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In this study, B4C–TiB2 composite ceramics with different TiB2 contents sintered via hot pressing are processed into ceramic tools to turn AISI 4340 workpieces. Finite element analysis using the Deform-3D software is conducted to examine the effects of the cutting speed, depth of cut, and feed rate on the main cutting force and tool temperature of the B4C–TiB2 ceramic tools. The wear mechanism is investigated through the microstructural analysis of the wear profile obtained after the turning experiments. Simulation results show that the B4C–30%TiB2 ceramic tool demonstrates the best cutting performance. The optimal cutting parameters for the B4C–30%TiB2 ceramic tool are a cutting speed of 300 m/min, depth of cut of 0.3 mm, and feed rate of 0.1 mm/r. The turning experiments reveal that the B4C–30%TiB2 ceramic tool has a longer tool life than a commercially available YD tungsten carbide tool. The main wear forms of the B4C–30%TiB2 ceramic tool are craters, chipping, and flank wear, and the wear mechanism can be attributed mainly to abrasive wear, adhesive wear, oxidative wear, and diffusion wear. This work can lay a theoretical foundation for the practical application of B4C–TiB2 ceramic tools.

Erosion may be defined as the destruction of a material by abrasive action of a liquid or gas. The wearing away is purely mechanical with no electro-chemical reaction. This process occurs on surfaces, pipelines wherever the flow of liquid along with particles in suspension causes erosion. In this investigation, the erosion rate on a coated surface was studied using pot erosion tester. The substrate material used was stainless steel of grade 316. The material was machined to the required dimensions and was coated one set with tungsten carbide- cobalt and another set with alumina. The coating was done using a detonation spray process. The specimens were weighed before and after the testing. The mass loss and erosion wear rate were calculated. It was found that the erosion wear rate was minimum when the speed of rotation was 3 m/ sec and increases as the speed increases. The SEM examination revealed the formation of flake type debris due to the interaction between the erodent and the specimen.

Machining of difficult-to-cut material such as 316 Stainless Steel has become a vital concern in machining industry. This is due to its mechanical properties of high hardness which leads to the high tendency of cutting tool breakage. Hence, the understanding of thorough progression of cutting tool deterioration is crucial, so that a better improvement of machining 316 Stainless Steel could be established. Thus, a series of documented experiments had been conducted to monitor and understand the tool deterioration of coated tungsten carbide insert in dry down-milling of 316 Stainless Steel. It was observed that the cutting tool started to deteriorate after the second pass of milling experiments and achieved VB = 0.3 mm after the sixth pass on average. Two types of tool deterioration mechanisms were identified which were tool wear and chipping. However, it was observed that the most predominant mode of tool deterioration was flank wear (tool wear). Cutting tools deteriorated gradually due to blunting and rubbing of tool edge over the surface of machined workpiece. .

Rational tuning the surface charge state for catalysts is an attractive strategy to promote their catalytic activity toward catalyzing diverse chemical and electrochemical reactions. In this work, we modified the surface of a pure tungsten carbide (WC) material with an ultra-thin nitrogen doped carbon (NC) layer (WC@NC) for catalyzing alkaline hydrogen evolution reaction (HER). The XPS studies revealed an increased electron density on WC when the NC layer was introduced on its surface. Thus, a significant decrease of 282 mV in overpotential at 10 mA cm−2 was observed on WC@NC electrode in comparison with the pristine WC electrode. The higher electrochemical active surface area, lower activation energy barrier, and excellent durability were identified by various electrochemical measurements. The three-dimensional charge density difference was also calculated and the results indicated that an electron-transfer process occurred from the NC layer (donor) to the WC layer (acceptor) through the interface of WC@NC composite material. The analysis explained the underlying mechanism for the promotion of the HER activity. Such a comprehensive study is expected to provide useful guidance for promoting the catalytic performance of diverse catalysts toward different reactions.

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.

Tungsten carbides (W2C and WC) materials, as promising non-precious electrocatalysts, possess highly efficient activity for HER. Herein, N-doped graphene supported tungsten carbide (N–W2C/WC) nanocomposite is synthesized by spray drying process followed with a two-step pyrolysis treatment, which exhibits a remarkable hydrogen evolution reaction (HER) activity and excellent stability in acidic solution and alkaline solution. N–W2C/WC displays low overpotentials of 166 mV and 125 mV to achieve a current density of 10 mA cm−2 and small Tafel slopes of 60.97 and 62.66 mV dec−1 in 0.5 M H2SO4 and 1.0 M KOH, respectively. After 1000 cycles, the electrocatalytic activity of N–W2C/WC is almost no change in acidic media but slightly decreases in alkaline media. This work might provide a new way to explore high comprehensive performance tungsten-based electrocatalyst for HER.

Precision grinding with ultrathin arc-shaped diamond (UAD) grinding wheels provides a satisfactory solution for the fabrication of high-quality microstructures on tungsten carbide (WC) molds. However, ultrathin grinding wheels are difficult to be trued, due to the limited small grinding wheel profile. In this paper, an on-machine truing method for ultrathin arc-shaped diamond grinding wheels is proposed. First, a model of the three-axis linkage controlling truing for the diamond grinding wheel was introduced. Then, the effects of the setting and measurement errors of the grinding wheel on the profile radius were theoretically analyzed. A mathematical model of the error was developed. Furthermore, an aspherical microstructure array of tungsten carbide was ground by the trued diamond grinding wheel. The experimental results demonstrated that the expected arc radius of the grinding wheel could be achieved and the binderless tungsten carbide mold could be ground efficiently and precisely. The profile error of the grinding wheel (diameter of 23 mm, thickness of 0.38 mm) reached 8.5 μm . An aspherical microstructure array surface of tungsten carbide with a form accuracy of 15 μm was obtained by grinding with the trued diamond grinding wheel without additional compensation.

The high reliability and extended life of seawater hydraulic components is dependent on the tribological properties of key friction pairs, more and more attention has been given to the performance degradation and lifetime of the friction pairs. In this paper, the wear process of Tungsten carbide (WC) with 6%wt of Ni (WC–6Ni)/SiC friction pair is studied through the tribological test under seawater lubrication. Considering the random effects and the complex wear mechanism of WC-6Ni/SiC, an efficient Inverse Gaussian (IG) process supported lifetime prediction model is established by coupling the multiple stresses under seawater lubrication, and the parameters in the proposed IG process model are derived. Two actual cases are used to validate the proposed method. The prediction model and experimental results show the high accuracy in time-varying lifetime prediction of WC-6Ni/SiC, which is of great significance to the evaluation of friction pair and the maintenance for seawater hydraulic components.

Tungsten carbide (WC) reinforced metal matrix composites are ideal protective coatings against wear and are widely used for surface coating. However, WC particle dissolution, subsidence, and coating cracking are some of the known challenges limit the application of the coating fabricated by plasma cladding with traditional synchronous feeding. To address this issue, a plasma remelting and injection (PRI) method is proposed to fabricate WC reinforced metal matrix composite coatings. The optimal injection angle of the WC particles was determined by infrared image and geometric calculations, to improve the utilization rate and decrease the dissolution of the particles. The microstructure, hardness, residual stress, and WC particle distribution of the coatings fabricated by the PRI and synchronous-feeding methods were investigated, and the mechanism of WC particle dissolution was analyzed. The results indicate that the WC particles of the synchronous-feeding coating obviously sank to the coating bottom, and transcrystalline cracks appeared inside the WC particles, resulting in serious cracking of the coating. By contrast, the PRI method could effectively avoid the subsidence of WC particles and reduce the thermal damage to WC particles, which increased the coating surface hardness and reduced the residual stress and cracking tendency of the coating.

This study proposed the methodology to produce silicon carbide particulate MMCs based on aluminum to create typical low-cost MMCs and achieve a homogeneous scattering of ceramic material. The trial was done with a different weight fraction of Silicon Carbide (2%, 3%) and Tungsten Carbide (2%, 3%) with all other parameters being maintained. A growing hardness was noticed with the rise in SiC & WC weight 2 to 3%. The advantages of this technique include improved mechanical characteristics, minimal residual stress and deformation, and fewer flaws. Although casting technique poses numerous technical obstacles, this problem can nevertheless be addressed. Aluminum materials with high strength to weight and low density have been proven to be the best option. As lightweight materials are developed, weight reduction has been offered several alternatives through conducting different tests to analyze different features such as mechanical and metallurgical characteristics.

The subsurface damage in the laser machining process dramatically affects the mechanical properties and the service life of the cemented tungsten carbide. To further reveal the interaction mechanics, the subsurface damage characteristics of WC/8Co cemented carbide ablated by a nanosecond UV laser is explored through the angle polishing method, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) combined with focused ion beam (FIB) milling. The results show that severe cracking and crushing behaviors appear in the re-solidified areas and the heat-affected zone (HAZ). Based on the temperature field and stress field simulation results, the high temperature gradient induced thermal stress is responsible for the subsurface damage behavior. The blocking of the ablated groove caused by the solidification of the melted material is identified. The XPS spectrums indicate that the machined cemented tungsten carbide is seriously oxidized in the surface and to some extent in the subsurface layer, with the main oxidization products to be WO3, CoWO4, WO2, CoO and Co3O4. In addition, the deformation behavior of WC grain and the disordered alignment of Co atoms are identified in the re-solidified area and HAZ.

To improve the efficiency, one of the important strategies adopted by automotive manufacturing industries is the lightweight materials usage. Magnesium based metal matrix composites (MMC) have the prospective to meet the demanded requirements. In this study, AZ91 based MMCs reinforced with 1.5 and 3.0 wt % of tungsten carbide (WC) particulates were investigated as the alternatives to existing material. The samples were then solutionised at 420 °C and artificially aged at 175 °C to improve their mechanical properties. Characterization revealed that there were the reductions in tensile strength whereas the enhancement in compressive strength with WC addition into the matrix. At product level experimental analysis, quasi-static load testing of pistons showed that AZ91 alloy piston resisted a load of 10 kN. WC addition improved the strength of the pistons by 30% and 70% (approx.). It encouraged the magnesium-based materials usage for piston application with a maximum weight reduction of 35%.

The development of inexpensive and efficient Pt-free electrocatalysts for the hydrogen evolution reaction (HER) is greatly crucial for water electrolysis. Tungsten carbide (WC) exhibiting a Pt-like electronic structure represents an attractive alternative, although its overall performance is limited by the strong W-H bond that impedes hydrogen desorption. Here, we employed an in-situ interface engineering strategy to construct high-performance and cost effective electrocatalysts comprising WC/tungsten phosphide (WP) heterostructures that were anchored on N,P-codoped carbon (WC/WP@NPC) via a one-step pyrolysis of a melamine polyphosphate/WO3 hybrid in an inert atmosphere. Owing to the crystal structure compatibility and electron-rich property of WP, it optimizes the electronic structure and hydrogen adsorption configuration of WC, thus significantly weakening the W-H bond with a thermoneutral Gibbs free energy of hydrogen adsorption (ΔGH*) of −0.05 eV. Additionally, NPC ensures fast electron transport and structural stability of the WC/WP@NPC ternary architecture. These synergistically lead to outstanding HER performances of the catalyst in acidic and alkaline media. Our finding offers a new strategy for designing Pt-alternative electrocatalysts with outstanding electrochemical performances for high-efficiency water splitting and other applications.

Tungsten carbide (W2C) has emerged as a potential alternative to noble-metal catalysts toward hydrogen evolution reaction (HER) owing to its Pt-like electronic configuration. However, unsatisfactory activity, dilatory electron transfer, and inefficient synthesizing methods, especially for nanoscale particles, have severely hindered its large-scale applications. Herein, a novel heterostructure composed of W2C and tungsten phosphide (WP) embedded in nitrogen-decorated carbon (W2C/WP@NC) was constructed as an efficient HER electrocatalyst. The as-prepared W2C/WP@NC catalyst exhibits remarkable electrocatalytic activity and robust durability toward HER both in acids and bases. More notably, the W2C/WP@NC catalyst demonstrates low overpotentials of 116.37 and 196.2 mV to afford a current density of 10 mA cm-2 and reveals slight potential decays of about 6.4 and 7.64% over 12 h continuous operation in bases and acids, respectively. The overall water-splitting performance was further evaluated using the W2C/WP@NC catalyst as the cathode and commercial RuO2 as the anode in an electrolyzer, which can realize an overall current density of 10 mA cm-2 and maintain long durability of more than 12 h with a small cell voltage of 1.723 V. This work opens up new opportunities for exploring cost-efficient electrocatalysts in sustainable energy conversion.

Alloying elements have been added to β-NiAl to improve strength and creep resistance at high temperature enhancing β-NiAl attractiveness and competitiveness. Particularly, tungsten carbides (WC) have been used to modify this aluminide, resulting in an increase in hardness and improved its tribological behavior in high temperature. However, the size of WC particles and the processing conditions account for the microstructure obtained and the resulting properties. This study takes an important step toward understanding how carbide particle size can contribute or interfere in the synthesis and microstructure of NiAl-based coatings. NiAl intermetallic coatings were processed by in situ synthesis during deposition by plasma transferred arc (PTA). Powder mixtures of elementary Ni and Al powders with and without the addition of 1 wt% carbide microparticles and of 1 wt% WC nanoparticles. Carbide microparticles increased the dilution with the substrate and consequently the density of point defects, which had a strong impact on hardness. However, the addition of WC nanoparticles had a negative impact on the synthesis of NiAl, delaying/inhibiting its formation, which was reflected on the microstructure and low hardness of coatings.

The precision machining of hard and ultra-hard materials by the laser beam is a key subject in the field of the modern manufacturing process. To improve the surface quality, the ablation threshold of a single pulse and the influence of the laser parameters on the surface characteristics of cemented tungsten carbide (WC-8Co) are firstly quantified and explored, where the material melting, the evaporation and the phase explosion are involved. The results also show that the scanning speed and the scanning times play important roles on the material removal efficiency. In addition, the crack formation seems to be inevitable under various parameters, where surface cracking in a certain direction to the laser scanning direction caused by the temperature gradient is found. The oxidization behavior is investigated by the XPS, the EDS and the Raman spectrum, which indicates that the main oxidation products are identified to be WO3, CoWO4, Co3O4 and CoO.

Made available in DSpace on 2022-04-28T19:42:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Introduction: This split-mouth randomized clinical trial aimed to compare the enamel surface roughness (SR) and color alteration after bracket debonding and polishing using 2 systems. Methods: After removal of excess adhesive using a 12-blade tungsten carbide bur on a low-speed handpiece, a randomized polishing procedure using Sof-Lex discs was applied on 1 side (n = 36) and Sof-Lex Spiral Wheels on the contralateral side (n = 36). Dental replicas were obtained with epoxy resin before bracket bonding and after tooth polishing. The SR was evaluated using a profilometer. The color was assessed using an Easyshade spectrophotometer before bracket bonding, immediately after tooth polishing, and 30 days after polishing. Two-way analysis of variance and t tests were applied for statistical analysis. Results: The SR of enamel showed similar results between the polishing systems (P = 0.309) and between moments (before bracket bonding and after tooth polishing) (P = 0.317). The color change was also similar between the polishing systems (P >0.05). Conclusions: The Sof-Lex discs and Sof-Lex Spiral Wheel polishing systems used after removal of excess adhesive using a 12-blade tungsten carbide bur on a low-speed handpiece did not appear to significantly damage the enamel surface, and the color change was similar between them. Division of Orthodontics University Ceuma Department of Orthodontics State University of São Paulo Department of Orthodontics Uninga University Center

Tungsten carbides have attracted wide attentions as Pt substitute electrocatalysts for hydrogen evolution reaction (HER), due to their good stability in an acid environment and Pt-like behaviour in hydrolysis. However, quantum chemistry calculations predict that the strong tungsten-hydrogen bonding hinders hydrogen desorption and restricts the overall catalytic activity. Synergistic modulation of host and guest electronic interaction can change the local work function of a compound, and therefore, improve its electrocatalytic activity over either of the elements individually. Herein, we develop a creative and facile solid-state approach to synthesize self-supported carbon-encapsulated single-phase WC hybrid nanowires arrays (nanoarrays) as HER catalyst. The theoretical calculations reveal that carbon encapsulation modifies the Gibbs free energy of H* values for the WC adsorption sites, endowing a more favorable C@WC active site for HER. The experimental results exhibit that the hybrid WC nanoarrays possess remarkable Pt-like catalytic behavior, with superior activity and stability in an acidic media, which can be compared to the best non-noble metal catalysts reported to date for hydrogen evolution reaction. The present results and the facile synthesis method open up an exciting avenue for developing cost-effective catalysts with controllable morphology and functionality for scalable hydrogen generation and other carbide nanomaterials applicable to a range of electrocatalytic reactions.

High-hardness TaN compacts with a diameter and height of 6 mm were synthesized through the phase transformation of CoSn-type into WC-type TaN under experimental conditions of high temperature and high pressure. The Vickers hardness of WC-type TaN compacts obtained at the pressure of 5 GPa and the temperature of 1873 K is found to be ~21.5 ± 1.5 GPa with a load of 3 Kg, which is comparable to that of the pure tungsten carbide compact (~20 GPa) and higher than those of ultrahigh temperature ceramics ZrB2 and HfB2 under the same load. The high hardness of WC-type TaN compacts presented in this work is attributed to the deviatoric strain and well-bonded nanograins. The synthesized WC-type TaN compacts also possess a high oxidation temperature (1072 K). These results suggest that the WC-type TaN with high hardness and high thermal stability holds great promise for industrial applications.

In this study, the impact of varying spraying current on tribological performance and microstructural properties for coating was investigated. Atmospheric plasma spraying (APS) was used as the technique of depositing coatings on Q235 grade steel (equivalent to ASTM A36 mild steel). The coated samples were characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), adhesion testers and microhardness tester. Scratch tests were carried out under ambient and dry environments using a pin-on-plate configuration against Tungsten Carbide (WC) body (pin/stylus) for a constant load. It was found that samples sprayed under higher current had better adhesive bond and erosion wear resistance, they also had the lowest wear loss and least percentage porosity. Additionally, hardness was improved almost 10 times of the base material in comparison to lower current samples. Resumen: En este estudio se investigó el impacto de la corriente de pulverización variable sobre el rendimiento tribológico y las propiedades microestructurales para el recubrimiento del Cr2O3. La pulverización con plasma atmosférico (PPA) se usó como la técnica para depositar recubrimientos de Cr2O3 sobre acero de grado Q235 (equivalente al acero dulce ASTM A36). Las muestras recubiertas se caracterizaron usando microscopía óptica (MO), microscopía electrónica de barrido (MEB), espectroscopia de energía dispersiva (EED), probadores de adherencia y probadores de microdureza. Las pruebas se llevaron a cabo en medios ambientales y secos utilizando una configuración de pin en placa contra el cuerpo de carburo de tungsteno (WC) (pin/stylus) para una carga constante. Se encontró que las muestras rociadas con una corriente más alta tenían un mejor enlace adhesivo y una mejor resistencia al desgaste por erosión, también tenían menor pérdida de desgaste y menor porcentaje de porosidad. Además, se mejoró la dureza casi 10 veces del material base en comparación con muestras de corriente más baja.

In the present study, we fabricated tungsten carbide (WC) coatings on tungsten using a recently proposed two-step interstitial carburization method and systematically investigated their mechanical behavior, including their responses to indentation, scratch, and wear. The coatings comprised WC and a very small amount of W2C dispersed at the coating–substrate interface. The volume fraction of the carbide phases nearly reached 100 %, and the grain size of WC increased with increasing distance from the surface, thus exhibiting a distinct gradient microstructure with columnar WC grains. Indentation experiments on the coating surface showed that the coating attained a hardness of 25 GPa and cracks were generated when the indentation load exceeded 5 N. The fracture toughness of the coating was estimated to be 2.5 MPa m1/2. The response of the coating to scratching was not sensitive to the scratching speed, and an increase in the scratching speed did not alter the geometry of the grooves, but it resulted in an earlier occurrence and a higher density of cracks; further, it leads to increased acoustic emission. Delamination of the coating did not occur when the normal load was in the range of 0–100 N, indicating that the adhesion strength of the coating was greater than 100 N. We studied the wear behavior using a ball-on-disc tribometer and found that the WC coatings exhibited extraordinarily high wear resistance, and both abrasive wear and adhesive wear mechanisms acted concurrently during wear. Therefore, we verified that the WC coatings prepared by interstitial carburization have a high hardness and excellent scratch and wear resistance.

Cu–Al2O3 composites are widely used in electrical contact fields because of their excellent electrical conductivity, thermal conductivity and arc erosion resistance. (WC + SiCw)/Cu–Al2O3 composites with better properties were prepared by powder metallurgy combined with an internal oxidation process that introduced micron-sized WC particles and SiCw into the Cu–Al2O3 composite. The synergistic strengthening mechanism effect of nano-Al2O3 particles, micron-sized WC particles and SiCw in copper matrix composites was analyzed. The results show that there is a semi-coherent interface between the nano-Al2O3 particles and the copper matrix. The ultimate tensile strength of the (1WC + 2SiCw)/Cu–Al2O3 composite is 531.6 MPa, which is 12.7% and 4.5% higher than that of the Cu–Al2O3 composite and the SiCw/Cu–Al2O3 composite, respectively. According to theoretical calculations and an analysis of the strengthening mechanism, the contributions of the Orowan strengthening and load transfer strengthening mechanism in the (1WC + 2SiCw)/Cu–Al2O3 composite are 27.3% and 16.6% respectively. The synergistic strengthening effect of particles and whiskers contributed 6.0% to the tensile strength of the (1WC + 2SiCw)/Cu–Al2O3 composite.

The high-performance tool materials have been inevitably used for most of the cutting tool applications where high reliability and difficult to cut materials are of major demand. The cemented carbides and its composites offer an excellent combination of the properties where it can be used for tool materials due to its high wear resistance, high hardness at elevated temperatures, and considerable fracture toughness. However to obtain optimum values of mechanical properties and uniformly distributed ultrafine grains, a number of new fabrication techniques, alteration in the content of cemented carbide composition, and variation in the parameters of fabrication process have been employed. This review paper will come in handy for researchers and scientists working on advanced cemented carbides and spark plasma sintering as it overviews the recent work done on tungsten carbide composites using the novel spark plasma sintering technique considering different process parameters in order to achieve ultrafine microstructures of sintered specimens, enhanced mechanical properties of composites in addition to energy as well as time saving considerations. The thorough review of various research papers revealed that the parameters of the sintering (sintering temperature, applied pressure, surrounding environment), additives in sintering (both content and composition), reinforcement of cemented carbide with other materials, nano-filler/whisker addition, partial or complete removal of metallic phase from the cemented carbide affect the properties of sintered specimens and their calculated as well as optimum setting can provide an excellent combination of properties desired in cutting tool operations.

In this work, an attempt was made to join Inconel 718 by FSW using a tungsten carbide tool. The influence of major operating parameters such as rotational and traverse speed on the thermal history, axial force, mechanical and microstructural properties of welded samples was investigated. To obtain a sound weld joint, lower rotational speed (i.e., 300 rpm) and moderate traverse speed (i.e., 90 mm/min) are preferable. A sound weld joint experienced a joint efficiency of 100.2% and the impact toughness was 84.5%, of the base material. Grain refinement occurs both in the stir zone (SZ) and thermo-mechanical affected zone (TMAZ), with lower rotational speed and increasing traverse speed. The grain refinement leads to the improvement of mechanical properties such as tensile strength, impact toughness and Vickers hardness. XRD analysis revealed the existence of both tungsten and cobalt particles in the weld zone which confirmed the tool wear happened during the FSW. From FESEM and transmission electron microscopy (TEM) investigations, it was observed that the SZ of the sound weld sample revealed the presence of refined grain with secondary phases, which are most likely to be responsible for enhancing weld strength.

Samples of chemically vapor deposited (CVD) coatings of tungsten carbides W45C55 and W60C40 and samples of hot-rolled tungsten were exposed to deuterium (D) plasma at sample temperatures ranging from 323 to 813 K, as a result of which the samples were irradiated with D ions with an energy of about 200 eV per D particle at a flux of D particles of about 1.1 × 1021 D·m−2·s−1 to a fluence of about 2 × 1024 D·m−2. The concentration of deuterium in these samples was examined by the D(3He,p)4He nuclear reaction. Based on the measured deuterium depth profiles and assuming that these profiles are determined by diffusing D atoms, the diffusion coefficients of deuterium in the CVD tungsten carbide coatings were determined. Using these diffusion coefficients, an estimate of the Arrhenius relation for the diffusion coefficients of deuterium in CVD tungsten carbide coatings was obtained: D = 2.5 × 10–3 exp(− 1.12 eV/kT) m2·s−1, where T is temperature expressed in Kelvin, and k is the Boltzmann constant. The concentration of trapped deuterium in the bulk of CVD tungsten carbide coatings is practically independent of the stoichiometry of the coatings. It decreases from about 5 × 10–2 to about 7 × 10–4 D/(W + C) with an increase in the deuterium plasma exposure temperature from 373 to 813 K. The concentration of trapped deuterium in hot-rolled tungsten, expressed in units of the D/W atomic ratio, is more than an order of magnitude lower than the concentration of deuterium in tungsten carbides, and also decreases with increasing plasma exposure temperature.

Surface topographies play a critical role in controlling friction, surface damage and transfer layer formation in engineering applications; hence understanding this is of great importance. In this work, experimental studies were carried out to understand the influence of surface topography on friction, scuffing and transfer layer formation in completely immersed lubricated sliding interactions. For this, sliding experiments were carried out in sphere on flat configuration using EN31 steel flats and Tungsten Carbide pin countersurface. Perpendicular and parallel surface topographies were induced onto the steel flats. Experiments were conducted at high normal loads of 1000N, 2000N and 3000N. The results show that Surface topography has a significant influence on the frictional response. When the topography directionality was perpendicular to the sliding direction, scuffing was observed only at a high load of 3000N. A ‘peak friction’ was also observed during the occurrence of scuffing. When the directionality in topography was parallel to sliding direction, scuffing and surface damage occurred from 2000N itself, accompanied by a high amount of transfer layer formation. This can be attributed to the directionality of parallel topography, which displaces away the lubricant during sliding interaction, creating metal-to-metal contact and hence leading to scuffing and higher transfer layer formation.

The influence of the grain size of tungsten carbide of tungsten-cobalts hard alloy, received as anode material for the electro-spark deposition (ESD) of steel 35, on its erosion resistance, on the weight gain of the substrate material, and on the coefficient of electro-mass transfer. It is shown that in the preparation of new anode materials with different structure, density, porosity, fracture strength, and grain size of tungsten carbide, a pressing charge with additives of 0.4% Cr3C2–0.4% VC grain growth inhibitors and grinding in alcohol and argon atmosphere at a grinding time of 20 to 320 minutes was used. The results of the erosion resistance and the use of the obtained new anode materials in the ESD of steel 35 are shown. When performing kinetic studies, a number of indicators of the efficiency of the formation of the doped layer were identified, taking into account the obtained values of the of additional weight of the cathode, the time of the ESD, the specific surface area of 1 cm2, and the coefficient of electro-mass transfer at the ESD of the studied anode materials. The results of the studies of the structure, thickness, composition of the doped layer, and of the heat resistance and wear resistance of the coating are shown. It was revealed that among the created new anode materials, the best oxidation resistance of the coating after ESD with the selected processing modes were obtained using a new nanodispersed anode material WC8%Co–0.4%Cr3C2–0.4%VC, with an average grain size of 0.8 microns WC.

In order to reduce the difficulty of preparing binder-less cemented carbide and further broaden its application prospects, tungsten carbide toughened by in situ elongated β-Sialon grains was developed via sintering ball-milled WC and α-Si3N4 powders using Al2O3–ZrO2 as a sintering aid and transformation additive. The two-step spark plasma sintering of the mixture at 1650 °C with dwelling at 1500 °C for 10 min was conducted under 30 MPa uniaxial pressure, and the densification behaviors, phase transformations, mechanical properties, and microstructures of the produced composites were investigated. The addition of Al2O3–ZrO2 reduced the initial temperature of the densification process by approximately 100 °C and its final temperature by 200 °C (compared with the densification temperatures of pure WC and Si3N4 materials) and fully transformed α-Si3N4 to Sialon (Si–Al–O–N) phases. Microstructural characterization data showed that the WC matrix contained homogeneously distributed equiaxed and elongated β-Si5AlON7 grains. The WC composites containing in situ elongated β-Sialon grains exhibited an optimal hardness of 18.93 ± 0.03 GPa and enhanced fracture toughness of 10.43 ± 0.27 MPa m1/2. The toughening mechanism of the β-Sialon phase involved the pull-out of elongated grains and crack bridging.

The electrochemical approach for the feasible ammonia production via N2 fixation is well-thought-out to be an eco-friendly strategy to replace the polluting Haber Bosch process. However, the impeding activation barrier of strong N≡N and the competing hydrogen evolution reaction constrain the Faradaic efficiency of the electrochemical nitrogen reduction reaction. Therefore, the implication of innovative strategies for designing an active electrocatalyst remains a crucial criterion to deliver operational efficiencies during electrochemical reactions. This study proposes a unique fabrication of three-dimensional (3D)-architectured electrodes encompassed with cobalt-rich tungsten carbide (Co-WC) as an electrocatalyst using a 3D-printing technique for the efficient electrochemical nitrogen reduction reaction. Here, the cobalt acts as a binder between tungsten carbide particles after sintering, and the particles are bonded to each other. The 3D-printing process generates 3D-architectured Co-WC electrodes with an average particle size of 1–3 µm through precise control of printing parameters. The electrochemical performance of the 3D-architectured Co-WC electrode reveals a better selectivity for N2 reduction under ambient condition. Substantially, the 3D-architectured Co-WC electrodes demonstrate an improved ammonia yield rate of 34.61 μg h−1 cm−2 and Faradaic efficiency of 2.12% at an applied potential − 0.6 V (vs. RHE). 3D-printing techniques can be an effective design method for manufacturing 3D-architectured active material with superior performance and selectivity.

The article is devoted to a comprehensive analysis of the coating of a component from the Ford Fo-cus 1.0 l EcoBoost engine. It is one of a pair of materially identical aluminum gears connected by a drive pulley and a drive. Aluminum gear components are surface treated with a mixture of metal powders using PVD technology, where the goal of the coating is to increase the hardness, abrasion resistance and heat of the base material. The chemical composition of the basic material of the gea-red aluminum drive wheel of the FORD engine proves that it is a component made by thermofor-ming and corresponds to the alloy EN AW 6061 (AlMg1SiCu) according to the standard CSN EN 573 1-3. The microstructure of the base material component exhibits fine intermetallic phases evenly dis-tributed throughout the cross-section of the base base material, without the occurrence of larger inc-lusions and/or porosity. The cross-sectional microstructure in the area of the coating demonstrates that the component has a continuous uniform surface layer of the coating formed without a defect and does not have a diffuse bond with the base material. The measurement of the coating thickness of the component shows a continuous surface layer formed by powder metallography, which ranges from 70.1 µm to 143.9 µm. The surface EDS of the surface proves that it consists of deposited tungsten carbides produced by powder metallography and the bonding material is cobalt. Area EDS analysis of the surface coating identified morphologically two distinct areas of dark and light, where tungsten carbides and cobalt are based, and only the tungsten carbide and cobalt carbide contents change. The oxygen and carbon content also changes in the dark and light areas.

The study investigated the effect of fibre laser processing (1060 nm, 240 ns pulse duration) on tungsten carbide (WC). Fluence, frequency, and the interaction effect of these were the most influential factors on the surface integrity and crack formation. In this paper, a crack classification system was developed, and a crack density variable was introduced to estimate the number of cracks and crack type within a 1 mm2 area size. ANOVA was used to analyse how fluence (0.05–0.20 J/cm2) and frequency (5–100 kHz) altered the crack density. The crack density increased between 0.050–0.099 J/cm2 across all frequency settings then decreased as the fluence increased to 0.20 J/cm2. Superficial cracks were present in all frequency settings but particularly with lower fluence settings. Micro-cracks were more likely to form between 0.050–0.135 J/cm2. Deep cracks did not present until 40 kHz or above 0.099 J/cm2 across the frequency settings and were situated around balling and splatter defects. The crack density was minimised at 0.149 J/cm2 fluence and 52.5 kHz. To the author’s knowledge for the first time a quantitative analysis of the crack formation mechanism for brittle materials is proposed (post laser processing). In addition, a linear model generated to predict surface roughness performed best at moderate to medium level of processing (fluences in the region of 0.050–0.099 J/cm2) with an error between 1 % to 10 %. The model failed to predict the material response as accurately at higher fluences with percentage errors between 15 % to 36 %.

The purpose of this research was to analyze the performance (wear resistance, surface roughness, chip formation, and noise level) of AlCrN, TiN, and TiAlN coated tungsten carbides in cutting composite boards. The composite boards of wood plastic composite, laminated veneer lumber, andorientedstrand board were cut by the coated tungsten carbide tools in a computer numerical control router. The results show that the differences in structure among the composite boards resulted in the difference in clearance wear, chip formation, surface roughness, and noise level phenomenon. The abrasive materials in wood plastic composite generated the highest clearance wear on the coated carbide tools tested. TiAlN coated carbide tool provided better wear resistance, smoother composite boards surfaces, and lower noise levels.

This study aimed to prevent the harmful consequences of the turning process. The use of micro-textured cutting inserts with a femtosecond laser an innovative efficient method to decrease chip adhesion to cutting of edge tools during titanium alloy (Ti6Al4V) turning was studied. Additionally, the effects of different micro-pattern geometries and sizes on the machining capacity of coated WC/Co cutting inserts in turning experiments with titanium–aluminium–nitride (TiAlN) were investigated based on various lubrication processes. The surface states of the micro-patterned TiAlN-coated inserts were analysed using scanning electron microscopy and optical microscopy. Subsequently, machining and measured tests on the titanium alloy were performed using the developed cutting tools. Tungsten carbide tools with textured cutting surfaces and different microstructures were fabricated, and their behaviours were compared with those of conventional coated tools. Thrust, cutting, and feed cutting force values were measured during machining using a three-component dynamometer. Based on the present investigation, the cutting tool with a cross texture exhibited greater reduction of machining forces, friction coefficients, and tool wear.

In this study, the enhancement of electrical conductivity and Oxidation Reduction Reaction (ORR) activity of tungsten carbide/carbon (WC/C) nanocomposite was successfully synthesized from palm oil by solution plasma process (SPP). For the synthesis, plasma fields with different frequency were applied the bipolar pulsed power supply connected with two tungsten electrodes. The properties of the synthesized WC/C nanocomposite were varied by using a different frequency. The electrical conductivity increased with the frequencies. The highest electrical conductivity was 4.27×10−2 S cm−1, which is higher than that of Ketjen Black (7.37 × 10−3 S cm−1). The WC/C nanocomposites were observed the surface area 160 m2 g−1, pore volume 0.53 cm3 g−1, average pore diameter 16.29 nm, basal plane crystallite size 18.0 nm, and the average compound granule diameter less than 100 nm. The cyclic voltammetry measurement was showed that the ORR activity of WC/C nanocomposites were obtained the good performance in alkaline solution for fuel cell application.

Optimization of process parameters for direct laser metal deposition of WC (88 wt%) and Co (12 wt%) mixed powder on SS304 substrate was carried out to obtain minimum dilution. The effect of process parameters on clad geometric elements was expressed through polynomial relations. A mathematical expression for dilution was developed in terms of clad geometric elements and then verified with experimentally obtained dilution. The regression analysis for each geometric element and dilution was also studied. To obtain an optimized set of process parameters four recently developed optimization algorithms were used, which was then followed by a confirmation test. Bonobo Optimizer algorithm was fast during the search for the globally optimum solution. A detailed macroscopic, microstructural, thermo-cycle and XRD analysis for the confirmed optimized run was carried out along with the comparison study. The hardness behaviour of clad tracks was also studied by comparing it with that of the substrate.

We prepared samples of composites based on tungsten carbide and cobalt with different concentrations (0–10 wt %) of chromium diboride, 10 mm in diameter and 8 mm in thickness, by cold pressing followed by vacuum hot pressing. A comprehensive study of composites using conventional methods of testing mechanical properties, combined with digital optical microscopy, transmission microscopy, and scanning atomic force microscopy, revealed stable correlations between the concentration of CrB2 additive with the average WC grain size and microstructure parameters, hardness, and fracture toughness of the composites. A coarse-grained structure is observed in WC–6Co (wt %) composites, with direct contact of WC grains and large regions of a cobalt binder. The introduction of CrB2 into the composite, on the contrary, ensures the formation of thin (~100 nm) and extended layers of a cobalt binder, even between fine WC grains. The CrB2 additive yields a finer-grained structure, the parameters of which can be purposefully controlled by changing the additive concentration. The addition of 4 wt % of CrB2 into the composite leads to a more than twofold increase in fracture toughness, that is, from 4.4 to 9.8 MPa m1/2, with a slight decrease in hardness from 15.1 to 13.0 GPa. With a further increase in the CrB2 concentration from 4 to 10 wt %, fracture toughness and hardness gradually decrease.

Cryogenic treatment is a sustainable manufacturing process preferred to improve the properties of the material. In the present study, the effect of cryo treated tungsten carbide cobalt bonded insert (WC-Co) measured in terms of tool life and surface finish on dry turning on high strength AISI4340 steel at different machine parametric conditions. The observations of Untreated (UT) and Deep Cryo Treated (DCT) inserts were compared. Formation and the distribution of eta phase carbides are verified by Scanning Electron Micrograph (SEM). The DCT insert shows a reduction in 27.27% tool wear with an acceptable level of surface finish. Taguchi's coupled Graph Theory and Matrix Approach (TC-GTMA) is used to predict the optimum machining condition and to substantiate the results the validation experiment is conducted and found satisfactory.

The use of nanoadditives in lubricants has gained much attention to the research community due to the enhancement of tribological properties and cooling capabilities. This paper studies the advantages of using a MQL (Minimum Quantity of Lubrication) system and nanoadditive in the manufacture of microneedle arrays in Ti6Al4V ELI alloy. Tungsten carbide ball nose tools with a cutting diameter of 200 µm were used in experimental tests. Surface and dimensional characterization was performed to evaluate the impact of a nanoadditive to a vegetable-based oil. Additionally, cutting forces and cutting edge radius (CER) were measured while needles were machined. Experimental tests confirmed that micro end milling with nanoadditives provide slightly better dimensional features and low cutting forces compared to oil. The performance of nanoadditives resulted in a reduction of surface roughness (~ 0.3 μm). Qualitative study of microneedles illustrated burr formation on needle surface manufactured without a nanoadditive solution. Results reveal an increment of CER using low feed rate values (2.0 µm/flute) while a reduction of CER was observed with feed rates up to 2.5 µm/flute. Our results indicated that the addition of nanoadditives to vegetable oil promotes a better product surface topography and cutting tool performance.

The present work explored the oxyacetylene brazing of two WC- (6, 10 wt.%) Co cemented carbides using Ag-based filler alloy at common interfaces. The study sought to develop a theoretical framework to explain the mechanism of forming interface structure and mechanical properties of joints when brazed at common interfaces, by studying the influence of different binder phase contents. Common interface brazing was explored to reduce the effect of residual stresses experienced when WC-Co cemented carbides are brazed to steel counterparts. Generally, interlayer thicknesses of several hundred microns are investigated. However, in this work, two different interlayer thicknesses of 8 and 24 μm were investigated as it was anticipated that this would give stronger braze joints. The brazing tests were carried out at 710 °C under atmospheric conditions, for 30 seconds. Microstructural and phase changes in the brazed joint zone were characterised by SEM, EDS and XRD. Increasing the Co binder content from 6 to 10 wt.% provided a better chance for the formation of island-like α-Cu (s.s) and feather-like Ag-Cu-Zn eutectic phases. Shear strength and hardness of the joints were measured to evaluate the mechanical properties of these braze joints. The α-Cu (s.s) appeared to have had a dispersion strengthening effect on the brazed joints. The WC-10wt.%Co brazed joints of 24 μm thickness achieved the highest shear strength of 298±15 MPa. The shear strength of the joints increased when the interlayer thickness was increased from 8 µm to 24 µm. The shear strength tests for the WC-6wt.%Co exhibited a brittle fracture mode, while WC-10wt.%Co showed a mixture of ductile and brittle fracture modes.

Good surface roughness and topography are of great importance in plastic mold materials. This study investigated the effects of cutting parameters on cutting temperature, vibration (g), surface roughness (Ra), and noise (N) in the turning of AISI P20 die steel using coated tungsten carbide cutting tools. Experiments were carried out using the Taguchi L-18 experimental design with cutting tools with two different types of coatings (CVD and PVD), three different cutting speeds (100, 150, and 200 m/min), three different feed rates (0.1, 0.15, and 0.2 mm/rev), and a constant cutting depth (1 mm). As a result of the study, the PVD-coated tools exhibited a higher performance for all outputs (cutting temperature, g, Ra, and N). It was observed that the vibration and surface roughness were proportional, vibration was mostly affected by feed rate, and increasing cutting speed and feed rate also increased the temperature and noise in the cutting zone. According to ANOVA results, the most effective parameter on surface roughness was feed rate (97.24%), the most effective parameter on vibration was cutting tool type (57.34%), and finally, the most effective parameter on noise was feed rate (50.37%). WOS:000687546800008 2-s2.0-85113340973

This study investigated the effect of boron-doped and undoped diamond coatings on the cutting performance of cobalt cemented tungsten carbide (WC-Co) drills when drilling CFRP. Three types of diamond coating, as boron-doped microcrystalline (B-MCD), boron-doped nanocrystalline (B-NCD), and undoped nanocrystalline (NCD), were deposited on specially designed for drilling of CFRP one-shot drills by the hot filament chemical vapor deposition (HFCVD) method. The coating characteristics, such as surface morphology, roughness, carbon structure, and interfacial adhesion, were investigated. Then cutting tests were carried out, and the tool’s flank wear, thrust force, and torque were evaluated. For comparison of cutting performance, non-coated WC-Co drills were used in the tests as well. Furthermore, drilled holes were inspected in terms of peel-up and push-out delamination. According to the results, the B-MCD coated drill presented advantages in tool life, and quality of drilled holes over the NCD and B-NCD coated drills. Also, the results confirmed the adhesion enhanced effect of diamond coating to WC-Co substrate through boron doping of the layer.

The aim of the study is to assess the effectiveness of Er,Cr:YSGG laser therapy as a method for recycling debonded stainless steel orthodontic brackets. Sixty extracted premolar teeth bonded to stainless steel brackets were tested for rebonded shear bond strength after recycling by three protocols and compared with a control group. These 60 samples were randomized into four groups which were recycled by three protocols, namely, sandblasting, adhesive grinding by tungsten carbide bur, and Er,Cr:YSGG laser (Waterlase, Iplus, Biolase Technology, CA, USA), emitting a wavelength of 2780 nm, with an average power of 5 W; repetition rate, 20 Hz; pulse duration, 60 µs; water, 80%; air, 60%; and the control group where new brackets were used. After recycling, stereomicroscope and shear bond strength analysis were used to analyze the efficiency of the recycling protocols. Laser group showed the highest shear bond strength values. There was no statistically significant difference between bur removal and sandblasting; both showed the lowest values. Er,Cr:YSGG laser was found to be the most efficient protocol for orthodontic brackets recycling.

A novel tungsten carbide (WC)- and ceria (CeO2)-reinforced cobalt (Co) matrix composite coating was synthesized through a one-step co-electrodeposition method. The growth mechanism of the coating and the formation mechanism of the protrusion and gully structure on the coating surface were explored. Furthermore, the mechanism of the influence of ceria concentration on the deposition rate and content of tungsten carbide is discussed. The results revealed that the coating fabricated at 6 g/l ceria achieved a dense structure, a fine grain size, a high content of tungsten carbide (19.9 wt.%) and a high deposition rate (78.2 μm/h). The average thickness of the coating was 118.48 μm, and the composite coating had a preferred orientation of cobalt (101) texture. In addition, the maximum microindentation hardness of the coating deposited at 6 g/l ceria was obtained as 627 HV. The electrodeposits possessed a superior anti-wear behavior, which was mainly ascribed to the synergistic effect of tungsten carbide and ceria in improving the mechanical properties of the cobalt matrix composite coating.

Purpose Aviation field requires a material with greater tribological characteristics to withstand the critical climate conditions. Hence, it is of paramount importance to enhance the wear resistance of material. AZ91D magnesium alloy is a light weight material used in the aviation field for the construction work. The purpose of this study is to augment the wear properties of AZ91D alloy by reinforcing with hard particles such as tungsten carbide (WC) and silicon dioxide (SiO2). Design/methodology/approach In this work, three types of composites were fabricated, namely, AZ91D – WC, AZ91D – SiO2 and AZ91D – (WC + SiO2) by ball milling method, and the tribological properties were analyzed using pin-on-disc apparatus. Findings Results showed that the hardness of AZ91D alloy was greatly improved due to the reinforcing effects of WC and SiO2 particles. Wear study showed that wear rate of AZ91D alloy and its composites increased with the increase of applied load due to ploughing effect and decreased with the increase of sliding speed owing to the formation of lubricating tribolayer. Further, the AZ91D – (WC + SiO2) composite exhibited the lower wear rate of 0.0017 mm3/m and minimum coefficient of friction of 0.33 at a load of 10 N and a sliding speed of 150 mm/s due to the inclusion of hybrid WC and SiO2 particles. Hence, the proposed AZ91D – (WC + SiO2) composite could be a suitable candidate to be used in the aviation applications. Originality/value This work is original which deals with the effect of hybrid particles, i.e. WC and SiO2 on the wear performance of the AZ91D magnesium alloy composites. The literature review showed that none of the studies focused on the reinforcement of AZ91D alloy by the combination of carbide and metal oxide particles as used in this investigation.

The object of the research is cement samples modified by agglomerates of tungsten carbide nanopowders obtained from carbide waste. The paper considers the influence of tungsten carbide nanopowder on the change in the main cement characteristics (density, water demand, setting time, kinetics of strength gain, compressive strength, bending strength). The optimum additive content in cement materials is 3%. This parameter is estimated by the maximum growth of compressive and flexural strength at all stages of hardening. The effect of WC powder additive on the structure of the cement matrix has been shown. Due to the high dispersibility of WC nanopowder, its particles act as additional crystallization centers, fill in the micropores of the cement stone and create a denser and stronger structure. The results of studying the microstructure of the cement stone with additions of WC powder indirectly confirm the results of strength characteristics. The cement-sand samples with the modifier are found to have a denser crystallized cement-sand stone compared to the control sample (without WC powder addition). The conducted researches have shown perspectivity of application of WC nanoparticles agglomerates as modifying additives for cement materials, which can be used in production of special purpose concrete (hydraulic, radioprotective, etc.). The economic effect of the use of WC nanoadditives obtained from hard-alloy production wastes can be obtained due to a reduction in costs at the stages of construction and operation of structures, buildings, structures based on it.

Tungsten carbide (WC) in Ni-based powders is a promising candidate for laser-based additive manufacturing because WC is an extremely hard material, whereas Ni is tough and weldable. However, WC par...