RETRACTED: Tribological and microstructure studies of LM26/SiC metal matrix composite materials and structures for high temperature applications

This study aimed to investigate the tribological and microstructural characteristics of LM26 composites reinforced with silicon carbide to evaluate their suitability for high-temperature applications. For the sample fabrication, the modified stir-casting method was optimized using a Taguchi L16 orthogonal array. The wear rate and friction behavior were evaluated using the Taguchi’s S/N ratio analysis. When SiC was incorporated into the composite, the wear resistance increased by up to 15 wt%. The wear resistance of the LM26/SiC composite was improved compared to that of the pure LM26 aluminum alloy. The results of this study provide useful information to improve the wettability of metal matrix composites made from commercial-grade LM26 aluminum alloy by adjusting the SiC weight percentage. This type of composite has the potential as a replacement material for traditional applications such as heat sinks, heat exchanger fins, and electronic packaging.


Introduction
Advanced composite materials have gained significant attention due to their exceptional properties, such as enhanced specific stiffness, low weight and high specific strength.This has led to rapid progress in their design and fabrication [1][2][3].Metal Matrix Composites (MMCs) are composed of two or more materials and exhibit superior properties compared to the individual constituents.A composite material has matrix and reinforcement phases.In a MMC material, the matrix is made of metal and the reinforcing material mainly consists of ceramics that come in different shapes such as continuous, whiskers or discontinuous particulate and fibers [4,5].
The use of MMCs in diverse industries has increased significantly to meet the high demand in producing necessary and complex components for marine, aircraft, and automotive applications.Govindarajan et al [6] emphasized on the importance of MMCs in automobile industries since they play a critical role in offering a lightweight material exhibiting both high stiffness and sturdiness.Santhosh et al [7] reported that MMCs containing magnesium is potentially going to become one of the widely-used materials due to possessing higher energy efficiency as well as recyclability.One prominent application will be in magnesium-based materials for the automotive industry for having approximately 20% to 30% fuel-saving ability.The aerospace and automotive industries require a material that has a combination of unique properties including light weight, hardness, strength, stiffness, and wear resistance.Composites, which are fabricated by combining two or more different components, are often the only materials that can meet the diverse and demanding requirements of modern engineering applications [8,9].Pank and Jackson [10] reported that MMCs with capabilities to withstand high temperature offer unique application for airspace industries by providing high strength and high modulus fibers.As a result, they can offer up to 50% reduction in weight with a potential application in the components of system components.Elanchezhian et al [11] investigated the potential application of MMCs such as the ones containing Grade 5 Titanium alloy, Kevlar, and carbon fibers in construction of the hull of naval worships.This is due to their enhanced properties such as high impact bearing capacity as well as high strength to weight ratio.This class of material can potentially reduce the size and costs while improving the corrosion, strength, manufacturability, and weldability.
MMCs consist of two main components including (1) matrix and (2) reinforcement.Based on their matrix phase, composites can be broken down into three broad categories: polymer-matrix composites (PMCs), metalmatrix composites (MMCs), and ceramic matrix composites (CMCs) [12].One of the most popular methods to manufacture MMCs is sir casting that has been increasingly used nowadays due to its efficient manufacturing process, and ease of mass production [13].In the next paragraph, the use of MMCs for high temperature applications is discussed by reviewing the literature: Ujah et al [14] demonstrated that inclusion of nano particles as a microstructural component, can enhance the wear resistance, reduce the wear volume, lower the coefficient of friction (COF) in MMCs, PMCs and CMCs.Wang et al [15] demonstrated that ceramic materials such as porous ceramic (C/C-SiC composite) combined with copper alloy have the capability to be utilized in high temperature application.The MMC C/C-SiC-Cu demonstrated to have a superior thermal conductivity, ablation resistance, and bending strength by an increase in the SiC content.Pawar and Kharde [16] investigated the tribological response of Hybrid Aluminum Matrix Composites(HAMCs), which is a form of MMC, by employing the Taguchi technique.They demonstrated that the tribological properties on this MMC material changes with an increase in the temperature and applied load.It was reported that the parameters including hybrid reinforcement and load results in 59.21% and 45.11% wear loss and Coefficient of Friction (COF), respectively.They concluded that the MMCs such as HAMCs have superior tribological properties.Liu et al [17] investigated the tribological response of a MMC known as A359-SiCp/Fe for the high temperature application.The reinforcement phase of this MMC was iron foam.They incorporated three-dimensional (3D) network structure iron foam as well as 20 wt% SiC particles into A359-SiCp/Fe using a new technique called vacuum assisted infiltration procedure.The dry-sliding tribological behavior of this type of MMC was explored using the HT-1000 ball-on-disc-type high temperature tribometer.To examine its tribological property, the A359-SiCp/Fe sample was subjected to a diverse range of loads and temperatures and their effect on friction coefficient and wear rate was studied.Their study demonstrated the suitability of A359-SiCp/Fe for the high temperature applications.
To improve tribological and mechanical properties, MMCs are enhanced with hard particles as reinforcement with a metal matrix, typically aluminum, titanium, or magnesium, due to high-strength-toweight ratio and low weight.The reinforcement materials for MMCs can include titanium bromide, aluminum oxide, silicon carbide, titanium nitride, boron carbide, and titanium carbide.Aluminum alloys have been found to be the most effective in improving the wear and mechanical properties required by industry due to their strength, low weight, and environmental friendliness [18][19][20].
Aluminum alloys 2024 and 7075 are typically used as matrix materials in MMCs.They have become the preferred choice for matrix materials in MMCs because of exceptional strength and fatigue resistance, making them ideal for aerospace applications.These alloys offer high strength, low density, and excellent machinability, making them perfect matrix materials in MMCs.Aluminum alloys 2024 and 7075 can be easily processed using commonly employed techniques such as casting, extrusion, and forging.These characteristics make them a desirable option for matrix materials in MMCs.The incorporation of these alloys can improve the mechanical properties of the composite, leading to increased strength and stiffness when compared to using the matrix material independently [21][22][23].Al/SiC composites highly suitable for electronic packaging applications owing to their excellent thermal conductivity and low coefficient of thermal expansion [24][25][26].The parameters for MMC production can be optimized using techniques like the Taguchi method, which employs a signal to noise ratio to evaluate deviation from the optimum value [27].
Several factors influence the selection of SiC (silicon carbide) as a reinforcement material in a variety of applications, including composites.Importantly, the choice of reinforcement material depends on the composite material's specific requirements and desired properties.Here are several reasons why SiC is chosen as a reinforcing material [28][29][30][31][32]: • Enhanced mechanical properties: SiC materials have excellent mechanical properties, including high strength and stiffness, making it suitable for applications requiring enhanced mechanical performance.It can significantly increase the composite material's strength and hardness.
• High temperature resistance: SiC possesses excellent thermal stability and high temperature resistance.It can retain its mechanical properties even at high temperatures, making it suitable for use in harsh environments, such as the aerospace and automotive industries.
• Enhanced wear abrasion resistance: the exceptional wear and abrasion resistance of SiC are well-known.It can withstand harsh conditions and maintain its integrity even in environments with high friction or abrasion, making it ideal for applications requiring wear resistance.
• Corrosion resistance: SiC materials are resistant to chemical attack from a wide variety of corrosive substances, including acids and alkalis.This quality makes it suitable for use in environments where corrosion is a concern.
• Light-weight: SiC materials are relatively lighter than other ceramic materials, which can be advantageous in weight-sensitive applications, such as aerospace or automotive components.
After review of the literature, this research aims for the following novel contributions: • Tribological and microstructure studies of LM26/SiC metal matrix Composites.
• Enhanced LM26/SiC metal matrix Composites for high temperature applications.
• Improving the wettability of LM26/SiC metal matrix Composites.
• Optimizing the modified stir casting method for sample fabrication.

Methodology
2.1.Materials LM26 which is an aluminum alloy is commonly utilized due to its exceptional wear resistance and favorable thermal properties, making it a an attractive option for various applications [33].In order to resist wear and tear, core materials require significant levels of hardness, which can be improved through the use of strong fillers [34].
The incorporation of high-strength and hard SiC (Silicon Carbide) ceramic nanoparticles with a particle size of 49 μm into the LM26 aluminium alloy matrix was carried out to achieve this.LM26 and SiC have the densities of 2.65 (g cm −3 ) and 3.21 (g cm −3 ), respectively.The chemical properties of LM26 are presented in table 1.

Composite's fabrication process
The LM26 MMCs were produced employing the stir casting method, which is widely recognized for its simplicity, high production volume, and superior quality outcomes [35].The stir casting process was performed using a temperature limiting unit, mold setup and a stirrer.To improve their wettability with the matrix material, get rid of any moisture, and increase their surface reactivity, particles of SiC were heated to 425 °C temperature of over the course of two hours.The mixture of ceramic and molten metal was subjected to stirring using a three-pin impeller blade, at 525 rpm retained for a period of 8-10 min.In order to minimize any adverse effects, such as excessive particle breakage or agglomeration, and to achieve efficient mixing of the molten metal and reinforcement particles, a stirrer speed of 525 (rpm) was selected.
The fabrication process of composites entails a critical step of achieving an extensive blending of the matrix and filler components.This is achieved through the activation of the stirrer throughout the process, which ensures the homogenous mixture of the matrix and filler components.The consistent mixing of the components facilitates the production of a composite material with a uniform microstructure, enhanced mechanical properties, and improved interfacial adhesion between the matrix and filler.
During the process of mixing, the mixture was thoroughly agitated, and the filled ceramic particles were completely absorbed by the vortex.Following the completion of the mixing process, any excess slurry adhering to the metal's surface was meticulously removed.The liquid metal was then poured directly into the preheated mold, which had been elevated to a temperature of 100 °C.Upon removal from the die, the equipment was left to cool down to ambient temperature for a period of ten hours.The samples were subsequently prepared using both abrasive cutters and automated CNC lathe machines.To guarantee proper testing of the metal samples, they were appropriately prepared, which involved mounting, polishing, and gold coating in accordance with the testing equipment's guidelines [36].

Sliding wear behavior of composite material
A pin-on-disc tribometer was employed to perform sliding wear tests, using an EN-24 steel disk as the tribological pair, characterized by a hardness of 50 HRC and a surface roughness (Ra) of 0.3 (μm).The objective of this research was to analyze the wear and friction characteristics of proposed hybrid aluminum composites by sliding against the EN 24 shaft.
The process parameters such as sliding speed within the range of [1][2][3][4] (m s −1 ), load (20N-80 N), filler content (0-20 wt%), and temperatures within the range of  (°C) were considered while maintaining a fixed sliding distance of 1400 (m) to evaluate the coefficient of friction (COF) and wear resistance of the experimental specimens.The composite configurations and their respective control factors can be found in table 2.
ASTM G99, which is the standard test method for wear testing with a Pin-on-Disk Apparatus, was used in the present study.This standard describes the procedure for conducting wear tests using a pin-on-disk apparatus.It provides guidelines for test specimen preparation, test conditions, and measurement of wear.
The consideration of wear rate is a crucial aspect in the design of components that are expected to undergo wear.Through comprehension of the variables that may impact the rate of wear, engineers possess the capability to devise components that exhibit greater resistance to wear.load refers to the magnitude of the external force exerted on the surfaces that are in contact.As the load increases, there is a corresponding increase in the rate of wear.The rationale behind this phenomenon is that an augmented load leads to an elevation in the contact pressure amid the surfaces, thereby resulting in an upsurge in both friction and wear.Similarly wear rate can be influenced by temperature in various ways.
The experiments were well-designed and conducted following the basic experimentation and data structure of the Taguchi method, with average results reported for discussion.The results from the experiments were analyzed using Minitab 18 and an ANOVA (Analysis of Variance) was conducted with a confidence level of 95% to determine the statistical significance and input factors effect on the rate of wear.The linear and nonlinear regression equations were derived to estimate the parameters of wear.In addition, the microstructural properties of the worn surfaces of the samples were studied with the use of x-ray absorption spectroscopy and scanning electron microscopy (SEM) imaging techniques.
Elevated temperatures have the potential to induce softening of materials, rendering them more vulnerable to wear phenomena.The reason for this phenomenon is attributed to the thermal energy that can lead to the disruption of interatomic bonds, thereby resulting in a reduction of the material's strength.Elevated temperatures have the potential to expedite the oxidation mechanism, thereby resulting in the generation of wear byproducts that can function as abrasive agents, consequently intensifying the wear phenomenon.wear rate can be influenced by the sliding speed.Elevated sliding velocities have the potential to augment frictional forces, thereby resulting in material degradation.The reason behind this phenomenon is that elevated sliding velocities can induce a rise in temperature at the contacting surfaces, leading to a reduction in material hardness and an escalation in frictional forces.Elevated sliding velocities may lead to prolonged contact duration between the surfaces, thereby augmenting the wear rate.

Taguchi analysis for design of experiments
The Taguchi method is a statistical approach that has proven to be a powerful and convenient tool for experiment design in many scientific and engineering applications.It utilizes orthogonal array tables to evaluate multiple input variables and their impact on the output response variable.The utilization of the Taguchi method in experimentation enables researchers to conserve valuable resources and optimize their experiments for maximum efficiency.This approach provides a cost-effective solution without compromising the accuracy of results, as it allows for the reduction of the required number of experimental runs.Wear experiments generally have multiple input parameters that can vary, leading to high characterization and fabrication costs, as well as complexity in the process.The Taguchi optimization approach provides a systematic method to evaluate these parameters using a standard matrix design.The orthogonal array prepared using the Taguchi method for a particular process offers a well-balanced combination of parameters, facilitating smoother experiment execution and producing reliable results for parameters with similar values.To form the orthogonal matrix, the statistical tool Minitab 18 was employed.The wear rate was scrutinized by utilizing the S/N ratio characteristic of 'the smaller the better' to obtain a more precise evaluation of the composite's performance.
In order to determine the S/N ratio for the Taguchi characteristic 'the smaller the better', equation (1) is used: Amidst this context, the computation of the signal-to-noise ratio (S/N) takes place by making use of the number of iterations (n) carried out for each trial and the result (yi) obtained from the ith experiment of each trial.This S/N ratio is meticulously scrutinized to ascertain the extent of influence of every individual parameter.A thorough statistical analysis of the variables is then conducted to determine which parameters hold statistical significance.By means of this analysis, researchers can predict the optimal combination of parameters that would yield the most desirable outcome.
Through the use of the Taguchi L16 orthogonal array, the sliding wear and coefficient of friction data for various configurations and their corresponding S/N ratios can be found in table 3.By analyzing this information, researchers can identify patterns and trends in the relationship between S/N ratio, wear rate and coefficient of friction.These findings can then be used to improve the material properties and wear resistance of the composite, providing valuable insights into the material's performance under different conditions.This analysis offers an opportunity to optimize the material's design, ultimately leading to enhanced performance and durability [37,38].
The correlation between coefficient of frictions, wear rate, and pin temperature of the test samples is displayed in table 3 through column 8 and 9.The findings of the study demonstrate a significant relationship between the wear rates of the samples and pin temperature, as well as the coefficient of friction.The S/N ratio analysis further confirmed the correlation between influential parameters, including sliding speed, temperature, load, and filler content (wt%) in the metal matrix composite.Prioritizing the effect of various variables and parameters on the wear behavior and coefficient of friction was accomplished by examining the rank or Δ (Delta) values, as presented in tables 4-7.

R e t r a c t e d
Delta values represent the ratio between the highest and lowest S/N values of the particular control parameter.It is important to note that the S/N values and control parameters are proportional to each other, with higher values indicating better performance.The control parameter with a larger difference between the mean of S/N ratios is considered to have a more significant impact.
Aluminum-based MMCs are prone to experiencing wear due to their composition of a pliant matrix material (aluminum) that is strengthened by rigid particles (e.g.ceramic or glass).The incorporation of rigid particles can serve as a protective measure for the matrix material against wear; however, it is important to note that these particles may also contribute to the wear process.
In table 4, the impact of the control parameters on the wear rate is demonstrated.The order of influence reveals that temperature is the most significant parameter impacting the wear rate, followed by load, filler percentage, and sliding speed.Similarly, table 6 highlights the impact of control parameters on the coefficient of friction.The order of influence demonstrates that temperature is the most dominant factor impacting the coefficient of friction, followed by load, filler percentage, and sliding speed [39][40][41].
After analyzing the data, the optimal conditions for minimizing wear rate were determined by examining figures 1 and 2. The results indicated that the combination of (A 1 B 1 C 1 D 3 ), which corresponds to a sliding velocity of 1 (m s −1 ), a temperature of 30 (°C), a load of 20 (N), and a composite containing 15 wt% SiC,

R e t r a c t e d
produced the most desirable outcome.The analysis also revealed that an increase in temperature, sliding speed, and load resulted in a significant reduction in the wear rate.These findings are consistent with previous research that has demonstrated the acceleration of wear rate at higher temperatures, sliding speeds, and loads.Moreover, the utilization of 15 wt% SiC in the composite was found to improve its wear resistance [42,43].

Analysis of variables using ANOVA for wear
A statistical analysis of the proposed hybrid composite process parameters was performed using the ANOVA tool .This enabled the identification of the individual variables' impact on the process with a 95% confidence level.The impact of each factor on the wear rate was quantified and recorded in table 8, column 6.The values of each factor, along with their significance, were documented in the same table.The P values, ranging from 0.5, were utilized to assess the significance of each factor.Factors with lower P values, such as temperature and applied loads, were found to be more critical.Conversely, factors with higher P values, such as sliding speed, were deemed to have a lesser impact on the wear parameters and sliding velocity [44,45].Table 8 provided insights into the relative importance or contribution of each individual parameter.The data clearly demonstrated that temperature is the most dominant factor, accounting for 71.23%, followed by applied load at 20.73%, filler percentage at 3.51%, and sliding speed at 3.03%.

Analysis of parameters on ANOVA and COF
The importance of accurately determining the coefficient of friction in the pursuit of enhancing the performance of high-wear rate composite materials cannot be overstated.To attain superior wear and tribological behavior, it is crucial to achieve a low coefficient of friction [46], as demonstrated in table 9.The findings show that the composite materials' coefficient of friction was lower than that of the pure LM26 aluminum alloy.As the temperature of the material increases, there is a corresponding decrease in its hardness, leading to the  penetration of the steel disc into the material, resulting in a ploughing effect.An increase in load leads to a higher contact between the disc and sample pin, resulting in plastic deformation.Surfaces can crack or tear as a result of shear forces if the sliding speed is increased.These factors, when combined, can intensify or cause wear on the surface.The coefficient of friction is generally based on the concentration of asperity junctions and it was observed from the results that 15 wt% SiC has a lower coefficient of friction compared to other configurations.This is attributed to the adhesion and wettability between the filler and matrix [47,48].The coefficient of friction in high-wear rate composite materials is primarily influenced by temperature and load, with sliding speed and filler ratio having a comparatively lesser impact.The contribution percentage for the coefficient of friction is displayed in table 9, column 7. Similar to the wear rate study, temperature contributes the most at 61.23%, while the remaining parameters, including load, filler percentage, and speed, contribute 30.73%, 3.5%, and 0.5%, respectively.

Confirmation experiment
To ensure the accuracy of the experimental results and optimization, the Design of Experiment (DOE) was validated through confirmation tests.Any deviations were noted for further examination during this stage.The Taguchi optimization method revealed that the (A 1 B 1 C 1 D 3 ) parameters displayed the best properties, which were verified through experimental verification as presented in table 10.
The experimental investigation's results were verified through the execution of confirmation tests, which aimed to guarantee the reliability and authenticity of the findings obtained from the experiments and optimization process [49,50].The investigation of wear parameters demonstrated a high degree of accuracy, as evidenced by the minimal 2.5% error observed between the experimental and predicted wear values.The results of the confirmation experiments, as shown in figures 4 and 5, indicate that a composite material reinforced with 15 wt% SiC exhibits superior resistance to wear with lower coefficient of friction compared to other compositions.This observation suggests that by incorporating a higher percentage of SiC particles, it is possible  to improve the overall performance of the composite material with respect to its ability to resist wear and friction [51][52][53][54].

Predictive equations for wear estimations
Linear and non-linear regression equations were evolved for prediction of wear rate of fabricated SiC configurations.Equation (2), derived using Minitab software, displays the correlations between rate of wear and applied parameters [55]: Similarly, Archard's nonlinear equation [56] (equation ( 3)) was derived from data fit which also represented wear rate predictions: WR stands for the linear and nonlinear wear rates (mm 3 m −1 × 10 −3 ) in equation (2) and equation (3), respectively.It must be noted that R 2 = 97.57 in equation (3).
In the equations, an increase in wear rate is denoted by a positive sign, whilst a decrease in wear rate is denoted by a negative sign.The R 2 values of 98.05 and 97.57respectively show that only 5% of the data deviated and the developed model can envisage the rate of wear with a high level of accuracy, specifically a 95% degree of accuracy [57].

Sliding wear prediction models comparison
Abrasion is identified as the primary cause of wear in aluminium composites.Abrasion refers to the phenomenon of material erosion caused by the frictional contact with a comparatively harder substance.Regarding aluminium composites, the presence of rigid reinforcement particles can result in the gradual erosion of the comparatively pliable aluminium matrix.
Predicted wear rates from developed liner and non-liner equations are reported in table 11 along with the pictorial depiction in figure 6.The results of the predicted wear rate for the silicon carbide filled composites were verified using the R 2 values, as depicted in figure 6.To achieve the desired wear rate, the R 2 values must be less than 1.The results show that both the linear and non-linear models have R 2 values less than 1, indicating that the models accurately forecast the rate of wear of the composites.Figure 6 compares the predicted wear rate using both the linear and non-linear models with the actual rate of wear.The error rate for the predicted models was found to be closer to ± 2.5%.Although both models provide a good representation of the wear rate, the non- linear model showed a smaller deviation from the actual wear rate compared to the linear model [58].The mechanical properties of aluminium composites may be significantly affected by wear, as suggested in this research proposal.
The wearing process has the potential to diminish the mechanical properties of composites, including their strength, stiffness, and toughness.These factors may result in a reduction in the fatigue life, an increase in the vulnerability to impact damage, and a decrease in the capacity to carry loads.This phenomenon can be attributed to factors such as inadequate lubrication, contamination, environmental conditions, excessive loading, and suboptimal design.

Morphology of worn surfaces
To examine the microstructure of the intact and fractured samples, high-resolution images were captured using a FESEM (field emission scanning electron microscope) technique.(Model make: FEI Quanta 400F/10 kV).
Prior to imaging, the samples were subjected to polishing with emery sheets followed by mirror polishing to achieve a smooth surface finish.The prepared samples were then mounted in a mold to enable microscopic examination.The fracture of a composite matrix can have detrimental effects on its microstructure, leading to  decreased strength and a shortened product lifespan.To examine the microstructural properties of the worn surfaces of the tested samples, FESEM was employed with varying magnification levels [59].The examination of the wear surfaces revealed the presence of parallel micro grooves, delamination, matrix adhesion, micro cracks, ploughing, and severe scratches along the sliding direction [60][61][62].Figure 7 presents microscopic images of the 0 wt%, 15 wt% and 20 wt% SiC configurations after the wear studies.NSE (Nash-Sutcliffe efficiency), MAE (Mean square absolute error) and RMSE (root means square error) are three commonly used metrics for evaluating the performance of models that predict numerical outcomes.NSE compares the mean squared error of a model to that of a hypothetical model that always predicts the mean of the observed data.RMSE measures the average distance between the predicted and actual values, with greater weight given to larger errors.MAE measures the average absolute difference between the predicted and actual values.Three variations like NSE, MAE, and RMSE was calculated and reported in table 9 which seems very small.This phenomenon indicates the developed model has higher level of the accuracy [63].
The addition of hexagonal silicon carbide particles in composite samples has the potential to significantly enhance the material's tensile strength and hardness.This improvement can reduce the wear and tear on the surfaces of the composite, as well as minimize the occurrence of delamination.Conversely, composite samples without these particles may have lower strength and hardness and be more susceptible to generating debris during wear.Figure 7 depicts a limited quantity of arbitrary adhesion debris, indicating that adhesion debris denotes diminutive pieces or fragments of the matrix material that have dislodged from the composite and clung  to the surface.These remnants may arise from various factors, including inadequate adhesion between the matrix and the reinforcement, mechanical strains, or environmental influences [64][65][66].
The microstructure of a composite material with 15 wt% silicon carbide (SiC) content is depicted in figures 8 and 9.The absence of delamination, as evidenced by the absence of visible separations between layers, indicates a strong bond between layers.Furthermore, the lower number of pores and micro cracks suggests that the composite material is denser and has fewer defects.The aforementioned qualities improve the strength, stiffness, and toughness of the composite material, as well as its mechanical performance.The wear resistance and thermal stability of the composite material are improved by the addition of SiC particles.The microstructure presented in figures 8 and 9 suggests that the 15 wt% SiC filled configuration has advantageous properties over other configurations [67,68].
Figure 10 represents the 20 wt% SiC configuration, where a higher quantity of debris, pores, micro cracks, and adhesion debris are visible [69,70].These may limit the wear and mechanical properties of the material.

Conclusion
The modified stir casting method was used to create aluminum-based MMCs by incorporating varying amounts of silicon carbide powder, namely 0%, 5%, 10%, and 15% by weight.The microstructure and resistance to wear  of these composites were then evaluated.The Taguchi approach was utilized to improve resistance to wear of a single response characteristic.The investigation of the wear resistance of SiC composites yielded favorable results.The SiC reinforcement had a dominant effect on the characterization of LM26 composites in terms of the applied input parameters.The resistance of the configurations was improved up to 15 wt% SiC however, its performance decreased with further increments of SiC.The coefficient of friction also decreased for the 15 wt% SiC configuration but improved for the other configurations.The optimization results revealed that among the four process parameters investigated, temperature had a dominant role of up to 80% in determining the wear rate consistently.An error rate of ± 2.5% was identified across various process parameters for the experimental results.The wear rate of the materials was predicted using both linear and non-linear models, and their accuracy was compared.It was observed that both models yielded comparable results, with only a slight deviation of 2.5% between them.The scanning electron microscopy images revealed that the matrix contained evenly dispersed particles and that the porosity levels increased as the reinforcement content increased.Further analysis showed that delamination and abrasion were lower in the 15 wt% SiC configurations.

Figure 2 .
Figure 2. Plot of COF a) SN ratios b) Means.

Figure 3 .
Figure 3. Surface plots for wear versus applied load and sliding speed.

Figure 4 .
Figure 4. Effect of load applied on friction co-efficient and wear rate of SiC composites at the constant temperature of 120 (°C) and sliding speed of 3.5 (m s −1 ): (A) wear rate and (B) COF.

Figure 5 .
Figure 5. Results of pin temperature on friction co-efficient and wear rate of SiC composites at the constant temperature of 120 (°C) and sliding speed of 3.5 (m s −1 ): (A) wear rate and (B) COF.

Figure 6 .
Figure 6.Experimental and predicted sliding wear values.

Figure 7 .
Figure 7.An observation of small number of random adhesion debris in a neat composite without the present of SiC filler.

Figure 8 .
Figure 8.A clear observation of minimal delamination and laser quality of pores along with the micro cracks which demonstrates a better quality.

Figure 10 .
Figure 10.A clear observation of a higher quantity of debris, pores, micro cracks, and adhesion when the 20 wt% SiC composite is considered.

Figure 9 .
Figure 9.The quantity of debris, pores, micro-cracks, and adhesion debris is higher compared to figure 8, which shows lower wear.

Table 1 .
Chemical mixture of Aluminum LM26 alloy.

Table 2 .
Control factors of wear study.

Table 4 .
SN ratios response (rate of wear).

Table 5 .
Means response for (rate of wear).

Table 7 .
Means response for COF.

Table 10 .
Results of confirmation test.