Tungsten Carbide Materials Research Articles

Multiple response optimization of WEDM parameters using grey relational method

Wire electrical discharge machining is a better choice for machining hard materials with very high accuracy which are difficult to machine. This work consists of optimizing the parameters of WEDM for better surface finish and diameter accuracy of tungsten carbide material. The grey relational analysis technique is used for the optimization of the process parameters. Three input variables of WEDM such as Current, Pulse off time, and Voltage were selected for finishing process. The parameters for the roughing process were current – 6 A, voltage – 8 V, Pulse off time – 3 µs and voltage gap – 55 V. Design of experiments has been developed using Taguchi method. The optimum machining parameters from the grey relational analysis was discharge current − 2 A, voltage − 5 V and pulse off time − 8 µs. The confirmation tests were carried out to validate the results.

Highly stable activity of cobalt based catalysts with tungsten carbide-activated carbon support for dry reforming of methane: Role of tungsten carbide

Although tungsten carbide (WC) has similar properties, it is easily oxidized and deactivated during dry methane reforming (DRM). Therefore, it is of great significance to investigate the influence of carburizing atmosphere on the structure and properties of the prepared tungsten carbide material. Here, using ammonium metatungstate as the tungsten source and activated carbon (AC) as the matrix, under different carburizing atmospheres, a tungsten carbide-activated carbon (WC-AC) composite support was prepared through in-situ reduction and carbonization technology. After further loading cobalt (Co) and cerium (Ce), a series of Co-Ce/WC-AC catalysts were prepared. The catalytic performance for dry reforming was investigated. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (H2-TPR) and Thermogravimetric (TG) were used to characterize the crystal phase, microstructure and chemical composition of different samples. The results show that the main component of tungsten carbide prepared in a carburizing atmosphere containing CH4 was bitungsten carbide (W2C); tungsten carbide prepared in a pure hydrogen carburizing atmosphere was composed of W2C and WC. After loading Co and Ce, the catalytic activity and stability of catalysts containing WC are significantly improved compared with those mainly containing W2C. Due to the presence of WC, the interaction between the metal and the carrier was enhanced, thereby improving the dispersibility and oxidation resistance of the active component Co species. At the same time, WC was helpful to transform Co3+ to Co2+ and Ce4+ to Ce3+ on the surface and inner of catalyst, which was conducive to the enrichment of chemically adsorbed oxygen on the catalyst surface and the formation of oxygen vacancies. It promoted the adsorption and activation of CO2, and improved the anti-carbon deposition performance of the catalyst.

Surficial charge state tuning of tungsten carbide for catalyzing alkaline hydrogen evolution reaction

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.

Surface generation of tungsten carbide in laser-assisted diamond turning

The removal mechanism of conventional cutting and in-process-heat laser-assisted cutting (In-LAC) of binderless polycrystalline tungsten carbide (WC) material is studied through systematic numerical analysis and experimental investigation. The proposed In-LAC model considers the accumulated thermal effect and the laser in-process-heat thermal boundary condition simultaneously. Results of molecular dynamics (MD) analysis are remarkably consistent with the experimental results qualitatively. The high-temperature nanoindentation test reveals the improved machinability of WC at an elevated temperature and provides a theoretical basis for cutting force reduction. A small Young's modulus measured at an elevated temperature presents a large elastic recovery value for the In-LAC model. The critical depth of no observed surface cracks of binderless WC increases from 26.6 nm to 106.3 nm, which can be attributed to in-process laser assistance. Furthermore, the In-LAC method is beneficial to avoid subsurface crystal bending and reduce subsurface damage in the MD model and the taper cutting sample subsurface. The existence of the laser annealing effect during the In-LAC process is directly proven by binderless WC cross-section transmission electron microscopy (TEM). According to the simulation analysis results and diamond turning chip morphology, the optimal laser power for polycrystalline WC ranges from 10 W to 15 W, which facilitates obtaining the surface finish of 4.66 nm in Sa and significantly improving the tool life.

Analysis of the impact factors from the friction stir welding process for dissimilar butt joints between semi-solid cast aluminum 356 and AISI 1018 carbon steel

This research aimed to study the impacts of three different rotation speeds of 710, 1000, and 1400 rpm and three welding speeds of 40, 56, and 80 mm·min-1, on dissimilar butt joints between semi-solid aluminum 356 and AISI 1018 carbon steel. Welding tools were made from tungsten carbide material, and the offset was 0 mm. It was found that an increase in the rotation speed and welding speed caused accumulated heat, which led to the appropriate changes in the metallurgical structure. The rotation speed and welding speed factors had the impact on the greater blending of the two metals at the SZ zone. A larger amount of semi-solid aluminum 356 infiltrated into the AISI 1018 carbon steel when the rotation speed and welding speed increased. The findings showed that the most influencing factors on the average tensile strength at the weld lines were the rotation speed of 1000 rpm and the welding speed of 56 mm·min-1. The experiment in this study showed the maximum average tensile strength of 139.9 MPa and the average hardness value of 264.5 HV as the highest hardness value at the welding rotation speed of 1400 rpm and the welding speed of 80 mm·min-1.

Effect of tool travel speed on tensile strength of friction stir welded dissimilar joint of aluminium AA6061 T6 alloy and maraging M250 steel

Friction stir welding (FSW) is a promising welding method to produce dissimilar joints between steel and aluminium. The formation of the intermetallic compound layer at the dissimilar joint interface affects the joint mechanical properties, which are also influenced by the FSW process parameters. In the present research work, M250 Maraging steel and AA6061 T6 aluminium alloy were joined by FSW. The joints were prepared with five different tool travel speeds ranging from 0.33 mm s−1 to 1 mm s−1 using a tapered tool pin made by tungsten carbide material, keeping tool rotational speed constant. The welded joints were analyzed for their tensile behaviour and microstructural change, including hardness measurement. The failed samples are analyzed using a scanning electron microscopy device for their mode of failure. In the Energy Dispersive X-Ray Spectroscopy (EDS) analysis, the formation of intermetallic compound (IMC) layers of Fe3Al, Fe4Al13, and Fe2Al5 are observed. When the thickness of the IMC layer increases, the joint strength decreases. It is found that the welding speed influences the thickness of the IMC layer formed, causing variation in the strength of the dissimilar joint. Better joint efficiency is obtained at a tool travel speed of 0.67 mm s−1.

The Impact of Low Plasticity Burnishing Process Parameters on Residual Stress and Percentage of Cold Working Distribution in Ti-6Al-4V Alloy

Compressive residual stress is a significant factor in influencing a fatigue failure of a mechanical component. In this perspective, the attempt has been made to induce beneficial compressive residual stress in Ti-6Al-4V alloy by using low plasticity burnishing process. The mechanism of LPB process includes rolling spherical balls made of tungsten carbide material over a material surface under fluid pressure supplied by a hydraulic unit. In this study, the cost-effective low plasticity burnishing tool with hydraulic fluid system is designed and fabricated. The LPB process was carried out on Ti-6Al-4V specimen with a suitable fixture. In this paper, the effect of burnishing process on residual stresses and cold working in Ti-6Al-4V was studied by using burnishing pressure and passes as a process parameter. The explicit module of the FE-Analysis code 6.17 was used with the aim of performing numerical simulation. The obtained experimentation results were considered to validate the results obtained by numerical FE analysis. It was found that there is good agreement between the experimental and numerical results. Both FEM simulation and experimentation results showed that hydraulic burnishing pressure is the most influential parameter in inducing beneficial compressive residual stress with less amount of coldwork.

Surface quality of cemented tungsten carbide finished by direct cutting using diamond-coated carbide end mill

• Superiority of direct cutting of cemented carbide with diamond-coated tool was shown. • Surface quality in direct cutting, electrical machining, and polishing was compared. • Specularity of finished surface similar to polishing was obtained via direct cutting. • Large compressive residual stress can also be obtained via direct cutting. • Higher transverse rupture strength can be achieved compared with polishing. This study addresses the finished surface quality of cemented tungsten carbide obtained via direct cutting with a diamond-coated carbide end mill under ultrasmall feed rates. The surface appearance, composition distribution, profile, roughness, residual stress, and transverse rupture strength were experimentally investigated. The finished surfaces obtained via electric discharge machining with two types of machining conditions and mechanical polishing processes were also evaluated to compare the surface quality. Two types of cemented tungsten carbide materials, TAS VC-70 and VM-40, were applied as the workpiece materials. A mirror surface can be obtained via direct cutting and mechanical polishing with both materials. The microstructure morphologies of the finished surface obtained via direct cutting were different from those obtained via mechanical polishing. In the case of VC-70 which has larger tungsten carbide grain size and higher cobalt content, the flat cross-section of the tungsten carbide grain under ductile mode cutting was conspicuous in direct cutting under small feed rate and depth of cut. In contrast, an extremely thin layer composed of fine grains of tungsten carbide and cobalt was observed on the finished surface in direct cutting under comparatively large feed rate and depth of cut. The surface roughness and profile of the finished surface resulting from direct cutting were comparatively rougher than those resulting from mechanical polishing, although the finished surface was significantly smoother than that resulting from electric discharge machining. The residual stress of the subsurface obtained via direct cutting showed larger compressive stress than that obtained via electric discharge machining and mechanical polishing under all cutting conditions and materials. Moreover, satisfactory transverse rupture strength can be obtained via direct cutting in both materials compared with other processes, and two times more transverse rupture strength can be achieved via direct cutting compared with the case of electric discharge machining in VM-40 cutting.

Influence of machining parameters on the response variable during drilling of the hybrid laminate

ABSTRACT Hybrid laminates made of Carbon Fibre and Glass Fibre Reinforcement have become widely popular in various applications which are mainly due to their excellent structural strength coupled with lower cost. In all these applications, drilling plays a crucial role during the assembly of these structural components. This paper deals with the examination of the influencing parameters (feed rate, tool material) on thrust force during drilling of hybrid laminates. Statistical Design of Experiments has been used for the analysis of the drilling parameters on the thrust force. Taguchi’s L9 (32) array has been used to determine whether the response function is minimised by feed rate or tool material. Hole drilling on hybrid FRP laminate has been done using Solid Tungsten Carbide and High-Speed Steel tool material under controlled machining operations. The results reveal that the tool material has a higher influential effect on the thrust force when compared with the feed rate. Also, the morphology of hybrid laminate was obtained using a Scanning Electron Microscope (SEM) and the results indicate that surface texture was observed to be optimum.

Performance characteristics of electrochemical micro machining of tungsten carbide

Electrochemical micromachining (EMM) is still an evolving process and a more number of research wants to be carried out to improve metal removal rate (MRR), surface finish and precision with optimization of its various process parameters. In the present work tungsten Carbide material, which is conventionally used as a tool for drilling, cutting, armour plating and surgical equipment is taken for studying the performance characteristics of EMM. However, its machining is very difficult by conventional machining processes due to its high hardness and wear resistance properties. The major purpose of this study is to find out MRR, surface roughness and over cut on machining Tungsten carbide using NaNO3 as an electrolyte in EMM. The process parameters that are to be varied in this study are concentration of electrolyte, tool feed rate and applied voltage. From the results of the experiment, optimized by Taguchi grey multi-response optimization technique the optimum input parameters are detected. The optimized parameters found for the EMM of tungsten carbide are the concentration of electrolyte 20 g/l, a tool feed rate of 0.9 μm/min and applied voltage of 9 V. It can be inferred from the results obtained that the feed rate of tool has a greater influence on the EMM process.

Automatic identification of edge chipping defects in high precision drilling of cemented carbide

Automatic visual inspection methods for product quality checking are spreading more and more in the present 4.0 manufacturing industry. This paper addresses the automatic inspection of edge integrity in accurate holes obtained by direct drilling of cemented carbide with innovative diamond coated tools. These revolutionary cutting tools, recently appeared on the market, can process extremely hard carbide in the sintered state, with massive increase of productivity with respect to standard methodologies like electrical discharge machining (EDM). However, due to the brittleness of the materials, the mechanical cutting process becomes critical and sensitive to tool breakage and workpiece defects generation. In particular, chipping of the hole edges represents one of the most important issues to monitor and take under control. A software procedure, that analyses high-resolution images taken from optical microscopes, was then developed for that aim. Image processing algorithms were designed and applied to enable the automatic extraction of the holes profile, thus permitting the identification and quantification of the leading edge damage in the radial direction. The proposed approach is fully automatic and is based on a profile segmentation that exploits an edge detection algorithm followed by a contour extraction method based on the solution of a partial differential equation. Dedicated metrics were specifically developed to evaluate the extracted profiles. The approach was validated with a factorial plane involving 1.6 mm diameter holes generated with different cutting parameters and tools on tungsten-carbide (WC) material. The technique resulted suitable for the aim, enabling the automatic characterisation of the defects generation phenomenon throughout the entire tools life. This moves a step toward the implementation of both in-line hole inspection procedures and advanced drilling process control.

Hot Pressing of Tungsten Monocarbide Nanopowder Mixtures by Electroconsolidation

The paper presents theoretical and experimental results in the field of the manufacturing of cemented tungsten carbide materials. The important issue of avoiding any additional substances like plasticizers was challenged in order to reach the maximal possible density of sintered material while keeping its purity. To solve the problem, the electroconsolidation method of hot pressing supported by direct current was applied. The respective apparatus was constructed that enabled WC nanopowders to be sintered under pressure and high temperature during a very short time of ca. 3 minutes. In the experiments, because of the short heating time, grain size of the sintered bulk WC increased insignificantly, in general, remaining smaller than 1 μm. Similarly, sintering under hot pressing with direct current, a mixture of 3% by weight Y2O3 stabilized ZrO2 and 50% by weight WC, produced a fine structure with a uniformly distributed WC grains. The applied electric field led to the formation of a temperature gradient around the pores, with a favourable impact on the compaction of large pores and an increase in the final density of the bulk material. The experimental research confirmed that the main mechanism of the densification of nanodispersed powders of tungsten monocarbide was a locally inhomogeneous diffusion-viscous flow with intergranular slipping.

Effect of Cryogenic treatment on Tool Wear, Chip Thickness of Uncoated Carbide Insert during Machining with AISI304 Stainless Steel

The cutting tool in the manufacturing industry is a key factor. The fulfilment of machining operation mainly depends on the tool material to improve the cutting life of the tool during machining with austenite stainless steel, however the austenite stainless steel difficult to machine and less amount of heat dissipation during machining in order to overcome. The aim of the investigation is to apply; the cryogenic treatment (CT) to the tungsten carbide insert, besides no study has been claimed on the chip thickness (tc), tool wear of machining with AISI 304. The machining test was conducted by three different speed and unchanged feed rate and depth of cut. The maximum flank wear was measured by using digital microscope also measured the chip thickness for both insert. The experimental results found that to reach the maximum flank wear for CT insert in all three speed was less in comparison with untreated insert (UT), chip thickness was also less in case of CT insert, built up edge were clearly observed in the UT insert, over all CT insert performed more desirable in compared with UT. The improvement in the microstructure properties of the CT insert owing to development of Eta (η) phase carbide and homogenous distribution in the tungsten carbide material, SEM and XRD tests are confirmed these results.

Friction Stir Welding of AA6082 Thin Aluminium Alloy Reinforced with Al2O3 Nanoparticles

ABSTRACTIn this present investigation, AA6082-T6 thin aluminium alloy plates of 2 mm thickness were friction stir welded using fine ceramic Al2O3 nanoparticles as the reinforcing materials between the adjoining plates. The joining was done by hexagonal pin profile tool of tungsten carbide material with tool rotational speeds 710 rpm and 900 rpm. The number of passes of the welds was 2 and 3 with constant tool traverse speed of 40 mm/min. Microstructural study was done by employing an optical microscope and electron microscopy. The microstructural results show that the weld produced with tool rotational speed of 710 rpm, tool traverse speed of 40 mm/min and the number of passes 3 has the good distribution of the alumina nanoparticles in the stir zone leading to grain refinement. The reinforced sample welded with 3 passes achieved the highest average grain size number of 16.02 and highest ultimate tensile strength of 227.61 MPa, yield strength of 154.9 MPa and elongation percentage of 10.5%. The reinforcement-included welded sample exhibited highest hardness value of 74 Hv in the weld nugget zone.

Design, Develop and Simulate Microdrilling Cutting Tool

Microdrilling has an important role in the world of modern industry, especially in terms of miniaturizing existing products or components. Through this research explain the design, development of design and simulate microdrilling cutting tools. By using four geometries that are different from the previous model of micro drilling tools, a development, modeling and simulation were carried out and analyzed using Finite Element Analysis (FEA) using ABAQUS Software. Titanium alloys (Ti6Al4V) and tungsten carbide (WC) materials were chosen as one of the materials for the workpiece and cutting tools respectively. Microdrilling device is a constant variable, as for the amount of flutes and point angles is an independent variable. Cutting force, cutting temperature and Von Voltage misses from the micro model are analyzed from the simulation results based on these independent variables. After observing it turns out that fewer flutes will cause a high value to cut the temperature, cut the strength and also Von Mises.

Influence of Router Tool Geometry on Surface Finish in Edge Trimming of Multi-Directional CFRP Material

The use of carbon fibres reinforced plastic (CFRP) composites material for product structures has been steadily increasing due to the superior material properties such as high strength, low weight and corrosion resistance especially in aerospace industry. This work presents a research on the influence of various router or burrs tool geometrical feature towards surface roughness in edge trimming process on a specific CFRP material. CFRP panel which measured in 3.41mm thickness with 28 plies in total has been chosen to be the main study material. Three various geometrical features of router tool made of uncoated tungsten carbide material with diameter of 6.35mm which vary in number of flute and helix angle were utilized to investigate the effect of surface roughness in edge trimming of CFRP material. Surface roughness measurement was taken using Mitutoyo Surftest SJ-410. Furthermore, optical microscope Nikon MM-800 is utilized to further observe the trimmed surfaces. The result reveals that tool type 3 (T3) resulted the lowest surface roughness with respect to the overall averaged Ra value which ranged between 2.22µm to 5.29µm whilst tool type 1 (T1) obtained the highest Ra values ranged between 2.86µm to 19.36µm. On the other hand, the tool type 2 (T2) falls in the middle between the rests of two others type of tool which stated the range of Ra average value was between 3.91µm to 5.28µm. This result is also supported by photomicrographs observation taken by optical microscope which elaborated and discussed further in this paper.

Transition Metal Induced the Contraction of Tungsten Carbide Lattice as Superior Hydrogen Evolution Reaction Catalyst.

Tungsten carbide (WC) materials have exhibited platinum-like catalytic behavior in many fields, whereas the adsorption of pure tungsten carbide for H is too strong and demonstrates low activity for hydrogen evolution reaction (HER). Herein, we successfully introduced transition metal into WC lattice and optimized the electron structure around Fermi level ( EF) of WC via facile annealing CoW-based metal-organic framework precursors. X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption fine structure verified the incorporation of Co and the contraction of WC lattice. Density functional theory calculations indicated that the doping of Co into WC significantly increases the state density of WC at EF derived from the delocalization of Co charge, resulting in the moderate H2O binding energy and weakened H adsorption. As expected, the optimal Co-doping WC (Co/W molar ratio = 3) efficiently catalyzed HER with a low onset potential (31 mV) and a current density of 10 mA cm-2 at a low overpotential of 98 mV in 1.0 M KOH media, which was superior to that of WC/CN and Co/CN. Similarly, Ni and Fe could also modulate the electronic structure of WC and improve the HER activity.

Assessment of Hard Thin Layers Deposited by Plasma Spray on Hydroboration

Chemical mixers used in pharmaceutic industry are mostly constructed from a series of iron, chrome and nickel alloys. These mixers are used for mixing corrosive chemicals (acid or base) that often contain solid particles acting as the abrasive particles on the mixer blades. In this paper, martensitic stainless steel AISI 415 is used as base material and powder based on tungsten carbide is used for deposition of hard thin film resistant at common action of abrasive particles. The properties of metallic materials can be improved by deposition of layers with special material by plasma spraying method. Microstructure of thin films made of tungsten carbide and base material was performed with Scanning Electron Microscopy (SEM). In order to determine the micro hardness of the base material and the deposited layer, Vickers micro hardness testing have carried out. For determination of roughness of the deposited layer, tests were carried out using the equipment Mitutoyo SJ 301.

Binderless tungsten carbide carbon control with pressureless sintering

Binderless tungsten carbide material systems can achieve properties which make them ideal for use within highly abrasive wear environments, though carbon control is essential for reaching maximum density and performance levels when sintered in the absence of applied pressure. Introducing WO3 and W additives coupled with controlled thermal processing cycles provides a means to moderate the excess carbon introduced coincident with greenware forming methods required for practical shaping. With sintering temperatures of 1700 °C, controlled final stoichiometry and hardnesses up to 2700 kg/mm2 are demonstrated.

The effect of steel disc surface texture in contact with ceramic ball on friction and wear in dry fretting

Ceramics are used in a wide range of applications including bearings. Ceramic—metal contacts are of great potential for the future. The purpose of this paper is to study the effect of a surface topography of a steel disc in contact with ceramic ball on friction and wear under dry gross fretting regime. Experiments were carried out using an Optimol SRV5 tribological tester under dry friction conditions in the gross fretting regime. The number of cycles was set to 18000, temperature was 30 °C, the stroke was set to 0.1 mm, the normal load was 45 N. A ceramic ball from tungsten carbide (WC) material of 10 mm diameter was put in contact with steel discs of various surface textures with hardness of 47 and 59 HRC. It was found that the average coefficient of friction and volumetric wear of the tribological system were inversely proportional to disc roughness height. These dependencies were stronger for higher disc hardness.