W2C phase was difficult at either target temperature yielding the W2C co-existed with free metallic W. It was noted that the thin top surface layer of the solar-synthesised tungsten carbide pellets heated to 1900°C was distinguishable from the rest of the bulk specimen showing localised growth of nano-meter scale WC whiskers over W2C grains. Detailed XRD (X-ray diffraction) results on the effect of both G/W ratio and temperature on W2C lattice parameters are discussed.

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Guan, Ruqi, Kailing Hu, Lihua Wang e Youjian Chen. "A Two Step Synthesis Route of WC Nanopowders". JOURNAL OF ADVANCES IN CHEMISTRY 6, n. 3 (7 dicembre 2010): 1103–8. http://dx.doi.org/10.24297/jac.v6i3.2648.

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Here, a novel molten salt route to synthesize ceramic WC nanopowders was presented. Compared to the traditional synthesis procedures, this method is relatively low cost involving two-step synthesis route. In the argon atmosphere at 650 oC, the powders were the mixed WC and W2C phases. These synthesized powders were transferred to a small crucible (30 mL) containing molten salt, which were put into a 500 mL crucible with some carbon powder in it as reducing atmosphere, followed by maintaining the reaction temperature at 1100 °C for 1 h. The phase purity and composition were characterized by the powder X-ray diffractometer (XRD). It was found that W2C was transformed thoroughly into WC, which indicated the successful synthesis of WC powders using this method. The mechanism of the reaction process in molten salt has been discussed finally. The thermogravimetric analysis indicated that the as-prepared samples showed good thermal stability and oxidation resistance in high temperature. The methodology reported in this work was fundamentally important, which may find potential industrial applications.

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Li, Jianing, Yuanbin Zhang, Hui Luo, Shuili Gong, Peng Li e Yushuang Huo. "Surface modification of Ti alloys with WC-TiB2-reinforced laser composite coatings". Science and Engineering of Composite Materials 23, n. 6 (1 novembre 2016): 737–41. http://dx.doi.org/10.1515/secm-2014-0171.

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AbstractLaser cladding of the TiAl/Fe+Co-coated WC+TiB2 pre-placed mixed powders on a Ti-6Al-4V alloy substrate can be used to form TiB2/α-W2C-reinforced composite coating, which improved the wear resistance of the substrate. To further improve the TiB2/α-W2C-reinforced composite coating, yttria partially stabilized zirconia (YPSZ) was added into the pre-placed powders. A metallurgical bonding was formed between the YPSZ-infused composite coating and the substrate. Many amorphous alloys were produced in this composite coating due to the action of YPSZ, and such coating showed fine microstructure. Thus, it is feasible to further improve the wear resistance of the laser clad TiB2/α-W2C-reinforced composite coating through the addition of YPSZ.

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Lantsev, Е. А., N. V. Malekhonova, Yu V. Tsvetkov, Yu V. Blagoveshchensky, V. N. Chuvildeev, А. V. Nokhrin, M. S. Boldin, P. V. Andreev, K. E. Smetanina e N. V. Isaeva. "An investigation of the peculiarities of high-speed sintering of plasma chemically synthesized tungsten carbide nanopowders with increased oxygen content". Physics and Chemistry of Materials Treatment 6 (2020): 23–39. http://dx.doi.org/10.30791/0015-3214-2020-6-23-39.

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Spark plasma sintering (SPS) of plasma-chemical nanopowders tungsten carbide with a high oxygen content are studied. The results show that the nanopowder WC shrinkages during SPS is limited by grain boundary diffusion with abnormally low activation energies. It is established that the decrease in the activation energy can be caused by the influence of oxygen on the diffusion permeability of the tungsten carbide grain boundaries at the stage of intense compaction, as well as by abnormal grain growth at the stage of high-temperature sintering. The SPS kinetics of WC-W2C-WO3-W nanopowder compositions at the stage of intense compaction is controlled by the rate of oxide particle sintering with their simultaneous transformation into W2C particles, and then, by the plastic flow of W2C particles in the presence of W particles at the stage of high-temperature sintering. Using the SPS method, we obtained ceramics with a high density (98-99%), ultrafine-grained structure (the average grain size is less than 0.3 mm), having an increased hardness HV = 30.5 GPa with a Palmquist crack resistance of ~6.5 MPa·m1/2.

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Zhanbolatova, G. K., A. Z. Miniyazov, T. R. Tulenbergenov, I. A. Sokolov e O. S. Bukina. "INVESTIGATION OF TUNGSTEN SURFACE CARBIDIZATION UNDER PLASMA IRRADIATION". NNC RK Bulletin, n. 3 (8 gennaio 2022): 37–43. http://dx.doi.org/10.52676/1729-7885-2021-3-37-43.

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This paper presents the results of a study of the formation of a carbidized layer under various experimental conditions and the choice of optimal parameters for carbidization of a tungsten surface under plasma irradiation. To study the effect of the surface temperature of a tungsten sample and the duration of plasma irradiation, experiments were carried out at a sample surface temperature of 1300 °C and 1700 °C with an irradiation duration of 300–2400 s. Analysis of the research results showed that the maximum formation of W2C on the surface is observed at a test temperature of 1700 °C. At a temperature of 1300 °C, the phase composition of the carbidized layer depends on the duration of plasma irradiation. According to the literature analysis, the formation of WC occurs on the surface of tungsten, from which C diffuses into the particle and forms the underlying layer of W2C. With an increase in the ion fluence, depending on the irradiation time and the temperature of the sample surface, the diffusion of C into W accelerates, the WC content decreases, and W2C becomes the dominant carbide compound.

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Telepa, V. T., M. I. Alymov, V. A. Shcherbakov, A. V. Shcherbakov e V. I. Vershinnikov. "Synthesis of the WC–W2C composite by electro-thermal explosion under pressure". Letters on Materials 8, n. 2 (2018): 119–22. http://dx.doi.org/10.22226/2410-3535-2018-2-119-122.

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Wei, Zhang, Yeo Jian Hua, Zhang Qun Li e Kong Fan Zhi. "Microstructure and Mechanical Characteristic of Nano-WC Composite Coating Prepared by Laser Cladding". Solid State Phenomena 118 (dicembre 2006): 579–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.118.579.

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The experiments of laser cladding nanometer-size WC powder on 2Cr13 stainless steel have been done using 7kW CO2 laser processing system. The microstructure and mechanical characteristic of the WC composite coating were tested by scanning electronic microscope (SEM), X-ray diffraction (XRD), energy dispersion analyzer of X-ray (EDAX) and microhardness tester. The WC composite coating exhibits compact dendritic and reticular interdendritic structure. The XRD data have revealed the phases of coating include Fe, WC, W2C and Fe3C. The nano-WC composite coating has excellent mechanic performances. The surface hardness of composite coating is about 1758HV0.2. Its abrasion proof is 3.5 times as high as that of parent metal.

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Sun, Hairong, Jinpeng Yu, Guoqing Gou e Wei Gao. "Mechanical properties and residual stress of HVOF sprayed nanostructured WC-17Co coatings". International Journal of Modern Physics B 34, n. 01n03 (30 dicembre 2019): 2040041. http://dx.doi.org/10.1142/s021797922040041x.

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Nanostructured WC-17Co, 2C-12Co coatings and conventional WC-17Co coating were prepared by High Velocity Oxygen Flame (HVOF) spray technique. The elastic modulus, fracture toughness and crack spread path were studied. The residual stress, different phases, microstructure from surface to the depth of coatings were also analyzed. While the nanostructured WC-12Co coating showed the highest elastic modulus, the nanostructured WC-17Co coating has the highest fracture toughness. The compressive residual stress of the nanostructured coatings was higher than the conventional coating. Both WC and W2C phases showed compressive residual stress, but Co6W6C phase showed tensile stress. The distribution of residual stress showed that the stress is the lowest at the surface and the highest close to the interface.

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Ren, Xiao Yong, Zhi Jian Peng, Hui Yong Rong, Ying Peng, Cheng Biao Wang, Zhi Qiang Fu, Long Hao Qi e He Zhuo Miao. "Phase Composition and Microstructure of Binderless WC-ZrC Cemented Carbides Fabricated by Spark Plasma Sintering". Key Engineering Materials 602-603 (marzo 2014): 556–60. http://dx.doi.org/10.4028/www.scientific.net/kem.602-603.556.

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Binderless WC-based cemented carbides with different fractions (0-9 wt.%) of ZrC nanopowder were fabricated through spark plasma sintering at 1600 °C under a uniaxial pressure of 50 MPa. The addition effect of ZrC nanopowder on the phase composition and microstructure of the fabricated materials were explored with the help of X-ray diffraction and scanning electron microscope. The results indicated that W2C phase was detected in the samples with 0-3 wt.% ZrC nanopowder, but with further increase in ZrC added fraction, ZrO2 phase instead of W2C phase was detected. The apparent density decreased gradually with the increase in added fraction of ZrC nanopowder, while the relative density increased initially and then decreased, reaching its maximum of about 98.2% when the added fraction of ZrC nanopowder was about 3 wt.%, indicating that appropriate added fraction of ZrC nanopowder can improve the densification of binderless WC cemented carbides. Without ZrC nanopowder, the coarsening and abnormal growth of WC grains were serious, resulting in many large prismatic WC grains in the samples. However, Such phenomena could be suppressed by adding ZrC nanopowder, resulting in much finer and more homogenous microstructure after 1-3 wt.% ZrC nanopowder was added. When the added fraction of ZrC nanopowder was higher than 3 wt.%, the agglomeration of ZrC nanopowder became more and more serious.

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Kim, Daeup, Young Choi, Yongil Kim e Seungboo Jung. "Characteristics of Nanophase WC and WC-3 wt% (Ni, Co, and Fe) Alloys Using a Rapid Sintering Process for the Application of Friction Stir Processing Tools". Advances in Materials Science and Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/343619.

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Microstructures and mechanical characteristics of tungsten carbide- (WC-) based alloys, that is, WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe, fabricated using a spark plasma sintering (SPS) method for the application of friction stir processing tools were evaluated. The sintered bodies with a diameter of 66 mm showed relative densities of up to 99% with an average particle size of 0.26~0.41 μm under a pressure condition of 60 MPa with an electric current for 35 min without noticeable grain growth during sintering. Even though no phase changes were observed after the ball milling process the phases of W2C andWC1-xappeared in all sintered samples after sintering. The Vickers hardness and fracture toughness of the WC, WC-3 wt% Ni, WC-3 wt% Co, and WC-3 wt% Fe samples ranged from 2,240 kg mm2to 2,730 kg mm2and from 6.3 MPa·m1/2to 9.1 MPa·m1/2, respectively.

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Pukas, S., L. Zinko, N. German, R. Gladyshevskii, I. V. Koval, L. Bodrova, H. Kramar e S. Marynenko. "Influence of the nano-WC content and Sintering Temperature on the Phase Composition of Hard Alloys in the System TiC–WC–VC–NiCr". Physics and Chemistry of Solid State 21, n. 3 (30 settembre 2020): 496–502. http://dx.doi.org/10.15330/pcss.21.3.496-502.

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The effect of the WC content and the sintering temperature, as the main technological factor, on the phase composition of TiC–xWC–5VC–18NiCr alloys was investigated by X-ray phase analysis. It was established that the main phases in the investigated alloys were the NaCl-type quaternary (Ti,V,W)C phase and a solid solution of Cr in Ni. Depending on the size of the WC particles used for the preparation, the metal binder could be described by the formula Ni0.75Cr0.25 (for nano WC) or Ni0.5Cr0.5 (for fine-sized WC). In alloys prepared with fine-sized WC, elementary Cr and traces of the Cr3C2 and Cr23C6 were also found. With increasing content of nano-sized WC and sintering temperature the solubility of W in (Ti,V)C increased. No W2C phase was detected under the conditions of the investigation.

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Du, Xiao Dong, Lian Ying Li, Guang Fu Liu, Jian Shen e Dan Zhou. "Dissolution of Tungsten Carbide in Remanufacturing Coating by Plasma Spray Welding". Advanced Materials Research 852 (gennaio 2014): 121–26. http://dx.doi.org/10.4028/www.scientific.net/amr.852.121.

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The tungsten carbide reinforced Ni-based alloy composite coatings are prepared on the surface of 45 steel by plasma spray welding in back feeding method. The dissolution of Ni-based WC composite coatings was investigated. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy diffraction spectrum (EDS) were used to examine the microstructure and composition of the coatings. The results show that the WC particles are well-distributed in the matrix. The WC particles have a good wettability with Ni-based substrate. In the spraying process, the WC particles have been dissolved obviously, and the diffusion occurs between the WC particles and Ni-based substrate. The surface of the coatings has a microstructure consisting of WC, W2C, Fe7C3, Cr7C3 and γ- (Fe, Ni) solid solution. The hardness increases from the matrix to the surface of coatings and is up to 2311 HV.

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25

Sugiyama, S., e H. Taimatsu. "Preparation of W-C-B Composites by Reactive Resistance-Heated Hot Pressing". Materials Science Forum 449-452 (marzo 2004): 309–12. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.309.

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Abstract (sommario):

Dense WC-base W-C-B composites were prepared by the reaction sintering of B4C-WWC (mole ratio 1 : x : 80 or 130, x = 1-9) powder mixtures using resistance-heated hot pressing. Sintered bodies were composed of different products depending on x both in B4C-xW-80WC and - 130WC: WC + WB when x ≤ 3, WC + W2B + WB when x = 5, and WC + W2B + W2C when x ≥7. They had the highest Young's modulus values 706 and 705 GPa for -80WC and -130WC at x = 3, respectively. The hardness was increased with x, depending on a decrease in the grain size of WC. Its highest value was 24.5 GPa both for -80WC and -130WC at x = 9. For the fracture toughness, the highest value 6.1 MPa m1/2 was obtained for -130WC at x = 5.

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26

Ding, Xiang, Du Ke, Chengqing Yuan, Zhangxiong Ding e Xudong Cheng. "Microstructure and Cavitation Erosion Resistance of HVOF Deposited WC-Co Coatings with Different Sized WC". Coatings 8, n. 9 (29 agosto 2018): 307. http://dx.doi.org/10.3390/coatings8090307.

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Abstract (sommario):

Conventional, multimodal and nanostructured WC-12Co coatings with different WC sizes and distributions were prepared by high velocity oxy-fuel spray (HVOF). The micrographs and structures of the coatings were analyzed by scanning electron microscope (SEM), X-ray diffractometer (XRD) et al. The porosity, microhardness and fracture toughness of the WC-Co coatings were measured. The coating resistance to cavitation erosion (CE) was investigated by ultrasonic vibration cavitation equipment and the cavitation mechanisms were explored. Results show that there is serious WC decarburization in nanostructured and multimodal WC-Co coatings with the formation of W2C and W phases. The nanostructured WC-Co coating has the densest microstructure with lowest porosity compared to the other two WC-Co coatings, as well as the highest fracture toughness among the three coatings. It was also discovered that the nanostructured WC-Co coating exhibits the best CE resistance and that the CE rate is approximately one-third in comparison with conventional coating.

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27

Nakamura, Daisuke, Kazuyoshi Iida, Kayo Horibuchi, Yuko Aoki, Naoko Takahashi, Yuto Mori, Miki Moriyama, Shugo Nitta e Hiroshi Amano. "Mechanism and enhancement of anti-parasitic-reaction catalytic activity of tungsten-carbide-coated graphite components for the growth of bulk GaN crystals". Applied Physics Express 15, n. 4 (17 marzo 2022): 045501. http://dx.doi.org/10.35848/1882-0786/ac5ba4.

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Abstract (sommario):

Abstract The working mechanism of the anti-parasitic-reaction (APR) catalyst of tungsten carbide (WC) coating on graphite in hydride vapor phase epitaxy GaN growth were examined. During NH3 annealing, the surface of WC is reduced as well as nitrided. The W2N topmost layer was found to work as an APR-active catalyst to suppress the formation of GaN polycrystals during high-rate HVPE-GaN growth, while the regions covered with thick pyrolytic graphite residues were catalytically inert. The formation of an additional W2C top layer on the WC underlayer was demonstrated to exhibit superior APR activity, i.e. complete suppression of GaN polycrystal formation.

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28

Guo, Chang Qing, e Xiao Ping Liu. "The Effect of Different Tungsten-Containing Materials Addition on the Reinforcements in the Surface Compound Layer with Steel Substrate". Applied Mechanics and Materials 651-653 (settembre 2014): 128–32. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.128.

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Abstract (sommario):

The effect of different tungsten-bearing materials addition in a surface preform, such as Ni-base WC particles, ferrotungsten powders and casting WC particles, on the reinforcement phases at the surface compound layer with a carbon steel substrate is investigated under the condition of vacuum expandable pattern casting V-EPC. The microstructures and reinforcement phases are characterized by optical microscopy, SEM and EDS. Experimental results show that it is impossible to synthesize the independent WC particles in each condition. The tungsten-containing materials are all inclined to decompose during steel infiltration and the released tungsten elements tend to combine with carbon to form fish born-like or strip-like WC or W2C carbides and dissolve in other type of carbides and matrix.

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29

Mohd Rabani, Nur Amira, e Zakiah Kamdi. "Characterisation of WC-17Co and WC-9Ni HVOF Sprayed Cermet Coatings". Materials Science Forum 840 (gennaio 2016): 331–35. http://dx.doi.org/10.4028/www.scientific.net/msf.840.331.

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Abstract (sommario):

Cemented tungsten carbides have been paid much attention due its better mechanical properties with excellent combination of hardness and toughness characteristics. The hard WC particles in the coating provide hardness and wear resistance, while the ductile binder such as Co and Ni contribute to toughness and strength. WC-17wt.% Co and WC-9wt.% Ni powders have been sprayed by the HVOF method to form coatings approximately 300μm and 150μm thick onto AISI 1018 steel substrate. Both coatings have been prepared and supplied by an external vendor. The coatings were examined using optical microscope (OM), scanning electron microscope (SEM), and X-Ray diffraction (XRD). The hardness of both coatings were also measured using Vickers micro-hardness tester. The microstructure of the coatings has been analyzed and found to consist of WC, brittle W2C phase, metallic W phase, and amorphous binder phase of Co and Ni. It is found that WC-Ni has a higher hardness value compared to WC-Co due to high porosity distribution.

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30

Tillmann, Wolfgang, Leif Hagen, Ingor Baumann e Michael Paulus. "WC Decomposition Phenomena in ID-HVOF-Sprayed WC-CoCr Coatings Using Fine Powder Feedstock". Coatings 12, n. 2 (23 gennaio 2022): 124. http://dx.doi.org/10.3390/coatings12020124.

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Abstract (sommario):

Over the last few decades, the high velocity oxygen fuel (HVOF) spraying of WC-CoCr for internal diameter (ID) coating has attracted much interest for hard chrome replacement. Current demands for the ID coating of small cylindrical parts necessitates the use of specialized spray gun equipment and powder feedstocks with small particle size fractions. Due to the limited spray distance inside cylindrical parts with small IDs, the process control, spraying fine WC-CoCr powders, meets new challenges to avoid significant WC decomposition, which increases the risk of mechanical degradation. Within the scope of this study, ID-HVOF spraying using a fine-structured WC-CoCr (−15 + 5 μm) feedstock with a mean WC particle size of 400 nm is examined with respect to the WC decomposition phenomena using X-ray diffraction (XRD). Hence, a statistical design of experiments (DoE) is utilized to systematically analyze various spray parameter settings along with their interaction as part of the WC to W2C conversion.

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31

Yang, Lian Wei, Rui Jie Wang, Yun Dong e Xiao Ping Lin. "Synthesis of Fine Co/ WC Composite and Application to Supersonic Plasma Spraying". Advanced Materials Research 454 (gennaio 2012): 110–13. http://dx.doi.org/10.4028/www.scientific.net/amr.454.110.

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Abstract (sommario):

Co/ WC composite powders (with 10 wt% content of Co) were synthesized by direct mechanical grinding in a rotary-vibration mill. The powders with different mill time were evaluated. WC and WC/Co composite coatings were prepared by supersonic plasma spraying. The results showed that the milled powders consist of composite particles that were formed in the first 2h of milling. Longer milling times improve the distribution of phases inside the composite particles. The formation of the composite particles involves sequential steps of deformation, fragmentation, cold welding, work hardening and piercing of particles of the hard phase in the soft phase. X-ray spectra of the sprayed coating are shown that only very weak W2C and Co6W6C peaks are observed. Compared with WC coating, the Co/ WC coating is denser, and less large pores within composite coating.

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32

Surzhenkov, Andrei, Janis Baroninš, Mart Viljus, Rainer Traksmaa e Priit Kulu. "Sliding Wear of Composite Stainless Steel Hardfacing under Room and Elevated Temperature". Solid State Phenomena 267 (ottobre 2017): 195–200. http://dx.doi.org/10.4028/www.scientific.net/ssp.267.195.

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Abstract (sommario):

The present research focuses onto sliding wear of novel plasma transferred arc welded (PTAW) hardfacing with the stainless steel (DIN X3CrNiMo18-13-3) matrix, reinforced with WC/W2C, under the room and elevated temperature. The hardfacing was produced, applying the optimized set of parameters (current – 55 A, reciprocating speed – 1.0 mm/s, oscillation frequency – 0.6 Hz). The average reinforcement content was 29.3 ± 4.0 vol %. The reinforcement consisted of W2C and WC, while M7C3- and M23C6-type (M = Fe, Cr, Mo, W) carbides were the main phases in the matrix. Universal hardness and Young’s modulus were approximately 5.3 and 1.9 times higher, than those of the reference steel (DIN X2CrNiMo18-14-3). The sliding wear of the hardfacing was 4.9 times lower under 20 °C and 3.1 times lower under 300 °C, but 1.8 times higher under 500 °C than the wear of the reference steel. Galling was the wear mechanism of the hardfacing under 20 °C, scoring – under 300 °C and combination of scoring and binder extrusion – under 500 °C

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33

Wang, Li Jun, Hui Chen, Yan Liu, Guo Qing Gou e Da Li. "Effects of Cr on Microstructure and Hardness of HVOF-Sprayed WC-Co Coating". Advanced Materials Research 317-319 (agosto 2011): 301–6. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.301.

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Abstract (sommario):

In the areas of remanufacturing and working conditions with requirements of wear and corrosion resistance, the WC-Co thermal spray coating has a wide applications. WC-10Co-4Cr is an excellent, has great application potential as a coating composition. In this research, the two kinds of coatings, WC-12Co and WC-10Co-4Cr, were sprayed by high velocity oxygen-flame(HVOF). The phase composition is studied by X-ray diffraction(XRD). The porosity is investigated by lase confocal scanning microscope(LCSM), and the micro-hardness is measured. The results show that, The porosity of two coatings don't differ, this maybe has relation with the parameters in the spraying process.The micro-hardness of WC-10Co-4Cr coating is higher than that of WC-12Co coating. Compared with the phase composition of WC-12Co coating, there are new phase composition Cr7C3, Cr23C6 and Cr2WO6 in the WC-10Co-4Cr coating. And the content of W2C and η phase are reduced in WC-10Co-4Cr coating. Cr had no effect on the lattice transformation of cobalt.

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34

Jin, Yong Zhong, Fa Ming Ye, Xian Guang Zeng e Rui Song Yang. "Carbothermal Synthesis of Cr₃C₂-WC-Ni Nanocomposite Powders". Advanced Materials Research 661 (febbraio 2013): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amr.661.3.

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Abstract (sommario):

Cr3C2-WC-Ni nanocomposite powders with ~50-100 nm were synthesized from precursors by vacuum-aided carbothermal reduction at only 750 °C for 2 h. The phase composition and microstructure of the synthesized products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The present study shows that Cr3C2-WC-Ni nanocomposite powders contain two kinds of solid-solution phases, namely Ni and (Cr, W)3C2solid solution, respectively. WC and W2C phases do not appear inreaction products due to the dissolution of tungsten atoms into Ni and Cr3C2unit cells. Especially, there is a change of the crystalline structure for (Cr, W)3C2phase from 750 °C to 800 °C.

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35

Wei, Xin. "Synthesis of Alumina-Tungsten Carbide Composites by Self-Propagating High Temperature Synthesis Process". Advanced Materials Research 415-417 (dicembre 2011): 226–31. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.226.

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Abstract (sommario):

Alumina-Tungsten Carbide (Al2O3-WC) composites were synthesized by self-propagating high temperature synthesis (SHS) from a powder mixture of WO3-C-Al. The reaction was carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The effects of carbon mole ratio in precursor mixture and diluents of NaCl and Al2O3 on the Al2O3-WC conversion were investigated using X-ray diffraction and scanning electron microscope technique. The as-synthesized products of Al2O3-WC2-WC powders were concurrently formed and the reduction of W2C phase was found when added diluents in precursors.

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36

Park, S. Y., Moon Chul Kim e Chan Gyung Park. "Improvement in Wear Resistance of Nano WC-Co Coatings Fabricated by Detonation Gun Spraying". Materials Science Forum 539-543 (marzo 2007): 1264–69. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1264.

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Abstract (sommario):

Nano structured WC-Co coatings with carbide size of 100−200nm were fabricated by detonation gun spraying. The fabricated nano coatings showed improved hardness and wear resistance compared to micron WC-Co coatings. Considerable phase decomposition of WC to W2C and amorphous phase in nano coatings was detected, which is known to degrade wear resistance of coatings. In order to improve the wear resistance of the coatings by recovering of dissociated carbide phases, post heat treatment was conducted in Ar environment at temperature range of 400−900°C. Harness, fracture toughness and wear resistance of nano coatings were significantly improved by post heat treatment. The improved properties were elucidated and discussed in terms of microstructure and phase compositions.

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37

Zhang, Zhong, Hong Xi Liu, Xiao Wei Zhang, Sheng Wei Ji e Ye Hua Jiang. "Dissolution Behavior of WC Reinforced Particles on Carbon Steel Surface during Laser Cladding Process". Advanced Materials Research 430-432 (gennaio 2012): 137–41. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.137.

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Abstract (sommario):

Ni60WC35 self-fluxing composite coating was fabricated by transverse-flow CO2 laser apparatus on 45 medium-carbon steel surfaces. The microstructure and phase transform behavior of WC reinforced particles under the laser cladding conditions was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS). The results show that laser scanning speed has a great important influence on the microstructure of Ni-based WC composite coating, WC particles has a transition to the Ni-based coating. The main feature of WC particle is its edge hard phase has transformed into needle phase, and the needle phase areas increase with the decrease of the laser scanning speed. Some WC particles turn into needle clusters structure, and then white block phase. In addition, WC particle has some microscopic defects, and the surface priority defect can be dissolved. When the pool temperature rises to 1250°C, WC decomposition reaction become W2C and C. The elements diffusion can promote the dissolution of WC particles when the pool temperature rises continuously.

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38

Lee, Seoung Soo, Dong Won Joo, Yeon Gil Jung e Chul Jin Choi. "Synthesis of WC Nanosized Powder by the Plasma Arc Discharge Process". Key Engineering Materials 336-338 (aprile 2007): 2086–88. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.2086.

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Abstract (sommario):

WC nanosized powders are synthesized by the plasma arc discharge process and annealing under an inert (Ar) atmosphere. The high temperature used during discharging at local region causes the work-piece and electrode to melt and evaporate. The melted tungsten on the arc discharge electrode and carbon arising from decomposition CH4 gas forms WC1-x nanosized powders. The WC1-x phase is encapsulated in a amorphous carbon shell. The WC1-x nanosized particles are annealed at 1200~1400°C under an Ar atmosphere. The WC1-x nanosized powder is transformed to the W2C phase, and then it becomes WC above at 1400°C.

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39

Ma, Ning, Huan Tao Wu, Fu Xing Ye e Guo Sheng Zhang. "Failure Analysis and Remanufacturing of Construction Machinery Shafts by HVOF Technique". Applied Mechanics and Materials 423-426 (settembre 2013): 771–74. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.771.

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Abstract (sommario):

In this work, a scrapped cross shaft which was assembled at the differential of ZL50C loader was analyzed by scanning electron microscopy (SEM) to examine the failure mechanism and was remanufactured by HVOF with ~500μm thickness WC-12Co coatings on it. The microstructure, phase compositions and properties of deposited WC-12Co coatings were investigated through optical microscope (OM), SEM, X-ray diffraction (XRD), microhardness tester and tensile testing machine. The results show that the coatings were very dense, and their porosities were lower than 1%. According to the X-ray Diffraction (XRD) analysis, the phase compositions of the sprayed coatings consisted of WC, Co and W2C. The microhardness of the coating was approximated to 1100 HV0.1and the bonding strength was higher than 63.7 MPa. It can be concluded that WC-12Co coating sprayed by HVOF was suitable for the remanufacturing of shaft parts.

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40

Liu, YangZhen, YeHua Jiang, Rong Zhou e Jing Feng. "Mechanical properties and chemical bonding characteristics of WC and W2C compounds". Ceramics International 40, n. 2 (marzo 2014): 2891–99. http://dx.doi.org/10.1016/j.ceramint.2013.10.022.

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41

Edigarov, Vyacheslav R., Alexey L. Akhtulov, Sergei E. Dadayan e Vyacheslav V. Maly. "Friction-Electric Modification of the Surfaces of Machine Parts with Tungsten Carbides". Key Engineering Materials 910 (15 febbraio 2022): 538–43. http://dx.doi.org/10.4028/p-ijrd46.

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Abstract (sommario):

The technology of friction-electric modification of the surfaces of machine parts with W2C and WC tungsten carbides is considered. A method of modifying the surface layer by implantation of materials based on tungsten carbides is investigated in order to increase the wear resistance of parts forming tribo-conjugations in heavily loaded units of multi-purpose tracked and wheeled vehicles.

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42

Wu, Xu, e Zhi Meng Guo. "The Research of the Wc-17co Abrasion-Resistant Coating by the D-Gun System on the Aluminium Alloy Substrate". Advanced Materials Research 650 (gennaio 2013): 211–15. http://dx.doi.org/10.4028/www.scientific.net/amr.650.211.

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Abstract (sommario):

This work use the D-gun system to spray the WC-17Co coating. analyzed the microstructure and performance of the coating by SEM, EDAX, XRD, HAXD. It gave a basis for the next research work for the anti-wear coating on aluminum alloy. The hardness of the WC-17Co coating is about HV1100~1300, the average porosity less than 1%. And the max diameter of the single hole is less than 0.012mm. There are no apparent oxide in the coating. The WC particles occurred decarburization during the spraying process and deposited the coating that composed with W2C and Co3W3C phases. The corrosion resistance of the coating is more ideal. But the phase distribution in the coating is not enough uniform.

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43

Sukhova, O. V., e Yu V. Syrovatko. "Contact interaction at the composites interfaces between the microcrystalline particulate and the molten matrix". Journal of Physics and Electronics 26, n. 2 (26 dicembre 2018): 29–32. http://dx.doi.org/10.15421/331819.

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Abstract (sommario):

The peculiarities in structure formation of interfacial zones at the composite’s boundaries between the molten Fe–C–B–P–Mo matrix and the filler’s solid phases of W2C and WC that have microcrystalline structure were investigated in this work. The structure of the interfaces was studied by methods of metallographic and automatized quantitative analyses. The interfaces of dissolution-and-diffusion type were observed between the matrix and the filler. A dissolution rate of the filler’s microcrystalline phases of W2C and WC was shown to decrease by ~ 1.7–1.8 times as against that of the crystalline phases of the same composition. This result was explained considering the dependence of an average shift of atoms from the equilibrium positions in the lattice on linear size of the phases. Since the average size of the microcrystalline phases is ~ 25 times smaller than that of the crystalline phases, the average shift of microcrystalline phase atoms from the equilibrium positions decreases by ~ 1.7 times. Correspondingly, the microcrystalline particulate dissolves in the molten matrix at the lower rate than crystalline one which prevents from formation of undesirable brittle compounds in the structure of composite’s interfacial zones during infiltration.

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44

Wang, Lei, Yi Xiang Cai, Xin Liu, Huan Wen Xie e Xin Tong. "The Spherical Casting WC Powder and its Application in Laser Surface Alloying Treatment". Advanced Materials Research 785-786 (settembre 2013): 910–13. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.910.

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Abstract (sommario):

The spherical casting WC powder is a kind of new potential wear-resistance ceramic material. In this paper, its chemical composition, surface morphology, microstructure, phase, microhardness and some powder characteristics were investigated, and then the powders were applied in laser surface alloying treatment on medium carbon steel. The results indicate that the spherical WC powder consists of (wt.%) 94.06 W, 4.03 C and 1.91 other elements including Fe, V, Cr and Nb. Most of powder particles have regular spherical shape and smooth surface, and the microstructure is acicular eutectic of WC and W2C, which leads to high microhardness of 2812 HV. The fluidity of powders is 5.97 s/50g, and the apparent density of powders is 10.1 g/cm3. The laser alloyed layer is characterized by dendritic primary phase, ledeburite microstructure and some residual WC particles. The laser surface alloying treatment with adding material of spherical casting WC powder can enhanc the abrasive wear resistance of medium carbon steel by over 200%.

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45

Gou, Guo Qing, Nan Huang, Hui Chen, Da Li, Yan Liu e Hua Ji. "Research on the Mechanical Properties and Residual Stress of HVOF Sprayed Nanostructured WC-17Co Coatings". Advanced Materials Research 291-294 (luglio 2011): 88–96. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.88.

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Abstract (sommario):

Nanostructured WC-17Co coatings, nanostructured WC-12Co coatings, conventional WC-17Co coatings were prepared by means of High Velocity Oxygen Flame (HVOF) technique. The characteristic of powders and coatings of nanostructured WC-17Co coatings, hardness of different coatings, distribution gradient of the hardness of the nanostructured WC-17Co coatings in the depth direction, fracture toughness and interface fracture toughness of different coatings, residual stress of different coatings, different phase and distribution of WC phase in the depth direction were investigated. The results indicated that the micro-crack is spread along the phase interface where the brittle phase are more in the Co rich area , where there are more different properties in the Co rich area and W rich area, where there are more defects close to the intend end in the W rich area, even spread through the WC particles in microcosmic and the different residual stress of different phase are because of different melting point and different expansion coefficient , so the WC, W2C produced compressed stress, the Co6W6C produced tensile stress. The residual stress manifested from higher to lower in the depth direction of the coatings.

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46

He, Jianhong, Leoanardo Ajdelsztajn e Enrique J. Lavernia. "Thermal stability of nanocrystalline WC–Co powder synthesized by using mechanical milling at low temperature". Journal of Materials Research 16, n. 2 (febbraio 2001): 478–88. http://dx.doi.org/10.1557/jmr.2001.0071.

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Abstract (sommario):

Nanostructured WC–18% Co powder was synthesized by using cryogenic mechanical milling, and the thermal stability of the nanostructured powder was investigated in detail. The results indicated that the as-synthesized WC–18% Co powder had an average WC particle size of 25 nm. Growth of WC particles occurred above 873 K; however, the average WC particle size remained smaller than 100 nm in the powder isothermally heated for 4 h at 1273 K. Thermal exposure in air at T < 623 K did not result in significant oxidation of the cryomilled powder. The thermal exposure did promote the formation of WO2 and WO3 oxides. The Co6W6C phase was detected by x-ray diffraction in the powder heated in nitrogen at 1273 K, and the phases associated with decarburization of WC, such as W2C, W3C phases, were not observed. With increasing temperature, the dissolution of W and C elements in the Co matrix led to a gradual increase in {111} crystallographic plane spacing, eventually leading to the formation of an amorphous phase.

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47

Qu, Hai Xia, e Shi Gen Zhu. "Phase Transformation during the Hot Pressing of WC-40vol.% Al₂O₃ Composites". Applied Mechanics and Materials 152-154 (gennaio 2012): 260–65. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.260.

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Abstract (sommario):

WC matrix composites toughened by commercial Al2O3composed of AlOOH, χ-Al2O3and amorphous Al2O3were prepared by high energy ball milling and then hot pressed at 769°C, 984°C, 1100°C, 1540°C for 90min, respectively, to investigate the phase transformation process. Microstructure and mechanical properties of WC-40vol.%Al2O3composites were studied as well. The results showed that, with the increasing hot pressing temperature, the commercial Al2O3 transformed to α-Al2O3completely through γ-Al2O3. WC could be oxidized and decarburized to W, C and W2C at low temperature when the vacuum degree was very low. The existence of W in the composites sintered at 1540°C for 90min could contribute to a metal particle toughening effect to the composites, resulting in the achievement of an excellent fracture toughness of 10.43MPa•m1/2, combining a Vickers hardness of 18.65GPa with a relative density of 97.98% for WC-40vol.%Al2O3composites.

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48

Cheng, Hu, Zhi Gang Fang, Xian Rui Zhao, Sheng Dai e Jian Yi. "Effect of Laser Cladding Technologies on Microstructure and Properties of Ni-Based WC Alloy Coatings". Advanced Materials Research 314-316 (agosto 2011): 245–48. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.245.

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Abstract (sommario):

The Ni-based WC alloy coatings were successfully fabricated on NAK80 mold steel by Nd:YAG and CO2 lasers. The microstructure and properties of the laser cladded coatings were analyzed by SEM, EDS, XRD and microhardness tester. The results show that phase constituents of both coatings are mainly composed of tungsten carbide (WC+W2C), Cr23C6, NiCr, CrB2 and γ-Ni. The excellent metallurgical bondings have formed at the interface between the substrate and the laser cladded coatings. Dendrite and white and block WC phase were observed in two kinds of laser cladded coatings, but the dendrite in Nd:YAG laser cladded coating is more fine. The microhardness of NAK80 mold steel is greatly improved by laser cladding, however the microhardness of the CO2 laser cladded coating is even higher than the Nd:YAG laser cladded coating.

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49

Bergant, Zoran, Barbara Šetina Batič, Imre Felde, Roman Šturm e Marko Sedlaček. "Tribological Properties of Solid Solution Strengthened Laser Cladded NiCrBSi/WC-12Co Metal Matrix Composite Coatings". Materials 15, n. 1 (4 gennaio 2022): 342. http://dx.doi.org/10.3390/ma15010342.

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Abstract (sommario):

NiCrBSi, WC-12Co and NiCrBSi with 30, 40 and 50 wt.% WC-12Co coatings were produced on low carbon steel by laser cladding with an Nd:YAG laser with a multi-jet coaxial cladding-nozzle. The microstructure properties after WC-12Co alloying were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and Vickers hardness tests. The resulting microstructures consisted of a γ-Ni and Ni3B matrix, strengthened with Co and W, Ni3Si, CrB, Cr7C3, Cr23C6, WC/W2C phases. In coatings with 30, 40 and 50 wt.% WC-12Co, a solid solution, strengthened multi-matrix NiCrWCo phase formed, which yielded a higher matrix hardness. Wear tests that monitored the friction coefficients were performed with a tribometer that contained a ball-on-disc configuration, Al2O3 counter-body and reciprocal sliding mode at room temperature. The major wear mode on the NiCrBSi coatings without the WC-12Co was adhesive with a high wear rate and visible material loss by flaking, delamination and micro-ploughing. The addition of WC-12Co to the NiCrBSi coating significantly increased the wear resistance and changed the major wear mechanism from adhesion to three-body abrasion and fatigue wear.

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50

Пак, Александр Яковлевич, Тамара Юрьевна Якич e Александра Ивановна Кокорина. "ЭЛЕКТРОДУГОВОЙ СИНТЕЗ КАРБИДА ВОЛЬФРАМА ИЗ РУДНЫХ КОНЦЕНТРАТОВ". Izvestiya Tomskogo Politekhnicheskogo Universiteta Inziniring Georesursov 332, n. 5 (21 maggio 2021): 170–78. http://dx.doi.org/10.18799/24131830/2021/5/3200.

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Abstract (sommario):

Актуальность исследования обусловлена растущим потреблением карбида вольфрама в связи с его применением в различных сферах: обрабатывающая промышленность, катализ, металлургия и др. Соответственно поиск новых малозатратных методов переработки вольфрамсодержащих руд является актуальной задачей. Цель: определить параметры безвакуумного электродугового синтеза карбидов вольфрама в атмосферной плазме с использованием в качестве исходного сырья концентрата вольфрамсодержащей руды, которые обеспечивают эффект самопроизвольного экранирования реакционного объема от кислорода воздуха. Объекты: синтез карбида вольфрама в плазме дугового разряда постоянного тока из концентрата вольфрамсодержащей руды безвакуумным методом. Методы: безвакуумный электродуговой метод синтеза, рентгенофазовый анализ на рентгеновском дифрактометре Shimadzu XRD 7000s (λ=1,54060 Å), электронная микроскопия, совмещенная с рентгенофлуоресцентным энергодисперсионным анализом на базе микроскопа TESCAN VEGA 3 SBU с приставкой OXFORD X-Max 50 с Si/Li (TESCAN, Чехия). Результаты. Проведена серия экспериментов по синтезу карбидов вольфрама в дуговом разряде постоянного тока из вольфрамового концентрата руды, в результате рентгенофазового анализа полученных образцов, растровой электронной микроскопии, совмещенной с энергодисперсионным анализом химического состава полученных из рудного концентрата образцов, было установлено, что в продуктах электродуговой переработки можно идентифицировать фазы карбида вольфрама WC и W2C, при этом полная переработка исходного сырья наблюдается при длительности электродуговой обработки не менее 30 с (при энергии дуги не менее 95 кДж). Было установлено, что с увеличением времени синтеза доля W2C убывает, при этом доля карбида вольфрама WC возрастает.

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