WC Addition Research Articles

Correlation between microstructure properties and the effect of WC addition on the interface, hardness and corrosion performance of thermally sprayed NiCrBSi-WC coating

ABSTRACT Ni super-alloy is based on a powder coating of NiCrBSi – WC from flexicord wire feedstock material. The role of the CMoAlNi thick layer on the microstructure and interface properties of the coating was examined. The microstructure and interface properties were analyzed for both NiCrBSi-WC and NiCrBSi-WC/CMoAlNi thick layer using optical microscopy (OM), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD). The mechanical property was evaluated by a Vickers hardness and nano-indentation measurement under 3N and 100mN, respectively. The performance of corrosion interface coatings was investigated in 3.5% of bentonite solution. The applied layer has a flame-spray morphology with unmelted and deformed particles associated with voids and porosities. In contrast, after CMoAlNi under-layers, the interface is a more compact boundary structure with no porosity or cracks. The as-sprayed NiCrBSi-WC coating exhibits high hardness (HIT≈6 GPa), and high Young's modulus (EIT≈ 240 GPa) The ability to resist cracking is significantly higher for the NiCrBSi-WC coating concerning the NiCrBSi-WC/CMoAlNi coating, 7.21 compared to 2.88 (GPA−3) x106. The electrochemical potentiodynamic polarisation results show that the NiCrBSi-WC coating's corrosion resistance is higher than that of the NiCrBSi-WC / CMoAlNi coating.

Wear, corrosion and cavitation erosion behavior of WC-reinforced FeCrNiMnAl ceramic-high entropy alloy composite coatings by laser cladding

FeCrNiMnAl/WC ceramic-high entropy alloy (HEA) composite coatings with various WC content are prepared on 304 stainless steel (304 SS) by laser cladding (LC). Experimental results show that residual tensile stress of coatings increases with the addition of WC content, and excessive addition of WC leads to cracking in 15WC and 20WC. All coatings are composed of BCC and WC duplex, and the addition of WC particles significantly refines grain size of the coatings. Compared with FeCrNiMnAl HEA coating, the coatings with WC addition exhibit improving mechanical properties and wear resistance due to the combined effect of multiple strengthening mechanisms. Among the tested coatings, 10WC exhibits the highest cavitation erosion (CE) resistance due to its excellent mechanical properties and corrosion resistance.

Microstructure and Tribological Properties of WC/Ni-MoS2 Titanium-Based Composite Coating on TC4

To improve the mechanical properties of a TC4 surface, TC4 + Ni-MoS2 + xWC (x = 5%, 10% and 15% wt.%) composite coatings were prepared by the coaxial feeding laser cladding technique, and the effect of the WC content on the microstructure and tribological properties of the coatings were investigated using multiple characterization methods. The results indicated that increasing the WC content negatively impacted the forming quality of the coating, but did not change the coating phase which predominantly comprised Ti2Ni, Ti2S, TiC, matrix β-Ti and residual WC. With the addition of WC, TiC exhibited an increase in both quantity and particle size, accompanied by a transition in growth morphology from spherical to petal-like. MoS2 completely dissolved in all coatings and the S element provided by it effectively synthesized a strip-like phase Ti2S which presented a morphology similar to the lubricating phase TiS in the Ti-based melt pool system. The microhardness and wear-resistance of all the coatings were higher than that of TC4 and gradually improved with the addition of WC, which indicated that raising the WC content was conducive to enhancing the mechanical properties of the coatings. The friction coefficient of TC4 was lower than that of the three WC content coatings, indicating that Ti2S was not the lubricating phase. The wear mechanism of all coatings was abrasive wear.

Effect of WC addition on microstructure and properties of laser melting deposited Ti6Al4V

Titanium alloys are generally characterized by low surface hardness, poor thermal conductivity, high friction coefficients and susceptibility to adhesive wear, which significantly hinder their industrial applications. To address this issue, we enhance the wear resistance of titanium alloys by incorporating nano WC particles. However, the optimal amount of WC to be added to titanium alloys remains unexplored. In this study, we prepared Ti6Al4V-xWC (wt%) (x = 0, 10, 20) coatings on Ti6Al4V substrates using laser melting deposition, specifically examining the effects of WC content on the microstructure and properties of the coating. The experimental findings indicate that the introduction of WC particles resulted in the formation of a TiC reinforced phase within the composite coating which promoted the equiaxialization of lamellae α phase. The hardness of the coatings increased significantly with the increase of the mass fraction of WC nanoparticles. Notably, the Ti6Al4V-10WC and Ti6Al4V-20WC coatings exhibited wear resistance that was 2.5 and 3.4 times greater, respectively, compared to the Ti6Al4V coatings. This enhancement in wear resistance can be attributed to the reinforcing phase (TiC) formed by the addition of WC. This experiment demonstrates a viable approach to improving the wear resistance of the Ti6Al4V titanium alloy through surface treatment.

Effect of WC content on the microstructure and properties of AlCoCrFeNi2.1 eutectic high entropy alloy coating prepared by ultra-high speed laser cladding technology

AlCoCrFeNi2.1 eutectic high entropy alloy coating with different WC content were prepared on 304 stainless steel surface by ultra-high speed laser cladding technology. Microstructure, phase distribution, Microhardness, friction, and wear properties were analyzed to investigate the influence mechanism of WC on the properties of alloy coatings. The results indicate that the addition of WC results in refined crystalline strengthening. The decomposition of WC leads to the formation of W2C and Cr23C6, which contribute to solid solution strengthening and second-phase strengthening. With increasing WC content, a noticeable improvement in microhardness and wear resistance properties is observed.

Research on microstructure, mechanical property and wear mechanism of AlCoCrFeNi/WC composite coating fabricated by HVOF

In this study, HVOF spraying technology was utilized to prepare AlCoCrFeNi/WC composite coatings with varying WC content on 40CrMnMoA steel substrate. The microstructure, elemental distribution, phase structure and chemical valence states of wear scratches of the composite coatings were analyzed using the SEM, EDS, XRD and XPS. Microhardness was measured using single-point digital microhardness tester, while nanohardness and elastic modulus were determined using a nano-indenter. The bonding strength of the composite coatings was evaluated using a tensile tester. Friction and wear tests were conducted to assess the wear behavior of the composite coatings. The results indicated that the microstructure, microhardness, nanohardness and elastic modulus of AlCoCrFeNi HEA coating increased with the addition of WC, attributed to the hard phase effects of WC. However, the bonding strength first decreased and then increased. Compared to the W 0 coating, the wear rates of the other composite coatings decreased by 30.5 %, 46.1 %, 65.3 %, and 82.1 %, respectively, which demonstrating that the effect strengthening of WC. After the friction and wear tests, the wear mechanism of the W 0 and W 1 coatings represents adhesive wear, abrasive wear and severe oxidation wear. In contrast, the W 2 and W 3 coatings exhibited slight adhesive wear, slight abrasive wear and slight oxidation wear, while the W 4 coating showed the slightest abrasive wear, the slightest adhesive wear and the slightest oxidation wear.

Interface migration and grain growth in NbC-Ni cemented carbides with secondary carbide addition

Cemented carbides are widely used for cutting and drilling tools. They usually combine a WC hard carbide phase and a Co-based ductile binder. NbC-Ni materials are considered as a possible alternative, especially for wear applications. The advantageous economic situation for raw materials sourcing, their interesting mechanical properties and low density have raised a new interest for these materials. However, mechanical properties can be limited by the rapid grain growth during liquid phase sintering, as compared to WC-Co. Grain growth can be controlled by the addition of secondary carbides. In this paper, a quantitative EBSD analysis of grain growth is performed for NbC-12 vol%Ni materials sintered at 1450 °C with controlled addition of Mo2C and WC. The average grain size decreases continuously with Mo2C addition. The results are discussed based on a more detailed interface characterization and on a previous model for the cooperative migration of phase boundaries and grain boundaries.

Enhanced mechanical and tribological properties of ultrasonically assisted stir-cast AA7075 metal matrix composites in challenging corrosive environments

Aluminum-based metal matrix composites (AMMCs) find extensive applications in aerospace, defence, automotive, and various sectors on account of remarkable mechanical properties, lightweight nature, and excellent dimensional stability. In this research, AA7075 matrix material was reinforced with tungsten carbide ceramic particles with various 0, 5, 10, 15 and 20 weight percentages (wt%) with the use of Ultrasonic assisted stir casing setup. The stir casted AA7075 MMCs were subjected to XRD, SEM, and density test to investigate the presence of elements, microstructure and density. The tensile, micro hardness, and wear test were performed on AL7075 based MMCs after conducting NaCl based spray test at the condition of spray pressure of 1.2 kg cm−2, spray duration of 120 h and PH value of 8.2 to determine the wear resistance, micro hardness and Ultimate Tensile Strength. The XRD test confirmed the presence of secondary phases such as Al2Cu, W2C, and MgZn2 with Al and WC phases. The SEM test confirmed the uniform dispersion and no more cluster formation upto 15 wt% WC addition and agglomeration of WC was occurred in the addition of 20 wt% of WC. The enhancing of wt% of WC improved the corrosion resistance, Micro hardness, UTS, wear and up to 15 wt% addition and decreases by the 20 wt% WC addition. The higher tensile strength 312 MPa was obtained from AA7075/15 wt%WC composite. The lower wear rate 0.11 mg m−1 was obtained from AA7075/15 wt%WC at 1000 m sliding distance with 1.2 m s−1 sliding velocity. The improved mechanical and tribological properties were mainly depended on strengthening mechanisms such as load transfer mechanism and dislocation strengthening mechanism.

Enhancement of mechanical properties of NbCN-Ni cermets via WC addition

In this study, the microstructural and mechanical properties of sintered NbCN-Ni cermets with various WC contents were investigated. The density and grain size of the NbCN-Ni cermets increased with an increase in the sintering temperature from 1420 to 1510 °C, whereas after WC addition, the average grain size of NbCN decreased significantly. The added WC was initially dissolved in the binder phase and then dissolved in NbCN crystals and formed a white W-rich (Nb,W)CN shell phase and gray Nb-rich (Nb,W)CN core phase structure for WC contents up to 10 wt%. Meanwhile, the formation of the shell-core structure enabled the morphology of NbCN grains to gradually change from polygonal to spherical, which can be attributed to the high solubility of WC in the Ni binder. The hardness and transverse rupture strength (TRS) of the cermets first increased and then decreased with increasing sintering temperature and WC content. At a WC content of 10 wt% and sintering temperatures of 1480 and 1450 °C, the HV10 and TRS of the cermets reached maximum values of 1405 kg/mm2 and 1280 MPa, respectively. The friction coefficient of the NbCN-Ni cermets decreased from 0.7 to 0.55–0.6 after WC addition. Hence, the cermets exhibited excellent wear resistance because the introduction of WC decreased their friction coefficient and increased their hardness.

Ablation Resistance of ZrB2-SiC-Si Composite Coatings Applied on Graphite Substrate by Spark Plasma Sintering

In this research, a protective composite coating made of ultra-high-temperature ceramics (UHTCs) was applied on the graphite substrate to boost the ablation resistance of the graphite substrate. Spark plasma sintering (SPS) was used to create such coatings on the graphite substrates. Efforts were made to identify the appropriate chemical composition for the composite coating and the conditions for the SPS (temperature, pressure and holding time). The coatings with a base composition of ZrB2-15 vol.% Si-15 vol.% SiC as well as MoSi2 and WC additives in the same amounts of 0 vol.%, 2.5 vol.% and 5 vol.% of each were applied on the graphite substrates under sintering conditions of final temperature of 1875 ± 25°C, initial pressure of 10 MPa, final load of 25 MPa and holding time of 5 min. The results obtained from the ablation test by oxyacetylene flame verified that the presence of the protective composite coating significantly increases the ablation performance of the graphite substrate. The sample without WC and MoSi2 additives had the lowest mass reduction in longer ablation times, which indicates the high ablation resistance of the base sample compared to the samples with those additives.

High‐Strength Wear‐Resistant Cu/Tungsten Carbide/Diamond Composites Fabricated by Powder Metallurgy

Copper‐based diamond composites are widely used for thermal management and wear‐resistant materials. In this work, Cu/diamond, Cu/tungsten carbide (WC)/diamond, and Cu–0.92Cr/WC/diamond composites are fabricated by high‐energy ball milling and rapid hot‐pressing sintering. Physical characteristics, compressive strength, and tribological properties of the studied composites are investigated. The compressive strength of Cu/7wt%WC/diamond composites is 102% higher than the Cu/diamond composites, reaching 415 MPa. Compression fractures extend from the interface due to compression cracks, consistent with the compression curves from molecular dynamics (MD) simulations. The crack propagates from the interface during the compression experiment, which is consistent with the result of MD simulation. The Cu/7wt%WC/diamond composites exhibit a wear rate of 0.6 × 10−6 mm3 (N m)−1 and a friction coefficient of 0.37 at 50 N. The addition of WC and diamond improves the compressive strength and wear resistance. These findings are helpful in the development of copper composites with high compression strength and wear resistance.

Enhanced Oxidation Resistance of ZrB2–SiC–WC Composite below 1800 °C

The effect of 3.6 vol% WC addition to ZrB2–20 vol% SiC (ZSW) on oxidation resistance is studied over a broad range of oxidation temperatures, 1000–1800 °C. Non‐WC‐containing samples (ZS) show significant surface damage and degradation during oxidation, losing protective B2O3 and SiO2‐based surface layers and exposing a porous ZrO2 layer and base material for further oxidation. ZSW samples preserve their surface protective layers during oxidation up to 1800 °C while the underlying ZrO2 scale remains dense. The appearance of convection cells on the surface of ZSW samples during oxidation above 1600 °C is reported. This confirms the presence of boron‐rich phases, suppressing oxygen permeation into the material and enhancing oxidation resistance of ZSW samples. During exposure of the samples to 1800 °C for 15 min, ZS and ZSW samples gain 11.1 ± 1.5 and 7.8 ± 0.3 mg cm−2, respectively, due to oxidation. Exposure of the composites for 5 h at 1600 °C results in weight gains of 10.5 and 7.0 mg cm−2 for ZS and ZSW samples, respectively. Cross sections of oxidized samples at 1800 °C show a tight zirconia layer below a glassy surface in ZSW and complete loss of surface glass in ZS, demonstrating the effectiveness of WC addition.

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.

Improvement of mechanical properties and investigation of strengthening mechanisms on the Ti 3AlC 2 ceramic with nanosized WC addition

Improvement of mechanical properties and investigation of strengthening mechanisms on the Ti ₃AlC ₂ ceramic with nanosized WC addition

Influence of nano-sized WC addition on the microstructure, residual stress, and tribological properties of WC-Co HVAF-sprayed coatings

It has recently been proposed to modify conventional WC-Co coatings with nano-sized particles to improve their properties. Modification of the coatings with nano-sized carbides may provide higher wear resistance or phase composition stability. This work characterized the changes in the residual stresses induced by introducing WC nanoparticles into a WC-Co coating and the resulting change in their sliding wear behavior.A powder mixture consisting of agglomerated and sintered WC-17Co feedstock powder and 5 % nano-sized WC was deposited on a carbon steel substrate using the High Velocity Air Fuel (HVAF) process. Microstructural characterization using scanning electron microscopy and EBSD confirmed that nano-sized WC particles were embedded in the coatings after the spraying process, primarily along the boundaries of the WC-Co lamellae. This resulted in an enhancement of microhardness, indentation fracture toughness, and dry sliding wear resistance, evaluated via ball-on-disk tests against Al2O3 counterparts. Residual stresses in the coatings were also measured by XRD using the sin2ψ method. The normal stress along the torch movement direction decreased significantly when nano-sized WC was added. The addition of nanoparticles also caused a slight decrease in the normal stress perpendicular to the torch movement.

Role of TiC and WC Addition on the Mechanism and Kinetics of Isothermal Oxidation and High-Temperature Stability of ZrB2–SiC Composites

Role of TiC and WC Addition on the Mechanism and Kinetics of Isothermal Oxidation and High-Temperature Stability of ZrB2–SiC Composites

Ultrafast high-temperature sintering (UHS) of WC and WC-containing ZrB2

WC and ZrB2 are refractory ceramics with excellent thermophysical properties and melting temperatures exceeding 2800°C. Both materials require the application of external pressure and long sintering times for their consolidation. In particular, commercially available ZrB2 powders are intrinsically difficult to sinter and usually need long pre-processing steps such as high-energy ball milling. Ultrafast high-temperature sintering (UHS) is a recently developed technique that enables the consolidation of bulk ceramics within minutes. In the present work, pure WC was efficiently densified to above 98% in just 3 min by UHS. Moreover, small WC additions enhanced ZrB2 densification by activating liquid phase sintering. Samples containing 5 and 10 vol% WC were sintered to 95 and 96%, respectively, in 2 min. All the WC initially present in the blend reacts to form a liquid phase during sintering and solidifies as WB and (Zr,W)C upon cooling. The formation of a ZrB2-(Zr,W)B2 core-shell structure was detected in all the sintered composites. The hardness of UHS samples reaches 15 GPa (WC - ZrB2 composites) and 21 GPa (pure WC), similar to that measured in materials obtained by slower and more sophisticated pressure-assisted sintering techniques.

Effect of WC content on microstructure and mechanical properties of (TiZrHfNbTaMo)C‐15 wt.% Co ceramics

AbstractThe (TiZrHfNbTaMo)C‐15 wt.% Co ceramics with excellent comprehensive properties were successfully prepared by vacuum liquid phase sintering. The effects of WC content on the grain size, microstructure, and mechanical properties were investigated. The results showed that WC was dissolved into (TiZrHfNbTaMo)C phase to form a seven‐component solid solution, and the independent WC phase disappeared. The addition of WC improved the wettability between the ceramic phase and the metal phase and promoted the densification of the ceramics. In addition, WC played a role in refining grains and inhibiting the grains growth to a certain extent. The comprehensive properties of ceramics were improved by solid solution strengthening and high entropy effect. When the WC content was 5 wt.%, the toughness reached the maximum of 9.41 ± 0.15 MPa·m1/2, and the hardness of the ceramic with 10 wt.% WC achieved the highest value of 18.18 ± 0.20 GPa.

Improving mechanical properties of an additively manufactured high-entropy alloy via post thermomechanical treatment

Thermomechanical treatment is applied to a CrMnFeCoNi high-entropy alloy fabricated via laser melting deposition (LMD) with 5 wt% WC addition to improve its mechanical properties. After the thermomechanical treatment, the yield strength of the LMD-fabricated alloy increases by 323 MPa, while the elongation remains nearly unchanged. Microstructures of the alloy before and after the thermomechanical treatment are thoroughly characterized. The LMD-fabricated alloy consists of the face-centered cubic matrix and M23C6 precipitates distributed both at grain boundaries and within matrix grains. The thermomechanical treatment leads to a significant refinement of the matrix grains and a more uniform distribution of the M23C6 precipitates, and largely these two factors give rise to the increase in yield strength. Numerous dislocations induced by internal thermal stress due to LMD are effectively eliminated through the thermomechanical treatment, contributing to the preservation of the ductility. The M23C6 carbide precipitates are characterized regarding their spatial distribution, chemical composition, and stacking faults, along with the orientation relationship and the interfaces between the matrix and the precipitates.

Microstructure and Properties of FeAlC-x(WC-Co) Composite Coating Prepared through Plasma Transfer Arc Cladding

Tungsten carbide (WC) is widely used in wear-resistant parts due to its excellent wear resistance. Iron-based alloys are used in the repair and remanufacturing of engine components due to their good compatibility with iron-based workpieces. In order to enhance the wear resistance of engine components in service under abrasive conditions, composite coatings have been prepared for cast iron engine components by adding WC-Co to iron-based powders. This study investigates the microstructure and wear properties of composite coatings of iron-based alloys reinforced with different contents of WC particles. The composite coatings mainly contained γ-Fe, α-Fe, WC and Fe3W3C. With the addition of the WC-Co strengthening phase, the average hardness of the FeAlC-x(WC-Co) composite coatings increases from 524 HV0.2 to 814 HV0.2. Wear test results showed that when the WC addition was 20%, it had the lowest frictional coefficient of 0.5 and the lowest wear mass loss of 1.3 mg. Compared to the original Fe-based alloy coatings, the WC particle-reinforced FeAlC composite coatings display improved wear resistance on a reduced friction basis, mainly benefiting from the high wear resistance of the graphite solid lubrication phase and carbides in the cladding.