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The present study reflects on the wear behaviour characteristics of A356 composite with trace addition of copper and copper-coated zinc as reinforcements. Dry sliding wear tests were conducted on fabricated as-cast and heat treated composites by varying load of 20-60 N under constant sliding speed of 1 m/s and sliding distance of 3000 m. Results confirmed that copper-coated zinc was successfully introduced as reinforcement into A356 matrix using two-step casting method. Scanning Electron Microscope (SEM) images confirmed the presence and homogeneous distribution of the added reinforcements in the matrix. T6 treatment with addition of Cu reinforcement facilitated age hardening showing 121% hardness improvement compared to as-cast matrix A356. At lower loads, wear results showed 117-134% enhanced wear resistance in composite reinforced with 1 wt.% Cu and aging at 100°C. However at higher loads, 153-210% improvement in wear resistance was observed. Overall, copper and Cu-coated zinc reinforced composite along with T6 treatment exhibited significant improvement in hardness wear property compared to as-cast matrix A356 alloy.

This study investigates the effects of magnesium (Mg) content, silicon carbide (SiC) reinforcement, and aging temperature (AT) on the ultimate tensile strength (UTS) and Brinell hardness number (BHN) of eutectic Al-Si composites using a full factorial experimental approach. The analysis reveals that increasing Mg content from 0 wt% to 1.5 wt% significantly enhances UTS, likely due to solid solution strengthening and improved particle reinforcement. Similarly, a rise in SiC content up to 4 wt% leads to a notable increase in UTS, indicating effective matrix reinforcement. AT is crucial, with the highest UTS achieved at 100 °C; however, overaging at 200 °C results in reduced strength due to precipitate coarsening. Interaction plots demonstrate a synergistic effect between Mg and SiC, where higher levels of both contribute to a more substantial increase in UTS. The results also show that while both Mg and SiC improve UTS, their effects are optimized with appropriate aging conditions, although overaging diminishes these benefits. Analysis of variance (ANOVA) highlights that AT, Mg, and SiC each significantly impact UTS and BHN, with SiC having the greatest effect of 47.92% on hardness and AT having the greatest effect of 36.58% on the UTS. The interaction between SiC particles and AT is particularly influential on BHN. These findings emphasize the importance of carefully optimizing processing conditions to enhance the mechanical properties of eutectic Al-Si composites. [ABSTRACT FROM AUTHOR]

The incorporation of filler materials to enhance the properties of fibre-reinforced plastics is a prevalent practise in materials science. Calcium carbonate is a commonly used inorganic filler in composite fabrication. Eggshell, a rich source of calcium carbonate, offers an organic alternative to conventional inorganic fillers. This study investigates the efficacy of different types of eggshells as filler materials. Three variants, viz., unhatched raw eggshell, unhatched boiled eggshell, and post-hatched eggshell, were used to fabricate composite variants, which were then subjected to mechanical characterization and compared with unfilled composites. The results indicated that composites filled with unhatched eggshells outperformed those with post-hatched eggshells. Tensile testing revealed a significant enhancement in the tensile properties of all eggshell-filled composites in comparison to the unfilled ones. The composite variant filled with unhatched raw eggshell filler showcased the utmost tensile modulus and strength, with a notable 36% improvement in comparison with the unfilled variant. Similarly, flexural tests demonstrated a 53% increase in flexural strength for unhatched raw eggshell-filled composites over unfilled composites. SEM imaging confirmed these findings by showing crack arrests, deviations, particle distribution, and strong interfacial bonding in the eggshell-filled composites. [ABSTRACT FROM AUTHOR]

The present work reflects the effects of trace addition of copper (up to 1 wt.%) and zinc (0.5 wt.%) on the microstructure and hardness property of heat treated A356 (Al-7Si) alloy. Small amount of zinc and copper was introduced into A356 in both atomic form (alloy) and powder form (composite) and its age hardening behaviour were investigated. To enhance the wettability during composite fabrication and solid solution strengthening in alloys, a small quantity of magnesium (1 wt.%) was added. The main objective of this study is to introduce lower melting point zinc reinforcement into A356 matrix alloy by copper coating of zinc particles and then reinforcing it into A356 matrix. All stir cast specimens were subjected to T6 treatment by solutionizing at 520 °C for 2 h followed by 60 °C water quench and then aging at 100 and 200 °C to determine peak hardness value. Microstructure analysis showed that a minimum 1 wt.% copper was required to form Al2Cu intermetallic phase during solidification resulting in finer grain structure with hardness improvement. Under as-cast conditions, a maximum hardness of 85 VHN was obtained in 1 wt.% copper reinforced composite. Under peak aged conditions, aging at 100 °C showed 116% hardness improvement in 1 wt.% Cu reinforced composite.

The use of natural fibres in making composites has increased drastically in the past few years because they produce strong composites that are environmentally friendly. The most used fibres are jute, kenaf, sisal and hemp. The use of palm fibres as reinforcement is quickly rising since they are abundantly available and showcase better mechanical properties than these other natural fibres. Palm trees have always been used for various other purposes, mainly for their fruit but now even fibres derived from various areas of the tree can be used to manufacture composites which are used in industrial applications. The process of manufacturing these composites right from the extraction of fibres to the fabrication of composites along with mechanical testing of the respective fibres and composites have been highlighted in this review paper. This study provides a database and platform for businesses to better understand how natural fibres can be used to make more sustainable and renewable fibre-reinforced composites. [ABSTRACT FROM AUTHOR]

This work emphasizes the optimization of preheating temperature of TiB2 reinforcement powder with LM4 composites, and statistical analysis for predicting hardness improvement during aging treatment using ANOVA, are illustrated in this article. A two-stage stir casting procedure was used to fabricate LM4 + TiB2 (1, 2 and 3 wt.%) composites. The impact of preheating TiB2 reinforcement powder at various temperatures such as 600, 500, 450, 350 and 250 °C, to attain uniform distribution of reinforcements in the matrix was studied. Optical microstructure analysis clearly shows that the optimum preheating temperature of TiB2 powder for effective preparation of composites is 350 °C for 30 min without agglomeration of reinforcement particles. After successful preparation of composites, the as-cast samples were subjected to single-stage and multistage solutionizing treatments and then artificially aged at 100 and 200 °C to obtain peak hardness. Micro Vickers Hardness test was done to calculate the hardness of both age hardened LM4 alloy and its composites and results were analyzed. An increase in wt.% of TiB2 (1–3%), the hardness of composites increased, and multistage solutionizing treatment followed by artificial aging at 100 °C was proven to achieve the highest peak hardness value for LM4 + 3 wt.% TiB2 composites. Compared to as-cast LM4 alloy, 80–150% increase in hardness was observed when aged at 100 °C and 65–120% increase in hardness was observed at 200 °C during SSHT and MSHT, respectively. ANOVA was performed with wt.%, solutionizing type, aging temperatures as factors, and peak hardness as the outcome. From the results, it can confirm that all three factors contributed effectively for achieving the peak hardness. R2 value validates that the factors account for 100% of the variance in the hardness results.

Current work focusses on stir cast Al6061 based composites with SiC (3, 6, 9 wt.%) and h-BN (1, 2, 3 wt.%) as reinforcements and subjected to heat treatments followed by mechanical characterization. Quality level of composites is confirmed from reinforcement distribution and hardness uniformity in castings after homogenization. The castings were further subjected to peak aging and hardness data is refined for accuracy using Spider web approach. Due to lack in the reinforcement spreadout, especially higher volume quantity of h-BN, the peak hardness of Al6061/9 wt.% SiC/3 wt.% h-BN as estimated by Spider web approach is less than the recorded value. The Minitab result is in line with that of experimentally supported Spider web approach. Due to the result of nonuniform dispersivity, beyond the optimum quantity of reinforcement content, fracture surface resulted coarse mirror facets with lower tensile and wear properties. 2 wt.% h-BN quantity with 6 wt.% SiC in the composite is regarded as the optimum quantity of reinforcement, resulted excellent tensile strength with least ductility among the family and is at par with hardness variation trend. It is found that optimum quantity of solid lubricant h-BN in the composite resulted excellent wear resistance even at higher normal loads.

This study explores the synergistic effects of incorporating coir fibers and nanoclay into epoxy resin composites. Coir, a renewable and cost-effective natural fiber, undergoes an alkaline treatment to influence its ability to form strong interfacial bonding with the epoxy matrix. To further enhance the mechanical properties of the composite, montmorillonite nanoclay, surface-modified with aminopropyltriethoxysilane and octadecyl amine, is introduced. The research investigates different combinations of coir fiber content (20, 30, and 40 wt%) and nanoclay loading (0, 2, and 4 wt%) with epoxy resin. The composites are fabricated through an open molding process, and the mechanical properties are evaluated using tensile and flexural tests according to the ASTM D638 and D7264 standards, respectively. The tensile and flexural strengths of the 40 wt% coir fiber-reinforced epoxy composite are found to be 77.99 MPa and 136.13 MPa, which are 44% and 23% greater than pure epoxy, respectively. Furthermore, the strengths displayed a 23% improvement in tensile strength with 4 wt% and a 31.4% improvement in flexural strength with 2 wt% nanoclay as additional reinforcement. Scanning electron microscopy is employed for fractographic analysis of the fractured specimens from the tensile test. The study underscores the importance of understanding the interplay between natural fibers, nanoclay, and epoxy resin for optimizing the composite's performance in real-world applications. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the variations in microstructure, hardness, wear and surface roughness between as-cast and heat treated trace elements added A356 alloy. Alloy A was prepared by adding 1 wt.% magnesium to A356 alloy which was used as the base material for the preparation of alloys with zinc (Zn) and copper (Cu) particles as alloying elements. Other set of samples was fabricated where Cu-coated Zn and Cu were added as reinforcements to base matrix A. The microstructural analysis indicated that the addition of Zn to A356 as an alloying element had a limited effect on controlling the grain size during solidification compared to Cu. The addition of Cu as reinforcement resulted in a higher proportion of pro eutectic α-Al phase, leading to finer grain boundaries. Micro-polishing test was conducted on the alloys and composites by determining the surface roughness (Ra) value using profilometer to study the changes in surface roughness under individual load conditions of 20 and 40 N. In the as-cast condition, the addition of Cu increased the hardness by 39% and 58% over the base alloy, respectively. Age-hardening treatment significantly enhanced the wear resistance properties of unreinforced alloys and composites at both aging temperatures, especially at 100 °C. Composite samples exhibited excellent surface finish (lower surface roughness) compared to alloy samples, attributed to the presence of hard reinforcement particles. [ABSTRACT FROM AUTHOR]

This study investigates the mechanical and microstructural properties of aluminum matrix composites (AMCs) reinforced with cobalt-coated carbon nanotubes (CNTs) and Al2024 powder, tailored for aircraft and automotive applications. Using Al7075 alloy as the matrix, composites were fabricated via stir casting, incorporating varying proportions of cobalt-coated CNTs and Al2024 powder. The electroless cobalt coating, applied at thicknesses of 4, 6, 8, and 10 µm, facilitated the uniform distribution and enhanced the compatibility of reinforcements with the Al7075 matrix. Four distinct samples were developed: pure Al7075 alloy, Al7075 with 2 wt.% CNTs, Al7075 with 2 wt.% Al2024 powder, and a hybrid composite combining 2 wt.% of each reinforcement. Microstructural analysis revealed that the 10 µm coating thickness was critical for maintaining reinforcement integrity during the melt phase, preventing crack formation and reinforcement agglomeration. Mechanical testing through vickers hardness and phase analysis using X-ray diffraction analysis, demonstrated that the hybrid composite (A3) exhibited superior hardness and reduced natural aging tendencies compared to its counterparts. Peak aging at 120 °C resulted in the formation of intermetallic compounds like CuAl2 and MgZn2, contributing to improved mechanical properties. These findings highlight the significance of optimizing coating thickness and aging conditions to enhance the performance of AMCs, making them suitable for high-performance applications in the aerospace and automotive industries. [ABSTRACT FROM AUTHOR]

Aluminium–Silicon (Al-Si) eutectic alloy matrix composites are widely used in engineering application. However, it is a well-known fact that this material is not heat-treatable. In order to take advantage of the improvement in the mechanical properties due to the heat treatment, it is essential to find a way to make the Al-Si composite heat treatable. The dissolution of magnesium in the matrix, makes the composite age-hardenable, showing improvements in hardness and tensile strength properties according to changes in aging kinetics. This study analyses the peak aging kinetics on the hardness-related property improvement according to the magnesium dissolution content in the matrix. Hence, this research focuses on the role of aging treatment on the mechanical properties, especially the hardness of stir-cast Al-Si matrix Silicon Carbide (SiC) composites with up to 1.5 wt. % Mg intentionally dissolved in base alloy. Two aging temperatures (100 and 200 °C) were pitched into the target peak hardness and peak-aged condition. A minor quantity of Mg dissolution in the Al-Si matrix SiC composite has resulted in the improvement of hardness up to 24%, and age-hardening conditions contributeed up to a 40% increase in peak hardness. Similarly, the peak aged condition tensile strength shows an increase of up to 45% during age hardening compared to the Mg-free as-cast composite. [ABSTRACT FROM AUTHOR]

Austempered ductile iron is an innovative material obtained by subjecting it to an austempering heat treatment. The wide application of this material is because its properties are comparable to those of steel, which has a much lower weight. However, the machinability of this material is always a difficult task owing to its high hardness. This problem becomes more complex when a considerable amount of Mn is added. In this study, a novel two-step austempering heat treatment was performed on spheroidal graphite iron containing different amounts of manganese. Although the novel heat treatment method helps to obtain a superior combination of hardness and impact, its effect on machinability must be determined. This study provides the results of machinability tests carried out on austempered ductile iron with various manganese contents produced using the novel method. Scanning electron microscope images of the microstructures revealed a typical ausferrite structure with no segregation of manganese at the grain boundary. This is evident from the good tool life obtained in the machinability tests. Regression equations are fitted to determine the tool life and surface roughness for machining parameters with a range of values considered in this study. The results obtained have shown that till 1 wt% of manganese alloyed austempered ductile iron can be successfully produced using the novel heat treatment method. This helps to obtain the optimum combination of strength and impact properties. [ABSTRACT FROM AUTHOR]

Green oils are plant extract oils such as Karanja, Pinnay, Coconut oil, which are non-corrosive, non-toxic and environmentally friendly, and are capable of replacing petrol oil quenchants. In this study, Pinnay oil, Karanja seed oil and their blends (equal volume in proportion) were used as quenchants. Before quenching for hardening, austenitising was performed at three different temperatures ranging from 890 °C to 950 °C. The effects of austenitising temperature and vegetable oil quenchants on the hardness, room-temperature impact toughness and microstructure of normalised 42CrMo4 steel were determined. Prior to the hardening treatment, the as-received 42CrMo4 steel was subjected to normalising treatment, which enhanced the hardness and toughness properties due to grain refinement of the as-received steel. As the oil viscosity decreases, the hardness increases with marginal alteration in the impact resistance. In all the quenching condition, with an increase in austenitising temperature up to 920 °C, there was an increase in hardness around 7% and decrease in toughness around 37%, whereas at 950 °C there was a decrease in hardness around 24% and an increase in the toughness of the steel around 47% as compared to that of 920 °C. Also, blend oil quenched specimens showed balanced hardness and impact toughness compared to Pinnay oil and Karanja oil quenched specimens. [ABSTRACT FROM AUTHOR]