Cemented Carbide Materials Research Articles

Densification and properties of WC-CoCrFeNi/Co cemented carbide fabricated via spark plasma sintering

The spark plasma sintering (SPS) technique was used to employe WC-CoCrFeNi/Co cemented carbides, incorporating CoCrFeNi and Co as low-coercivity binder phases, resulting in the development of cemented carbides with exceptional mechanical properties. The densification mechanism varying with increasing sintering temperature and the effect of densification on the mechanical properties were investigated using the creep deformation model. In the temperature range of 1100 °C–1300 °C, the main factors contributing to densification behavior are particle rearrangement and grain boundary diffusion due to the viscous flow of the binder phase. The densification mechanism gradually transforms into dislocation climbing with increasing temperature. When the sintering temperature exceeded 1300 °C, the WC grain size increased significantly with increasing temperature and holding time, and the dominant mechanism for grain growth was grain boundary diffusion. The high densification resulted in a substantial increase in effective grain boundary area, thereby increasing both hardness and fracture toughness of the material. Benefiting from the fine grain strengthening effect of the high-entropy alloys (HEAs) and the excellent wettability of Co, a highly dense cemented carbide material with excellent hardness and fracture toughness is achieved at the sintering temperature of 1300 °C, characterized by a relative density of 99.3 %, a hardness of 2064.9 MPa, and a fracture toughness of 11.5 MPa m−2.

Dry Sliding Wear Behavior of Cemented Carbide at Elevated Temperatures

The material for a cutting tool needs to be carefully selected to withstand high temperatures during cutting and have good wear performance. The use of cutting tools made from cemented carbide material was studied due to its potential in terms of mechanical properties that are ideal at high temperatures up to 1000 °C and being cheaper than other materials. This investigation of the dry wear of this cutting material focused on temperatures of 25 °C, 200 °C, and 300 °C, with loads of 50 N, 100 N, and 150 N. The weight loss, friction coefficient, and change of the pin microstructure were determined. It was found that the higher the temperature and load applied to the cemented carbide pin, the more the microstructure changed, and the percentage of weight loss increased up to 0.55%. The wear rate on the cemented carbide pins was higher when applied to a stainless steel disc compared to a mild steel disc. The simulation revealed that the von Mises stress on the stainless steel disc was 51.759 Pa, while that on the mild-steel disc was 60.379 Pa. This indicates that both materials did not fail because the von Mises stress was lower than the disc yield stress.

Study on interface characteristics of WC-Co doped Y rare earth element cemented carbide cutting tool and its influence on material properties

The influence of doping rare earth element Y on the material properties at the W and C interfaces of WC (0001)/Co (111) was studied using first principles calculations, taking into account adhesion work, interface energy, density of states, and Mulliken population. The grain size of WC-Co cemented carbide doped with rare earth element Y was analyzed before and after doping through cellular automata simulation. The microscopic morphology of the cemented carbide materials before and after doping with Y element was observed and analyzed by experiments, and their mechanical properties were tested. The research results have shown that the interface structure doped with Y has smaller interface energy, greater adhesion work, and stronger interface bonding ability. All four interface models exhibit metallic properties, and the addition of Y element enhancing the metallicity of WC-Co. The W-d and Y-p orbitals undergo orbital hybridization and generate covalent bonds, improving the durability and bonding strength of the material. The bond length of C-W at the interface after doping is smaller than that before doping, and the population is greater than that before doping, indicating an enhanced stability of the interface. After the addition of rare earth element Y, the crystals underwent through-crystal fracture, and the fracture showed irregular shapes, which improved the bonding strength of the interface. Through the cellular automata simulation, it was found that the grain size after doping with Y element was significantly smaller than that before doping, and it was experimentally verified that the doping of rare earth element Y played the role of grain refinement. At the same time, it could reduce the coefficient of friction of the material, and improve the overall performance of the cemented carbide material.

Effect of MoS2 element diffusion under high temperature condition on the tribological properties of cemented carbide materials

To further clarify the effect mechanism of MoS2 element diffusion on tribological properties of cemented carbide materials, an investigation was carried in this study. The diffusion process between cemented carbide inserts and MoS2 powder under high temperature condition was carried out in a muffle furnace device. The surface morphology and chemical element content of test samples were observed and measured with scanning electron microscope, energy spectrum, and X-ray diffraction instruments. The kinetics of the diffusion process was quantitatively discussed by thermodynamic experiments. Tribological experiments were carried out using friction and wear machine with which the friction coefficient and wear scar were obtained. The experimental results show that high temperature has a significant effect on physical and mechanical properties of cemented carbide materials. Moreover, MoS2 elements diffusion on sample surface is existed and induced by thermal action, which results in a further changing of material properties of cemented carbide. The WC grain growth is inhibited when molybdenum element is only infiltration on sample surface at 500 °C, which improves the surface morphology and hardness of test sample. However, the oxidation rate, friction coefficient, and wear rate of test sample are the highest when heating temperature larger than 500 °C. The main reason is that, as the temperature increasing, the diffusion of sulfur elements is occurred and intensified the loss of cobalt element on sample surface. So, the bonding ability of it is decreased due to the loss of bonding phase Co. Thus, the surface hardness and wear resistance of test sample is deteriorated. This study provides a theoretical foundation for the application of molybdenum disulfide in tool cutting lubrication condition.

Effect of Nickel Element Diffusion on the Tribological Properties of Cemented Carbide Materials under High Temperature Condition

Effect of Nickel Element Diffusion on the Tribological Properties of Cemented Carbide Materials under High Temperature Condition

Hardness prediction of WC-Co cemented carbide based on machine learning model

The hardness of cemented carbides is a fundamental property that plays a significant role in their design, preparation, and application evaluation. This study aims to identify the critical factors affecting the hardness of WC-Co cemented carbides and develop a high-throughput predictive model for hardness. A dataset consisting of raw material composition, sintering parameters and characterization results of cemented carbides is constructed in which the hardness of cemented carbide is set as the target variable. By analyzing the Pearson correlation coefficient, Shapley additive explanations (SHAP) results, WC grain size and Co content are determined to be the key characteristics influencing the hardness of cemented carbide. Subsequently, machine learning models such as support vector regression (SVR), polynomial regression (PR), gradient boosting decision tree (GBDT), and random forest (RF) are optimized to construct prediction models for hardness. Evaluations using 10-fold cross-validation demonstrate that the GBDT algorithm model exhibits the highest accuracy and strong generalization capability, making it most suitable for predicting and analyzing the hardness of cemented carbides. Based on predictions from GBDT algorithm model, PR algorithm model is established to achieve high-precision interpretable prediction of the hardness of cemented carbides. As a result, a quantitative relationship between hardness and Co content and WC grain size is obtained, demonstrating that reducing grain size and Co content is the key to obtaining high hardness of cemented carbide. This research provides a data-driven method for accurately and efficiently predicting cemented carbide properties, presenting valuable insights for the design and development of high-performance cemented carbide materials.

Experimental research on the welding strength of PCBN and cemented carbide materials for cutting tools application

The PCBN tools has extensive applications in machining of various ferrous materials. The welding process is the necessary step to connect the PCBN tool nose and cemented carbide tool body. This paper conducted a series of welding experiments between PCBN and cemented carbide, the effect of filler alloy, surface treatment and heating parameters on the shearing strength has been tested and analyzed. The results showed that the addition of active element In in filler alloy can increase the shearing strength by 19.9%, and the side and bottom surface polishing treatment can increase the shearing strength by 124.1% and 96.8%. The adequate heating temperature and time to ensure full chemical metallurgical reaction is significant to obtain the higher shearing strength. At finally, the optimal welding parameters were used in PCBN tool application to improve the welding strength.

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.

Study on the rapid synthesis of high-entropy carbonitride powder and its remarkable hardening effects on cemented carbide tool materials

As a novel high-entropy ceramic material with a multi-cation and multi-anion sublattice structure, high-entropy carbonitride ceramics (HECNs) have exhibited outstanding comprehensive properties and attracted increasing attention. In this study, a new WC-based cemented carbide material reinforced by high-entropy carbonitride (Ti0.2W0.2Mo0.2V0.2Nb0.2)(C0.7N0.3) (marked as HECN) was successfully fabricated by vacuum hot-pressed sintering. The mutual constraints between hardness and fracture toughness in extant WC-Co cemented carbide tool materials and their deficient high-temperature mechanical properties were effectively addressed. Moreover, for the low efficiency of the traditional carbothermal reduction nitridation, a novel method for rapidly preparing HECN powder was firstly proposed, namely the microwave-assisted carbothermal reduction nitridation, which could accelerate the heating rate and shorten the holding time. Single-phase HECN powder was successfully synthesized by this method, and the impacts of varying HECN content on the room and high-temperature mechanical properties of WC-based cemented carbide were investigated combined with the microstructure analysis by XRD\\SEM. The results revealed that HECN effectively inhibited the grain growth of WC in cemented carbide, and the refined WC grains provided a high-volume fraction of grain boundaries, which prevented dislocation movement and increased the hardness. With the optimized HECN content of 10 wt%, the Vickers hardness and fracture toughness of WC-HECN-Co composite reached 21.58 ± 0.36 GPa and 12.27 ± 1.17 MPa∙m1/2 respectively. Furthermore, WC-10HECN-10Co composites possessed outstanding high-temperature hardness and maintained a high hardness value of 13.16 ± 0.30 GPa at 800 °C, 37% higher than that of WC-10Co. The findings of this research hold significant practical implications for applying cemented carbide cutting tools in high-speed dry cutting.

Energetic characterization during plasma electrolytic polishing of cemented tungsten carbide

Electrical and thermal measurements were conducted during the plasma electrolytic polishing (PEP) of cemented tungsten carbide (WC-Co) materials to characterize energetic aspects of the process in relation to the temporal development of the gaseous layer near the workpiece. The power transferred to the workpiece is determined using a calorimetric probe and employing the time derivative of the temperature curve. It shows distinct heating phases due to the generation of the gaseous layer. At the beginning of the process, a typical power of 367 ± 17 W is transferred to the workpiece of a surface area of 14 cm2. At longer process times, a stabilized gaseous layer limits the power transferred to the workpiece to 183 ± 3 W. In an attempt to describe the heat transferred to the electrolyte, the electrolyte temperature was measured using a thermocouple situated 15 mm away from the workpiece. The local electrolyte temperature increases from 70 to 81 °C for an immersion depth of 20 mm. Moreover, the spatiotemporal development of the electrolyte temperature was obtained by 2D-hydrodynamic modeling using COMSOL Multiphysics®. The modeling results for the local temporal temperature development are in excellent agreement with the experimental values when the turbulent model is applied up to t = 65 s. Afterward, the laminar model leads to a better agreement. Furthermore, line scan x-ray photoelectron spectroscopy revealed that aliphatic carbon was preferentially removed. Only a slight compositional gradient in the vertical direction after the PEP process was observed.

Study of the Friction Behavior of Embedded Fibers in YG8 Surface Grooves.

YG8 is a common cemented carbide material with excellent mechanical properties and mechanical properties, so it is widely used in the actual industry. However, due to the active chemical properties and strong affinity of tungsten alloy steel, it is easy to produce bonding and peeling in application, resulting in an unstable process and short service life. In order to control and reduce the surface wear of YG8 cemented carbide, groove-textured surface (GS) and flocking surface (FS) were prepared on smooth surface (SS). The friction characteristics of the samples were studied under different applied load conditions. The results show that the average friction coefficient of SS, GS and FS is inversely proportional to the load in dry/oil environment. Compared with SS, FS exhibits the lowest friction coefficient, which is reduced by 30.78% (dry friction) and 13.13% (oil lubrication). FS effectively improves the tooth jump phenomenon of the sample and the amplitude of the friction coefficient, friction force and load, and has the best anti-friction characteristics. At the same time, the FS with the fastest contact angle drop at any time also showed excellent wetting ability, and the wear rate decreased by an order of magnitude. The implantation of fibers in the groove inhibits the spalling and furrow of wear track, which is attributed to the effect of fibers on damage repair. In the friction process, FS increases the content of the O element and induces the formation of oxides. The friction mechanism is mainly chemical wear. The excellent tribological properties of FS have a good guiding significance and theoretical support for improving the tribological properties of high hardness material surfaces.

Mechanism of high corrosion resistance for cemented carbide materials coated with CrN via interface analysis

Cemented carbide materials contain expensive rare metals and are used in diverse processes as substrates for moulds, cutting tools, and metal products due to their hardness and strength. Applying a hard coating to these substrates extends the service life and enhances functionality such as corrosion and wear resistance. Hard coatings are comprised of different elements (e.g., Ti, Cr, or multiple elements) and take different forms (mono and multilayers). Although research on hard coatings is becoming more sophisticated, the interaction between the substrate and hard coating is rarely examined. Cr-based hard coatings are often applied on cemented carbide materials because it generates a high adhesion and corrosion resistance. However, the origin of these features is unclear. Here, we focus on the interaction that occurs at the interface between substrates (cemented carbide and high-speed steel) and hard coatings (CrN and TiN). Specifically, the elemental composition and crystal structure of the interface are analysed to elucidate the factors that lead to high adhesion and corrosion resistance. Cr ions more readily penetrate the surface of cemented carbide and react with W than Ti ions. Coating CrN on cemented carbide spontaneously forms an approximately 10-nm-thick CrW bonding layer at the interface. Also, the formation of the bonding layer does not occur when the substrate is high-speed steel. Additionally, electrochemical characterisation shows that the CrW bonding layer protects cemented carbide materials from corrosion under both acidic and basic conditions. Thus, using a thin film as a bonding layer contributes not only to high adhesion between the substrate and hard coating but also corrosion resistance of cemented carbide materials coated with CrN. These results should help effectively select the appropriate elements, substrates, and hard coatings according to the intended purpose.

Preparation of Ti-coated diamond/WC-Co-based cemented carbide composites by microwave-evaporation titanium-plating of diamond particles and microwave hot-press sintering

Diamonds are considered ideal additives for improving the wear resistance of cemented carbide materials and thus for extending their service life. However, the poor wettability and thermal stability of diamonds limit their effectiveness. To solve this problem, in this study, microwave-evaporation technology, a low-cost and simple approach, was used to prepare a uniform titanium coating on diamond surface with an optimized diamond-to-titanium-hydride ratio of 5:3 and an optimized holding time of 1 h at 760 °C. The TiC interlayer with needle-rod microstructure was observed. The coating could increase the oxidation weight-loss temperature by 152.7 °C. The different steps of the high-temperature ablation process of Ti-coated diamond were also revealed. Then, Ti-coated diamond/WC-Co-based cemented carbide composites with uniform microstructure, good interfacial bonding, and no thermal burning loss of diamond were prepared using microwave hot-press sintering with a temperature of 1050 °C only and a pressure of 40 MPa, leading to good wear resistance. The wear rate of the composites prepared with Ti-coated diamond was 25.7% lower at room temperature and 50.7% lower at 400 °C than that of the uncoated diamond. This approach minimized the thermal damage to diamond since both Ti-coated diamond and the composites were prepared at low temperatures.

Preparation of Cemented Carbide and Study of Copper-Accelerated Salt Spray Corrosion and Erosion Behavior.

(1) Mud pulser carbide rotors, as a core component of ground communication in crude oil exploration, are often subjected to mud erosion and acid corrosion, resulting in pitting pits on the surface, which affects the accuracy. The purpose of this study was to investigate the acid corrosion and erosion behavior of cemented carbide materials and provide a reference for the wider application of cemented carbide materials in the petrochemical industry. (2) Experimental samples of tungsten–cobalt carbide were sintered at a low pressure by powder metallurgy. The petrochemical application environment was simulated by accelerated salt spray corrosion and solid slurry erosion with the aid of acidic copper, and the experimental phenomena were analyzed by SEM (scanning electron microscope), EDS (Energy Dispersive Spectroscopy), and XRD (X-ray diffraction). (3) The experimental results show that the coercivity of the pitted cobalt-cemented tungsten carbide prepared in this study was 17.89 KA/m, and the magnetic saturation strength was 14.42 G·cm3/g. The corrosion rate was the fastest during the acidic copper acceleration experiments from 4 h to 16 h, and the corrosion products of WCo3 and Co3O4 were generated on the corrosion surface. The maximum erosion rate of 0.00104 in the erosion experiment corresponds to a corrosion sample with a corrosion time of 36 h. (4) Therefore, the coercive magnetic force and magnetic saturation strength could be derived from the prepared carbide hard phase grains and carbon content in the appropriate range. The corrosion product in the corrosion process slowed the corrosion rate, and a large amount of cobalt and a small amount of tungsten was lost by oxidation during the corrosion process. The corrosion time had the greatest effect on the erosion performance of the carbide, and the long corrosion time led to surface sparseness, which reduced the erosion resistance.

Neutron diffraction characterizations of NbC-Ni cemented carbides thermal residual stresses

Cemented carbide materials develop very large micro-stresses due to the coefficient of thermal expansion (CTE) mismatch between the metallic carbide phase and the binder phase. While micro-stresses developed in WC-Co cemented carbides have been investigated, there is very little to no information on the micro-stresses developed in NbC-Ni materials.In this study the thermal stresses developed in NbC-Ni materials as a function of the carbide grain size (from 2.5 μm to 12.8 μm) and the binder content (from 8 vol% to 12 vol%) were characterized by neutron diffraction. It was found that the residual stresses decreased with the increase of the binder content and the increase of the carbides grain size. For both binder and carbide phases, stresses were higher for smaller NbC particles, reaching 4 GPa in Ni at the lowest binder content. In general, stresses were higher than the ones measured in WC-Co or WC-Ni composites. This unexpected finding was attributed to the very different shapes presented by the carbide particles; NbC particles are almost spherical, and WC particles are triangular plates with truncated corners. These different shapes create different strain/stress distributions on the microscopic level around the carbide particles.

Effect of Textured Dimples on the Tribological Behavior of WC/Co Cemented Carbide in Dry Sliding with Al2O3/WC Ceramic

Micro-dimples were fabricated on the surface of WC/Co cemented carbide disks by laser, and dry friction tests were carried out by sliding with Al2O3/WC ceramic balls. Results show that the textured cemented carbide can reduce the average friction coefficient by about 30% compared to the smooth sample, while the textured cemented carbide with solid lubricants can reduce the average friction coefficient by about 50%. The density of textured dimples has no obvious influence on the friction coefficient. The wear rates of worn ceramic balls continue to decline with the increase in sliding speeds. The wear rates of the ceramic balls can be reduced by 40~50% for textured samples and about 65% for textured samples with solid lubricants compared to the untextured ones. The mechanism for improving the tribological properties of cemented carbide materials is that the textured dimples can store lubricants and capture wear debris, which would play an important role in promoting the engineering application of surface texturing in cemented carbide materials.

Development of an Energy-Sensitive Detector for the Atom Probe Tomography.

A position and energy-sensitive detector has been developed for atom probe tomography (APT) instruments in order to deal with some mass peak overlap issues encountered in APT experiments. Through this new type of detector, quantitative and qualitative improvements could be considered for critical materials with mass peak overlaps, such as nitrogen and silicon in TiSiN systems, or titanium and carbon in cemented carbide materials. This new detector is based on a thin carbon foil positioned on the front panel of a conventional MCP-DLD detector. According to several studies, it has been demonstrated that the impact of ions on thin carbon foils has the effect of generating a number of transmitted and reflected secondary electrons. The number generated mainly depends on both the kinetic energy and the mass of incident particles. Despite the fact that this phenomenon is well known and has been widely discussed for decades, no studies have been performed to date for using it as a means to discriminate particles energy. Therefore, this study introduces the first experiments on a potential new generation of APT detectors that would be able to resolve mass peak overlaps through the energy-sensitivity of thin carbon foils.

Analysis of large edge breakage of WC-Co cemented carbide tool blades emerging in precision grinding process

This paper analyzes the edge damage characteristics of the cutting blade made of WC-Co cemented carbide material after precision grinding. The edge damage characteristics present tiny cracks and serrated continuous edge breakage. The main causes of the edge damage were explored regarding the edge residual stress, microstructure, and the change of element content. The results show that the value of the average residual compressive stress on the rear surface of the caving edge is −1745.7 MPa, which is much larger than that recorded before grinding (−578.6 MPa). The content of element C and element W on the surface increased obviously (from 28.35% to 34.29% and 54.51%–61.06% respectively). The increase of WC grains and the decrease of Co content will lead to the decrease of the bonding strength of the corresponding material, which will easily lead to the crack at the edge and cave. The grinding experiment of WC-Co cemented carbide was carried out with a bowl shape resin-bonded diamond grinding wheel and was optimized with the orthogonal experimental method. The optimized results show that the single grinding amount was the biggest factor affecting the processing time. The angular speed of rotation and the single grinding amount was listed as the factors that had the greatest influence on the blade rejection rate. Considering the processing efficiency and quality comprehensively, adopting the improved combination during the grinding process, the experimental results were as follows the blade rejection rate is 10%, and the processing time of a single blade is 205 s.

High temperature oxidation and tribological properties of cemented carbide material under different cooling condition

For further clarify the correlation mechanism between the high temperature oxidation and tribological properties of cemented carbide, two groups of test samples of YT15 cemented carbide were prepared and heated to 500 °C ~ 900 °C, then cooled to room temperature in air and cutting fluid medium respectively. The surface morphology, oxidation characteristics, hardness, wettability, and tribological property were measured with white light interferometer, XRD instrument, contact angle measuring instrument, and MWF-500 friction tester. Experimental results indicate that the surface roughness and oxidation degree are increased with the increasing of heating temperature and independent of the cooling medium. Thus, a decrease law of friction coefficient and a worsening trend of surface wear quantity are observed due to low surface hardness under dry friction condition. For cutting fluid lubricating case, the friction coefficient of test sample is firstly decreased with the heating temperature increasing, and then an increased trend is occurred when the heating temperature is more than 800 °C. The main reason is that more wear particles are produced due to the low surface hardness and big contact pressure which deteriorated the lubrications conditions. The main contribution of this work is in providing a reference resources for the tool surface wear mechanism.

Effects of Ultrasonic Shot Peening and Multi-arc Ion Plating on Microstructure and Properties of TiAlN-Coated Cemented Carbide Materials

Effects of Ultrasonic Shot Peening and Multi-arc Ion Plating on Microstructure and Properties of TiAlN-Coated Cemented Carbide Materials