This study presents a pioneering methodology for the synthesis of aluminum matrix composites (AMCs) fortified with biochar, sourced from renewable biomass feedstocks. Employing a systematic approach, various biochar weight percentages were meticulously investigated to discern their impact on the mechanical and tribological properties of the resulting composites. Through a comprehensive battery of tests, encompassing evaluations of compressive strength and hardness, the study elucidated significant enhancements in mechanical robustness consequent to biochar integration. Notably, the mixture formulation with 7.5 wt. % biochar emerged as the optimal configuration, showcasing an impressive 8.83% augmentation in compressive strength and a notable 15% elevation in the hardness relative to the pristine aluminum pure matrix. The research extends beyond traditional analyses, introducing an exploration of tribological performance. The incorporation of biochar is anticipated to impart solid lubricating properties, influencing wear and friction characteristics. Future research directions may delve into the nuanced interplay between biochar content and tribological enhancements, offering insights into the tailored manipulation of mechanical and tribological properties in AMC through biochar reinforcement. The examination of wear and friction exhibited that the friction coefficient decreased by 6.4% when 10 wt. % of biochar was added. Furthermore, the wear resistance improved proportionally with the biochar weight percentage, regardless of the normal loads applied. The finite element model further demonstrated an enhancement in load-carrying capacity due to biochar incorporation. Finally, analysis of the texture of the rubbed surface presented that the inclusion of biochar in an AL matrix changed the way wear occurs and decreased the amount of weight lost during friction. The resulting materials not only exhibit improved mechanical strength but also hold promise for applications in industries that demand robust, environmentally conscious solutions with enhanced tribological performance.

There remains an urgent need to develop advanced materials with exceptional mechanical properties and high resistance to wear and friction. This quest is driven by the escalating demands within critical sectors such as space technology,1,2 automobiles,3 and construction manufacturing,4 in which materials must adhere to rigorous standards of durability and performance.5 In response to this imperative, there has been a notable shift toward exploring sustainable additives as a means of aligning with global efforts toward engineering solutions that are environmentally conscious. In this research, the domain of Al composites (AMCs) reinforced with biochar additives made from biomass sources is thoroughly investigated.6 

Driven by the desire to break beyond the limitations of traditional materials and explore previously uncharted territories, materials research continues to be anchored by the relentless search for novel materials.7 The pyrolysis of organic matter produces biochar, which is becoming more and more well-known for its unique structural qualities, high carbon content, and wide range of uses.8,9 Although biochar has long been recognized for its functions in carbon sequestration and soil improvement, it is currently becoming a focus of materials research due to its potential benefits for improving the tribological characteristics of materials that are composite.10,11 The amalgamation of biochar with metal matrix composite (MMC) marks a promising frontier in materials engineering, presenting an innovative path for the development of sustainable materials. While the potential benefits of aluminum renowned for its lightweight and tribological performance have been extensively explored, the reinforcement attributes of biochar in aluminum matrix composites remain relatively uncharted.12–14 

Sustainable reinforcement materials have gained increasing attention in recent years due to the need for materials that can meet both mechanical demands and environmental standards. Biochar, a carbon-rich solid derived from biomass, offers a promising reinforcement option due to its potential for enhancing material properties without relying on non-renewable resources.15,16 The inherent porosity and high surface area of biochar allow for improved interaction with matrix materials, potentially leading to better mechanical interlocking and load distribution in the composite.17 This is particularly advantageous in tribological applications where enhanced wear resistance and reduced friction are critical. The current work aims to explore these interactions in greater detail, contributing to the emerging field of biochar-reinforced aluminum matrix composites.

In addition to its structural benefits, biochar has been identified as a solid lubricant, capable of reducing friction and wear in material interfaces.18 This characteristic, when combined with aluminum’s tribological performance, suggests a synergistic effect that could offer substantial advantages in applications where sliding or contact friction is prevalent. Recent studies have shown that biochar’s ability to form a protective tribolayer during sliding can mitigate wear mechanisms such as abrasion and adhesion.19 By investigating the optimal concentrations of biochar in AMCs, this research seeks to uncover the conditions under which these composites exhibit maximum tribological performance, making them suitable for a variety of demanding industrial applications.

This study is motivated by more than one objective: the refinement of mechanical properties and the investigation of tribological performance in aluminum matrix composites. In this context, the introduction of biochar as a reinforcing agent introduces a subtle variable, unraveling the synergistic effects between aluminum and biochar. Unlike conventional reinforcement materials, such as ceramic or carbon structures, the integration of biochar adds a unique dimension, showcasing not only the intrinsic characteristics of aluminum but also the distinctive properties related to biochar material. At the heart of this study lies a commitment to eco-conscious engineering, where the deliberate choice of biochar as a reinforcement material aligns with the global shift toward sustainability. Previous investigations have highlighted the success of biochar in enhancing mechanical properties and thermal stabilization when introduced into polymers20 and ceramics.21 This paper builds upon this foundation, aiming to advance our understanding of the intricate interplay between aluminum and biochar, with a focus on tribological performance, to contribute to sustainable solutions in materials engineering.

The incorporation of carbon additives in aluminum matrix composites not only enhances their mechanical properties but also imparts significant improvements in their tribological performance.22 Tribological studies on these composites, involving multiwall nanotubes (CNTs),23 graphite and graphene,24 or 2D carbon structures,25 have demonstrated reduced friction coefficients (FCs) and enhanced wear resistance.26,27 The synergistic effects of aluminum and carbon additives create a composite material with superior tribological characteristics, making it suitable for applications where materials experience friction, abrasion, and wear.28,29 In tribological applications such as sliding components in machinery or bearings, the improved wear resistance of aluminum matrix composites with carbon additives becomes a critical advantage.30,31 The potential for these composites to withstand harsh operating conditions, reduce wear rates (WR), and exhibit lower frictional forces positions them as promising candidates for components subjected to repetitive motion and contact. This makes them particularly relevant in industries where tribological performance is a crucial factor, including manufacturing, automotive engineering, and aerospace applications.32,33 Ongoing research efforts continue to explore novel combinations of carbon additives and aluminum matrices, aiming to optimize tribological properties and unlock the full power of these advanced composites for a broader range of applications.34,35

Drawing inspiration from studies such as Abdo et al.,20 which demonstrated biochar’s prowess as a solid lubricant in LDPE composites, and research by Udaya and Peter Fernandes and Udaya36 and Sabitha Jannet et al.,6 showcasing the benefits of incorporating biochar in aluminum composites for enhanced hardness and low WR, this investigation systematically examines a range of weight percentages of biochar (0, 2.5, 5, 7.5, and 10 wt. %) in aluminum matrix composites. The objective is to elucidate the intricate interplay between biochar concentration and the balance between mechanical strength and tribological characteristics. The investigation encompasses a comprehensive array of tribological tests, including wear resistance and FC, offering great understandings for the potential of biochar-reinforced AMC for applications requiring superior tribological properties.

The current research centered on the utilization of pure aluminum as the base metal matrix, sourced from Merck Company, Darmstadt, Germany, with a 99.9% purity level and average particle size diameters of 150 ± 50 μm. Biochar was utilized as the additive or reinforcement, which was produced in our laboratory using agricultural waste, demonstrating an efficient repurposing of waste material into a valuable resource.

To fabricate samples of Al/biochar composites with a homogeneous dispersion of biochar throughout the matrix of aluminum, a series of methods are employed, as illustrated in Fig. 1. A high-energy milling process was selected to mix the aluminum powder with biochar, aiming to ensure the homogeneous dispersion of biochar particles within the aluminum powder. Initially, the aluminum powder undergoes a 25-min mixing in a jar of stainless-steel within a planetary ball mill machine. This essential step is intended to break down any aggregated powder particles, thereby facilitating improved dispersion. For this purpose, the desktop type vibratory ball mill with high energy, sourced from Across International Company, Livingston, Montana, United States, equipped with an 80 ml jar, is specifically utilized. Following this, aluminum powder is mixed with biochar at five variant weight percent gradations (0, 2.5, 5, 7.5, and 10 wt. %) for a duration of 30 min. By implementing this rigorous process, the biochar is uniformly distributed throughout the aluminum matrix, leading to the formation of a remarkably blended composition.

FIG. 1.

Schematic for the fabrication of the Al/biochar composite samples.

FIG. 1.

Schematic for the fabrication of the Al/biochar composite samples.

Close modal

After the Al/biochar mixture was prepared, a complex sintering process for consolidation underwent in an induction furnace, as illustrated in Fig. 2. This was accomplished by utilizing the functionalities of the high-frequency sintering system, which was designed and manufactured by Eltek Company, Gyeonggi-do, South Korea. The carefully blended Al/biochar mixture was carefully placed within a 10 mm inner diameter graphite die with a height of 30 mm. Temperature regulation was exactly controlled during sintering with the aid of both an optical pyrometer and a thermocouple for more measurement accuracy. The applied pressure during the sintering procedure was maintained at 40 MPA and a gradual heating rate of 90 °C/min in order to reach a maximum temperature of 580 °C within 6 min approximately. To safeguard against undesirable oxidation of the composite samples, the entire sintering operation was conducted within the confines of a vacuum chamber, in which the negative pressure was maintained at 5 × 10−3 Torr with a little fluctuation. Following the meticulous sintering process, the sintered composite underwent a cooling process naturally without any regulations, gradually bringing them down to room temperature. This slowly uncontrolled cooling procedure played a vital role in ensuring the integrity and stability of the fabricated samples.

FIG. 2.

Schematic for the consolidation process using HFIHS.

FIG. 2.

Schematic for the consolidation process using HFIHS.

Close modal

After the completion of tribological testing, a thorough investigation into the surface morphology of the wear composite samples was carried out using scanning electron microscopy (SEM) branded by JEOL, JSM7600F, and equipped by an EDS accessory. This analytical approach is acceptable for a detailed investigation of the microstructural features and integrity of the composites. In parallel, the physical properties represented by the relative density of the Al/biochar composite were assessed employing Archimedes’ principle divided by the theoretical density. This methodological approach offers a critical assessment of the effectiveness of the sintering process.

For a comprehensive evaluation of the mechanical attributes exhibited by the generated composites, a meticulous analysis of their hardness and compression properties was conducted. The determination of hardness involved a polishing process followed by a Vickers hardness test, executed with a Buehler-MicroMet 5114 Vickers hardness tester ZHVm sourced from Zwick/Roell, Germany. Each sample underwent a meticulous hardness test, applying a load of 250 g and maintaining 10 s of dwell time to ensure precision. The standard error was meticulously calculated, and the average hardness of five samples of each composite was measured in order to maintain strict accuracy. Additionally, the mechanical behavior of the Al/biochar composite samples was evaluated through compression tests, according to the ASTM E9-89a standard.37 The experiments were performed using universal testing equipment (INSTRON Model 3385H) that had a capacity of 150 kN. A crosshead moving of 2.5 mm/min rate was utilized to conduct the experiments, and five samples of each composition were evaluated to assure a comprehensive analysis for the compression test.

The wear characteristics of the Al/biochar composites were assessed in accordance with the ASTM G99-95 standards38 using a pin-on-disc tribometer. The experiments were conducted under controlled dry-sliding conditions at 30% humidity and a temperature of 23 °C. In the tribometer setup, the composite samples were utilized as the pins, while the disk counterpart was fabricated from stainless-steel, boasting a surface-roughness of 13.5 μm and a 7 cm diameter measuring. Before each test session, thorough cleaning of the contact surfaces was diligently performed using acetone prior to drying with hot air to ensure the elimination of any lingering impurities during different tests. Tribological assessments were executed under various loads, starting at 5 N up to 20 N, while maintaining a consistent sliding speed of 0.4 m/s. The study investigated the impact of different sliding distances, including options of 240, 480, 720, or 960 m. To guarantee the reliability of the results, each test underwent five repetitions. The average FC was computed, accounting for standard errors. Precise documentation of the sample mass both before and after the experiment enabled the specific WR calculation using the following equation:
(1)
where Δm is the difference in mass before and after the tribological test, ρ is the density of the composite specimen, Fn is the normal load (NL), and L is the sliding distance.

Following the friction experiments, the composite samples were analyzed using a scanning electron microscope (JCM-6000Plus; JEOL, Japan).

As mentioned in Ref. 34, the distribution of contact stresses on the manufactured composite samples can be analyzed to determine the load-carrying capacity (LCC). In order to explore the distribution of contact stress, a pin-on-disk setup was built using ANSYS software, and this allowed for the simulation of the tribological test, as shown in Fig. 3. The contact between the surfaces was determined to be frictional in order to calculate the stresses that were produced as a result of the pin rubbing against the disk. A 3D model was created for the pin, which had a 20 mm length and an 8 mm diameter, and the disk, which had a 200 mm diameter and a 10 mm thickness. The grids of the pin and disk were then created by combining tetrahedral and hexahedral elements through the use of automatic mesh. There were 112 elements and 637 nodes in the pin, and 1623 nodes and 214 elements in the disk. To achieve accurate measurements, boundary conditions were set: a 20 N applied force was exerted in the z-direction on the specimen surface, and the composite specimen was limited in the x and y directions. The stainless-steel disk continued to spin at a constant 250 rpm in a clockwise direction. To make the analysis accurate, the mechanical properties of the composite specimens—which were determined from experimental data—were entered into the ANSYS model.

FIG. 3.

Finite element model of the tribological test.

FIG. 3.

Finite element model of the tribological test.

Close modal

SEM micrographs, featured in Fig. 4, meticulously depict the biochar intended for reinforcing the aluminum matrix. These images, captured at varying magnifications, offer insights into the notable porosity present within the particulate biochar. Analysis revealed an average particle size of the biochar ranging from 45 to 100 μm, along with a typical pore size ranging from 4 to 18 μm in average. This porous architecture carries inherent advantages for improving the mechanical strength of the composite, as it provides a larger surface area conducive to a wide range of potential applications.

FIG. 4.

SEM images for the biochar reinforcement at different zooming factors (a)–(c), and (d) EDS analysis for the pink rectangular in (c) showing the elemental analysis of the biochar.

FIG. 4.

SEM images for the biochar reinforcement at different zooming factors (a)–(c), and (d) EDS analysis for the pink rectangular in (c) showing the elemental analysis of the biochar.

Close modal

Energy-Dispersive X-ray Spectroscopy (EDS) emerged as an indispensable tool for scrutinizing the elemental analysis of the biochar used in this study as a reinforcement. The obtained results of EDS analysis provide confirmation that the used biochar is predominantly composed of oxygen and carbon. Furthermore, minute quantities of potassium, calcium, and zirconium were identified. It is noteworthy to mention that the platinum content observed in the EDS pattern is due to the precise application of a platinum coating onto the sample before taking images. The critical function of this coating is to increase the sample surface conductivity, subsequently eliminating the white spots due to charging that may occur during SEM imaging and helping to obtain clear images. In order to mitigate its potential influence, the elemental results deliberately excluded the percentage of platinum, which explains the absence of a designated Pt peak in the EDS pattern. The elemental composition and porous structure of biochar collectively position it as a promising reinforcement material within the composite matrix, with the potential for significant enhancements in both mechanical and tribological properties as well.

1. Samples designation

In the context of composite materials, such as Al/biochar, the Rule of Mixture serves as a predictive concept for overall properties based on individual components. For the sintered samples, the relative density, crucial for quality assessment, plays a vital role. The presented Al-biochar composites (ALB0, ALB2.5, ALB5, ALB7.5, and ALB10) exhibit a systematic decrease in relative density with an increase in biochar content. The observed difference in density between aluminum and biochar can be ascribed to the latter’s origin from biomass pyrolysis, which is inherently porous and lightweight. The introduction of void defects within the fabricated samples due to the porous structure of biochar impacts the observed reduction in relative density. The hardness values, outlined in Table I, exhibit a slight enhancement with an increase in biochar filler, with the most notable change occurring up to 7.5 wt. %. The enhanced load-bearing capacity is ascribed to the prevention of dislocation movement, which results in this hardness enhancement. The observed correlation between the trend in hardness and the trend in relative density prior to this indicates that the decrease in relative density, specifically in ALB7.5 and ALB10, could potentially impact the composite’s overall hardness by causing fluctuations in particle distribution and bonding. This relationship underscores the intricate interplay between density, distribution, mechanical properties, and wear behavior.

TABLE I.

Designation of the Al/biochar composite samples with varied biochar weight percentage corresponding to its relative density and Vickers’s hardness.

SampleComposition wt. %Relative density (%)Vickers’s hardness
ALB0 Pure Al 99.6 33.2 
ALB2.5 2.5 99.0 36.3 
ALB5 98.9 37.6 
ALB7.5 7.5 98.1 38 
ALB10 10 97.5 36.1 
SampleComposition wt. %Relative density (%)Vickers’s hardness
ALB0 Pure Al 99.6 33.2 
ALB2.5 2.5 99.0 36.3 
ALB5 98.9 37.6 
ALB7.5 7.5 98.1 38 
ALB10 10 97.5 36.1 

2. Mechanical properties

The compression test results, as depicted in Fig. 5, offer valuable conclusions into the mechanical behavior of the Al-biochar across varying biochar weight percentages. While yield strength (YS) exhibits nuanced variations, ultimate compressive strength (UCS) consistently increases with higher biochar content. This trend aligns with biochar’s reinforcing properties, emphasizing its structural integrity and strength. The stress at fracture further underscores the enhanced resistance to compression failure, particularly in ALB7.5 and ALB10. These findings suggest biochar’s potential as a robust reinforcing agent in metal matrix composites, showcasing improved resistance to deformation and plastic flow.39,40

FIG. 5.

The extracted compressive-strength (UCS), and yield strength (YS).

FIG. 5.

The extracted compressive-strength (UCS), and yield strength (YS).

Close modal

The increase in UCS values that have been observed can be ascribed to the strengthening properties of biochar additives, which are widely recognized for their intrinsic fortitude and ability to maintain structure. The elevated UCS values observed in ALB5, ALB7.5, and ALB10 serve as evidence that biochar has a beneficial effect on the composite’s capacity to efficiently endure compressive stresses. A notable trend in yield strength (YS) shows subtle fluctuations with varying biochar content, initially decreasing before exhibiting an upward trend. This dynamic behavior implies that biochar reinforcement influences the material’s resistance to disfigurement and flow plasticity, highlighting the intricate interplay between biochar content, distribution, and bonding with the Al base. The correlation noticed between UCS, YS, and the earlier discussed trends in hardness and relative density underscores the complex mechanical responses influenced by biochar content in the Al-biochar composites.

To investigate the impact of using biochar on the wear characteristics and FC of aluminum composites, composite samples were subjected to rubbing against a stainless-steel disk with a 0.4 m/s sliding speed under the effect of different loads ranging from 5 to 20 N, and the average FC was registered. As illustrated in Fig. 6, the average FC was measured for the friction of the aluminum composites against the stainless-steel disk at various loads. Comparing to the pure aluminum specimen ALB0, it was observed that samples ALB2.5, ALB5, ALB7.5, and ALB10 exhibited lower FC under various NLs. Specifically, the lowest FC was seen for ALB10 (0.46), representing a 4.35% decrease compared to ALB0 (0.48) at a NL of 5 N. At 20 N, the FC for ALB10 was ∼6.4% lower than that of ALB0. In addition, the FC demonstrated an increasing trend with the rise of NLs. This increase in FC could be attributed to the increase in temperature experienced during sliding under high loads.41 Additionally, according to Chang et al.,42 the FC may elevate due to the increased contact temperature between the rubbing surfaces.

FIG. 6.

FC of pure Al and different biochar composite samples under different NLs.

FIG. 6.

FC of pure Al and different biochar composite samples under different NLs.

Close modal

To examine the impact of sliding distance on the FC of the aluminum composites, frictional tests were carried out over distances of 240, 480, 720, and 960 m at a constant NL of 20 N. The results, illustrated in Fig. 7, reveal a clear trend: as the sliding distance increases, the FC decreases. Remarkably, despite this variation in sliding distance, the tribological performance of the aluminum composites remained consistent, with ALB10 consistently exhibiting the lowest FC. This decline in the FC with increasing sliding distance can be attributed to the surface smoothing effect resulted from prolonged sliding distances and abrasion against the steel counterpart.

FIG. 7.

FC of pure Al and different biochar composite samples for different sliding distances.

FIG. 7.

FC of pure Al and different biochar composite samples for different sliding distances.

Close modal

In order to evaluate the wear properties of the manufactured aluminum composites, the specific WR was assessed for both pure aluminum and aluminum/biochar composites. This was performed by subjecting them to different NLs while maintaining a constant speed of 0.4 m/s. Figure 8 displays the findings from these measurements. The decrease in the wear, specifically, is attributed to the enhanced mechanical characteristics of the composites as the concentration of biochar increases. These findings indicate that the aluminum composites exhibited enhanced strength with increasing biochar concentration. As a result, the increased bonding strength between the aluminum matrix and the biochar particles strengthens the composite surfaces from degrading during the sliding test, thus decreasing the WR. On the other hand, the rise in the NL resulted in a significant increase in the specific WR. This rise can be attributed to the heat that results from the kinetic energy exerted by the relative movement among the fractioned surfaces. In addition, the increased contact temperature reduced the shear strength of the matrix, resulting in the release of some biochar particles from the matrix during the tribological procedure. Subsequently, these particles functioned as a solid lubricant, resulting in a decrease in the specific WR when in comparison with pure aluminum. Figure 9 demonstrates the correlation between the sliding distance and the specific wear rate of the aluminum composites. A longer sliding distance was shown to be associated with a lower specific WR. The cause of this phenomenon can be ascribed to a reduction in shear resistance among the friction surfaces, which is enhanced by the existence of biochar particles functioning as a solid lubricant between the sliding surfaces.

FIG. 8.

Specific WR of pure Al and different biochar composite samples under different NLs.

FIG. 8.

Specific WR of pure Al and different biochar composite samples under different NLs.

Close modal
FIG. 9.

Specific WR of pure Al and different biochar composite samples for different sliding distances.

FIG. 9.

Specific WR of pure Al and different biochar composite samples for different sliding distances.

Close modal

The decrease in both the FC and specific WR can be attributed to the improvement in the LCC of the composites resulting from the inclusion of biochar, as noted before. The LCC can be determined by estimating the contact stress that occurs on the composite surface during the tribological experiment. Figure 10 illustrates the equivalent stress distribution on the aluminum/biochar surface. The concentration of stress along the edge of the sample surface is clearly apparent, most likely as a result of the movement direction. The addition of biochar resulted in a decrease in the maximum equivalent stress on the composite surface. The observed improvement in composite strength and LCC leads to a drop in the FC, which can be attributable to these findings.43  Figure 10 illustrates the relationship between the biochar particle loading and the consequent shear stress. It reveals a decrease of around 4.2% in shear stress with an increase in biochar content. This drop correlates with a decrease in the FC. Figures 8 and 9 demonstrate that the particular WR decreased as the weight fraction of biochar rise during the tribological test. Consequently, the finite element findings accurately depicted the estimated values of friction stress and wear layer thickness, as shown in Fig. 10. This illustrates a concurrence between the simulated and experimental outcomes. An increase in the proportion of biochar in the mixture resulted in a reduction in the force applied to the surfaces of the specimen and the resistance between the separated surfaces. As a result, there was a reduction in the thickness of the wear layer, leading to a reduction in the specific WR of the composites.

FIG. 10.

Different generated stresses and removed layer thickness for pure Al and different biochar composite samples.

FIG. 10.

Different generated stresses and removed layer thickness for pure Al and different biochar composite samples.

Close modal

Both the modeling and experimental findings demonstrated that the extent of wear in the Al/biochar composite was contingent upon the biochar content. In order to gain a deeper understanding of the enhanced wear properties of pure aluminum and Al/biochar composites, the rubbed surfaces were analyzed using scanning electron microscopy (SEM), as shown in Fig. 11. ALB0 exhibited degraded layers and peeling due to the scraping of its sliding surface, leading to a rise in the specific WR. In addition, eliminating weak layers may raise shear resistance and, thus, increase the FC. In pure AL, the primary wear mechanism is delamination, resulting in elevated coefficients of friction and specific WR.44 In contrast, the surface morphology of the other aluminum composites exhibited a reasonably smooth appearance. This could be attributed to the enhanced hardness and strength, which resulted from the increased biochar concentration. As a result, there were smaller layers that had deteriorated, leading to a reduction in the specific WR and FC. ALB2.5 and ALB5 showed a fatigue wear mechanism, as evidenced by the presence of cracks caused by plowing. As the amount of biochar increased to 8 and 10 weight percent, there was an enhancement in the transmission of stress between the aluminum matrix and the biochar particles. As a result, the pace at which wear occurs lowered significantly, and the negative effect of plowing was nearly eradicated. Consequently, ALB7.5 and ALB10 showed a notable decrease in the number of cracks and had a smoother surface, resulting in a decrease in shear force and the FC. Furthermore, the biochar particles that were released from the matrix became more noticeable as the biochar weight percentage increased, working as a solid lubricant. This process resulted in a reduction in both the FC and the specific WR.

FIG. 11.

SEM images for the rubbed composites surface.

FIG. 11.

SEM images for the rubbed composites surface.

Close modal

The synthesis of Al/biochar composites was accomplished through the powder metallurgy approach, involving the blending of aluminum and biochar at various ratios using the ball milling technique. Subsequently, the homogeneous mixture underwent consolidation via inductive sintering under controlled conditions. The nanocomposite samples derived from this process underwent comprehensive characterization, encompassing mechanical testing and tribological evaluation. To gain understandings into the microstructural and chemical aspects, advanced techniques such as FE-SEM and EDS were employed. The tribological analysis rendered the biochar addition’s beneficial impact on the friction coefficient as well as wear resistance parameters. Analysis of friction and wear revealed a 6.4% reduction in the friction coefficient upon the addition of 10 wt. % of biochar. Moreover, the specific wear rate showed a noticeable decrease with the increase of biochar weight fraction, irrespective of the magnitude of the applied normal load. The finite element analysis showed that increasing biochar weight percentage led to a reduction in the different types of stresses besides the reduction on the removed wear layer. Ultimately, examination of the surface of the rubbed surface revealed that the incorporation of biochar was able to change the wear mechanism and resulted in a reduction in the amount of weight loss during friction.

The authors present their appreciation to King Saud University for funding this research through Researchers Supporting Program No. RSPD2024R1098.

The authors have no conflicts to disclose.

Hany S. Abdo: Conceptualization (equal); Data curation (equal); Formal analysis (equal); Investigation (equal); Methodology (equal); Project administration (equal); Resources (equal); Software (equal); Supervision (equal); Writing – original draft (equal); Writing – review & editing (equal). Ubair Abdus Samad: Methodology (equal); Software (equal); Validation (equal). Ibrahim A. Alnaser: Methodology (equal); Resources (equal); Supervision (equal); Validation (equal). Sameh A. Ragab: Data curation (equal); Formal analysis (equal); Software (equal); Visualization (equal). Ahmed Fouly: Conceptualization (equal); Data curation (equal); Funding acquisition (equal); Investigation (equal); Methodology (equal); Writing – original draft (equal); Writing – review & editing (equal).

The data that support the findings of this study are available within the article.

1
J.
Qadir
,
A.
Savio Lewise
,
G.
Jims John Wessley
, and
G.
Diju Samuel
, “
Influence of nanoparticles in reinforced aluminium metal matrix composites in aerospace applications – A review
,”
Mater. Today: Proc.
(published online)
(
2023
).
2
F. J.
Lino Alves
,
A. M.
Baptista
, and
A. T.
Marques
, “
Metal and ceramic matrix composites in aerospace engineering
,” in
Advanced Composite Materials for Aerospace Engineering: Processing, Properties and Applications
(
Elsevier
,
2015
), pp.
59
99
.
3
N.
Fatchurrohman
and
S.
Sulaiman
, “
Metal matrix composites for automotive components in depth case study: Development of automotive brake disc
,”
Encycl. Mater.: Compos.
1
,
540
556
(
2018
).
4
B.
Sadeghi
,
P.
Cavaliere
, and
A.
Shabani
, “
Design strategies for enhancing strength and toughness in high performance metal matrix composites: A review
,”
Mater. Today Commun.
37
,
107535
(
2023
).
5
K.
Maclin John Vasanth
,
P. S.
Lokendar Ram
,
V.
Pon Anand
,
M.
Prabu
, and
S.
Rahul
, “
Experimental investigation of mechanical and tribological properties of Aluminium metal matrix composites fabricated by powder metallurgy route – A review
,”
Mater. Today: Proc.
33
,
1058
1072
(
2020
).
6
S.
Jannet
,
R.
Raja
,
V.
Arumugaprabu
,
G. B.
Veeresh Kumar
,
S.
Vigneshwaran
,
P. S.
Rama Sreekanth
, and
K.
Naresh
, “
Effect of neem seed biochar on the mechanical and wear properties of aluminum metal matrix composites fabricated using stir casting
,”
Mater. Today: Proc.
56
,
1507
1512
(
2022
).
7
H. S.
Abdo
,
U. A.
Samad
,
M. S.
Abdo
,
H. I.
Alkhammash
, and
M. O.
Aijaz
, “
Electrochemical behavior of inductively sintered Al/TiO2 nanocomposites reinforced by electrospun ceramic nanofibers
,”
Polym
13
,
4319
(
2021
).
8
S. Y.
Foong
,
K. Y.
Cheong
,
S. H.
Kong
,
C. L.
Yiin
,
P. N. Y.
Yek
,
R.
Safdar
,
R. K.
Liew
,
S. K.
Loh
, and
S. S.
Lam
, “
Recent progress in the production and application of biochar and its composite in environmental biodegradation
,”
Bioresour. Technol.
387
,
129592
(
2023
).
9
D.
Castilla-Caballero
,
A.
Hernandez-Ramirez
,
S.
Vazquez-Rodriguez
,
J.
Colina-Márquez
,
F.
Machuca-Martínez
,
J.
Barraza-Burgos
,
A.
Roa-Espinosa
,
A.
Medina-Guerrero
, and
S.
Gunasekaran
, “
Effect of pyrolysis, impregnation, and calcination conditions on the physicochemical properties of TiO2/biochar composites intended for photocatalytic applications
,”
J. Environ. Chem. Eng.
11
,
110274
(
2023
).
10
Q.
Liang
,
D.
Pan
, and
X.
Zhang
, “
Construction and application of biochar-based composite phase change materials
,”
Chem. Eng. J.
453
,
139441
(
2023
).
11
J. Z.
Su
,
C. C.
Wang
,
M. Y.
Zhang
,
X. B.
Zong
,
X. F.
Huang
,
Z. H.
Deng
, and
P.
Xiang
, “
Advances and prospectives of iron/biochar composites: Application, influencing factors and characterization methods
,”
Ind. Crops Prod.
205
,
117496
(
2023
).
12
M. M.
Billah
, “
Carbon nanotube reinforced aluminum matrix composite: Recent advances and future prospects
,”
Compr. Mater. Process.
12
,
87
(
2024
).
13
Y.
Zhang
,
W.
Wang
,
J.
Liu
,
T.
Wang
, and
T. J.
Li
, “
Fabrication of carbon fiber reinforced aluminum matrix composites by inorganic binders
,”
J. Alloys Compd.
968
,
172213
(
2023
).
14
D.
Gu
,
X.
Rao
,
D.
Dai
,
C.
Ma
,
L.
Xi
, and
K.
Lin
, “
Laser additive manufacturing of carbon nanotubes (CNTs) reinforced aluminum matrix nanocomposites: Processing optimization, microstructure evolution and mechanical properties
,”
Addit. Manuf.
29
,
100801
(
2019
).
15
L.
Chen
,
H.
Wang
,
Z.
Tu
,
J.
Hu
, and
F.
Wu
, “
Renewable fuel and value-added chemicals potential of reed straw waste (RSW) by pyrolysis: Kinetics, thermodynamics, products characterization, and biochar application for malachite green removal
,”
Renewable Energy
229
,
120724
(
2024
).
16
A. H.
Seikh
,
I. A.
Alnaser
,
H. F.
Alharbi
,
M. R.
Karim
,
J. A.
Mohammed
,
M. O.
Aijaz
,
A.
Hassan
,
H. S.
Abdo
,
H. F.
Alharbi
,
I. A.
Alnaser
et al, “
Study on process parameters in hydrothermal liquefaction of rice straw and cow dung: Product distribution and application of biochar in wastewater treatment
,”
Processes
11
,
2779
(
2023
).
17
M.
Petousis
,
E.
Maravelakis
,
D.
Kalderis
,
V.
Saltas
,
N.
Mountakis
,
M.
Spiridaki
,
N.
Bolanakis
,
A.
Argyros
,
V.
Papadakis
,
N.
Michailidis
, and
N.
Vidakis
, “
Biochar for sustainable additive manufacturing: Thermal, mechanical, electrical, and rheological responses of polypropylene-biochar composites
,”
Biomass Bioenergy
186
,
107272
(
2024
).
18
N.
Kunaroop
,
S.
Rimdusit
,
P.
Mora
,
S.
Hiziroglu
, and
C.
Jubsilp
, “
Carbonized hemp hurd powder for eco-friendly polybenzoxazine composite brake material: Excellent friction property and high mechanical performance
,”
Arabian J. Chem.
17
,
105769
(
2024
).
19
K. P.
Das
,
P.
Chauhan
,
U.
Staudinger
, and
B. K.
Satapathy
, “
Exploring sustainable adsorbents to mitigate micro-/nano-plastic contamination: Perspectives on electrospun fibrous constructs, biochar, and aerogels
,”
Environ. Sci. Adv.
3
,
1217
1243
(
2024
).
20
H. S.
Abdo
,
I. A.
Alnaser
,
A. H.
Seikh
,
J. A.
Mohammed
,
S. A.
Ragab
, and
A.
Fouly
, “
Ecofriendly biochar as a low-cost solid lubricating filler for LDPE sustainable biocomposites: Thermal, mechanical, and tribological characterization
,”
Int. J. Polym. Sci.
2023
,
1
13
.
21
G.
Zhang
,
X.
Zhu
,
M.
Yu
, and
F.
Yang
, “
Electrochemical activation of peroxymonosulfate using chlorella biochar modified flat ceramic membrane cathode for berberine removal: Role of superoxide radical and mechanism insight
,”
Sep. Purif. Technol.
318
,
124002
(
2023
).
22
F.
Lin
,
M.
Ren
,
H.
Wu
,
F.
Jia
,
Y.
Lu
,
M.
Huo
,
M.
Yang
,
Z.
Chen
, and
Z.
Jiang
, “
Investigation of microstructure and tribological performances of high-fraction TiC/graphene reinforced self-lubricating Al matrix composites
,”
Tribol. Int.
177
,
108018
(
2023
).
23
Y.
Zhang
,
Q.
Wang
,
G.
Chen
, and
C. S.
Ramachandran
, “
Mechanical, tribological and corrosion physiognomies of CNT-Al metal matrix composite (MMC) coatings deposited by cold gas dynamic spray (CGDS) process
,”
Surf. Coat. Technol.
403
,
126380
(
2020
).
24
T.
Zhou
,
M.
Lei
, and
J.
Xu
, “
Recent progress in the development and properties of aluminum matrix composites reinforced with graphene: A review
,”
Mater. Today Sustainability
25
,
100674
(
2024
).
25
A. V.
Muley
and
Ruchika
, “
Wear and friction (Tribological) characteristic of aluminum based metal matrix hybrid composite: An overview
,”
Mater. Today Proc.
(published online)
(
2023
).
26
M.
Tabandeh-Khorshid
,
E.
Omrani
,
P. L.
Menezes
, and
P. K.
Rohatgi
, “
Tribological performance of self-lubricating aluminum matrix nanocomposites: Role of graphene nanoplatelets
,”
Eng. Sci. Technol. Int. J.
19
,
463
469
(
2016
).
27
Z.
Lv
,
J.
Sha
,
G.
Lin
,
J.
Wang
,
Y.
Guo
, and
S.
Dong
, “
Mechanical and thermal expansion behavior of hybrid aluminum matrix composites reinforced with SiC particles and short carbon fibers
,”
J. Alloys Compd.
947
,
169550
(
2023
).
28
N.
Singh
and
R. M.
Belokar
, “
Tribological behavior of aluminum and magnesium-based hybrid metal matrix composites: A state-of-art review
,”
Mater. Today: Proc.
44
,
460
466
(
2021
).
29
M. S.
Hasan
,
T.
Wong
,
P. K.
Rohatgi
, and
M.
Nosonovsky
, “
Analysis of the friction and wear of graphene reinforced aluminum metal matrix composites using machine learning models
,”
Tribol. Int.
170
,
107527
(
2022
).
30
T.
Yu
,
J.
Liu
,
Y.
He
,
J.
Tian
,
M.
Chen
, and
Y.
Wang
, “
Microstructure and wear characterization of carbon nanotubes (CNTs) reinforced aluminum matrix nanocomposites manufactured using selective laser melting
,”
Wear
476
,
203581
(
2021
).
31
S.
Zhang
,
Z.
Chen
,
P.
Wei
,
W.
Liu
,
Y.
Zou
,
Y.
Lei
,
S.
Yao
,
S.
Zhang
,
B.
Lu
, and
L.
Zhang
, “
Wear properties of graphene/zirconia biphase nano-reinforced aluminium matrix composites prepared by SLM
,”
Mater. Today Commun.
30
,
103009
(
2022
).
32
M. Y.
Khalid
,
R.
Umer
, and
K. A.
Khan
, “
Review of recent trends and developments in aluminium 7075 alloy and its metal matrix composites (MMCs) for aircraft applications
,”
Results Eng.
20
,
101372
(
2023
).
33
M. I. U.
Haq
,
S.
Mohan
,
A.
Raina
,
S.
Jayalakshmi
,
R. A.
Singh
,
X.
Chen
,
S.
Konovalov
, and
M.
Gupta
, “
Mechanical and tribological properties of aluminum based metal matrix nanocomposites
,”
Encycl. Mater.: Compos.
1
,
402
414
(
2021
).
34
P. D.
Srivyas
and
M. S.
Charoo
, “
Role of reinforcements on the mechanical and tribological behavior of aluminum metal matrix composites – A review
,”
Mater. Today: Proc.
5
,
20041
20053
(
2018
).
35
P. D.
Srivyas
and
M. S.
Charoo
, “
Tribological characterization of hybrid aluminum composite under boundary lubricating sliding conditions
,”
Mater. Today Proc.
26
,
492
500
(
2020
).
36
P.
Fernandes
and
Udaya
, “
Novel carbon nanotube and fly-ash reinforced Al composites for automobile and aerospace applications
,”
Mater. Today: Proc.
35
,
456
460
(
2021
).
37
ASTM E9-89a (2000) E9 Standard Test Methods of Compression Testing of Metallic Materials at Room Temperature available online: https://www.astm.org/e0009-89ar00.html (accessed 24 Dec 2023).
38
G99-17, A. Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus. ASTM Int. West Conshohocken, PA, USA,
2017
.
39
G.
Xu
,
Y.
Lv
,
J.
Sun
,
H.
Shao
, and
L.
Wei
, “
Recent advances in biochar applications in agricultural soils: Benefits and environmental implications
,”
Clean: Soil, Air, Water
40
,
1093
1098
(
2012
).
40
C.
Das
,
S.
Tamrakar
,
A.
Kiziltas
, and
X.
Xie
, “
Incorporation of biochar to improve mechanical, thermal and electrical properties of polymer composites
,”
Polymers
13
,
2663
(
2021
).
41
N. W.
Khun
,
H.
Zhang
,
L. H.
Lim
,
C. Y.
Yue
,
X.
Hu
, and
J.
Yang
, “
Tribological properties of short carbon fibers reinforced epoxy composites
,”
Friction
2
,
226
239
(
2014
).
42
L.
Chang
,
Z.
Zhang
,
H.
Zhang
, and
K.
Friedrich
, “
Effect of nanoparticles on the tribological behaviour of short carbon fibre reinforced poly(etherimide) composites
,”
Tribol. Int.
38
,
966
973
(
2005
).
43
W.
Tang
,
Y.
Zhou
,
H.
Zhu
, and
H.
Yang
, “
The effect of surface texturing on reducing the friction and wear of steel under lubricated sliding contact
,”
Appl. Surf. Sci.
273
,
199
204
(
2013
).
44
A. M. M.
Ibrahim
,
A. F. A.
Mohamed
,
A. M. R.
Fathelbab
, and
F. A.
Essa
, “
Enhancing the tribological performance of epoxy composites utilizing carbon nano fibers additives for journal bearings
,”
Mater. Res. Express
6
,
035307
(
2018
).