WC Composites Research Articles

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.

A comparative investigation on microstructure evolution and mechanical property of WC particle reinforced CrFeNiB0.03Si0.03 medium entropy alloy by direct energy deposition

WC spherical particles of x wt% (x=0,10,20,30) were added into CrFeNiB0.03Si0.03 medium entropy alloy (MEA) prepared by the laser direct energy deposition. The effects of WC content on the microstructure, the mechanical properties and the friction and wear properties of CrFeNiB0.03Si0.03/ WC composites were systematically discussed. Results indicate that most of the WC particles are not completely dissolved and evenly dispersed in the CrFeNiB0.03Si0.03/WC composite matrix, while the dissolved W and C elements diffuse into the matrix and form a eutectic structure containing carbides. With the increase of WC content, the hardness of CrFeNiB0.03Si0.03/WC increase correspondingly. At the same time, compared with CrFeNiB0.03Si0.03, CrFeNiB0.03Si0.03/WC has better wear resistance and higher yield strength. In particular, the wear resistance of CrFeNiB0.03Si0.03 with 30 wt%WC is increased by 4.1 times and the yield strength is increased by more than 1.6 times. It proves that the yield strength and wear resistance of laser deposited CrFeNiB0.03Si0.03 MEA can be improved by adding WC.

Effects of TaCx on the microstructure and properties of WC composites

WC-5vol%TaCx (where x = 0.5, 0.7, 0.8 and 0.9) binderless cemented carbides with different carbon vacancy contents were prepared by spark plasma sintering (SPS) at a lower sintering temperature of 1800 °C. The phase evolution, microstructure and mechanical properties of these materials were investigated. The results show that the presence of WC, W2C and (Ta1-x, Wx)Cn phases in the sintered body. The formation of (Ta1-x, Wx)Cn solid solution is attributed to the dissolution of WC into TaCx, and the existence of vacancies promotes the atomic diffusion. (Ta1-x, Wx)Cn solid solution was uniformly distributed around the WC matrix, which inhibited the WC grain growth. In terms of fracture mode, the WC-5vol%TaCx composites exhibit a combination of intergranular and transgranular fracture, with crack deflection and bridging contributing to enhanced fracture toughness. Compared to other WC-TaCx composites with varying carbon vacancy content, the WC-5vol%TaC0.8 composite possesses the smallest average particle size and highest intrinsic hardness. Additionally, a semi-coherent interface is formed between (Ta1-x, Wx)Cn and WC, leading to improved mechanical properties such as highest hardness (24.4 GPa) and fracture toughness (8.5 MPa·m1/2). The WC-5vol%TaC0.8 composite, however, exhibits the lowest oxidation onset temperature attributed to its relatively smaller grain size. The introduction of carbon vacancies serves to facilitate atom diffusion and lower the densification temperature, while also functioning as a toughening agent.

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.

Optimization on stir casting process parameters of Al7050 based composites using Taguchi technique

Aluminium Alloy Metal Matrix Composites (AAMMCs) are broadly used for various applications such as aerospace, military, marine, transport and automobile applications. Aluminium alloys are not sufficient for satisfying the needs of the fastest growing industries. The more combination of properties are needed for fulfil the need of fastest growing countries. The input process parameters of fabrication methods of composites are more important in connection with mechanical and tribological properties. In this research, optimization on stir casting input process parameters of AA7050/4wt.%WC composite was done by utilizing the Taguchi technique. The melting temperature (650, 700 and 750 °C), stirring speed (150, 200 and 250 rpm) and stirring duration (10, 20 and 30 min)were selected as input parameters to optimize the stir casting input process parameters. The chosen response parameter for the investigation was wear loss. The wear test was conducted by using pin on disc setup at the condition of 2500 m sliding distance, 25 N applied load and 1.5 m/s sliding velocity. The optimized input process parameters of stir casting is high level of melting temperature (750 °C), low level of stirring speed (150 rpm) and low level of stirring duration (10 min). The increasing of melting temperature decreases the wear loss and increasing of stirring duration and stirring speed enhances the wear loss due to accumulation of reinforcements in the matrix AA7050. The contribution percentage of melting temperature, stirring speed and stirring duration is 81.02 %, 12.4 % and 6.4 % respectively. The high strength MgZn2 precipitate was formed while using optimized stirring temperature, stirring duration and stirring speed and it was confirmed by XRD. The SEM image of AA7050/4wt.%WC confirmed that uniform distribution of WC in matrix AA7050 material and it caused to offer higher wear resistance. The obtained low wear loss for confirmation test specimen is 16 mg.

Microstructure, mechanical and friction-wear properties of SiC-WC composite with Al and C as sintering aids

Low strength and poor performance of SiC–WC composite for seals, attributable to the use of a large amount of liquid phase sintering additives, limit the application prospects of these materials. This study focuses on preparing high-strength, high-toughness, and wear-resistant SiC–WC composite using a small amount of aluminum and carbon black as sintering additives. The results revealed that the specimen containing 50 wt% WC exhibited the maximum flexural strength and fracture toughness of 645.9 MPa and 7.49 Mpa m1/2, respectively. These improvements were attributed to the deoxidizing and solid-solution effects of Al and the reinforcing effect of the WC second phase. Moreover, the specific wear rate was measured at 8.06 × 10−7 mm3 N−1 m−1, which was 56.9 % lower than that of monolithic SiC. Results from Raman spectral analysis provided evidence of the presence of W–O bonds on the wear surface, indicating that the SiO2 film could be successfully replaced by a WO3 film.

Effect of η-carbides on the microstructure and elevated-temperature tribological behavior of cobalt-based composites

(CoCrNiMoW)-WC composites were prepared by powder metallurgy. The microstructure, tribological properties and wear mechanisms of the composites were investigated at room temperature, 400 °C, and 800 °C. Multiple carbides are generated in situ in the sintered composites. Increased WC content enhanced the hardness and promoted the microstructural evolution of the composites. The phase composition of the composite changes from FCC phase + η carbide to FCC phase + η carbide + WC + Cr23C6, and the microstructure changes from individual island-like to connected island-like structure. High-temperature negative wear phenomena were observed in the 30 wt % and 50 wt % WC-added composites at 800 °C, which contributed to the friction-induced high-temperature oxide volume increase compensating for the volume loss due to wear.

Novel TaC0.8 incorporated WC composites with enhanced mechanical properties by spark plasma sintering

The WC-based composites incorporated with different concentrations of TaC0.8 were solidified by using ball milling and spark plasma sintering (SPS). The impact of TaC0.8 content on the densification, phase composition, microstructure and mechanical properties of WC-TaC0.8 composites was evaluated. The major constitutions of WC-TaC0.8 composites were WC matrix, (W1−x, Tax)Cn solid solution and W2C phase. The adequate amounts of TaC0.8 additive had promoter function on the generation of W2C and the densification of WC-based composites through carbon vacancies. The (W1−x, Tax)Cn and W2C phases were uniformly dispersed in the WC matrix, effectively bringing a refinement of WC grains. There were the coherent interface of WC (01̅10)/W2C (101̅0) and semi-coherent interface of (W1−x, Tax)Cn (200)/WC (101̅1) in the WC-7.5 wt%TaC0.8 (WTa7.5) composite. The nearly-full densified WTa7.5 composite (99.3%) rendered the best overall mechanical properties, featuring high hardness of 24.9 GPa and high fracture toughness of 8.3 MPa·m1/2. The high fracture toughness was justified by several factors including highly dense and fine microstructure, coherent and semi-coherent interfaces, and a combination of transgranular and intergranular fracture, as well as crack deflection and crack bridging.

Case study for the formation of a surface alloy on cemented tungsten carbide using ultrashort MHz to GHz burst-pulses

The authors of this paper report on the generation and utilization of high-frequency combined MHz- and GHz-bursts consisting of ultrashort laser pulses in order to form a surface alloy on the composite material cemented tungsten carbide. The resulting topographies, ablation depths and chemical compositions of the irradiated material surfaces were characterized with respect to the modification of the surface of a composite material whose elements tungsten carbide (WC) and cobalt (Co) permit the formation of a surface alloy only in a common meta-stable liquid phase. The results of this case study demonstrate that using high-frequency bursts of ultrashort laser pulses in the investigated parameter range, the formation of a surface alloy is possible without a tendency to change the chemical composition of WC and Co, and the depth of re-solidified material depends on the combination of MHz and GHz burst-pulses.

Analysis of friction and wear of aluminium AA 5083/ WC composites for building applications using advanced machine learning models

Analysis of friction and wear of aluminium AA 5083/ WC composites for building applications using advanced machine learning models

Effect of CNT content on the microstructure and friction characteristics of DED-fabricated CNTs-Ni60/WC coatings

The microstructure and tribological behavior of CNTs-reinforced Ni60/WC composites fabricated by directed energy deposition (DED) are studied. The effect of CNTs content is investigated and compared to that of a CNTs-free composite sample. The improvement of hardness, thermal stability, and wear resistance caused by microstructural refinement is observed in the CNTs reinforced composites. Different additions of CNTs may be responsible for the aforementioned performances. The microstructure and micro-protrusions growth characteristics are investigated using SEM and AFM, linked to the CNTs content, which refines the microstructure. The hardness, TG/DSC, and friction coefficient curves establish 1.5 wt% CNTs as the optimal addition amount. Additionally, the tribological characteristics are discussed based on the wear behavior and wear scar EDS analysis. The main friction mechanisms of the composites are abrasive wear and adhesive wear. The wear loss reduction peaked at 67.9 % in the 1.5 wt% CNTs-Ni60/WC composites. The mechanical properties of the coating are improved by CNTs. This clearly demonstrates the guiding significance of CNTs-reinforced composites for tribological development.

Additive manufacturing and spark plasma sintering as effective routes for manufacturing of AISI 316L austenitic stainless steel - WC composites

Metal matrix composites (MMCs) are lightweight, high-performance materials with continuous expansion in industrial applications. In this study, Laser Powder Bed Fusion (LPBF), Binder Jetting (BJ), and Spark Plasma Sintering (SPS), were used to produce AISI 316L austenitic stainless steel (SS316L)-WC composite with different compositions and powder preparations. In the present study, the products manufactured with these different technologies and material compositions were compared in terms of final density, microstructure, and mechanical property. Results show a significant difference in the microstructure of the parts produced by these different manufacturing techniques with microstructural analysis showing that samples processed by LPBF exhibit the finest grain size, while the BJ processed samples exhibit the coarsest grain size. Furthermore, analysis of the micrographs and the XRD patterns obtained for all processing routes suggest that there was some level of WC dissolution followed by inter atomic diffusion occurring between the WC inclusions and the SS316L matrix, involving dissolved W and C atoms from the inclusions and Cr and Fe atoms from the steel matrix, with the final structure and microhardness of the composite system depending on the kinetics of the manufacturing process.

RESEARCH OF THE STRUCTURAL-PHASE STATE OF TUNGSTEN SURFACE LAYER CROSS-SECTION AFTER CARBIDIZATION IN A BEAM-PLASMA DISCHARGE USAGE ELECTRON MICROSCOPY METHODS

This paper presents research results on the structural-phase state of a tungsten surface layer cross-section after carbidization in a beam-plasma discharge. Tungsten surface carbidization in a beam-plasma discharge was conducted in a plasma-beam installation (PBI). Research on the cross-section structure of the surface layer of tungsten samples after carbidization at temperatures of 1000 °C, 1200 °C, and 1400 °C was conducted using transmission and scanning electron microscopy. Based on the results of SEM studies, a multilayer EMF map and local elemental analysis were obtained, based on which the depth of penetration of carbon atoms into tungsten was evaluated. It is established that the penetration depth is ~20 µm. The surface layer fine structure was researched using TEM. For TEM analysis of the tungsten sample cross-section with a carbidized layer, sections were prepared by ion thinning using an Ion Slicer EM-09100 IS unit. According to the research results, it was revealed that after carbidization, tungsten is available in the surface layer mainly in the composition of carbides WC and W2C. On bright-field TEM images of the cross-section of the surface layer of tungsten samples after carbidization at a temperature of 1200 °C and 1400 °C, bending extinction contours are revealed, which indicate the elastically stressed state of the sample surface layer, which leads to bending-torsion of the foil.

Synthesis, Microstructure Investigation, Mechanical and Tribological Behaviour of the AA5083-WC Composite.

In this study, AA5083-WC composites were developed by ball milling followed by hot consolidation. The microstructures of the developed composites were investigated using XRD, SEM, EDX, and EBSD. The developed composites exhibited a homogeneous dispersion of WC particulates in the AA5083 matrix without any interactions at the matrix/reinforcement interface. The results confirmed the development of a refined equiaxed grain structure of AA5083-WC composites where the EBSD results revealed an average grain size of 4.38 µm and 3.32 µm for AA5083-6%WC (AW-6) and AA5083-12%WC (AW-12) composites, respectively. The results showed that incorporating WC particulates in the AA5083 alloy matrix significantly improved the compressive stress-strain behaviour and considerably enhanced the resistance to wear and friction. The AA5083-12%WC (AW-12) composite displayed the maximum strength and the highest resistance to wear and friction, whereas the as-milled AA5083 alloy (AW-0) exhibited the lowest strength and the least resistance to wear and friction. The AA5083-12%WC (AW-12) composite exhibited the optimum mechanical and tribological behaviour of the developed composites, making it a promising candidate for tribological applications.

Abrasive Wear Behavior of Al–4Cu–1.5Mg–WC Composites Synthesized through Powder Metallurgy

Different Al–4Cu–1.5Mg/WC composites were synthesized through powder metallurgy to establish the effect of WC particle addition on the abrasive wear behavior of an Al–4Cu–1.5Mg (wt. %) alloy. The wear tests were performed using a pin-on-disc tribometer at room temperature in dry conditions using SiC abrasive sandpaper as a counterbody and tribometer of linear configuration. The results showed that WC additions increase the hardness of the Al–4Cu–1.5Mg alloy due to the strengthening effect of particle dispersion in the aluminum matrix, which generates an improvement in the wear resistance of the composites by preventing direct contact of the sample with the counterbody, in turn delaying the plastic deformation phenomena responsible for the degradation sequence. In addition, the dominant wear mechanism was abrasive wear, and the increased friction coefficient did not bring a rapid wear rate, which was related to the enhanced deformation resistance due to the high hardness.

Effects of a porous boron nitride nanofiber on nano-mechanical properties in shallow surface of WC-Si3N4 composite

The nanoindentation technique has been applied to materials research for decades, such as WC, Si3N4, and other ceramics or composites. However, nano-mechanical properties in shallow surfaces were often unstable, especially for ceramics-based composites. In this paper, the mechanical properties of WC-10 wt.% Si3N4 without and with the addition of ultrafine porous boron nitride nanofiber were investigated by nanoindentation continuous stiffness measurement in this study. The effects of the porous fiber on elastic modulus and hardness were revealed, which led to more stable and regular profiles of the elastic modulus and hardness versus displacement curves. The curves were cut out and shown before the 30 nm displacement of the tip, which displayed the regularity of the profiles caused by the porous fiber more directly. The values were statistically analyzed at intervals of 10 nm after 30 nm displacement, and then lower standard deviations were observed. The different Si3N4 cracks made from Vickers indentation on the composites were photographed and associated with the regularity of the curves after the fiber addition. It’s considered that the regularity effects on mechanical properties of the porous boron nitride nanofiber on ceramics composites can be helpful in thin film studies, which are also in difficulties of mechanical properties scattering on the nanometer scale using continuous stiffness measurement.

Creating metal-carbide interactions to boost ammonia oxidation activity for low-temperature direct ammonia fuel cells

Low-temperature direct ammonia fuel cell (DAFC) can easily transform the chemical energy into green in-commission power, yet remains great challenging due to kinetically sluggish ammonia oxidation reaction (AOR). The interface engineering is a promising strategy to take advantage of synergistic proficiencies and electronic properties, which was widely applied in heterogeneous catalysis but rarely studied in AOR. Herein, non-oxide-based metal–metal carbide interfaces were employed to construct excellent AOR catalysts. The as-built Pt/WC and PtIr/WC catalysts with the excellent peak current densities of 96.5 and 61.7 A gPGM−1, respectively, which are over 3.5-fold and 2.7-fold than those of carbon-supported catalysts. Both experimental and theoretical studies reveal that the charge transfer between PtIr NPs and WC regulates the work function and d-band center of catalysts and further alters adsorption energies of intermediates. The WC also plays an important role for water dissociation and hydroxyl group activation. Based on the understanding, maximizing active interfaces by dispersing PtIr–WC composites onto CNTs (PtIr–WC/CNT) achieves a compelling peak power density of 140.0 mW cm−2 at 80 °C in a DAFC test, which is at the top of previously reported catalysts at similar conditions. Our study provides a way to design highly-active catalysts for AOR and DAFC by interface engineering.

Effect of laser dwell time on pore elimination in powder bed fusion of metal matrix composites: experimentally validated modeling

Many studies have been conducted to better understand the relationship between additive manufacturing (AM) process parameters and the resulting structure and properties of manufactured parts. It is quite clear that defects associated with AM parts are detrimental to part performance and are thus a major concern for a broader application of AM processed parts. In this study, we aim to investigate the influence of process parameters such as laser dwell time in mitigating pore formation during powder bed fusion of AISI 316L austenitic stainless steel (SS316L)-WC composites. Single-track experiments are conducted with varying printing parameters, while discrete element modeling (DEM) is employed for simulating powder-bed packing for composite system. Results show that the filling of the pores between ceramic particles by the molten SS316L is dependent on the laser dwell time, which in turn, depends on the volume fraction of ceramic reinforcement and initial pore sizes between inclusions. Our experiments, in agreement with model analysis, show that with the information of the materials property of the metal phase in a composite system such as viscosity, surface energy and initial pore sizes between ceramic inclusions, the printing parameters can be chosen to yield the appropriate dwell time for pore free composites.

Synergistic Effect of Work Function and Acoustic Impedance Mismatch for Improved Thermoelectric Performance in GeTe-WC Composite.

The preparation of composite materials is a promising methodology for concurrent optimization of electrical and thermal transport properties for improved thermoelectric (TE) performance. This study demonstrates how the acoustic impedance mismatch (AIM) and the work function of components decouple the TE parameters to achieve enhanced TE performance of the (1-z)Ge0.87Mn0.05Sb0.08Te-(z)WC composite. The simultaneous increase in the electrical conductivity (σ) and Seebeck coefficient (α) with WC (tungsten carbide) volume fraction (z) results in an enhanced power factor (α2σ) in the composite. The rise in σ is attributed to the creation of favorable current paths through the WC phase located between grains of Ge0.87Mn0.05Sb0.08Te, which leads to increased carrier mobility in the composite. Detailed analysis of the obtained electrical properties was performed via Kelvin probe force microscopy (work function measurement) and atomic force microscopy techniques (spatial current distribution map and current–voltage (I–V) characteristics), which are further supported by density functional theory (DFT) calculations. Furthermore, the difference in elastic properties (i.e., sound velocity) between Ge0.87Mn0.05Sb0.08Te and WC results in a high AIM, and hence, a large interface thermal resistance (Rint) between the phases is achieved. The correlation between Rint and the Kapitza radius depicts a reduced phonon thermal conductivity (κph) of the composite, which is explained using the Bruggeman asymmetrical model. Moreover, the decrease in κph is further validated by phonon dispersion calculations that indicate the decrease in phonon group velocity in the composite. The simultaneous effect of enhanced α2σ and reduced κph results in a maximum figure of merit (zT) of 1.93 at 773 K for (1-z)Ge0.87Mn0.05Sb0.08Te-(z)WC composite for z = 0.010. It results in an average thermoelectric figure of merit (zTav) of 1.02 for a temperature difference (ΔT) of 473 K. This study shows promise to achieve higher zTav across a wide range of composite materials.

Effect of hybrid ultrasonic-electromagnetic field on cracks and microstructure of Inconel 718/60%WC composites coating fabricated by laser cladding

In this study, a novel hybrid ultrasonic-electromagnetic (UEM) field was introduced into laser cladding (LC) to fabricate Inconel 718/60% tungsten carbide (WC) metal matrix composites (MMCs) coating on Inconel 718 substrate. Effects of hybrid UEM field on macrostructural, microstructure, phase composition, crack propagation and microhardness of MMCs coating were studied. Results show that under hybrid UEM field, the height of the MMCs coating increases, the cracks in MMCs coating can be effectively eliminated, the distribution of WC particles in the coating becomes more homogeneously, and the heat damage degree of WC particles is significantly decreased. Moreover, hybrid UEM field helps refine the microstructure and promote the transition of coarse carbide precipitates to the smaller spherical carbides. As a result, the microhardness of MMCs coating distributes more evenly in the coating under hybrid UEM field.