Ni WC Research Articles

Effects of WC/TiC addition on the thermodynamic behavior of TiB2-based cermet during sintering process

The heat absorption, weight change and exhaust behavior of TiB2-based cermet powder mixtures with additions of WC, TiC and WC-TiC were analyzed by a simultaneous thermal analyzer coupled with a mass spectrometer (TG/DSC-QMS). Thermodilatometry was used to investigate the densification behavior due to sintering process of cermets. During the sintering process, the order of degassing is: water vapor, CO2 released by the reduction of adsorbed oxygen in the raw material powder, CO and CO2 released by the reduction of surface oxides of Co and Ni powder, WC powder, TiB2 and TiC powder. The addition of WC, TiC and WC-TiC accelerated the reduction of oxides on the surface of Co and Ni powders, and decreased the temperature point of liquid phase formation in TiB2-based cermet. WC and TiC dissolved in liquid CoNi binder and then precipitated on the undissolved TiB2 particles to form a typical core-rim structure during the sintering. This study is expected to lay a solid foundation for the development of high-performance TiB2-based cermets based on TiB2-CoNi, TiB2-WC-CoNi, TiB2-TiC-CoNi and TiB2-WC-TiC-CoNi cermets in the future.

Insight into the microstructure and properties of Ni–WC composite through vacuum induction melting (VIM): The effects of thermal damage behaviour of cast WC controlled by VIM temperature

Ni–tungsten carbide (WC) composites were prepared using cast WC as hard particles. In this study, the thermal damage behaviour of cast WC particles and its effects on the microstructure and mechanical properties of Ni–WC composites were investigated. Results show that cast WC particles undergo edge dissolution and particle disintegration at 1600 °C and 1800 °C, respectively. The degree of thermal damage to cast WC particles increases from 30.55% to 48.84% when the melting temperature increases from 1600 °C to 1800 °C. In this process, the Ni-based melt gradually erodes the cast WC particles from the edge towards the centre. This leads to severe dissolution of the W2C phase, while the WC phase only dissolves partially. Notably, the degree of thermal damage to cast WC directly correlates with the W content in the melt. An increase in the W content enhances the volume fraction and nano-hardness of the M23(B, C)6 compound, improving the wear resistance of the composites.

A photocatalyst with an enhanced Schottky effect and an efficient electron-transfer channel fabricated by assembling Ni–WC heterojunction nanoparticles on g-C3N4 for highly efficient removal of chlorophenols

An enhanced Schottky effect and efficient electron-transfer channel in Ni–WC/CN enable the efficient separation and transfer of photoexcited electrons, which boosts efficient photocatalytic degradation of toxic 4-chlorophenol.

Microstructure and tribology of cold spray additively manufactured multimodal Ni-WC metal matrix composites

Cold spray produces thick and dense deposits that can be applied in additive manufacturing or as a repair to recover damaged components. One potential materials system is WC-reinforced Ni composites, which are known for a combination of high hardness and toughness. WC particle size and distribution are some of the most important variables that impact the mechanical properties and wear resistance. In this study, thick multimodal Ni-24 vol%WC composite coatings were additively manufactured using the cold spray technique. Spherical Ni powder and two types of WC particles, i.e., cast and agglomerated, were used as feedstock materials. The microstructure, porosity, WC distribution, and microhardness of coatings were investigated in comparison with cold-sprayed Ni and Ni-agglomerated WC coatings with similar WC fill ratios. Dry sliding wear of multimodal Ni-WC coatings was studied with a sliding speed of 3 mm/s under normal loads of 5 and 12 N and was then compared to Ni and composite coatings made with only agglomerated WC. Multimodal Ni-WC coatings with an altered distribution of WC particles offered an improvement in friction and wear as compared to Ni-agglomerated WC coatings. Characterization of worn surfaces revealed the formation of tribofilms following compaction of wear debris. A more stable tribofilm that developed to a higher coverage was identified for coatings with multimodal WC particles at both tested loads. However, the protective role of tribofilms was reduced at a higher load, caused by subsurface crack propagation. Subsurface microstructure of worn surfaces that are induced by sliding wear was studied, and a correlation between the mechanical properties and microstructure and wear mechanism of coatings was made. Overall, our findings highlight the potential of cold spray additive manufacturing in producing multimodal Ni-WC composite coatings with enhanced wear resistance.

Microstructure and Wear Resistance of Ni–WC–TiC Alloy Coating Fabricated by Laser

In this study, a Ni–WC–TiC alloy coating was fabricated by laser to improve the wear resistance and service life of Cr12MoV die steel. The microstructures and phases of the coating were analyzed by a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The properties of the coating were tested by a hardness and friction wear tester. The results show that the coating has a good metallurgical bond with the substrate. The microstructures from top to bottom are mainly equiaxed crystal, columnar dendrite, and cellular dendrite. Combined with the physical phase analysis and elemental distribution of the coating, there are some phases, such as γ~(Fe, Ni), Cr23C6, WC, TiC, Fe3W3C, and Cr2Ti. Compared with the Cr12MoV steel substrate, the Ni–WC–TiC alloy coating has good properties of hardness and wear resistance. In the coating, the background region of the grains is γ~(Fe, Ni). From the EDS results, it can be seen that there are some rod-like particles, Cr23C6, which are uniformly distributed on the top of the coating. Some W and Ti carbides form in grains. The addition of TiC particles improves the WC particles refinement. The highest hardness of the coating is 770.7 HV0.5, which is approximately 3.3 times higher than that of the substrate. The wear volume is 0.26 mm3, or approximately 8.6% of the substrate, which is contributed to the reinforced phases and finer microstructure of the coating. The wear volumes of the Cr12MoV substrate are 1.8 and 4.5 mm3 at 20 and 60 min, respectively. While the wear volumes of the Ni–WC–TiC coating are 0.2 and 0.7 mm3 at 20 and 60 min, respectively. The increased amplitude of the coating’s wear volume is smaller than that of the substrate. The results show that this Ni–WC–TiC alloy coating is helpful for improving the properties and service life of Cr12MoV die steel.

Synthesis of Ni-WC/Al-Ni functionally graded coating with advanced corrosion and wear resistance on AZ91D Mg alloy by laser cladding

The low hardness and poor wear and corrosion resistance of Mg alloys restrict their further applications. Laser cladding technology has been employed to prepare coatings on metals and alloys, but owing to the low melting point of Mg alloy, it is difficult to clad high-performance coatings that usually have high melting points directly. To achieve superior corrosion and wear resistance, a Ni–WC/Al–Ni functionally graded coating was designed and prepared on AZ91D Mg alloy. The microstructure, hardness, corrosion resistance, and tribological behaviors of the coating were studied. The results showed that good metallurgical bonding was obtained between the coating layers and substrate. The Ni–WC top-layer had excellent mechanical performance, and corrosion and wear resistance. The wear resistance of the top-layer was 5–8 times that of the substrate and contributed to the simultaneous enhancement of hardness and corrosion resistance. The results suggest that the use of a functionally graded prepared coating is a good strategy to form a high-performance coating on Mg alloy.

Effect of Ti2SnC mass fraction on microstructure and friction–wear performance of laser cladded Ni–WC coatings under WS2 lubrication condition

Ni–WC coatings with the different Ti2SnC mass fractions were prepared on the substrate of S136 steel by laser cladding (LC), in which the metallurgical bonding was formed at the coating interfaces. The microstructure and phases of obtained coatings were analyzed using a super depth of field microscope (SDFM) and X-ray diffraction (XRD), respectively. The effect of Ti2SnC mass fraction on the microstructure and tribological properties of Ni–WC coating were investigated using a ball-on-disc wear tester, and the wear model was also established to analyze the role of Ti2SnC phase in the friction process. The results show that the Ni–WC–8%Ti2SnC coating has the lowest coefficient of friction (COF) and wear rate among the three kinds of coating, and the wear mechanism is abrasive wear, which is contributed to the friction reduction and wear resistance roles of Ti2SnC phase. Furthermore, the COF and wear rate of Ni–WC coating can be reduced by the addition of appropriate Ti2SnC mass fraction, which may provide the reference for the friction and wear of Ti2SnC MAX phase in the coating field.

Wear and corrosion mechanisms of Ni–WC coatings modified with different Y2O3 by laser cladding on AISI 4145H steel

Abstract In order to evaluate the effect of rare earth Y2O3 on the wear and corrosion properties of WC–Ni composite coatings, X-ray diffraction, scanning electron microscopy(SEM), electrochemical polarization curve, electrochemical impedance spectroscopy (EIS), and friction and wear tests were used to analyze the metallographic structure, corrosion characteristics in simulated seawater and friction and wear principle of the composite coatings. Results of SEM revealed that the microstructure of the Y2O3 added coatings was refined with the grains changing smaller and the impurity disappearing. The EIS results proved that the addition of Y2O3 brought a positive influence on the corrosion resistance by reducing the capacitance and increasing the R f and R c. The hardness of the coatings with Y2O3 addition tends to be smooth without wild fluctuation, and the coating with 0.5 wt% Y2O3 owned the hardness values reaching 850 HV. With the addition of rare earth elements, the coefficient of fiction values decreased, reaching the lowest (0.3418) at the content of Y2O3 of 0.5 wt%. The surface of the coating without Y2O3 appears grooved due to the abrasive wear; the coatings with Y2O3 did not suffer serious wear and tear. The coating with 0.5 wt% Y2O3 exhibited the best corrosion resistance and wear resistance properties in all the specimens.

Density functional theory study of CH4 dissociation and C[sbnd]C coupling on W-terminated WC(0001) surface

To explore the catalytic activity of tungsten monocarbide (WC), the methane (CH4) dehydrogenation and further CC coupling process on WC surface have been studied systematically by performing density functional theory (DFT) calculations. The scaling relationship of the adsorption energies of CHx intermediates on W-terminated WC(0001) surface has been summarized together with those cases on pure metal surfaces. By the way, we also studied the thermal stabilities of low Miller index surfaces of WC to obtain the Wulff construction of WC nanocrystal. The W-terminated WC(0001), W-terminated WC(112̄1), and WC-terminated WC(112̄0) facets constitute more than 96% of the total exposed surface in the WC Wulff construction. The van der Waals (vdW) interaction between adsorbate and W-terminated WC(0001) surface is corrected by the BEEF-vdW functional. Our calculations show that W-terminated WC(0001) surface is the most favorably exposed surface with a lower surface energy. Based on the data collected from literature, the linear relationship between the CHx adsorption energies and the x in CHx on metal (e.g., Fe, Co, Ni, Cu, Pt, Ir, Rh, Ru, Pd, Ag, and Au) surfaces has been analyzed. More interestingly, we found that the Co(111), Ni(111), and W-terminated WC(0001) surfaces possess very close slope factors in such a linear relationship, suggesting the similar catalytic property of methane dehydrogenation on these surfaces. More importantly, the rate-limiting step of CH4 dissociation on W-terminated WC(0001) surface corresponds to CH∗→ C∗+H∗. The energy barrier [i.e., 1.46 eV (1.63 eV) with (without) zero point energy (ZPE) correction] for this reaction step is slightly larger than the one on Ni(111) surface and smaller than the one on Cu(111) surface. Furthermore, we have studied the CC coupling through the CH∗ intermediates on W-terminated WC(0001) surface and found that the formation of C2H2 is kinetically favorable. Our results provides useful information for the development of tungsten-carbide-based catalyst materials.

Investigation of adhesion and diffusion activity of Cu – Mn – Ni brazing filler metal with WC – 8Co cemented carbide

In this work, the interaction between Cu – Mn – Ni brazing filler metal (BFM) melt and WC – 8Co cemented carbide is studied. In particular, the diffusion interaction in a binary system (BFM-cemented carbide substrate) and a ternary system (steel-BFM-cemented carbide substrate) is considered. An attempt has been made to control the interaction process by applying thin metal coatings (Ti, Cr, Al, Ni, Cu) by the magnetron sputtering method. For the CuMn24Ni9 filler metal temperature dependences of contact angles on cemented carbide are obtained. Their dependences on the coating material and the depth of interaction between BFM melt and cemented carbide substrate is also estimated. It was found that the thickness of the diffusion layer of brazing filler metal into the cemented carbide depends on the temperature and does not depend on the coating material and the amount of liquid interacting with the substrate. The depth of copper diffusion into the cemented carbide is 100 ± 5 μm for a heating temperature 1120 oC and 50 ± 8 μm for a temperature 960 oC. Without coating, the contact angle is 15. The minimum contact angle obtained on the Ni coating is 6. For Al, Cr and Ti coatings, to obtain a contact angle of less than 10, high temperatures are required, over 1200 oC. The evaluation of the failure mechanism of brazed samples with preliminary deposited metal coatings during shear testing has been carried out. Fracture of all brazed samples took place on the cemented carbide, except for those coated with Ti. Cracks in all samples originated in the region above the fillet, and then penetrated deep into the material. The reported study was funded by RFBR according to the research project № 20-32-90011.

Self-Grinding Silage Knife Strengthened with Ni–WC Alloy Prepared by Laser Cladding

The working environment of agricultural cutting tools is poor, and the operational quality and efficiency are reduced after they become blunt. This study aimed to develop a high wear-resistant agriculture knife with a long life. A Ni–WC alloy, wear-resistant layer was prepared using laser cladding technology on one side of the cutting edge of a 65 Mn silage knife. A self-grinding edge was formed when the cladded knife was used, which improved the cutting quality and service life of the knife. The microstructure, phase, composition, and hardness distribution of the cladding layer were detected and analyzed. The impact toughness and wear resistance of the laser-cladded samples were analyzed, and the cladded knife was tested in the field. The results show that a cladded layer with a dense microstructure formed metallurgical bonds with the substrate. The microhardness was uniform across the cladded layer, and the average hardness of the micro Vickers was approximately 1000 HV(0.2), which was approximately three times the hardness of the substrate. The impact toughness and wear resistance of the coated knife were obviously higher than those of uncoated knives. The field tests showed that compared with a conventional 65 Mn knife, the self-grinding knife with laser cladding could maintain its sharp cutting shape after operation for 76 h, which greatly extended the service life of the knife. This study improved the service life of an agricultural cutting tool, which enhanced the cutting performance and efficiency at the same time.

Microstructure, microhardness and corrosion resistance of laser cladding Ni–WC coating on AlSi5Cu1Mg alloy

The microstructure, microhardness, and corrosion resistance of laser cladding Ni–WC coating on the surface of AlSi5Cu1Mg alloy were investigated by scanning electron microscopy, X-ray diffraction, microhardness testing, immersion corrosion testing, and electrochemical measurement. The results show that a smooth coating containing NiAl, Ni3Al, M7C3, M23C6 phases (M=Ni, Al, Cr, W, Fe) and WC particles is prepared by laser cladding. Under a laser scanning speed of 120 mm/min, the microhardness of the cladding coating is 9–11 times that of AlSi5Cu1Mg, due to the synergistic effect of excellent metallurgical bond and newly formed carbides. The Ni–WC coating shows higher corrosion potential (−318.09 mV) and lower corrosion current density (12.33 μA/cm2) compared with the matrix. The crack-free, dense cladding coating obviously inhibits the penetration of Cl− and H+, leading to the remarkedly improved corrosion resistance of cladding coating.

Electrodeposition Based Preparation of Zn–Ni Alloy and Zn–Ni–WC Nano-Composite Coatings for Corrosion-Resistant Applications

Zinc (Zn) is one of the five most widely consumed metals in the world. Indeed, more than 50% of all the zinc produced is used in zinc-galvanizing processes to protect steel from corrosion. Zn-based coatings have the potential for use as a corrosion-resistant barrier, but their wider use is restricted due to the poor mechanical properties of Zn that are needed to protect steel and other metals from rusting. The addition of other alloying elements such as Ni (Nickle) and WC (Tungsten Carbide) to Zn coating can improve its performance. This study investigates, the corrosion performance of Zn–Ni coating and Zn–Ni–WC composite nanocoatings fabricated on mild steel substrate in an environmentally friendly bath solution. The influence of WC nanoparticles on Zn–Ni deposition was also investigated. The surface morphologies, texture coefficients via XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), and EDS (Energy-dispersive X-ray spectroscopy) were analyzed. The electrochemical test such as polarization curves (PC) and electrochemical impedance spectroscopy (EIS) resulted in a corrosion rate of 0.6948 Å/min for Zn–Ni–WC composite nanocoating, and 1.192 Å/min for Zn–Ni coating. The results showed that the Zn–Ni–WC composite nanocoating reduced the corrosion rate by 41.71% and showed an 8.56% increase in microhardness compared to the hardness of the Zn–Ni coating. These results are augmented to better wettable characteristics of zinc, which developed good interfacial metallurgical adhesion amongst the Ni and WC elements. The results of the novel Zn–Ni–WC nanocomposite coatings achieved a great improvement of mechanical property and corrosion protection to the steel substrate surface.

Cavitation erosion resistance in NaCl medium of HVOF sprayed WC-based cermet coatings at various flow velocities: A comparative study on the effect of Ni and CoCr binder phases

High-velocity oxygen-fuel (HVOF) spraying was employed for depositing the WC-10Ni (WN) and WC-10Co-4Cr (WCC) powders in the form of coatings on 1Cr18Ni9Ti stainless steel substrate. In spite of higher elastic modulus (E) and hardness (H) as well as lower porosity, the WN coating showed higher values of H/E and H3/E2 as well as resistance to CE at various flow velocities in NaCl medium in comparison with the WCC coating. WN and WCC coatings both showed an increment in the volume loss rates (VLR) in NaCl medium as the flow velocity increases. The change of the CE progresses in NaCl medium of the WN and WCC coatings at various flow velocities was compared and the CE mechanisms were revealed.

Nickel–Promoted Molybdenum or Tungsten Carbides as Catalysts in Dry Reforming of Methane: Effects of Variation in CH4/CO2 Molar Ratio

Ni–Mo2C and Ni–WC were evaluated in dry reforming of methane employing different CH4/CO2 ratios. Ni–Mo2C remained active under an excess of CH4, but deactivation occurred under an excess of CO2. Ni–WC was resistant to excess of CO2 but showed carbon deposition under excess of CH4.

Effect of carbon nanotubes content on microstructure and properties of WC/Ni laser cladding coatings

ABSTRACT To enhance the mechanical properties of Ni–WC coatings, the carbon nanotubes were used as reinforced materials by laser cladding. Optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to investigate the effect of CNTs content on the phase composition and microstructure. The microhardness and wear resistance were measured by Vickers hardness testing and friction wear testing. Experimental results showed that the new phases Cr2Fe14C are found in the coatings with CNTs, the grain size is finer than that of the coating without CNTs. The microhardness and wear resistance of the coatings with CNTs content ranging from 0 to 5 wt-% present increase initially and then decrease trend. The coatings with 3 wt-% CNTs have the highest microhardness and wear resistance, which proved that the appropriate amount of CNTs addition is 3 wt-%.

Friction and Adhesive Wear Study of HVOF Sprayed Ni–WC–Co-Based Powder Coating

Ni-based alloys are being widely used to improve the wear resistance of various industrial components in normal and severe environments and addition of rare earth elements to these alloys further improves the various mechanical and tribological properties of the coatings. In the present work, commercially available MEC 86 (NiCrBSi/WC–Co = 65/35) powder was modified with the optimum addition of 0.4 wt.% La2O3. The coatings were deposited by high velocity oxy-fuel (HVOF) spraying process. Rare earth addition refines the microstructure and increases the microhardness of the coatings. The increase in microhardness with the addition of La2O3 is approximately 22%. Sliding wear resistance of the coating modified with La2O3 is higher than of that without La2O3. The average wear resistance increases by approximately 14%. Further, the addition of La2O3 to the coating reduces the friction coefficient as compared to the one without the rare earth element. The coefficient of friction was found lower with the addition of La2O3, which is approximately 18%.

Processing of Ni–WC–Cr3C2-based metal matrix composite cladding on SS-316L substrate through microwave irradiation

The present paper reports on the development of metal matrix composite clads of Ni–WC–Cr3C2-based materials through microwave heating route. In this study, metal matrix composite clads were deposited on austenitic stainless steel (SS-316 L) inside a multimode-type domestic microwave oven. Experiment trials were carried out at a microwave power of 900 W and frequency of 2.45 GHz. The optimal exposure time for processing of metal matrix composite clads was varied from 60 to 360 s. The microstructural analysis of processed clads revealed that the metal matrix composite clads of approximately 0.85 mm thickness were free from any type of voids and cracks. The WC and Cr3C2 particles were dispersed inside the Ni matrix. The phase analysis results revealed the formation of Cr7Ni3, NiC, Fe6W6C, Co3W3C4, FeNi3, NiW phases inside the clad layer. The formation of hard carbide phases resulted in higher microhardness of the clad layer. The average value of Vicker’s microhardness was observed to be 503 ± 34 HV, which is almost 1.6 times that of the substrate.

La doping inhibits stress production at the grain boundaries in Ni–WC coating

Ni–WC–La2O3 wear-resistant coatings are prepared by a plasma spray method on the pure iron. The microstructure and wear resistance of the coating are investigated. After La2O3 doping, the wear resistance of modified coating was enhanced significantly. The amount of coating wear was reduced by 61.9% and the friction coefficient was reduced by 35.7% because of the La2O3 content of 1.5 wt.% compared with the Ni–WC coating. La2O3 can suppress WC precipitation along the grain boundaries, and reduce the number of cracks in the substrate near the WC phase. Furthermore, the diffusion and segregation behavior of La atoms is studied by first-principle calculation. The simulation results show that La doping can increase the bonding energy between the WC particles and the Ni substrate, consequently improve the abrasion properties of the coating. The cohesive energy of the interface is the smallest when the La atoms occupies Ni atomic sites of the interface, as result a stable Ni–WC interface is formed on the interface. A Ni–La amorphous transition layer is formed on the Ni–WC interface. Its structure has rheological properties and relaxes the thermal stress of the interface, which reduces the Ni–WC interface cracking and improves the bonding strength.

Mechanical and tribological performance of a hybrid MMC coating deposited on Al-17Si piston alloy by laser composite surfacing technique.

Laser composite surfacing (LCS) is a photon driven manufacturing technology that can be utilized for depositing hybrid metal matrix composite coatings (HMMC) on softer Ti/Al/Mg alloys to enhance their tribo-mechanical properties. LCS offers the advantages of higher directionality, localized microstructural refinement and higher metallurgical bonding between coating and substrate. The current research presents the tribo-mechanical evaluation and characterization of solid lubricant based Ni–WC coatings deposited by LCS on Al–Si piston alloy by varying the concentration of graphite between 5-to-15-weight percentage. The tribological behavior of LCS samples was investigated using a ball-on-plate tribometer. Results indicate that the surface hardness, wear rate and friction coefficient of the Al–Si hypereutectic piston alloy were improved after LCS of graphite based HMMC coatings. The maximum surface hardness of 781Hv was acquired for the Ni–WC coating containing 5 wt% graphite. The friction coefficient of Al–Si under dry sliding conditions was reduced from 0.47 to 0.21. The reduction in the friction coefficient was attributed to the formation of a shearable transfer layer, which prevented delamination and reduced adhesion, abrasion and fatigue cracking.