Tungsten Carbide Nanopowders Research Articles

Synthesis of tungsten carbide nanopowder by a one-step carbothermal reduction-carbonization method

Tungsten carbide (WC) nanopowder is crucial for preparing high-performance WC-Co cemented carbides, but the synthesis of WC nanopowder still remains huge challenges. In this study, we report a novel method for synthesizing high-purity WC nanopowder by carbothermal reduction-carbonization. The effects of the reaction atmosphere, temperature, and time on the morphology and size of WC powder were studied. It was found that vacuum atmosphere was more conducive to prepare WC nanopowder, which could reduce the onset temperature of carbothermal reduction reaction and effectively improve the reaction efficiency. The final products in vacuum were more homogeneous and smaller compared with argon atmosphere. Furthermore, the mechanism of effect of atmosphere on prepared WC nanopowder was analyzed in detail. The particle size of WC showed an increasing trend with the increase of temperature and holding time. Following calcination at 1100 °C for 5 h, the as-prepared WC nanopowder attained an average particle size of 82 nm.

Optimization of Isotactic Polypropylene Nanocomposite Content of Tungsten Carbide for Material Extrusion 3D Printing

In this study, innovative nanocomposite materials for material extrusion (MEX) 3D printing were developed using a polypropylene (PP) polymer with tungsten carbide (WC) nanopowder. The raw materials were converted into filaments using thermomechanical extrusion. The samples were then fabricated for testing according to the international standards. Extensive mechanical testing was performed on the 3D-printed specimens, including tensile, impact, flexural, and microhardness assessments. In addition, the impact of ceramic additive loading was examined. The thermal and stoichiometric characteristics of the nanocomposites were examined using thermogravimetric analysis, energy-dispersive X-ray spectroscopy, differential scanning calorimetry, and Raman spectroscopy. The 3D-printed shape, quality, and fracture process of the specimens were examined using scanning electron microscopy. The results showed that the filler significantly enhanced the mechanical characteristics of the matrix polymer without reducing its thermal stability or processability. Notably, the highest level of nanocomposite mechanical responsiveness was achieved through the inclusion of 6.0 and 8.0 wt. % fillers. The 10.0 wt. % loading nanocomposite showed significantly increased microhardness, indicating a possible high resistance to wear.

A Novel Approach to the Rapid in situ Synthesis of Tungsten Carbide Nanopowder by Plasma Milling and Carbothermal Reduction

Plasma milling results in more reactive sites and a larger contact area between WO3 nanoparticles and C atoms, and simultaneously generats more oxygen vacancies and defects on the surfaces of WO3 and C respectively via plasma discharge as describe in the article, number 2200175 by Zhongchen Lu and co-workers. Thus, the reaction temperature for the carbothermal reduction reaction reduces significantly by plasma milling.

Optimization of pulse bi-directional electrolysis in-situ synthesis of tungsten carbide by response surface methodology

The response surface methodology was used to optimize the parameters of pulse bi-directional electrolysis (PBE) in-situ synthesis of tungsten carbide (WC) in NaF-KF molten salt system. The process of PBE synthesis of WC is a short process method of in-situ synthesis of WC powders in molten salt electrolyte. WC were used both as cathode and anode. A symmetrical bi-directional pulse is applied between the two electrodes. Tungsten ions dissolved by forward pulse, and WC were produced in situ with carbon near the electrode during reverse pulse. During the research, it was found that the factors affecting the phase of the experimental product were Current intensity, Pulse period and Electrolysis duration. In this paper, the cathode and anodic dissolved mass and the Proportion of WC in the product were used as the response values. The Box-Behnken center combined test and response surface analysis are used to optimize the factors that affect significantly, and the optimal process parameters were determined. Finally, the model was experimentally verified. Under the optimized experimental conditions, high-performance tungsten carbide nanopowders were prepared with short-process and high-efficiency.

A Novel Approach to the Rapid in situ Synthesis of Tungsten Carbide Nanopowder by Plasma Milling and Carbothermal Reduction

This work prepares nanocrystalline tungsten carbide (WC) powder using conventional ball milling or plasma milling (P‐milling) to process tungsten trioxide (WO3)–carbon (C) mixtures, with subsequent carbothermal reduction. The aim is to assess the effects of a discharge plasma on the microstructure of these materials. The results indicates that WC powders with particle sizes of less than 100 nm could be fabricated through heating at a relatively low temperature of 1150 °C for 1 h under vacuum after P‐milling. This process is found to allow a lower processing temperature and provided more complete carburization in comparison with conventional ball milling. P‐milling is determined to produce more loosely adhering WO3 nanoparticles and a higher surface area, resulting in more reactive sites and a larger contact area between WO3 nanoparticles and C atoms. This technique simultaneously generates more oxygen vacancies and defects on the surfaces of the WO3 and C, respectively, based on the use of a plasma discharge. It is evident that this new technology permits nanocrystalline WC to be readily obtained from WO3 and C in a reduced time span and at a lower cost and greater efficiency. This technique could also be used to fabricate WC nanopowders on an industrial scale.

Preparation of nanoscale WC powders by sol-gel synthesis and carbon monoxide carbonization

In this study, tungsten carbide (WC) nanopowders with an average size of about 10 nm were synthesized by a three-step process: the sol-gel preparation of nanoscale WO3, reduction and carbonization in carbon monoxide (CO) atmosphere and short time high-energy ball milling. The average particle size of the sol-gel synthesized WO3 precursor is about 31 nm. Through low-temperature reduction and carbonization at 700 °C in CO, spherical and dendritic WC powders were obtained. After high-energy ball milling at 800 rpm for 10 min and 20 min, the average particle size of WC decreases to 16 nm and 10 nm, respectively. This method provides a facile method for the preparation of nanoscale WC powders with the advantages of low cost, simple process and suitability for industrial production.

ВЛИЯНИЕ АГЛОМЕРАТОВ НАНОПОРОШКА КАРБИДА ВОЛЬФРАМА НА СВОЙСТВА ЦЕМЕНТА

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.

Study of the Effect of Tungsten Carbide Nanopowder Agglomerate Additives on the Strength Properties of Carbon Fiber-Reinforced Plastic

The paper presents the results of tests of carbon plastic samples consisting of carbon fabric Grafill TR30S-S (Italy) and epoxy resin binder EPR 320 modified by WC tungsten carbide nanopowders in the form of agglomerates. The positive effect of additives on the tensile strength and on the modulus of elasticity at transverse bending of the concentration of additives 1-3% is shown.

Tungsten Carbide Nanopowder Influence Study on Tensile Strength of GRP Specimens Made of Lavesan Glass Fabric and EPR 320 Momentive Epoxy

This paper presents the test results of fiberglass samples consisting of glass fiber Lavesan (Italy) and a binder - EPR 320 epoxy resin modified with tungsten carbide (WC) nanopowder. The positive effect of nanopowder on the tensile strength and the increase in tensile strength of more than 1.5 … 2.5 times with the addition of additives in the mass concentration of 1 … 4% to the mass of the resin are shown.

Tungsten Carbide Nanopowder Synthesis under the Influence of Microwave Electromagnetic Radiation on a W–C System Nanocomposite Produced in a Thermal Plasma

Tungsten Carbide Nanopowder Synthesis under the Influence of Microwave Electromagnetic Radiation on a W–C System Nanocomposite Produced in a Thermal Plasma

Investigation of the Effect of Tungsten Carbide (WC) Nanopowder on Iron-Based Powder Structural Materials

Studies of a powder used as a modifier obtained from solid-alloy waste, such as tungsten carbide (drill balls), are presented. Dispersion, particle morphology and phase analysis of the powder were studied. The powder obtained from solid-alloy waste is a phase – it is tungsten carbide WC, it consists of nanoobjects of various shapes (nanoparticles, nanoplastics) up to 100 nm in size, with a slight presence of agglomerates up to 250 nm in size. The influence of tungsten carbide nanopowder as a modifier on the mechanical properties (strength and hardness) of PK70D3 iron-based powder structural steel has been studied. For the study, two different modes of preparation of powder alloy have been used with the use of one-stage and two-stage sintering. The influence of additive nanopowder of tungsten carbide on the mechanical properties of structural alloy powder based on iron PK70D3 has been defined: strength increases by more than 23% (in single-stage sintering), by more than 28% (in double-sintering), hardness decreases by more than 6% in single-stage sintering and increases by more than 26% with two stages of sintering, compared to the initial alloy. It has been shown that samples, obtained using double sintering with a tungsten nanopowder modifier (2.5%), have higher values of strength (more than 80%) and hardness (more than 13%), compared to modified samples, obtained by single-stage sintering technology. Thus, the modification of a 2.5 % nanoprobe of tungsten carbide, a widely used structural powder alloy based on iron PC70D3 allows for a significant change in mechanical properties. The use of powder alloys in double sintering technology provides the material hardness and the strength increase.

Investigation of the effect of tungsten carbide nanopowder additives on the strength properties of fiberglass, based on LAVESAN glass fabric and EPR 320 epoxy resin

The paper presents the results of tests for modulus of elasticity and tensile strength of fiberglass samples consisting of glass fiber Lavesan (Italy) and epoxy resin binder EPR 320 with hardener EPH 162, modified with WC tungsten carbide nanopowder, obtained from carbide waste. The positive effect of WC nanopowder on tensile strength and modulus of elasticity is shown. With the addition of nanoadditives in the mass concentration of 1 … 4% of the resin mass, the increase in tensile strength was more than 1.5 … 2.5 times, with no significant change in material elasticity.

Investigation of the influence of tungsten carbide nanopowder WC and the mixture of tungsten carbides and titanium carbides (WC, TiC) on the change of concrete performance properties

The paper deals with the possibility of changing the operational properties of concrete (strength, water absorption, corrosion resistance) by adding WC tungsten carbide nanopowders and a mixture of WC tungsten carbide and TiC titanium carbides obtained from hard-alloy waste to the initial composition. As a result of the research, the concentrations of nanopowders were determined, at which the maximum change in strength is observed. Changes in water absorption at different time intervals and corrosion resistance of concrete samples at optimal concentrations were studied. The paper shows a positive effect on the performance of concrete mixture of WC, WC and TiC nanomodifiers.

Study on influencing factors and mechanism of high-quality tungsten carbide nanopowders synthesized via carbothermal reduction

In this study, high-quality WC powders with 100 nm were synthesized using a simple and efficient carbothermal reduction method. The effects of carbon source and temperature on the synthesis process, nucleation and growth mechanism of WC nanopowders were investigated in detailed. The results show that acetylene black with small particle size and good dispersion is the optimal carbon source to prepare WC nanopowders. The uniform precursor synthesized by acetylene black can significantly increase the contact probability of WO3 and C particles, greatly reduce the activation energy, and effectively improve the reaction efficiency during subsequent carbothermal reduction process. Moreover, the formation temperatures of WC are reduced to 1000 °C compared with other three carbon source. Further increasing carbothermal reduction temperature can provide the driving force of diffusing atoms, which promotes the carbothermal reduction reaction, but also significantly increases the diffusion rate of grain boundary resulting in rapid grain growth.

Spark plasma sintering of fine-grained WC hard alloys with ultra-low cobalt content

The results of investigations of spark plasma sintering (SPS) kinetics of tungsten carbide nanopowders with different Co content (0.3, 0.6, and 1.0 wt%) and graphite (0.3 and 0.5 wt%) are described. The α-WC nanopowders were obtained by direct current (DC) arc plasma synthesis followed by annealing in hydrogen. Ultrathin Co layers were deposited onto the nanoparticles by a chemical-metallurgical method from a salt solution. The excess carbon was introduced by mixing the WC-Co powders with graphite that resulted in the increase of the oxygen concentration. The carbonization of the tungsten carbide hard alloy specimens was demonstrated to take place in SPS. It resulted in different phase compositions, along with hardness within surface and central layers of sintered ceramic specimens. The effects of the initial particle size, of the Co concentration, and of the graphite one on the stages of the SPS of the ultra-low Co hard alloys were studied. The specimens with uniform fine-grained structure, increased density, and improved mechanical characteristics were obtained. The hardness Hv for WC-0.6%Co-0.3%C hard alloy with averaged grain size 1.0–1.5 μm was 20.2–20.5 GPa at the minimum fracture toughness coefficient KIC = 9.2–10.4 MPa m1/2.

Investigations of the influence of tungsten carbide and tungsten oxide nanopowders on the radiation protection properties of cement matrix-based composite materials

The influence of tungsten carbide and tungsten oxide nanopowders on radiation-protective properties of a composite material based on a cement matrix has been studied. These powders are obtained from carbide scrap production. In the radiation energy range of 0.06…1.408 MeV the gamma radiation attenuation coefficients at various concentrations of nanopowders WC and WO3 (3.6%, 6.4%, 9.6% of the material mass) have been considered. The mass attenuation coefficient and the multiple of attenuation of radiation of investigated materials are calculated. It is shown that nanomodified composite material has high radiation protection characteristics and can find wide application as a radio protection material.

Experimental analysis of wear resistance of compacts of fine-dispersed iron powder and tungsten monocarbide nanopowder produced by impulse pressing

The paper presents the results of studying the structure and wear resistance of compacts produced from fine dispersed reduced iron powder (average particle size 3–5μm) with the addition of tungsten carbide (WC) nanopowder with the average particle size of 25–30 nm. The mass fraction of tungsten carbide (wolfram carbide) in the powder composition was 5% and 10% of the total mass. Impulse pressing was conducted using the modified Kolsky method at compacting temperatures of 20 °C to 300 °C. The produced compacts had relative density of over 90%.Metallographic studies using the scanning electronic microscopy method on a TESCAN VEGA II electronic microscope have shown that the produced compacts have a fairly homogeneous fine-grained structure, with a uniform pattern of pore distribution, the form of the pores being close to spherical. X-ray microanalysis using an INCA Energy 250 energy-dispersion spectrometer with scanning along the surface line and transversal laps testifies to the fact that, in the considered temperature range, dynamic compaction does not lead to any noticeable changes in the distribution of the Fe, W and C elements over the bulk of the specimens. The conducted measurements of micro-hardness of the compacts have shown that it increases considerably with the pressing temperature.The produced compacts were tested for wear resistance in a dry friction regime, using the ‘rotating disk – stationary specimen’ configuration. Mass loss of the compacts as a function of testing time is presented. Wear resistance of compacts depends on pressing temperature and concentration of the WC powder in the matrix of reduced iron. It has been experimentally determined that maximal wear resistance is observed in the compacts with the mass fraction of WC equal to 10%, produced at a pressing temperature of 300 °C.

Синтез нанопорошка карбида вольфрама WC при воздействии СВЧ электромагнитного излучения на нанокомпозит системы W-C, полученный в термической плазме

Синтез нанопорошка карбида вольфрама WC при воздействии СВЧ электромагнитного излучения на нанокомпозит системы W-C, полученный в термической плазме

Spark Plasma Sintering of high-strength ultrafine-grained tungsten carbide

The paper dwells on the research conducted into high-rate consolidation of pure tungsten carbide nanopowders using the Spark Plasma Sintering. Studies included the effect that the original size of WC nanoparticles and their preparation modes have on density, structure parameters, and mechanical properties of tungsten carbide. It has been found that materials that show abnormal grain growth during sintering have lower values of sintering activation energy as compared to materials the structure of which is more stable during high-rate heating. A qualitative model is proposed that explains this effect through the dependence of the grain boundary diffusion coefficient on the grain boundary migration rate.

Spark plasma sintering of tungsten carbide nanopowders obtained through DC arc plasma synthesis

Abstract The paper dwells on the research conducted into high-rate consolidation of pure tungsten carbide (WC) nanopowders using the Spark Plasma Sintering technology. Studies included the effect that the original size of WC nanoparticles and their preparation modes have on density, structure parameters, and mechanical properties of tungsten carbide. Samples of high-density nanostructured tungsten carbide characterized by high hardness (up to 31–34 GPa) and improved fracture toughness (4.3–5.2 MPa m 1/2 ) were obtained. It has been found that materials that show abnormal grain growth during sintering have lower values of sintering activation energy as compared to materials the structure of which is more stable during high-rate heating. A qualitative model is proposed that explains this effect through the dependence of the grain boundary diffusion coefficient on the grain boundary migration rate.