Tungsten Carbide-cobalt Research Articles

Quercetin has a protective impact on human umbilical vein endothelial cells against tungsten carbide cobalt nanoparticle-induced cytotoxicity, oxidative stress, apoptosis

Oxidative stress is a pivotal factor in the pathogenesis of various cancer diseases. In fact, oxidative DNA damage is described as the type of damage probably to occur in cancer cells. This study examined the protective impact of the polyphenolic compound quercetin on human umbilical vein endothelial (HUVEC) cells against tungsten carbide cobalt nanoparticles (WC-Co NPs)-induced oxidative stress, cytotoxicity, and apoptosis. One of the most often used models for studying endothelial cells in vitro is the human umbilical vein epithelial cell. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to measure the size of the NPs prior to WC-Co NPs treatment. WC-Co NPs had a polygonal form and measured 45.26 ± 1 nm in size. Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT),neutral red uptake(NRU) and lactate dehydrogenase (LDH) assays, the cytotoxicity of WC-Co NPs on HUVECs cells was assessed. The cytotoxicity of NPs increased in a concentration-dependent way. The MTT result was used to calculate the median inhibitory concentration (IC50) for HUVEC cells at 24 h, which came out to be 23.14 μg/ml. Intracellular reactive oxygen species(ROS) and lipid peroxidation(LPO) levels were elevated at 17 g/ml WC-Co NPs and then reduced in HUVECs cells upon immediate exposure to 150 µM quercetin (QR). Using JC-1 staining, the loss of mitochondrial membrane potential(MMP) in control, WC-Co NPs alone and WC-Co NPs plus QR exposed cell were evaluated. In HUVECs cells, maximum apoptotic cells were seen at increasing NPs concentrations. Based on the impacts of NPs on HUVECs cells, the data suggests that QR may work on the process of scavenging ROS, which is responsible for DNA repair. Consequently, the above findings highlight the significance of these QR as defenses against DNA damage brought on by oxidative stress, which frequently happens in a number of cancer disorders.

Multiple solutions of tungsten carbide-cobalt cutting tool turning performance optimization results by Taguchi's combined multiobjective approach analysis an exponentiated exponential Weibull Dagum distribution model

Manufacturers employ various techniques to enhance tool life and influence both production costs and surface finish quality. Recently, cryogenic treatment has gained attention for improving machining performance. In this study, tungsten carbide-cobalt (WC–Co) cutting tools underwent cryogenic treatment at −196 °C for 24 h followed by tempering at 200 °C for 2 h. Machinability characteristics including Tool Wear Rate and Surface Roughness (Ra) were assed for Cryo Treated (CT) cutting tool during spinning operations on Al6063 alloy. This evaluation was compared with an untreated tool. Results demonstrate that the CT tool significantly enhances tool longevity while ensuring a satisfactory surface finish. To optimize the performance of the CT tool in turning processes, multiobjective optimization techniques, namely Taguchi's Grey Relational Analysis and Technique for Order Preference by Similarity to Ideal Solution, were utilized. In this research exponentiated exponential Weibull Dagum (EEWD) model has been utilized with the goal of increasing the tractability of the DGM (Dagum) in modeling the real-world data. The main object of this work, an innovative generalization of the EEWD distribution of Quantile Function (QntFEEWD) has been derived with six parameters. This QntFEEWD is significantly influent in driving measures of position such as the Qutl (quartiles), Octl (octiles), Decl (deciles), Pecl (percentiles), and median of EEWD distribution. The T-R{.} framework has been recently used to generalize different distributions; however, the DGM distribution's viability has not been examined. The T-R{.} combines three distributions, with one acting as a standard distribution. Each distribution's combined potency, which is a weighted hazard function of the baseline distribution, would have more parameters but be able to handle dataset bimodality with great flexibility. In order to generalize the DGM distribution, this paper used the quantile function of the Weibull distribution. The current study presents the EEWD, a novel generalized six parameter (6P) model.

Effects of zirconium diboride addition on porosity reduction in laser metal deposition of tungsten carbide–cobalt cermet material

Laser metal deposition of tungsten carbide–cobalt (WC-Co) cermet material is a promising means of improving the wear resistance of metal products. However, laser metal deposition of WC-Co has constraints on its practical use because a clad bead of WC-Co often includes numerous gas pores. Earlier studies have found CO gas generation in a molten pool by reaction of carbon and oxygen to be the main cause of gas porosity in a WC-Co clad bead. Preventing the gas reaction is important to obtain clad beads with few pores. The addition of elements with strong affinity for oxygen, such as aluminum, was found to be effective for porosity reduction in a clad bead. However, the addition of highly reactive pure aluminum particles on WC-Co powder presents some difficulties for industrial use. For this study, zirconium diboride (ZrB2), a chemically stable compound, was used as an additive to WC-Co powder. After WC-Co powder with adhered ZrB2 particles was prepared using a wet granulation process, laser metal deposition was conducted. Zirconium stemming from the dissolution of ZrB2 in the molten pool was found to have the effect of trapping oxygen elements as solid zirconium oxides. Consequently, gas generation in the molten pool by the reaction of carbon and oxygen was restrained. Clad beads having few pores and fine microstructures were obtained. Observations of the molten pool behavior taken using a high-speed camera indicated that ZrB2 addition drastically improves process stability compared to processes using conventional WC-Co powder.

Obtaining of WC–Co- and WC–TiC–Co-Based Ultradispersive Alloys Modified with B<sub>4</sub>C–TiB<sub>2</sub> Quasieutetic

Tungsten carbide WC-based materials characterized by high hardness and wear resistance have long been widely used in manufacturing cutting and mining tools. They are alloyed or modified with different ceramic phases to improve operational characteristics further. There are obtained the hard tungsten carbide–cobalt WC–Co and tungsten carbide–titanium carbide–cobalt WC–TiC–Co metal-ceramic alloys ultradispersed powders modified with quasieutectic ceramic alloy B<sub>4</sub>C–30wt.%TiB<sub>2</sub> and complex samples compacted from them. The quasieutectic alloy used as a modifier has almost as high hardness as pure boron carbide. Still, it is characterized by higher electrical and thermal conductivities of several orders of magnitude. Two groups of hard alloys modified with B<sub>4</sub>C–30wt.%TiB<sub>2</sub> were studied: ВK8 grade WC–Co and T30K4 and T15K6 grades WC–TiC–Co. Metal-ceramic composite powders of different concentrations are obtained by chemical synthesis and mechanical dispersion in an attritor. The particle size of chemically synthesized composite powders is ≤0.3 μm, and those obtained by mechanical dispersion are ≤0.8 μm. SPS (Spark-Plasma Sintering) and HTS (High-Temperature Sintering) methods compact these powder materials. Phase composition of the obtained materials, distribution of chemical elements in them, and structural features are investigated by the XRD (X-Ray Diffraction) method and EDX (Energy Dispersive (micro)X-ray) spectrometry and optical and electron microscopies, respectively. Key physical-mechanical characteristics of the received samples, such as hardness, microhardness, and bending strength, are studied. Ultradispersed (≤0.8 μm) metal-ceramic alloys of the WC–Co–B<sub>4</sub>C–TiB<sub>2</sub> system with interesting characteristics have been obtained using the WC–Co hard alloy of BK8 grade as the matrix. A SPS-compacted sample's hardness, microhardness, and bending strength are 93.0 HRA, 3350 kgf/mm<sup>2</sup>, and 100 kgf/mm<sup>2</sup>, respectively. Among the WC–TiC–Co system materials, the Т15K6 grade-based hard alloy modified with 15wt.%(B<sub>4</sub>C–30wt.%TiB<sub>2</sub>) has the best characteristics with hardness, microhardness, and bending strength of 91.5 HRA, 2900, and 117 kgf/mm<sup>2</sup>, respectively. A preliminary study of the problem of environmentally safe utilization of tungsten-containing scrap and tungsten waste is also carried out as part of the work. In particular, the tungsten heater waste is treated in hydrogen peroxide, and by adding specific liquid components to the tungsten-containing proper solution in a single utilization–synthesis cycle, the target product – ultradispersed WC–Co hard alloy is obtained.

3 Body abrasion test of HVOF sprayed WC-10Co-4Cr and WC-10Co-4Cr + 2 % graphene coating on IS-2062 steel

This study investigates the microstructural characteristics, mechanical properties, and slurry abrasion resistance of WC-10Co-4Cr and WC-10Co-4Cr + GNPs coatings deposited using the High-Velocity Oxy-Fuel (HVOF) process. Cross-sectional micrographs, EDS line scans, and spectra reveal uniform distribution and proper adhesion of tungsten carbide particles, cobalt, chromium, and graphene nanoplatelets (GNPs) throughout the WC-10Co-4Cr + GNPs coating. Microstructural analysis indicates denser structure and reduced porosity in the WC-10Co-4Cr + GNPs coating, leading to enhanced abrasion resistance. Mechanical testing demonstrates higher microhardness and bond strength in the WC-10Co-4Cr + GNPs coating, attributed to the incorporation of GNPs and Laser Surface Texturing (LST). Slurry abrasion tests show substantial reductions in mass loss for both coatings compared to the pristine substrate, with the WC-10Co-4Cr + GNPs coating exhibiting superior performance due to its densification and lubrication effect of GNPs. Overall, the WC-10Co-4Cr + GNPs coating presents a promising solution for applications requiring high wear resistance and durability in harsh environments.

Fused Filament Fabrication of WC-10Co Hardmetals: A Study on Binder Formulations and Printing Variables

This research explores the utilization of powder fused filament fabrication (PFFF) for producing tungsten carbide-cobalt (WC-10Co) hardmetals, focusing on binder formulations and their impact on extrusion force as well as the influence of printing variables on the green and sintered density of samples. By examining the interplay between various binder compositions and backbone contents, this study aims to enhance the mechanical properties of the sintered parts while reducing defects inherent in the printing process. Evidence suggests that formulated feedstocks affect the hardness of the sintered hardmetal—not due to microstructural changes but macrostructural responses such as macro defects introduced during printing, debinding, and sintering of samples. The results demonstrate the critical role of polypropylene grafted with maleic anhydride (PP-MA) content in improving part density and sintered hardness, indicating the need for tailored thermal debinding protocols tailored to each feedstock. This study provides insights into feedstock formulation for hardmetal PFFF, proposing a path toward refining manufacturing processes to achieve better quality and performance of 3D printed hardmetal components.

Investigation of the influence of cobalt content and grain size of WC-Co cemented carbides on wear when shear cutting electric sheet metal

In the production of electrical machines, shear cutting of electrical steel laminations before further processing into rotors and stators represents an essential manufacturing process. Investigations have shown that using abrasively worn active elements while shear cutting increases the hysteresis losses in the electrical steel sheet due to introduced deformations and resulting residual stresses. Therefore, knowledge of suitable tool materials is of great importance for producing high-quality electric motors. Due to its high silicon content, electrical steel has a strong abrasive effect on the tools, which is why Tungsten carbide cobalt (WC-Co) cemented carbides are commonly used. In this work, continuous stroke tests are carried out on an electric sheet with punches made of different WC-Co cemented carbides, differing in cobalt content and grain size. The punches are examined with increasing wear regarding cutting-edge geometry, surface condition and microstructure. The resulting cutting parts are inspected for cutting surface characteristics. In addition, the influence of geometry and tribology of the punches regarding residual stresses in the material is investigated by FEM-Simulation. The investigations will provide information on the wear development and causes when shear cutting electrical sheets and the effects on electric losses.

A Comparative Study of the Life Cycle Inventory of Thermally Sprayed WC-12Co Coatings

In this research, a life cycle inventory (LCI) is developed for tungsten carbide–cobalt (WC-Co) coatings deposited via atmospheric plasma spray (APS), high-velocity oxy-fuel (HVOF), and cold gas spray (CGS) techniques. For the APS process, a mixture of Ar/H2 was used, while the HVOF process was fueled by H2. The carrier gas for CGS was N2. This study aims to determine and quantify the inputs (consumption of inputs and materials) and outputs (emissions to air, soil, water, and waste generation) that could be used in the life cycle analysis (LCA) of these processes. The dataset produced will allow users to estimate the environmental impacts of these processes using WC-Co feedstock powder. To obtain a complete and detailed LCI, measurements of electrical energy, gas, WC-CO powder, and alumina powder consumption were performed (the use of alumina was for sandblasting). Furthermore, emissions like carbon dioxide (CO2), carbon monoxide (CO), and noise were also measured. This practice allowed us to determine the input/output process quantities. For the first time, it was possible to obtain LCI data for the APS, HVOF, and CGS deposition processes using WC-12Co as a feedstock powder, allowing access to the LCI data to a broader audience. Comparisons were made between APS, HVOF, and CGS processes in terms of consumption and emissions. It was determined that the APS process consumes more electrical energy and that its deposition efficiency is higher than the other processes, while the HVOF process consumes a large amount of H2, which makes the process costlier. CGS has comparatively low electricity consumption, high N2 consumption, and low deposition efficiency. The APS, HVOF, and CGS processes analyzed in this study do not emit CO, and CO2 emissions are negligible.

Comprehensive behavior of reduced graphene oxide (rGO) reinforced plasma sprayed nanostructured WC–Co coatings

The effects of reduced graphene oxide (rGO) as an additive on the microstructure, mechanical properties, and tribological behavior of air plasma sprayed (APS) nanostructured tungsten carbide–cobalt (WC-25 wt.%Co) coatings were studied. The rGO was added in three distinct weight percentage proportions of 0.5, 1, and 1.5 wt.%. The microhardness and surface roughness of the APS sprayed nanostructured WC-25 wt.%Co coatings reinforced with rGO were changed significantly. Microstructural alterations in the coatings were also noticed with the addition of additives. Gluing of rGO amid coating splats was also seen in the microstructure of the coatings. The coatings’ microstructure revealed the presence of tungsten (W), tungsten carbide (WC), and semi-tungsten carbide (W2C) as the primary phases. The existence of the W2C phase in the microstructure of the coatings was mostly due to the decarbonization of WC at higher temperatures during plasma spraying. It was also found that the amount of wear of the coatings was exceptionally low because the rGO could not be extracted from the 1.5 wt.% rGO-reinforced coatings particularly. The wear degradation in the 0.5 and 1.0 wt.% rGO added coatings was mostly due to delimitation and the subsequent pulverization, notably at loads and sliding speeds of 1.5 kgf and 0.17 m/s.

Adapting the in vitro micronucleus assay (OECD Test Guideline No. 487) for testing of manufactured nanomaterials: recommendations for best practices.

The current Organisation for Economic Co-Operation and Development test guideline number 487 (OECD TG No. 487) provides instruction on how to conduct the in vitro micronucleus assay. This assay is one of the gold standard approaches for measuring the mutagenicity of test items; however, it is directed at testing low molecular weight molecules and may not be appropriate for particulate materials (e.g. engineered nanoparticles [ENPs]). This study aimed to adapt the in vitro micronucleus assay for ENP testing and underpins the development of an OECD guidance document. A harmonized, nano-specific protocol was generated and evaluated by two independent laboratories. Cell lines utilized were human lymphoblastoid (TK6) cells, human liver hepatocytes (HepG2) cells, Chinese hamster lung fibroblast (V79) cells, whole blood, and buffy coat cells from healthy human volunteers. These cells were exposed to reference ENPs from the Joint Research Council (JRC): SiO2 (RLS-0102), Au5nm and Au30nm (RLS-03, RLS-010), CeO2 (NM212), and BaSO4 (NM220). Tungsten carbide-cobalt (WC/Co) was used as a trial particulate positive control. The chemical controls were positive in all cell cultures, but WC/Co was only positive in TK6 and buffy coat cells. In TK6 cells, mutagenicity was observed for SiO2- and both Au types. In HepG2 cells, Au5nm and SiO2 showed sub-two-fold increases in micronuclei. In V79 cells, whole blood, and buffy coat cells, no genotoxicity was detected with the test materials. The data confirmed that ENPs could be tested with the harmonized protocol, additionally, concordant data were observed across the two laboratories with V79 cells. WC/Co may be a suitable particulate positive control in the in vitro micronucleus assay when using TK6 and buffy coat cells. Detailed recommendations are therefore provided to adapt OECD TG No. 487 for testing ENP.

Ultrasound-assisted electrodialytic separation of cobalt from tungsten carbide scrap powder

Recycling of tungsten carbide-cobalt (WC–Co) will considerably grow in the future. Thus, efficient and greener methods for the recovery of the critical raw materials, Co and W, will be necessary. In this work, we evaluate the separation of Co from WC using an electrodialytic (ED) process alone and coupled with ultrasound-assisted extraction (UAE). The WC-Co powder was suspended in different leaching agents, and the effects of UAE amplitude (probe system), pulse periods, and treatment time were evaluated. The Co extraction was mainly dependent on the leaching agent when only UAE was applied, being more efficient under acidic pH. The ED process, alone and coupled to UAE, was then applied using a reactor with two compartments separated by a cation exchange membrane with nitric acid as anolyte; and the effect of DC intensity was tested for Co separation from WC. Between 24 % and 58 % of Co were solubilized when ED was applied alone, but these values increased up to 96 % through the combination with UAE. The ED process was also applied without the use of nitric acid, taking advantage of the acid generated through water electrolysis, aiming for a more environmentally friendly process. The best Co selective recovery was achieved when ED-UAE was used, reaching 99 % of Co solubilization and 90 % of the total Co electromigration to the cathode compartment, leaving behind the WC residue at the anode. The ED-UAE process presents as a greener process for Co separation from WC residues, with further tests needed to include W recovery.

Improving reliability and service life of industrial products via composite electrochemical coatings

The paper considers a method for obtaining hard, wear-resistant composite electrochemical tungsten carbide-cobalt (WC-Co) coatings with high adhesive strength. Such coatings are used to enhance surface hardness and wear resistance of parts and tooling. It is challenging to obtain hard, wear-resistant coatings on the surface of industrial parts and tooling. It is proposed to use an eco-friendly cobalt electrolyte with tungsten carbide additive for the electrodeposition of composite electrochemical coatings. The electrodeposition technique provides high output and quality of the applied coating with the ability to control its thickness.

Comparison of atomic force microscopy and dynamic light scattering on the size characterization of surfactant-modified WC/Co nanoparticles dispersed in aqueous media

Tungsten carbide cobalt nanoparticles (WC/Co NPs) are extensively employed to fabricate wear-resistant parts, cutting tools, and rock drills. The colloidal stability of the WC/Co NP suspension plays a vital role in determining the mechanical properties of WC/Co-based products. In this work, dispersion of WC/Co NPs in aqueous media was conducted using surfactants (cationic, anionic, nonionic) with different concentration conditions. The z-average hydrodynamic diameters measured using dynamic light scattering (DLS) revealed the optimal surfactant for WC/Co NP dispersion: cationic hexadecyltrimethylammonium bromide (CTAB) which induces interparticle electrostatic repulsion forces at a concentration of 2 g/L. The capping behavior of CTAB was demonstrated using Zeta-potential analysis, Fourier transform infrared spectroscopy, and X-ray diffraction measurements. The mean size measurement of immobilized WC/Co NPs was also conducted using atomic force microscopy (AFM). We demonstrate a comparative protocol between number-weighted mean sizes measured using AFM (dAFM) and DLS (dDLS) in relation to the relative standard deviation (RSD) from AFM measurements. A highly linear correlation was demonstrated between dDLS/dAFM and RSD. We indicate that for polydisperse (RSD > 0.1) and non-spherical NPs, the highest correlation between dDLS and dAFM exists when the RSD is 0.37, where dDLS/dAFM is close to 1.

Microstructural Evaluation of Tungsten Carbide Cobalt (WC-17Co) Alloy Deposited by High-Velocity Oxygen Fuel, High-Velocity Air Fuel, and Cold Spraying Technologies

Microstructural Evaluation of Tungsten Carbide Cobalt (WC-17Co) Alloy Deposited by High-Velocity Oxygen Fuel, High-Velocity Air Fuel, and Cold Spraying Technologies

Experimental evaluation of a WC–Co alloy layer formation process by multibeam-type laser metal deposition with blue diode lasers

A tungsten carbide–cobalt (WC–Co) composite layer was formed on a stainless-steel type 304 (SS304) substrate using multibeam laser metal deposition (LMD) with blue diode lasers. This paper aims to provide WC–Co layer formation with low porosity and high layer formation efficiency by using the multibeam LMD process. The effects of process parameters such as laser output power and powder feed rate are tied together to explain the geometry of the melt layer as well as the fraction of the laser energy used for melting a material. The experimental results show that the porosity rate and layer formation efficiency were recorded at 0.3% and 0.0042 mm3/J, respectively, at the laser output power of 180 W and a powder feed rate of 75 mg/s. It was revealed that layer formation efficiency was dependent on the laser output power.

Multiphase simulation of sustainable nanoenhanced ionic liquid coolants for improved thermal performance in Ti–6Al–4V alloy drilling

Extensive research has been conducted by the manufacturing industry to enhance the efficiency of drilling processes by focusing on the utilization of nanoenhanced cutting fluids that possess excellent heat conductivity. Due to their eco-friendliness and adaptability of physical and chemical properties, ionic fluids offer enormous potential for application as cutting fluids. This study investigates the computational fluid dynamics analysis of the heat transfer performance of various ionanofluid pairs dispersed with nanoparticles as cutting fluids in the drilling process using Ansys Fluent software. For this purpose, 1-Hexyl-3-methyl-imidazolium-tetrafluoroborate is considered the ionic fluid, and its thermal behavior is examined by dispersing it with nanoparticles of copper, silver, and multiwalled carbon nanotubes (MWCNT) at different particle volume fractions and Reynolds numbers. The workpiece is composed of an alloy of titanium Ti–6Al–4V, while the drill bit is made of tungsten carbide-cobalt. It is observed that the ionic nanocoolant mist emanates from the spray tip and moves towards the drill bit-workpiece interface. Initially, the coolant's velocity is greatest close to the orifice, and as time passes, it approaches the drilling space. The data indicates that the spraying velocity of the coolant augments over time and that it disperses heat at the tool-chip interface. The results help us validate the flow and interaction of ionanocoolant with the drilling zone. With a rise in the volume fraction of added nanoparticles and Reynolds number, the results indicated a significant decrease in the drilling temperature. With a higher particle volume fraction, the MWCNT-ionic coolant combination decreases the drilling temperature of pure ionic liquid by 25.64 %. The copper, silver, and MWCNT ionanofluids enhance the average heat transfer coefficient of pure ionic coolant by 35.14 %, 47.42 %, and 62.75 %, respectively. In addition, MWCNT nanocoolants demonstrated improved thermal performance and heat removal rate in comparison to copper and silver ionanocoolants.

Parametric investigation and optimization in laser based directed energy deposition of tungsten carbide-cobalt

Cemented carbide (WC-Co), the widely used tool-die material, is difficult to be machined by conventional and nonconventional techniques. This inspired exploring additive manufacturing (AM) of this material. However, porosity, brittleness due to cobalt depletion, etc. have been reported in the literature with rare success. For the AM of WC-Co, the current work focuses on directed energy deposition, which can be implemented with existing laser cutting-welding workstations, with modifications. To ensure the retention of cobalt even after inevitable vaporization of some of its initial content during deposition, 20 wt. % of Co was mixed with WC powder by low-energy ball milling. Laser power, scan speed, and powder flow rate were varied following a full-factorial design of experiments. The analysis of variance revealed that the experimental model and most of the parameters were significant. Only the laser power came out to be insignificant for the contact angle. The track height and width increased with the laser power and reduced with the scan speed. The contact angle increased with the scan speed and reduced with the powder flow rate. Cross sections of the deposited track showed no pores or cracks. Multiobjective optimization with gray relational analysis was conducted to get the parameter combination giving high values of the contact angle, track height, and width simultaneously. The optimum parameter combination, thus, obtained is 700 W laser power, 5 mm/s scan speed, and 5 g/min powder flow rate. This yielded 305 ± 40 μm track height, 2132 ± 33 μm width, and 152° ± 2° contact angle.

Using particle-loaded inks to selectively change the material properties in binder-jetted WC–Co parts

Functionally graded hardmetals offer a superior combination of fracture toughness and wear resistance and alleviate the compromise that conventional hardmetals must face between these two material properties. In tooling applications, they exhibit superior cutting performance compared to the conventionally employed hardmetals. Traditionally, graded tools are enabled by a surface treatment with nitrogen or carbon. This enables a tungsten carbide–cobalt (WC–Co) tool with a surface layer containing less cobalt (Co) than the core of the part. With this Co gradation, the wear properties can be improved due to the harder surface. If different loads act at different points in a tool and the geometric complexity of a tool increases, the requirements for a targeted positioning of the Co gradients become higher. A simple surface treatment does not allow a flexible distribution of the desired gradients. Binder jetting provides a solution to produce location-independent graded structures. In this work, the process was evaluated for the generation of Co gradients in WC–Co structures. Inks loaded with graphite particle contents of 2.5, 5, 7.5, and 10 m% were used to create differences in the carbon content in the green part. This induced a Co migration during the liquid phase sintering process. The sintering parameters were varied in time and temperature and studied regarding their effect on the microstructure and the porosity, the formation of the Co gradient, and the hardness. At low sintering times and temperatures, all carbon differences led to a Co gradient in the sintering part with a deviation of up to 10 m%. With an increase in sintering time and temperature, the Co distribution began to even out, and a deviation was observed only in the parts created with the inks containing 7.5 and 10 m% of particles. Hardness values of up to 1300 HV10 were obtained, which is comparable to conventionally produced WC–Co parts. The excess of carbon resulted in porosity in the parts leading to a reduced density. However, with inks containing 10 m% particles, densities of 94.26% were achieved at the longest sintering times and the highest temperature.

Design of metal-cutting tool coatings at the atomic level

The research aims to lower tooling costs by reducing the time allotted to designing coatings on domestic cemented carbide metal-cutting tools by using the atomic force approach. The object of the study is coatings on cemented carbides of the tungsten carbide group such as titanium carbide (TiC), titanium nitride (TiN), and titanium (Ti) coatings or a nitride-based titanium, chromium and aluminum (Ti,Cr,Al)N composite coating. To select the most rational coatings, the article employed the method of calculating the functionals of interatomic systems using the density functional description of single atoms. The simplest measure to reduce the cost of designing metal-cutting instruments for manufacturing parts made of difficult-to-machine materials is to develop coatings for this tool type. The article considers various atomic arrangements in the coating material in relation to the WCo8 cemented carbide (VK8, tungsten carbide-cobalt alloy containing 8% cobalt). The calculated values of the interaction energy of the coating material atoms with one another and with the cemented carbide material ranged from 3.04 to 3.5 J/m2. Moreover, the research has established a correlation between the calculation results and the performance parameter of metal-cutting tools considering fracture toughness K1c (MPa ∙ √m). The main result of the study is that the employed computational method made it possible to determine the adhesion value for the atoms of the above-mentioned coating materials with tungsten carbide and cobalt atoms packed in different scale configurations. This enables the classification of coatings from the perspective of ensuring maximum performance properties of the tooling material. The present article assumes that the higher the adhesion value, the better the performance properties. The hypothesis has been confirmed experimentally as well as by the values of fracture toughness K1c. Thus, the most rational coating options have been selected for specified operating conditions of a metal-cutting tool, which permits reduction of tool design costs and makes it possible to predict the performance properties of tools at the design stage.

In-situ laser-assisted ultraprecision cutting of WC-Co cemented carbide for creating microstructure arrays

Tungsten carbide-cobalt (WC–Co), as a typical cemented carbide, is widely used in the manufacturing field. However, creating high-quality microstructure arrays on its surfaces remains challenging due to its extraordinary hardness. To solve this problem, this study proposes an in-situ laser-assisted ultraprecision cutting (LAUC) process to machine different microstructure arrays on the WC-Co surfaces. Experimental results show two kinds of microstructure arrays, namely bi-sinusoidal microstructure array and micro-lens array, are successfully created on the WC-Co surfaces. The average error of feature sizes is less than 2%, showing the high cutting accuracy of the in-situ LAUC process. The average surface roughness of microstructure arrays is below 6 nm, showing the high cutting quality of the in-situ LAUC process. Furthermore, a comparison experiment with the traditional ultraprecision diamond turning process shows the proposed in-situ LAUC process improves the machinability of the WC-Co and decreases the tool wear, further demonstrating its superiority. Therefore, this work provides a new and effective method of creating microstructure arrays on WC-Co surfaces, which greatly enhances the machining quality and extends tool life.