Formation Of WC Research Articles

Preparation and formation mechanism of (W) WC/Fe bundle reinforced iron matrix composites

To address the issue of strength and toughness inversion in traditional metal matrix composites, which are reinforced by uniformly distributed ceramic particles, this research developed a novel space bundle configuration of reinforced iron matrix composite using tungsten wire (W) and tungsten carbide (WC). This composite was prepared using a lost foam casting process combined with in-situ reaction. Microstructural analysis revealed that WC particles are distributed along the tungsten wire, with larger particles at the center and smaller ones at the edges. The formation of the reinforcement occurs in two stages: first, a solid-liquid reaction between the solid tungsten wire and molten iron during the lost foam casting process, promoting WC formation at high temperatures and carbon potential; second, an in situ solid-solid reaction where Fe diffuses and Fe3W3C decomposes, forming a composite structure of WC and α-Fe. The composite obtained at 1100°C for 9 hours exhibited a compressive strength of 836.59 MPa and a fracture strain of 18.69%, representing increases of 48.46% and 48.69% respectively compared to grey cast iron (GCI). The (W) WC/Fe bundle reinforcement effectively enhances the strength and toughness of the composite through the high volume fraction and gradient distribution of WC particles, combined with the synergistic effect of α-Fe. This research provides a new strategy for improving the mechanical properties of composite materials and resolving the issue of strength-toughness inversion.

Effect of WC content on the microstructure and properties of AlCoCrFeNi2.1 eutectic high entropy alloy coating prepared by ultra-high speed laser cladding technology

AlCoCrFeNi2.1 eutectic high entropy alloy coating with different WC content were prepared on 304 stainless steel surface by ultra-high speed laser cladding technology. Microstructure, phase distribution, Microhardness, friction, and wear properties were analyzed to investigate the influence mechanism of WC on the properties of alloy coatings. The results indicate that the addition of WC results in refined crystalline strengthening. The decomposition of WC leads to the formation of W2C and Cr23C6, which contribute to solid solution strengthening and second-phase strengthening. With increasing WC content, a noticeable improvement in microhardness and wear resistance properties is observed.

Femtosecond Laser Carburization of WS2 Flakes to W2C for Enhanced Photothermal Conversion Efficiency

Photothermal therapy is a new, promising approach for treating cancer in a noninvasive way. Herein, a photothermally efficient nanomaterial is synthesized by exposing bulk WS2 powder, dispersed in carbon‐rich acetonitrile, to high‐intensity femtosecond laser pulses. The photothermal measurements show a significantly higher rise in temperature and enhance photothermal efficiency for the laser‐treated material. The attribution is on the enhancement to the formation of tungsten semi‐carbide (W2C), which is verified by morphological and structural characterization. The tungsten semi‐carbide is formed by laser‐induced carburization; intense laser pulses knock S atoms out of the WS2 lattice and dissociate the acetonitrile molecules, resulting in the formation of W2C. Interestingly, the hexagonal W2C has a two‐dimensional (2D) layered morphology like that of the WS2, suggesting its morphology is not random and might be determined by the morphology of the parent material. The study provides a simple route to transform a 2D transition‐metal dichalcogenide into a 2D transition‐metal carbide, which is useful for applications including photothermal therapy.

Microstructural characteristics and wear-resistant mechanisms of WC-TiC-co coatings with varying TiC contents

In this work, the microstructural characteristics and tribological properties of HVOF-sprayed WC-TiC-Co coatings with varying amounts of TiC addition were studied, along with a comparison with those of the traditional WC-Co coating. The incorporated TiC exhibited a diverse presence in the coatings, including (Ti,W)C solid solution particles and interfacial layers, residual TiC particles, as well as Ti-monolayer that induced planar defects within WC grains. The high stability of (Ti,W)C layers at the WC/Co interfaces effectively suppressed the formation of W2C in the WC-TiC-Co coatings. Notably, the coating with 10 wt% TiC demonstrated superior wear resistance owing to the hardening effects of (Ti,W)C particles and interfacial layers. This effectively mitigated the wear mechanisms such as plastic deformation, extrusion, and micro-cutting of the Co binder, which would otherwise lead to the pull-out of WC particles and accelerate the wear process. These findings provide valuable insights into the microstructure design and performance optimization of WC-based coatings.

Analyzing the preparation, oxidation-related behavior, and electrochemical properties of three-dimensional hierarchical porous WC/C composites

In this study, we prepared biomass porous WC/C composites with a three-dimensional porous structure, and investigated their pore structure, oxidation-related behavior, and electrochemical properties. The results showed that a higher reaction temperature was conducive to the formation of WC on the carbon template. The porous WC/C composites retained the porous structure of the biomass carbon material, and had a large specific surface area (364.19 m2⋅g−1). The overpotential and slope of the Tafel curve of the WC/C composites were lower by 281 mV and 197 mV·dec−1, respectively, than those of the carbon template, while they exhibited a significant increase in electrocatalytic activity. The activation energy of the oxidation reaction of the composites (68.95 kJ⋅mol−1) was higher than that of the carbon template (42.19 kJ⋅mol−1), and their resistance to oxidation improved.

Elevated temperature ablation mechanisms of Cu@rGO/CuW nanocomposites under oxyacetylene torch flame

Copper-tungsten (CuW) composites have been explored in throat lining applications for the rudders and nozzles in the rocket motors, hence it is crucial to investigate their high-temperature ablation behaviors and the corresponding failure mechanisms. Herein, xCu modified reduced graphene oxide reinforced CuW (named as Cu@rGO/CuW) composites (x = 0, 1, 3 and 5 wt%) were fabricated using spark plasma sintering to evaluate their ablation resistances under an oxyacetylene torch flame and to improve their high temperature ablation resistance with in-situ formed tungsten carbides (WC and W2C) during sintering. The composite's surface after ablation can be clearly divided into two regions, i.e., central erosion region and edge transitional region. The ablation products were mainly consisted of WO3, CuWO4 and WC phases. The mass ablation rate and linear ablation rate of 3 wt% Cu@rGO/CuW composite were 0.015 g/s and 0.0023 mm/s, which are 0.25 and 0.3 times smaller than those of the monolithic CuW alloy, respectively. The superior elevated temperature ablation resistance of the composites was attributed to transpiration cooling of Cu and WO3, heat consumptions of the remained Cu@rGO with a high thermal conductivity, and in-situ formation of WC or W2C particles with high melting points. The key failure mechanisms of the Cu@rGO/CuW composites during ablation process with high temperature are thermo-chemical oxidation and thermo-mechanical ablation of oxides such as WO3, Cu2O and CuWO4.

Picosecond laser-textured WC-10Co4Cr metal-ceramic composite coatings with high wear resistance property

The wear resistance properties of anilox roller have been a compelling challenge. A periodic array patterned WC-10Co4Cr metal-ceramic composite coatings is prepared by picosecond laser texturing. Coupled with the generation of cobalt oxide (CoO), tungsten oxide (WO3), di‑tungsten carbide (W2C), the laser processing mechanism is verified to involve the thermal vaporization of the metallic binder phase cobalt (Co), follow by the coulomb explosion removal of ceramic phase tungsten carbide (WC). The nano-hardness of the hexagonal (60°) mesh wall is maintained and even slightly increased by the synergy and competition among the formation of W2C, the removal of the metallic binder phase Co and the annealing softening of thermal effect. The prepared micro-structures on the surface which can capture debris and form stable lubricant film leads to a substantial reduction in both friction coefficient and wear rate, thereby resulting in remarkable improvements in wear resistance. In addition, the primary wear mechanism of the textured coating is found to be abrasive wear, accompanied by adhesive wear and oxidation wear. The integration of the metal-ceramic coatings and technology with laser processing enables the preparation of anilox roller with high hardness and exceptional wear resistance.

Effect of vanadium addition on the microstructure and properties of NiCuBSi-WC60 composite coatings deposited by laser direct deposition

There is an urgent need to extend the tool life of shield boring machines for complex working conditions. Here, NiCuBSi-WC60 composite coatings with different vanadium contents were prepared by laser direct deposition on the surface of shield boring machine cutter rings, and the influence mechanism of vanadium(V) addition on the microstructure and properties of the coatings was studied. The microstructure of the coatings was analyzed by SEM, XRD, EBSD and TEM to reveal the mechanism of microstructure evolution during laser deposition. The microhardness was tested by Vickers hardness tester, and the wear resistance was tested in practical engineering applications. The results show that the addition of V can promote the formation of W2C and VC, and with the increase of V content, the W2C precipitated in the coating gradually grows and changes from flocculent to plate. The coating containing V mainly consists of Ni(Cu) bonded phase, WC, W2C and VC reinforced phase and Ni10(WC)3 transition phase. HRTEM found that the orientation relationship between W2C and VC interface is W2C (111) // VC (001), W2C [011¯] // VC [11¯0], the angle difference between the Ni(Cu) (111) direction and the Ni10(WC)3 (101¯2) direction is 5.13°, and the lattice mismatch is 12.35%. The average hardness of the coating at the locations without spherical WC particles was statistically analyzed and the highest hardness of 739.90 ± 82.58 HV was found for the coating with 2 wt% V. A small amount of V addition effectively improves the distribution of the reinforcing phase in the coating, thus increasing the wear resistance of the coating. Practical engineering application shows that the wear rate of V-modified NiCuBSi-WC60 coated cutter ring is only 4.6% of that of ordinary 5Cr5MoSiV1 steel ring in the same trajectory line during the boring process of 1521 m in Chengdu sand and pebble strata.

Study on Tungsten Metallization and Interfacial Bonding of Silicon Nitride High-Temperature Co-Fired Ceramic Substrates

For the first time, Si3N4 HTCC has been prepared using W as the metal phase by high-temperature co-firing (1830 °C/600 KPa/2 h) as a potential substrate candidate in electronic applications. It was discovered that the addition of Si3N4 to the W paste has a significant impact on thermal expansion coefficient matching and dissolution wetting. As the Si3N4 content increased from 0 to 27.23 vol%, the adhesion strength of W increased continuously from 2.83 kgf/mm2 to 7.04 kgf/mm2. The interfacial bonding of the Si3N4 ceramic and the conduction layer was discussed. SEM analysis confirmed that the interface between Si3N4 and W exhibited an interlocking structure. TEM, HRTEM and XRD indicated the formation of W2C and W5Si3 due to the interface reactions of W with residual carbon and Si3N4, respectively, which contributed to the reactive wetting and good adhesion strength between the interface. Suitable amounts of Si3N4 powder and great interfacial bonding were the main reasons for the tough interfacial matching between the Si3N4 ceramic and the conduction layer.

STUDY OF THE STRUCTURE AND PROPERTIES OF THE SURFACE OF HARD ALLOY VK10KS AFTER TWO-COMPONENT ELECTRICAL EXPLOSION TREATMENT WITH SYNTHETIC DIAMONDS

The article presents the results of studies of the VK10KS hard alloy after two-component electroexplosive treatment (EVL) with synthetic diamonds. Aluminum was used as the exploding conductor. The choice of aluminum is based on the experimental data of a number of researchers who note that in order to increase the strength properties of hard alloys at elevated temperatures, it is necessary that particles with a size of hundredths of a micron of ultrafine α-Al2O3 be present in the cobalt binder. Thus, the addition of aluminum to the bond significantly increases the hardness, wear resistance and bending strength. The essence of the EVL is the accumulation of energy by a battery of impulse capacitors up to 10 kJ and its subsequent discharge for 100 μs through a conductor that experiences explosive destruction. In this case, the treated surface is heated and saturated with explosion products, followed by self- hardening due to heat removal to the environment and deep into the material. To increase the hardening effect, a powder sample of synthetic diamond powder AC2 weighing 60 mg was additionally added to the explosion area. It was experimentally revealed that alloying the surface of the VK10KS hard alloy with the products of aluminum electric explosion with a sample of diamond powder did not lead to the formation of a hardened diamond-type layer. During processing, the diamond powder trans-formed into graphite. Despite the fact that the diamond layer was not formed, surface hardening of the VK10KS hard alloy occurred after the electric explosion of diamond powder with aluminum as a conductor. The thickness of the hardened surface layer is about 15 µm with a nanohardness of 24000 MPa, which is 2 times higher compared to the initial state. The increase in hardness is associated with the refinement of phases in the surface layer and the formation of W2C and α-Al2O3 type carbides. The surface roughness of machined carbide inserts does not exceed the values corresponding to the technical requirements.The study of the cobalt binder in the heat-affected zone after two-component EVL found that the cobalt binder is additionally alloyed with tungsten, carbon, aluminum, which are part of the explosive materials and the base. Additional alloying of the cobalt binder will lead to its hardening, which will positively affect the service life of tungsten carbide hard alloys in general.

Promising WC-30WB-10Co Cemented Carbide Coating with Improved Density and Hardness Deposited by High Velocity Oxy-Fuel Spraying: Microstructure and Mechanical Properties

WC-Co coatings sprayed by HVOF attracted much attentions, benefiting from the satisfactory wear resistance and high bonding strength to the steel substrates. Nevertheless, high density of conventional coatings required excessive Co binder, which decreased the hardness and operation life. Based on this, a strengthened WC-30WB-10Co coating was developed with both high density and improved hardness, using high-qualified thermal sprayed composite powders. Comparison between the phase composition, microstructure, interfacial bonding strength and properties of the newly developed coatings and WC-12Co conventional coatings was clarified in detail. Compared to WC-12Co powders, spherical WC-30WB-10Co powders showed higher apparent density and flowability, due to the in situ formed CoWB and CoW2B2 phases during the accelerated metallurgy reaction. Oxidation and decarburization were confirmed during HVOF spraying with the formation of W2C, Co3W3C and Co6W6C phases in both coatings. Attracting WC-30WB-10Co coating with microhardness of 1639HV0.3 and relative density of 99.44% was achieved, higher than those of 1222 HV0.3 and 99.27% of WC-12Co. This was attributed to the formation of the ternary compounds and the consumption of the ductile Co binder in the WC-30WB-10Co coatings. The hard alloy coatings are expected to be well applied in aggressive wear and corrosion environments due to the high hardness and low metal phase content.

Taguchi-based experimental investigation into weld cladding of Ni-WC MMC overlays by CMT process

In the search for versatile and effective weld cladding processes to deposit ultra-wear-resistant Ni-WC MMC (Ni-based tungsten carbide metal matrix composite) overlays for mining applications, there is an increasing interest in exploring advanced low-heat-input cold metal transfer (CMT) method. Depositions of single weld bead tracks of Ni-WC MMCs on steel plates were performed by employing the CMT process; Taguchi’s design of experiments was used to plan the experimental investigation. All weld tracks exhibit continuous and uniform bead profile and sound metallurgical bonding to the substrate. Retained WCs are present in the overlay tracks relatively uniformly. The formation of primary WC and secondary carbides is observed depending on the level of dilution. In contrast to standard gas metal arc welding processes, the volume fraction of retained WC, which is negatively correlated with dilution level, is not directly interrelated with heat input for the CMT process and can reach a high level together with improved weld bead appearance at high deposition rate. Deposition rate has a positive correlation with average instantaneous power, which is, in turn, positively correlated with wire feed speed. The addition of oxygen into shielding gas mixtures promotes carbide transfer from cored feed wire to the weld track and increases the volume fraction of retained WC. Analysis of signal-to-noise ratios shows that it is difficult to find a single set of optimized processing parameters, and trade-offs are needed in engineering practice. The present investigation demonstrates that the Taguchi method is a powerful tool in process improvement for weld cladding of Ni-WC MMC overlays.

Thermodynamic analysis and microstructural evolution of the W-Mo-Ni-C system produced by mechanical alloying

In this research, the microstructural evolution of the W-Mo-Ni-C system was studied by conducting a thermodynamic analysis of formation enthalpies using the Miedema model. Samples were synthetized with different milling times of up to 240 h and analyzed using X-ray diffraction to determine the phases that were produced at each stage of the synthesis. The experimental results indicated carbon diffusion into the transition metal lattice, as WC formation was observed at 120 h and NiC formation was observed at 160 h. Nanostructured MoNi3 and MoW alloys were identified at initial stages from 40 h to 120 h, and as carbon diffusion continued, the MoW alloy transformed into WMoC carbide at 200 h. The Miedema model predictions established that the necessary energy for carbide formation is much larger than that for the formation of alloys of transition metals, demonstrating that these alloys must be formed first, which was validated by experimental data. It was found that the mechanical alloying process produced materials that were out of equilibrium.

In-situ electrochemical reconstruction of tungsten carbide using Na2CO3-containing molten salt

This paper reports a novel method for rapid atomic-level reconstruction of tungsten carbide (WC) using Na2CO3-containing molten salt. Herein, WC was used as consumable anode and Na2CO3 was active species on WC anode and carbon donor. Thermodynamic calculations were used to verify the feasibility of this electrolytic method for reconstructing WC. Experimental results showed that the addition of Na2CO3 significantly enhanced dissolution efficiency of WC. Therefore, more tungsten (W) source was supplied. Electrochemical analysis demonstrated that Na2CO3 also supplied carbon by two-step reduction process, which led to the formation of WC. These experiments confirmed that cathode product was converted from W to WC by the introduction of Na2CO3 additive into molten salt. WC phase started to form at cell voltages above 2.2 V. In initial stage of reaction, carbonate was preferentially reduced in cathode region to form amorphous C. As the reaction proceeded, W ions migrated from anode and began to participate in reduction process, forming W. Finally, W was transformed to WC by carbonization process.

In Situ Tungsten Carbide Formation in Nanostructured Copper Matrix Composite Using Mechanical Alloying and Sintering.

In this study, an in situ nanostructured copper tungsten carbide composite was synthesized by mechanical alloying (MA) and the powder metallurgy route. The microstructure and phase changes of the composite were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Tungsten carbide phases (WC and W2C) were only present after MA and combination of sintering. Higher energy associated with a longer milling time was beneficial for the formation of WC. Formation of W2C and WC resulted from internal refinement due to heavy plastic deformation in the composite. The solubility of the phases in the as-milled and sintered composite was described by the changes of the lattice parameter of Cu. Chemical analysis of the surface of a composite of W 4f and C 1s revealed that the increased defects introduced by MA affect the atomic binding of the W-C interaction.

INVESTIGATION OF TUNGSTEN SURFACE CARBIDIZATION UNDER PLASMA IRRADIATION

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.

Phase Formation and Physicomechanical Properties of WC–Co–CrB2 Composites Sintered by Vacuum Hot Pressing for Drill Tools

Phase Formation and Physicomechanical Properties of WC–Co–CrB2 Composites Sintered by Vacuum Hot Pressing for Drill Tools

Corrosion characteristics of plasma spray, arc spray, high velocity oxygen fuel, and diamond jet coated 30MnB5 boron alloyed steel in 3.5 wt.% NaCl solution

Abstract 30MnB5 boron alloyed steel surface is coated using different coating techniques, namely 60(Ni-15Cr-4.4Si-3.5Fe-3.2B 0.7C)-40(WC 12Co) metallic powder plasma spray, Fe-28Cr-5C-1Mn alloy wire arc spray, WC-10Co-4Cr (thick) powder high velocity oxy-fuel (HVOF), and WC-10Co-4Cr (fine) diamond jet HVOF. The microstructure of the crude steel sample consists of ferrite and pearlite matrices and iron carbide structures. The intermediate binders are well bonded to the substrate for all coated surfaces. The arc spray coated surface shows the formation of lamellae. The cross-section of HVOF and diamond jet HVOF coated surfaces indicates the formation of WC, W2C Cr, and W parent matrix carbide structures. The corrosion characteristic of the coated steel has been investigated in 3.5 wt.% NaCl solution using electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDAX) techniques. The results reveal that the steel corroded in the medium despite the coatings. However, the extent of corrosion varies. HVOF coated sample demonstrated the highest corrosion resistance while arc spray coated sample exhibited the least. EDAX mapping reveals that the elements in the coatings corroded in the order of their standard electrode potential (SEP). Higher corrosion resistance of HVOF coated sample is linked to the low SEP of tungsten.

Laser remelting of WC-CoCr surface coated by HVOF: Effect on the tribological properties and energy efficiency

In this article, the tribological behavior and energy efficiency of surfaces coated with WC-CoCr/HVOF were evaluated after a laser remelting process, using low and high laser energy densities, respectively, 33.3 and 150 J/mm2. The purpose of laser remelting was to adequately modify the microstructure of the coatings and promote better performance during surface sliding. Therefore, the microstructure, phase composition and microhardness of the coatings were investigated, and heat effect on the substrate. During dry and lubricated tribological tests, friction coefficient (COF), wear, and surface roughness also were evaluated. In the dry tests, friction, wear and heat dissipation energies were obtained, which were then correlated with the energy consumed by the tribometer. A HEPR-type biodegradable oil was used in the lubricated tests. The proper formation of W2C and Co3W3C, obtained for the lower energy density, increased the hardness, without weakening the material, while the CrC phase acted as an anti-wear barrier. Whereas for the high energy density, thermal decomposition produced fragile phases, which were easily removed from the matrix during the wear test. The sample tested in as-sprayed condition had a high adhesion and friction compared to the remelted samples. On the remelted surfaces, greater friction stability was obtained. The lower dry friction was not linked to the lower power consumption, a result which was then attributed to the higher heat dissipation from the surface during the tests. Finally, this study proposes a methodology for quantifying the efficiency of sliding surfaces and points to a sustainable solution for tribology.

Method of obtaining multicomponent fine-grained powders for boron carbide matrix ceramics production

The paper presents a low-temperature method for the synthesis of tungsten boride containing ultra-fine powders of boron carbide matrix ceramics constituting an important class of superhard materials with diversity of industrial applications. Wet chemical method was used to prepare preceramic precursors. The technique provides annealing of a viscous paste of the mixture of ammonium paratungstate–zirconium(IV) oxide–cobalt acetate tetrahydrate–sucrose–amorphous boron at 200 °C in air and then at 600 °C in argon atmosphere for 2 h with the further grinding and additional annealing of the obtained powders at 800–1500 °C. Hot pressing of the complex ceramic powders at 1000–1700 °C was realized by using the SPS method. It was established that at 600 °C there were formed WO3–x, Co3O4, CoO, and amorphous carbon. The XRD data confirmed low temperature (800–1000 °C) formation of WC–Co, ZrB2, B4C, and W2B5. Tungsten carbide was completely converted into tungsten boride. Structural-morphological characteristics of the obtained samples were studied by using the SEM.