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Article

Mechanical and Wear Behaviour of Microwave Sintered Copper Composites Reinforced with Tungsten Carbide and Graphite Under Different Lubrication Conditions

by
V. S. S. Venkatesh
1,
B. Surekha
2,
Pandu Ranga Vundavilli
1,* and
Manas Mohan Mahapatra
1
1
School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Khordha 752050, India
2
School of Mechanical Engineering, KIIT University, Khordha 751024, India
*
Author to whom correspondence should be addressed.
Lubricants 2026, 14(2), 54; https://doi.org/10.3390/lubricants14020054
Submission received: 31 December 2025 / Revised: 22 January 2026 / Accepted: 26 January 2026 / Published: 27 January 2026
(This article belongs to the Special Issue Tribology for Lightweighting)
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Abstract

This present study epitomises the fabrication of Cu-15%WC-X%Gr (X = 0, 3, 6, 9, 12) hybrid composites through a microwave sintering process. The synthesised composites were evaluated for hardness and compression strength as per ASTM standards. The composite corresponding to Cu-15%WC-9%Gr shows the optimal compression strength of 395 MPa. Based on this, the composite corresponding to the maximum compression strength was selected for subsequent wear investigations under dry, oil, and SiC nanofluid lubrication conditions. The SiC nanofluids were prepared by dispersing 1 wt% SiC, 1.5 wt% SiC, and 2 wt% SiC nanoparticles in soluble oils. Increasing the nanoparticle content enhanced both the thermal conductivity and zeta potential, indicating an improved heat transfer and dispersion stability. The wear test under different lubricating regimes demonstrates that the lubricating type had a pronounced influence on the wear rate and C.O.F. The minimum rate of wear of 0.0235 mm3/m and C.O.F. of 0.28 were achieved for the 2 wt% SiC nanofluid lubrication. The worn surfaces under dry and oil-lubricated regimes revealed prominent microcracks and delamination wear. In contrast, surfaces tested under nanofluid lubrication exhibited smoother grooves with minimal surface damage and an absence of microcracking.

1. Introduction

Copper (Cu) is extensively employed in industrial and engineering applications owing to its outstanding electrical and thermal conductivity, excellent corrosion resistance, and superior formability. These attributes make copper a critical material in sectors such as electronics, automotive systems, electrical power transmission, and heat exchange technologies [1,2,3]. Its wide availability and cost-effectiveness further establish copper as a preferred base material for both structural and functional components. Despite these benefits, pure copper’s lack of mechanical properties and poor wear characteristics limit its applicability in situations involving prolonged mechanical loading or high temperatures. [4,5]. Considerable research has focused on the manufacturing of copper matrix composites (CMCs) to overcome these intrinsic constraints. The incorporation of suitable reinforcements aims to preserve copper’s excellent thermal and electrical properties while substantially enhancing its mechanical characteristics, including hardness, strength, thermal stability, and wear resistance. Such enhancements are particularly critical in applications where structural reliability must coexist with high conductivity. To improve the properties of copper, a variety of reinforcement materials have been investigated, such as titanium carbide (TiC), graphene nanoplatelets (GNPs), silicon carbide (SiC), and titanium dioxide (TiO2). These reinforcements exhibit distinct strengthening mechanisms and impart varying influences on the overall composite behaviour [6,7]. For instance, in Tugba et al. [8], the Cu–8 wt% TiO2 composite fabricated via spark plasma sintering followed by hot extrusion exhibited a superior 290 MPa yield strength, representing a 72% improvement over pure copper while retaining appreciable ductility. EI-Zaidia et al. [9] investigated Cu/graphene/flyash composites and found that, at an 8 wt% graphite reinforcement and 850 °C sintering temperature, the optimal tensile and hardness values of 323.3 MPa and 735.3 MPa were attained. Samal et al. [10] reported that the incorporation of Gr phases into the copper matrix enhanced the densification and hardness, resulting in a relative density of up to 96%. Additionally, the rupture strength improved with the addition of graphite reinforcement up to 5 vol.%, beyond which it decreased at higher graphite concentrations.
Based on previous studies, the present work focuses on the development of a copper metal matrix composite reinforced with tungsten carbide and graphite particles. The composite was synthesised using microwave sintering, and its mechanical and tribological behaviours were evaluated under dry, oil, and nanofluid lubrication regimes.

2. Materials and Methods

2.1. Materials

A copper powder with an exceptional purity level of 99.9% and an average particle size of 30 micrometres was selected to serve as the matrix phase. The copper powder used in the present study was procured from Vedayukt Company, East Singhbhum, India. The chemical composition of the matrix and reinforcement phases is shown in Table 1. Tungsten carbide (WC) powder, having a similar mean particle size (~30 μm) and a purity of 99.5%, together with graphite (Gr) particulates having an APS less than 30 μm, was incorporated as a reinforcement phase, as shown in Figure 1.

2.2. Fabrication of the Composite

Cu-WC-Gr hybrid composites were synthesised by incorporating the 15 wt% WC particles and Gr (3 wt%, 6 wt%,9 wt%, 12 wt%) into the copper matrix. The composite powders were homogenised through dry mixing in a planetary ball mill for a milling duration of 2 h under an argon atmosphere, employing WC balls having a 5 mm diameter as milling media and a WC vial with a charge ratio of 10:1 [11,12]. The blended powders were subsequently cold compacted using a 13 mm diameter steel die under an applied uniaxial pressure of 350 MPa [13,14]. To identify the optimum sintering conditions to achieve the maximum densification of copper, the preliminary sintering trials were performed on pure copper at 950 °C with holding times of 30, 60, and 120 min. Among the investigated conditions, a 60 min holding time yielded the highest density. The green compacts were heated using a microwave furnace (900 W and frequency of 2.35 GHz) at a sintering temperature of 950 °C at an 80 °C/min sintering rate, with the samples embedded in a graphite bed to facilitate uniform heating [15,16]. The diagrammatic representation of the complete process is shown in Figure 2.

3. Characterization Techniques

Microhardness evaluation was carried out on the polished sample surface using a Vickers hardness tester (Koopa universal hardness tester, UV1, Sari, Iran). Ten successive indentations were performed for each sample under an applied load of 98.1 N with a dwell time of 10 s at room temperature [17,18,19]. Compression tests were performed according to ASTM E9 standards [20]. The wear rate and C.O.F. were evaluated on the pin-on-disc wear tester in accordance with the ASTM-G99 standard. The composite pins were pressed against the EN 31 steel disc under the dry, oil, and nanofluid lubricating conditions. The tribology test was performed at a constant applied load of 40 N at the tract radius of 50 mm for 30 min time, which corresponds to a sliding distance of 3000 m [21]. The morphological features and elemental distribution of the synthesised composites and the wear track after the wear test were examined using Scanning Electron Microscopy (SEM, Zesis Supra 55, Oberkochen, Germany) coupled with an EDS analyser. XRD (SmartLab, Tokyo, Japan) was performed to reveal the phases present in the composite [22,23].

4. Preparation of SiC Nanofluids and Thermal Conductivity Measurement

SiC nanoparticles (<100 nm) were purchased from the nanoshell company, Bhubaneswar. Nanofluids with SiC nanoparticles were synthesised through a two-step approach by dispersing in ethylene glycol at concentrations of 1 wt% SiC, 1.5 wt% SiC, and 2 wt% SiC. The mixture was initially mixed with a magnetic stirrer at 600 rpm, followed by probe ultrasonication (FS-300 N, 24 Hz, 8 mm probe dia) to ensure homogeneous dispersion of SiC nanoparticles [24,25]. Sonication was performed for a 15 h duration in a 100 mL container at ambient temperature, as depicted in Figure 3.
The thermal conductivity (K) plays a decisive role in the energy dissipation capability of the nanofluids. In the present work, the “K” of the SiC nanofluid was determined using a hot disc thermal analyser at 25 °C for the 1 wt% SiC, 1.5 wt% SiC, and 2 wt% SiC nanofluids [26,27]. The results indicate that the “K” was increased from 0.761 W/m·K to 0.792 W/m·K with the addition of SiC nanoparticles from 1 wt% to 2 wt%. This improvement in “K” was due to the increased presence of the highly conductive SiC nanoparticles within the ethylene glycol matrix. The addition of SiC nanoparticles beyond 2 wt% leads to an agglomeration of SiC nanoparticles, leading to a reduction in the “K” of the nanofluid, as shown in Figure 4.

5. Stability Analysis of the SiC/Ethylene Glycol Nanofluids

The dispersion stability of the SiC/ethylene glycol nanofluids was evaluated using Zetasizer Nano ZS integrated with a He-Ne laser and a fixed disposable folded capillary cell containing integrated electrodes connected to the instrument’s voltage terminals. Under the applied electric field, the SiC nanoparticles migrated through the ethylene glycol medium with velocities proportional to their zeta potential [28,29]. Nanoparticles exhibiting higher zeta potentials indicate a higher electrophoretic mobility. The SiC nanoparticle movement was quantified through laser Doppler velocimetry as the laser beam passed through the charged suspension.
The zeta potential experiments were performed at 28 °C for SiC wt% of 1 wt% SiC, 1.5 wt% SiC, and 2 wt% SiC, and the results are illustrated in Figure 5. The zeta potential values in this present study exceeded 45 mV, with a maximum value of 58 mV attained for the 2 wt% SiC nanofluid, signifying a uniform dispersion and minimal agglomeration. Consequently, the 2 wt% SiC nanofluids were selected for the tribological analysis owing to their superior thermal conductivity and electrostatic stability.

6. Results and Discussion

6.1. Morphological Study of the Cu-WC-Gr Composite

The synthesised composites were investigated to reveal the reinforcement dispersion through SEM analysis. The addition of the graphite (Gr) reinforcement up to 9 wt% leads to a uniform dispersion inside the copper matrix, as shown in Figure 6a,b for 6 wt% and 9 wt% Gr particles. However, the addition of Gr phases at 12 wt% creates brittle agglomerations by reacting with the softer copper matrix at the reinforcement and matrix interfaces, as depicted in Figure 6c. The peak related to the agglomerated peak was confirmed through the XRD analysis, and it was concluded that the peak at 43° matches with the Cu2C2 intermetallic, confirmed by ICDD card number 25-0015, as shown in Figure 7 [30,31]. The uniform dispersion of the tungsten, carbon, and graphite phases was clearly identified through the EDS mapping of the corresponding composite, as shown in Figure 6a,b. The formation of the secondary agglomerations acted as an efficient interlocking among the copper matrix and reinforcement phases, thereby enhancing the load transfer among the interface particles. A controlled extent of interlocking is treated as beneficial. However, the existence of higher activation energies at the agglomeration regions leads to brittle and impurity-rich intermetallic layers, which create pores at the interfaces and decline the mechanical properties of the composites [32,33].

6.2. Mechanical Properties of the Synthesised Cu-WC-Gr Composite

6.2.1. Hardness Result for the Cu-WC-Gr Composite

Figure 8 illustrates the variation in the Vickers hardness with the Gr wt%. The hardness increases from 180 HV for the Cu-15%WC to 239 HV for the Cu-15%WC-12%Gr composite, corresponding to an enhancement of 32.7% for the 12 wt% Gr addition compared with the unreinforced graphite (Cu-15%WC). The hardness improvement was due to the wetting property of the reinforced Gr particles among the copper matrix and reinforcement phases. The enhanced wettability accelerates the efficient load transfer among the interfaces of the matrix and reinforcement phases, thereby resulting in the higher Vickers values [34,35]. In addition to this, the incorporation of the Graphite phases into the ductile copper matrix, along with their uniform dispersion, significantly improves the resistance to the penetration of the indenter of the hardness tester. The attained hardness values are 14.32% and 20% higher than the hardness values attained by Manikandan et al. [36] and Abhijit Bhowmik et al. [37]. The improvement in hardness was due to the addition of the graphite particles, which establishes the strong interfacial and intermetallic bonding with the adjacent reinforcements. Additionally, the uniform sintering during the MAS process at short durations ensures a rapid heat dispersion and promotes the generation of clean and robust interfaces, which further improves the hardness of the microwave sintering Cu-WC-Gr composite [15,38].

6.2.2. Compression Strength Analysis of the Synthesised Cu-WC-Gr Composite

The variation in the compression strength of the Cu-WC-Gr composite with the wt% of Gr particles is illustrated in Figure 9. It was observed that the compression strength of the Cu-15%WC-9%Gr composite exhibited a remarkable increase of 38.59% over the Cu-15%WC composite. The optimum compression strength of 395 MPa was attained for the Cu-15%WC-9%Gr composite. The improvement in the compression strength was due to the incorporation of the Gr particles, which refine and strengthen the grain boundaries at the matrix and reinforcement interfaces [39]. These strengthened grain boundaries act as effective barriers to microcrack initiation and propagation under compressive loading, thereby enhancing the composite compression strength up to the 9 wt% graphite addition. Furthermore, the incorporation of graphite as an impurity restricts the dislocation movement near the interfaces, leading to dislocation pile-up at the grain boundaries and consequently increasing the strength of the composite through the Orowan strengthening mechanism [40]. However, when the graphite particles exceeded more than 9 wt%, a reduction in the compression strength was observed. This decline is attributed to the formation of the intermetallic at the interfaces, as shown in Figure 6c. These agglomerations develop additional slip planes, facilitating atomic movement even under the lower magnitude of the compressive loads [41]. Hence, based on the compression strength results, the composite corresponding to the 9 wt% graphite reinforcement was selected for the tribological investigations in the present study.

6.3. Tribological Analysis

6.3.1. Wear Rate

The variation in the wear rate of the Cu-15%WC-9 wt%Gr composite under different lubrication conditions as a function of the sliding time is shown in Figure 10. The results indicate that the presence of the nanofluids at the interface of the pin and disc remarkably declines the wear rate of the composite compared to dry and oil lubrication. At an applied load of 40 N and a sliding duration of 30 min, the wear rate under 2 wt% SiC nanofluid lubrication decreased by 53.18% and 58.7% relative to oil-lubricated and dry sliding conditions, respectively. The lowest wear rate of 0.0235 mm3/m observed under 2 wt% SiC nanofluid conditions is due to the generation of a stable tribofilm at the interface. This tribofilm serves as a protective film, preventing the direct asperity contact between the mating surfaces and partially lifting the pin form the disc surface, resulting in an apparent reduction in the wear rate of the Cu-15%WC-9%Gr composite.
Despite this, when the sliding time exceeds 30 min, the heat generated at the interface leads to the breakdown of the tribofilm, thereby increasing the wear rate of the composite pin against the steel disc. The sustained presence of the nanofluids containing SiC particles at the interfaces of the composite pin and counter disc minimises the surface contact and leads to an improved lubrication performance [42]. Apart from this, the SiC nanofluids present at the interfacial regions are capable of absorbing and dissipating the generated heat, which declines the plastic deformation of the Cu-WC-Gr composite and surpasses the wear of the composite pin.
From the figure, it is also clear that the rate of wear also increases with prolonging the sliding time for all lubricating regimes. However, the magnitude of the wear rate is strongly influenced by the type of lubricant used between the contact surfaces. After 30 min of sliding time, the wear rate values recorded under dry, oil, and nanofluid lubrication with 1 wt%, 1.5 wt%, and 2 wt% were approximately 0.0563 mm3/m, 0.0502 mm3/m, 0.0432 mm3/m, 0.0320 mm3/m, and 0.0235 mm3/m, respectively. Notably, the presence of the 2 wt% SiC nanofluid resulted in a substantial decline in the wear rate. These results clearly highlight the superior lubricating efficiency of nanofluids, particularly at higher nanoparticle concentrations.
The enhancement in the wear resistance when increasing the SiC nanofluid content is attributed to the synergistic effect of the improved thermal conductivity, homogeneous dispersion of the nanoparticles, and development of the protective tribofilm at the contact interface. The uniform dispersion of the SiC nanoparticles induces rolling and polishing mechanisms that substantially reduce abrasive contact among the disc and composite pin surfaces. Apart from this, these nanoparticles exhibit a mending effect by filling surface microcracks and defects, thereby limiting material loss. Overall, the findings demonstrate that nanofluids containing 2 wt% SiC deliver a superior tribological performance, clearly outperforming both conventional oil lubrication and dry sliding conditions.

6.3.2. Coefficient of Friction

The C.O.F. for the microwave sintered Cu-15%WC-9%Gr composite is depicted in Figure 11. The maximum C.O.F. of approximately 0.38 was observed under dry sliding conditions, primarily due to the strong adhesive interactions between unlubricated contact surfaces, which result in elevated frictional forces. In contrast, the lowest C.O.F. of 0.28 was recorded under 2 wt% SiC nanofluid conditions. This significant reduction in the friction is partly attributed to the presence of the SiC nanoparticles at the interfaces, which leads to the formation of a tribofilm, thereby preventing direct metal-to-metal contact [43]. Apart from this, the presence of graphite phases in the composite, which form the wear debris during the sliding, further contributes to lowering of the C.O.F. In contrast, the highest value of the C.O.F., 0.38, under dry conditions was attained due to the pure metal-to-metal contact during the sliding. Notably, nanofluid lubrication demonstrated the most effective friction reduction, with the C.O.F. decreasing progressively as the SiC nanoparticle concentration increased.
The C.O.F. findings demonstrate that nanofluids provide a superior friction reduction compared to conventional oil, with their effectiveness improving as the nanoparticle concentration increases. The enhanced lubricating performance is attributed to the generation of a protective tribofilm, improved heat dissipation, and the rolling action of uniformly dispersed nanoparticles, which collectively minimise direct surface contact [44]. Among the tested conditions, the nanofluid containing 2 wt% SiC exhibited the highest efficiency, resulting in a substantial reduction in friction and a marked improvement in the overall tribological performance of the composite.

6.4. Worn Surface Morphology

Figure 12 represents the SEM micrographs for the worn surfaces of the Cu-15 wt% WC-9 wt% Gr composite under dry, oil, and 2 wt% SiC nanofluid lubricant conditions for a 30 min time interval sliding time. Under all lubrication regimes, continuous grooves aligned with the sliding direction are evident, arising from the ploughing action of the hard WC particles against the EN31 counter steel disc.
Under dry sliding conditions, Figure 12a, the direct interaction between the Cu-WC-Gr composite pin and counter surface results in significant frictional heat, leading to thermal softening and severe damage to the composite surface [45]. Moreover, the hard WC particles tend to debond from the matrix and fracture into fine abrasive debris. The fractured reinforcements from the surface create the preferential sites for the initiation of microcracks, ultimately promoting the delamination wear mechanism. The presence of surface microcracks and the delamination wear under dry sliding conditions was depicted in Figure 12a. The extent of surface damage is further influenced by localised stress concentrations at asperity contacts, which intensify with increasing applied loads.
Figure 12b depicts the worn surface morphology under soluble oil lubrication. Although pronounced furrows and grooves are still observed, the overall worn surface appears comparatively smoother than that formed under dry conditions. The reduced wear rate in oil-lubricated conditions is primarily attributed to the diminished direct asperity contact due to the presence of the lubricating film, which facilitates the transition from severe to mild wear regimes [46]. Furthermore, the existence of the oil film surpasses the temperature rise at the interfaces, leading to lower friction. The lubricant also aids in removing the wear debris from the contact zone, thereby minimising third-body abrasion and oxidation wear compared to dry conditions.
In contrast, under a 2 wt% SiC nanofluid lubricating condition, the presence of SiC nanofluid particles transforms the dominant sliding contact into a combined rolling–sliding mechanism. Uniformly dispersed SiC nanoparticles promote controlled micro-abrasion, producing a polishing effect at the contact regions, as depicted in Figure 12c. The combined rolling and polishing actions significantly reduce the C.O.F. at an optimal concentration of 2 wt% SiC. Beyond this level, nanoparticle agglomeration diminishes these beneficial effects. Additionally, the nanoparticles exhibit a mending effect by filling surface defects and microcracks, thereby limiting material loss. As a result, the synergistic rolling, polishing, and mending mechanisms account for the superior anti-wear and anti-friction performance under 2 wt% SiC nanofluid lubrication.
Although a direct chemical characterization of the tribofilm was not performed, its existence is strongly supported by indirect tribological evidence. The marked reductions in the wear rate and C.O.F. under a 2 wt% SiC nanofluid lubrication, along with the smoother worn surfaces and the absence of severe delamination, indicate the formation of a stable protective tribofilm. This tribofilm is proposed to comprise compacted SiC nanoparticles, graphite-rich wear debris from the Cu–WC–Gr composite, and tribo-oxidised copper species. The uniform dispersion of SiC nanoparticles promotes rolling, mending, and load-bearing effects, while graphite debris provides solid lubrication and shear accommodation. In addition, the high thermal conductivity and stability of the SiC nanofluid enhance heat dissipation, suppressing thermal softening and tribofilm degradation. The synergistic action of these mechanisms results in a mechanically stable and continuously replenished tribofilm, accounting for the improved wear resistance observed. The significant reduction and stabilization of the C.O.F, along with the transition from severe ploughing to mild polishing wear observed in the worn surface morphology, strongly indicate the operation of a third-body lubrication mechanism.

7. Conclusions

The key conclusions drawn from the present study are briefly presented below.
(1)
Cu–15%WC–X%Gr composites fabricated through microwave sintering showed a uniform reinforcement dispersion up to 9 wt% Gr, while 12 wt% Gr caused Cu2C2 agglomeration and interfacial defects.
(2)
The hardness increased from 180 HV (Cu–15%WC) to 239 HV (Cu–15%WC–12%Gr), achieving a 32.7% improvement due to enhanced interfacial bonding and load transfer.
(3)
A maximum compression strength of 395 MPa was obtained for Cu–15%WC–9%Gr, representing a 38.59% increase over Cu–15%WC, attributed to grain boundary strengthening and dislocation blocking.
(4)
The tribological performance improved significantly under 2 wt% SiC nanofluid lubrication, yielding the lowest wear rate of 0.0235 mm3/m, with reductions of 53.18% and 58.7% compared to oil and dry conditions, respectively, while simultaneously reducing the C.O.F. from ~0.38 (dry) to ~0.28 due to tribofilm formation, nanoparticle rolling, and the lubricating action of graphite.
(5)
The Cu–15%WC–9%Gr composite exhibited a superior tribological performance when combined with 2 wt% SiC nanofluid lubrication, demonstrating a clear synergistic effect between the optimised material system and the lubrication condition.
(6)
The presence of graphite within the composite and uniformly dispersed SiC nanoparticles in the nanofluid promoted stable tribofilm formation, enhanced heat dissipation, and reduced direct asperity contact, resulting in the lowest wear rate of 0.0235 mm3 m−1 and a reduced C.O.F. of 0.28.
(7)
Worn surface analysis revealed a severe delamination under dry sliding, moderate abrasion with oil, and smooth, crack-free surfaces under nanofluid lubrication due to rolling, polishing, and mending effects.

Author Contributions

Conceptualization, V.S.S.V.; Methodology, V.S.S.V.; Validation, B.S.; Formal analysis, B.S.; Investigation, P.R.V.; Data curation, M.M.M.; Writing—original draft, V.S.S.V. and M.M.M.; Writing—review & editing, P.R.V. and M.M.M.; Supervision, B.S.; Project administration, P.R.V. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. SEM and EDX mapping of as-received (a) copper, (b) graphite, and (c) WC particles.
Figure 1. SEM and EDX mapping of as-received (a) copper, (b) graphite, and (c) WC particles.
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Figure 2. Schematic of composite Ffbrication and characterizations performed.
Figure 2. Schematic of composite Ffbrication and characterizations performed.
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Figure 3. Schematic of the SiC nanofluid preparation.
Figure 3. Schematic of the SiC nanofluid preparation.
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Figure 4. Thermal conductivity (K) of nanofluids with wt% of SiC particles.
Figure 4. Thermal conductivity (K) of nanofluids with wt% of SiC particles.
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Figure 5. Zeta potential values for the prepared SiC nanofluids.
Figure 5. Zeta potential values for the prepared SiC nanofluids.
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Figure 6. SEM and EDS images for (a) Cu-15%WC-6 wt% Gr, (b) Cu-15%WC-9 wt% Gr, and (c) Cu-15%WC-12 wt% Gr composites.
Figure 6. SEM and EDS images for (a) Cu-15%WC-6 wt% Gr, (b) Cu-15%WC-9 wt% Gr, and (c) Cu-15%WC-12 wt% Gr composites.
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Figure 7. XRD pattern for the Cu-15%WC-X%Gr (X = 3, 6, 9, 12.) hybrid microwave sintered composite.
Figure 7. XRD pattern for the Cu-15%WC-X%Gr (X = 3, 6, 9, 12.) hybrid microwave sintered composite.
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Figure 8. Variation in the hardness of the Cu-WC-Gr composite with the Gr content.
Figure 8. Variation in the hardness of the Cu-WC-Gr composite with the Gr content.
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Figure 9. Variation in the compression strength of the Cu-WC-Gr composite with the Gr content.
Figure 9. Variation in the compression strength of the Cu-WC-Gr composite with the Gr content.
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Figure 10. Effect of lubrication regimes on the wear of the HMMC pin with time.
Figure 10. Effect of lubrication regimes on the wear of the HMMC pin with time.
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Figure 11. Effect of the lubrication regimes on the C.O.F. of the HMMC pin with time.
Figure 11. Effect of the lubrication regimes on the C.O.F. of the HMMC pin with time.
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Figure 12. Wear track morphology of the HMMC under (a) dry, (b) oil, and (c) SiC nanofluid lubrication conditions.
Figure 12. Wear track morphology of the HMMC under (a) dry, (b) oil, and (c) SiC nanofluid lubrication conditions.
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Table 1. Chemical composition of the matrix and reinforcement particles.
Table 1. Chemical composition of the matrix and reinforcement particles.
MaterialComposition (wt%)/Purity
Copper matrix99.9%
Tungsten carbideWC ≥ 99%
GraphiteC ≥ 99%
Composite materialCu–15%WC–9%Gr
Nanofluid lubricantSoluble oil + 2 SiC
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MDPI and ACS Style

Venkatesh, V.S.S.; Surekha, B.; Vundavilli, P.R.; Mahapatra, M.M. Mechanical and Wear Behaviour of Microwave Sintered Copper Composites Reinforced with Tungsten Carbide and Graphite Under Different Lubrication Conditions. Lubricants 2026, 14, 54. https://doi.org/10.3390/lubricants14020054

AMA Style

Venkatesh VSS, Surekha B, Vundavilli PR, Mahapatra MM. Mechanical and Wear Behaviour of Microwave Sintered Copper Composites Reinforced with Tungsten Carbide and Graphite Under Different Lubrication Conditions. Lubricants. 2026; 14(2):54. https://doi.org/10.3390/lubricants14020054

Chicago/Turabian Style

Venkatesh, V. S. S., B. Surekha, Pandu Ranga Vundavilli, and Manas Mohan Mahapatra. 2026. "Mechanical and Wear Behaviour of Microwave Sintered Copper Composites Reinforced with Tungsten Carbide and Graphite Under Different Lubrication Conditions" Lubricants 14, no. 2: 54. https://doi.org/10.3390/lubricants14020054

APA Style

Venkatesh, V. S. S., Surekha, B., Vundavilli, P. R., & Mahapatra, M. M. (2026). Mechanical and Wear Behaviour of Microwave Sintered Copper Composites Reinforced with Tungsten Carbide and Graphite Under Different Lubrication Conditions. Lubricants, 14(2), 54. https://doi.org/10.3390/lubricants14020054

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