Effect Of WC Particle Size Research Articles

Effect of WC particle size on the microstructural evolution and tribological properties of laser cladding Ti-bearing Co-based WC reinforced coating

To improve the wear resistance of 300 M steel under reciprocating wear in landing gear shock strut, Ti-bearing Co-based WC reinforced coatings with three different WC particle sizes (280 mesh, 200 mesh, and 150–300 mesh) were successfully fabricated by laser cladding method. The effect of WC particle size on phase composition, microstructure, microhardness and tribological properties were systematically investigated. The results show that the phase composition of these coatings consists mainly of γ-Co, TiC, WC, Cr23C6 and CrCo, and that varying the WC particle size changes the morphologies of the second phases. With the increase of WC particle size, the morphology of TiC is dendritic, ellipsoidal and block, respectively; the morphology of Cr23C6 changes from discontinuous fine particles to grid-like at grain boundaries. And the TiC-WC composite phases appear when the particle size of the added WC particles is a mixture. The coating with a mixture of 150–300 mesh WC particles, has the highest hardness range, the lowest average friction coefficient of 0.372, and the lowest wear rate of 9.61 × 10−5 mm3/N·m. The wear mechanisms of all three coatings are abrasive wear and oxidation wear, and the oxide film on the worn surface of the coatings gradually becomes denser and more continuous with increasing WC particle size.

Effect of WC particle size on the microstructure and tribological properties of high-speed laser cladding Ni/WC composite coatings

Ni/WC composite coatings with WC particle sizes of 30–65, 65–100, and 100–145 μm were prepared on 304 steel using high-speed laser-cladding (HSLC). The phase composition, microstructure, and wear mechanism of the composite coatings were studied. The dendrite-growth mechanism around WC with different particle sizes and the effects of WC with different particle sizes on the microhardness and tribological properties of the composite coatings were analyzed. The results demonstrated that the composite coating consisted of intermetallic compound Ni3Fe and secondary carbides W2C and (Cr, Fe)7C3. The composite coating exhibited good macroscopic morphology and uniform microstructure. The WC particle size obviously influenced the columnar and cellular dendrites in the coating. The microhardness values of the three groups of composite coatings were 419.35, 314.64, and 331.65 HV. The average friction coefficients were 0.4876, 0.5693, and 0.5439. The wear volumes were 0.001, 0.0015, and 0.002 mm3. The wear mechanisms included adhesive, abrasive, and oxidation wear mechanisms. The results verified that the WC coating with a small particle size possessed the best microhardness and tribological properties.

Wear performance of Ni-WC composites and heat-damage behaviour of WC particle during vacuum-induction melting process

Ni-WC composites were prepared by vacuum-induction melting (VIM). A ball-on-disc wear test was performed using an Si3N4 ball as a friction pair to study the wear performance of the composites. The effects of WC particle size (average particle size of 68 μm and 23 μm) on the mechanical properties of the composites and the heat-damage behaviour of WC particles during the melting process were investigated. The results indicate that the wear rate of Ni-WC composites with coarse WC particles was lower than that of Ni-WC composites with fine WC particles. The predominant wear mechanism of composites with coarse WC particles was mechanical wear of the WC particles; the predominant wear mechanisms of composites with fine WC particles were oxidation wear and three-body abrasive wear. The coarse WC particles provide better wear resistance than fine WC particles. The WC particles underwent heat erosion and dissolution caused by the Ni-based melt. Increasing the size of the WC particles can significantly reduce the degree of heat damage to the WC particles and improve the hardness of the composites.

Effect of WC Particle Size on Microstructure and Mechanical Properties of WC‐10CoCrFeNiAl Composites

The present study focuses on the synthesis of three distinct WC‐HEA hard alloys using the SPS method, using three different grades of tungsten carbide with varying particle sizes. Subsequently, an investigation is conducted to analyze the influence of WC particle size on the microstructure and properties of WC‐10CoCrFeNiAl hard alloys. Additionally, an investigation was conducted to assess the influence of small particle size WC addition content on both the microstructure and properties of this advanced alloy. The results indicate that a reduction in the particle size of WC leads to an increase in hardness, while exhibiting a nonmonotonic change in fracture toughness of WC‐10CoCrFeNiAl hard alloy. The presence of smaller WC particles promotes the formation of N7C3 and η phase (M3W9C4), which compromises its toughness while simultaneously enhancing its hardness. The mechanical properties are optimized when the particle size of WC is ≈1 μm. The incorporation of fine WC particles significantly enhances hardness while compromising fracture toughness. When the content of small particle WC reaches 25 wt%, the mechanical properties of the dual‐scale hard alloy are optimized, the hardness and fracture toughness are 18.8 GPa and 11.1 MPa.m1/2, respectively.

Effect of WC Particle Size on the Microstructure, Mechanical and Electrical Properties of Ag/WC Sintered Electrical Contact Material

Effect of WC Particle Size on the Microstructure, Mechanical and Electrical Properties of Ag/WC Sintered Electrical Contact Material

Effect of WC particle size on the microstructure and mechanical properties of Ni–Co coarse grain cemented carbide

AbstractThe effect of different WC grain size additions on the microstructure and grain distribution of Ni–Co coarse crystalline cemented carbide was studied. And then the effect of grain distribution on the mechanical properties of cemented carbide was discussed. The effect of WC grain size on the grain size and coherency of cemented carbide was analyzed by microstructure. And the distribution of grains in the microstructure was investigated by the truncation method. The addition of fine (1.1–1.4 μm), medium (2.3–2.7 μm), and coarse WC (5.6–6.0 μm) particles can increase the nucleation rate of WC grains in the bonded phase. And the higher grain growth driving force can produce the theoretical limitation of nucleation and inhibit the coarsening of WC grains to a certain extent. The WC grain size has an insignificant effect on the frequency of the occurrence of super‐coarse grains in coarse crystalline cemented carbide. The average grain size and super coarse grains in microstructure gradually decrease, which promotes the improvement of transverse rupture strength. The increase of the adjacent degree and the decrease of the mean free path reduce which is beneficial to the improvement of the corrosion resistance of the alloy. The best overall performance of the alloy is achieved when fine‐grained WC is added.

WC-reinforced iron matrix composites fabricated by wire arc additive manufacturing combined with gravity-driven powder feeding: particle transportation and size effects

Purpose A new wire arc additive manufacturing (WAAM) process combined with gravity-driven powder feeding was developed to fabricate components of tungsten carbide (WC)-reinforced iron matrix composites. The purpose of this study was to investigate the particle transportation mechanism during deposition and determine the effects of WC particle size on the microstructure and properties of the so-fabricated component. Design/methodology/approach Thin-walled samples were deposited by the new WAAM using two WC particles of different sizes. A series of in-depth investigations were conducted to reveal the differences in the macro morphology, microstructure, tensile performance and wear properties. Findings The results showed that inward convection and gravity were the main factors affecting WC transportation in the molten pool. Large WC particles have higher ability than small particles to penetrate into the molten pool and survive severe dissolution. Small WC particles were more likely to be completely dissolved around the top surface, forming a thicker region of reticulate (Fe, W)6C. Large WC particles can slow down the inward convection more, thereby leading to an increase in width and a decrease in the layer height of the weld bead. The mechanical properties and wear resistance significantly increased owing to reinforcement. Comparatively, samples with large WC particles showed inferior tensile properties owing to their higher susceptibility to cracks. Originality/value Fabricating metal matrix composites through the WAAM process is a novel concept that still requires further investigation. Apart from the self-designed gravity-driven powder feeding, the unique aspects of this study also include the revelation of the particle transportation mechanism of WC particles during deposition.

Microstructure and properties of CVD coated on gradient cemented carbide with different WC grain size

In this paper, cemented carbides with gradient surface enriched in Co phase and depleted of cubic phases were prepared by one-step vacuum sintering. The gradient cemented carbides of different WC grain size were used as the substrates of CVD coatings. The effects of WC particle size on the formation of gradient layer, microstructure and properties of the gradient cemented carbides were investigated. Besides, the influence of WC grain size and gradient layer on microstructure, growth and adhesion strength of the coatings were studied. The results showed that the thickness of surface gradient layer decreased with increasing WC particle size, which was attributed to the decreased diffusion paths and the increased diffusion distance. The interface between the surface gradient layer and the bulk was disordered due to abnormal grain growth of WC in ultrafine cemented carbide. The microhardness across the direction of the fcc-free (Face Center Cubic Free) surface layer to the bulk were similar in the three gradient cemented carbides, and could be expressed as: from the surface to the inner, the microhardness decreased firstly, then increased sharply around the interface, and subsequently dropped to the bulk level. The coating on the fcc-free surface layer was thicker than that on bulk, and the coating on the substrate with fine-sized WC grains is the thickest. The increase of the WC grain size in the substrate could improve the bonding strength of the coating. Furthermore, the presence of Co-rich layer could improve the bonding strength. However, bonding strength was poor for the grain size of ultrafine.

Effects of WC Particle Size and Co Content on the Graded Structure in Functionally Gradient WC-Co Composites

Functionally gradient WC-Co composites having a Co depleted surface zone and not comprising the h phase can be manufactured via carburizing process. During carburizing, besides carburizing process parameters, the microstructural parameters of WC-Co materials, such as WC grain size and Co content, also have significant influences on the formation of Co gradient structure. In this study, the effects of WC particle size and Co content on the gradient structure within gradient hardmetals have been studied, based on a series of carburizing experiments of WC-Co materials with different WC particle sizes and cobalt contents. The results show that both the thickness and the amplitude of the gradients within gradient WC-Co materials increase with increasing initial WC particle size and Co content of WC-Co alloys. The reason for this finding is discussed.

Effects of WC particle size on sintering behavior and mechanical properties of coarse grained WC–8Co cemented carbides fabricated by unmilled composite powders

Three sets of coarse grained WC–8Co cemented carbides were fabricated by unmilled composite powders using three different-sized raw WC powders. Effects of WC particle sizes on shrinkage behavior and microstructure evolution of coarse grained WC–8Co cemented carbides during a sintering process were investigated by dilatometer and a scanning electron microscope. Furthermore, the mechanical properties and their wear properties were evaluated for the forthcoming potential applications. It was found that during the sintering process the densification and grain growth of the WC–8Co cemented carbides with finer carbide particles as raw materials started earlier than coarser powders regardless of the effects of lattice distortion. With increasing initial WC particle size from 2.01μm to 4.37μm, mean WC grain size of coarse grained WC–8Co cemented carbides rose from 3.19μm to 6.03μm, the Co mean free path rose from 0.67μm to 1.24μm. At the same time, with the increasing grain size, the transgranular fracture though the carbide phase and binder phase increased, while intergranular fracture decreased, correlating to that the transverse rupture strength and fracture toughness increased from 2264MPa, 19.13MPam1/2 to 2769MPa and 25.24MPam1/2, respectively. The dominant wear mechanism in sliding wear test for the WC–8Co cemented carbides transferred from extraction of small WC grains to cracking and fragmentation of the large carbide grains with the increasing grain size.

Effect of WC particle size and Ag volume fraction on electrical contact resistance and thermal conductivity of Ag–WC contact materials

Abstract In this work, theoretically dense (> 99%) composites of Ag and WC have been prepared by press–sintering–infiltration for making electrical contacts used as an arc-resistant material in a model switching device. Composites with varying silver content and WC particle size were investigated to get an insight on their electrical contact resistance (Rc) and their ability to withstand enormous thermal stresses during switching. A break-only model switching sequence was used, where the evolution of Rc was measured over 50 cycles and the post-switching microstructures were investigated for thermal stress induced crack formation. A well-established 2D computational microstructure based model, object-oriented finite element analysis version 2 (OOF2), was used to determine the composite thermal conductivity (k) for various grades as a function of temperature. Rc was observed to be consistently low for the coarser WC containing composite and higher silver content composites. This response was attributed to the ductility of the surface layers formed during switching. Crack formation after switching was found to be a direct consequence of large thermal gradients during 50 cycles, which was minimal for coarser WC grained and higher silver content composites which have a higher thermal shock resistance.

Effects of WC particle size on the wear resistance of laser surface alloyed medium carbon steel

The CO2 laser surface alloying technique was used to form wear resistance layers on medium carbon steel with a kind of spherical WC powder. The effects of WC particle size on the abrasive wear resistance were thoroughly investigated. The results indicate that the laser alloyed layer is characterized by dendritic primary phase and ledeburite microstructure, consisting of austenite, martensite and carbides of Fe3W3C, W2C and WC. The laser surface alloying with WC powder could improve the abrasive wear resistance of the medium carbon steel by over 63%. The factors such as the hardness, the amount and the distribution of WC particle determined the laser alloyed samples’ wear resistance, and the laser alloyed sample with WC powder of 88–100μm diameter presented the best wear resistance in this study. Furthermore, the wear resistance mechanisms of the laser alloyed layers were also explored.

Deposition effects of WC particle size on cold sprayed WC–Co coatings

The WC particle size and its influence on the deposition of Co-based cermets are examined. Micron and nanostructured powders with similar Co content were employed. Varying the WC particle size influenced significantly the deposition efficiency of the coating process. Micrometer-structured WC–Co feedstocks did not permit coating build up when processed under comparable or elevated thermal spray parameters used for the nanostructured WC–Co feedstocks. In addition, micrometer-structured WC–Co coatings exhibited a conjoint erosion and deposition effect on the surface. Fine WC particles (< 1 μm) were observed near the substrate interface and larger WC particles (1–2 μm) in the vicinity of the coating surface. These observations indicate the existence of a critical WC particle size for deposition by the cold spray method and that the size criteria arises due to the formation and cohesion mechanisms within the coating layer. Nanostructured test specimens displayed (i) a dense microstructure with little presence of porosity, (ii) a crack free interface between the coating and substrate that indicated good adhesion, and (iii) no observable phase changes. The XRD patterns of each powder and their respective coatings did not have observable peak differences but the diffraction peak broadening of coatings indicated that there was grain refinement during the coating process. Furthermore, all nanostructured as-sprayed WC–Co coatings exhibited Vickers hardness values above HV1000. The nanostructured WC–Co coatings demonstrated adhesive strengths that exceeded the limits of the glue (60 MPa).

Spark Plasma Sintering Densification Mechanism for Cemented Carbides with Different WC Particle Sizes

The paper is focused on understanding the densification characteristics of WC–Co composite powders by the spark plasma sintering (SPS) technique, especially the essential mechanisms for the distinct differences of the effects of WC particle size on the densification behavior between the SPS and the conventional sintering technologies. For the particular combination and contacting state between WC and Co after ball milling in which Co forms thin films coating the WC particles, a model that quantitatively describes the densification process of SPS WC–Co powders with different WC particle sizes has been developed. The calculated results show that both the actual temperature in the Co film and the melting temperature of the Co film increase with the increase of the WC particle size. As a result, the formation and growth of the sintering necks due to the rapid melting and solidification of the Co films turn to be weakly influenced by the WC particle size, and hence the SPS densification is almost independent of the WC particle size. The model calculations are consistent with the experimental findings that in the SPS processes the temperatures corresponding to the start of the densification and the peak of the displacement rate, respectively, are nearly the same for the WC–Co powders with different WC particle sizes.

Effects of WC particle size on densification and properties of spark plasma sintered WC–Co cermet

Abstract The WC–Co cermet bulks were prepared by spark plasma sintering (SPS) using powder mixtures with different-scaled WC particles. The SPS densification process was studied by calculating the current distribution between the powder sample and the die in the SPS system. The microstructures were characterized and compared for different samples by the WC grain size, Co mean free path and contiguity of WC grains. In spite of a weak effect of WC particle size on the SPS densification stages, the WC particle size plays a significant role in the homogeneity of the cermet microstructure. Good mechanical properties of the SPSed cermet were obtained with an optimized WC and Co particle-size combination. The effects of scale combination of WC and Co particles on the microstructure hence the properties of the SPSed cermet were discussed.

Effect of WC nanoparticle size on the sintering temperature, density, and microhardness of WC-8 wt % Co alloys

Using X-ray diffraction, scanning electron microscopy, and density measurements, we have studied the effect of WC particle size (20 to 150 nm) on the optimal sintering temperature of the WC-8 wt % Co alloy and the effect of sintering temperature (800–1600°C) on its phase composition, density, and microhardness. The results indicate that, during sintering of the starting powder mixture, the first to form is the ternary carbide phase Co6W6C. At sintering temperatures of 1100°C and above, this phase reacts with carbon to form Co3W3C. Sintering above 1000°C leads to the formation of a cubic solid solution of tungsten carbide in cobalt, β-Co〈WC〉, along with the ternary carbide phases. The density and microhardness of the alloy have been measured as functions of sintering temperature. The use of WC nanopowder has been shown to reduce the optimal sintering temperature of the WC-Co alloy by about 100°C.

Effect of WC particle size on Co distribution in liquid-phase-sintered functionally graded WC–Co composite

Functionally graded WC–Co materials can be manufactured by controlling liquid phase migration or liquid redistribution during liquid phase sintering. The driving force of liquid phase migration is liquid migration pressure Pm which depends on the solid particle size d and the liquid phase volume fraction u. In this study, the effect of d on Pm has been studied experimentally for WC–Co system. The results show that Pm is proportional to 1/d0.4 which is different from previous postulation that Pm is proportional to 1/d. The reason for this difference is that the previous postulation was based on the assumption that all the solid particles in a composite are mono-sized and isometric-shaped, while in real WC–Co composites WC particles usually have non-isometric shape and there is a wide particle size distribution. The dependence of Pm on both d and u has been quantitatively established, enabling the prediction of final Co composition gradient in liquid-phase-sintered WC–Co composites.

Effect of WC particle size on the microstructure, mechanical properties and fracture behavior of WC–(W, Ti, Ta) C–6wt% Co cemented carbides

Abstract This study deals with the microstructure and mechanical properties of WC–(W, Ti, Ta) C–9 vol.% Co cemented carbides fabricated by conventional sintering. The conventional WC particles of 4 μm size and ultrafine particles of 0.2 μm were introduced in the system with varying ratio. The ratios of conventional WC particles to ultrafine WC particles were 2:1, 1:1, and 1:2. The microstructures of sintered WC–(W, Ti, Ta) C–9 vol.% Co cemented carbides were sensitively dependent on the ratio of conventional WC particles to ultrafine WC particles. The rim phase increased with the increase in the amount of ultrafine particles. Hardness of WC–(W, Ti, Ta) C–9 vol.% Co cemented carbide increased with increase in the amount of rim phase and decrease in the average grain size of WC particles. The bending strength showed the similar trend of the hardness. The fracture morphologies are reported. The fracture behavior changed from mixed mode to transgranular fracture mode, when the ratio of conventional WC particles to ultrafine WC particles was changed from 2:1 to 1:2.

Effect of WC particle size on microstructure and rim composition in the Ti(C 0.7N 0.3)–WC–Ni system

Ti(C 0.7 N 0.3 )– x WC–20Ni systems were studied to investigate the effect of WC particle size on the microstructure and rim composition of the systems. Variations in the content and particle size of the added WC had a negligible influence on changes in the phase and microstructure of the Ti(C 0.7 N 0.3 )– x WC–20Ni system, sintered at 1510 °C for 1 h. Based on the rim composition in the Ti(C 0.7 N 0.3 )– x WC–20Ni system, the particle size of the added WC appears to play a role in determining the composition of the rims.

Effects of WC size and amount on the thermal residual stress in WC–Ni composites

Effects of WC particle size and volume fraction on the magnitude and distribution of thermal residual stresses (TRS) in WC–Ni cemented carbide composites were studied by neutron powder diffraction. Samples of high (0.3) and low (0.1) Ni volume fraction and coarse (1.7μm) and fine (0.5μm) WC particle size were employed. Thermal residual strain and stress values were obtained at temperatures between 100 and 900K. The magnitude of the mean (compressive) WC stress increased as WC fraction decreased, while the mean (tensile) Ni stress did the opposite. For both phases, stresses were highest for fine WC particles, reaching over 3GPa in Ni. Elastic strain distributions, due to the sharp edges and corners of WC particles, were characterized by analyzing diffraction peak widths. The range of stress increased with the magnitude of the TRS. Even though the mean TRS is compressive in WC, regions of tension exist, and, for Ni, regions of compression are present.