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The present study aims to optimize the compressive properties of porous aluminum composites fabricated using the powder metallurgy (PM) space holder technique. These properties were optimized by taking into consideration different processing factors such as sintering temperature, compaction pressure, and sintering time. The experimental design was formulated using L9 orthogonal array by employing these three parameters at three levels. The density, porosity, plateau stress, and energy absorption capacity were determined and analyzed. The impact of individual input parameters was evaluated using the Taguchi-based S/N ratio and analysis of variance (ANOVA). The main effect plots outlined the optimum parameter levels to achieve maximum values for compressive properties (plateau stress and energy absorption capacity). The results revealed that the sintering temperature and time significantly impact compressive properties. The ANOVA analysis exhibited similar results, with maximum contribution from sintering temperature. Further response optimization of compressive properties concluded that the maximum values could be achieved at optimum parameters, i.e., a sintering temperature of 590 °C, compaction pressure of 350 MPa, and sintering time of 90 min. Further, confirmation tests on the optimized parameters revealed improved results and some minor errors and deviations indicating that the selected parameters are vital for controlling the compressive properties of the aluminum composites.

Porous aluminum (Al) composites are lightweight and high-strength materials composing of Al as a matrix material with some strengthening reinforcements and pore-forming agents that result in the formation of new material with superior physical properties and energy absorption capacities. This work gives an overview of the porous Al-foams developed thus far, including the foaming agents and space holders, their properties, production techniques, and applications. First, it deliberates the foaming agents and space holders responsible for the foaming and formation of pores in the composites followed by the mechanical properties of the foams. Al has huge potential for applications that require lightweight, high-strength, and high-energy absorption capacity materials, especially in structural construction and automobile manufacturing. Although Al-foams have been successfully used in automobiles for crashworthiness, lightweight structure, and other functional applications, the development of Al foams with enhanced characteristics and properties has limitations. This review discusses various reinforcements used for improving the characteristics of Al-foams. This review also provides an overview of various commercial foams and their contribution to several applications. Finally, it attempts to reveal impediments in foam production with suggested solutions for overcoming the problems in this area.

Aluminum matrix composites (AMCs) have been extensively studied primarily due to higher strength-to-weight ratio, lower cost, and higher wear resistance properties. However, increasing demand for economical and energy-efficient materials in the automotive, aerospace and other applications is tailoring research area in the agro-based composite materials. Therefore, the aim of this systematic review work is to study the influence of agro-based reinforcements on the tribological and mechanical properties of AMC’s processed by various techniques. It was observed that the processing conditions can be designed to obtain uniform structures and better properties AMCs. The agro-waste reinforcement materials, such as rice husk ash, bamboo stem ash, coconut and shell ash can result in a reduction in the density of AMC’s without compromising mechanical properties. Moreover, the efficient utilization of the agro-waste leads to a decrease in manufacturing cost and prevents environmental pollution, hence, can be considered as a sustainable material. The state-of-the-art revealed that the agro-based reinforcements do not form brittle composites, as in the case of ceramic reinforced composites. Hence, the study concludes that the agro-based AMCs have great potential to act as a replacement for costly and environmentally hazardous ceramic reinforced-AMCs which can especially be used in various automotive applications that demand higher strength-to-weight ratio, lower cost, and higher wear resistance.

Metal foams possess remarkable properties, such as lightweight, high compressive strength, lower specific weight, high stiffness, and high energy absorption. These properties make them highly desirable for many engineering applications, including lightweight materials, energy-absorption devices for aerospace and automotive industries, etc. For such potential applications, it is essential to understand the mechanical behaviour of these foams. Producing metal foams is a highly challenging task due to the coexistence of solid, liquid, and gaseous phases at different temperatures. Although numerous techniques are available for producing metal foams, fabricating foamed metal still suffers from imperfections and inconsistencies. Thus, a good understanding of various processing techniques and properties of the resulting foams is essential to improve the foam quality. This review discussed the types of metal foams available in the market and their properties, providing an overview of the production techniques involved and the contribution of metal foams to various applications. This review also discussed the challenges in foam fabrications and proposed several solutions to address these problems.

In this work, porous Al alloy-based composites with varying Ti-coated diamond contents (0, 4, 6, 12 and 15 wt.%) were prepared, employing the powder metallurgy route and using a fixed amount (25 wt.%) of polymethylmethacrylate (PMMA) as a space holder. The effects of the varying wt.% of diamond particles on the microstructure, porosities, densities and compressive behaviors were systematically evaluated. The microstructure study revealed that the porous composites exhibited a well-defined and uniform porous structure with good interfacial bonding between the Al alloy matrix and diamond particles. The porosities ranged from 18% to 35%, with an increase in the diamond content. The maximum value of plateau stress of 31.51 MPa and an energy absorption capacity of 7.46 MJ/m3 were acquired for a composite with 12 wt.% of Ti-coated diamond content; beyond this wt.%, the properties declined. Thus, the presence of diamond particles, especially in the cell walls of porous composites, strengthened their cell walls and improved their compressive properties.

The compressive properties of powder metallurgy (PM)-based porous aluminum (Al) composites were optimized at three levels based on the following parameters: titanium (Ti)-coated diamond content, polymethylmethacrylate (PMMA) particle content, and PMMA particle size. A 3 × 3 matrix was used in the experimental design of an L9 orthogonal array to get nine sets of combinations. These nine compositions were then tested and analyzed for density, porosity, plateau stress, and energy absorption capacity. The effect of individual input parameters was assessed using the Taguchi-based means ratio and analysis of variance (ANOVA). The main effect plots articulated the optimal parameter levels for achieving maximum compressive property values (plateau stress and energy absorption capacity). The findings show that diamond content and PMMA particle size have a major impact on compressive properties. The ANOVA analysis yielded similar results, with diamond content accounting for the greatest value. Further, the response optimization of compressive properties revealed that maximum values could be obtained at optimum parameters: diamond content of 12 wt.%, PMMA particle size of 150 μm, and PMMA particle content of 25 wt.%. Confirmation tests on the optimal parameters revealed improved results as well as some minor errors and deviations, indicating that the chosen parameters are critical for controlling the compressive properties of Al composites.

This paper aims to investigate the thermal behavior and crystallization kinetics of TiZrHfNiCu high entropy bulk metallic glass (HE-BMG) alloy using the standard procedure of Differential Scanning Calorimetric (DSC) annealing technique. The alloy was produced using an arc melting machine with a critical diameter of 1.5 mm. The crystallization kinetics and phase transformation mechanism of TiZrHfNiCu HE-BMG was investigated under the isochronal condition at a single heating run based on the Johnson-Mehl- Avrami (JMA) theory. In isochronal heating, the apparent activation energy for glass transition and crystallization events was analyzed by Kissinger and Ozawa methods. The average activation energy value for crystallization of TiZrHfNiCu amorphous alloys in isochronal modes was 226.41 kJ/mol for the first crystallization and 297.72 kJ/mol for second crystallization stages. The crystallization mechanism of the first step was dominated by two- and three-dimensional growth with increasing nucleation rate, while the crystallization mechanism in the second stage was dominated by two-dimensional crystallization growth with a constant nucleation rate. The diffusion mechanism result proved the theory of sluggish atomic diffusion of HEA at elevated temperature.

Porous aluminum has been extensively studied, particularly in the field in which lightweight and high stiffness properties are essential. In this study, a preliminary investigation is performed to determine the optimum sintering temperature to develop porous aluminium by a powder metallurgy technique, using polymethylmethacrylate as a space holder. The effects of the sintering temperatures on the physical characteristics, oxidation level, microstructure and sintered density of the porous specimen are systematically evaluated. Based on the results, an increase in the sintering temperature from 580 °C to 600 °C changes the colour of the porous aluminum body from a silver‐like colour to a gold‐like colour, with some of the specimens encountering severe cracking, spalling and even collapsing. As such, the oxygen content is significantly increased from 0.45 wt.% to 2.14 wt. %, suggesting the oxidation phenomenon. In line with this, an obvious appearance of particle boundaries with less macro‐pores formation is also observed. Additionally, the sintered density of the porous specimen is found to reduce from 1.305 g/cm3 to 0.908 g/cm3. Therefore, fabrication of the resultant porous aluminium at 580 °C is an ideal condition in this study, owing to the ideal combination of physical characteristics, microstructure, oxidation level and sintered density

Azo dye is widely used in the textile industry since it is cost effective and simple to use. However, it becomes a continuous source of environmental pollution due to its carcinogenicity and toxicity. Various methods had been used to remove the azo dye in solution. One of the famous and repeatedly used is Fenton process. The Fenton’s process is one of the advanced oxidation process where iron catalysed hydrogen peroxide to generate hydroxyl radical. Treating azo dyes in solution requires a catalyst to enhance the process of degradation. Herein, high entropy alloy (HEA) has been proposed as a catalytic material to enhance the performance of Fenton process for azo dye degradation. HEA has been reported as a promising catalyst due to its high surface area. The higher the number of active sites, the higher the rate of azo dye degradation as more active sites are available for adsorption of azo dyes. The results have shown that HEA can be used as a catalyst to fasten the Fenton’s reaction since the degradation time is proven to be shorter in the presence of HEA. The method derived from the result of this study will contribute in treating azo dyes for wastewater management in Fenton process.

This study was conducted to improve the life-span of the biofilm produced from algae by evaluating the decomposition rate with the effect of cinnamon extraction oil (CEO). The biofilm was fabricated using the solution casting technique. The soil burying analysis demonstrated low moisture absorption of the biofilm, thus decelerating the degradation due to low swelling rate and micro-organism activity, prolonging the shelf-life of the biofilm. Hence, the addition of CEO also affects the strength properties of the biofilm. The maximum tensile strength was achieved with the addition of 5% CEO, which indicated a good intermolecular interaction between the biopolymer (algae) and cinnamon molecules. The tensile strength, which was measured at 4.80 MPa, correlated with the morphological structure. The latter was performed using SEM, where the surface showed the absence of a separating phase between the biofilm and cinnamon blend. This was evidenced by FTIR analysis, which confirmed the occurrence of no chemical reaction between the biofilm and CEO during processing. The prolongation shelf-life rate of biofilm with good tensile properties are achievable with the addition of 5% of CEO.

The aim of the current study is to investigate the effect of milling time and speed on mixing properties of aluminium (Al)/copper (Cu) alloy and Al/Cu composite. Ethanol and argon gas were employed as process control agent and milling atmosphere. Mechanical alloying process by means of high-energy ball milling was performed to produce alloy and composite metal powder. This process proceeds through repeated deformation, cold welding and fracturing of powder particles mixture with a controlled fine microstructure. X-ray diffraction and particle size analyser confirmed particle size reduction of Al/Cu alloy with increasing milling time and speed. On the other hand, the addition of reinforcement particles was found to accelerate the milling process of Al/Cu composite. Scanning electron microscope micrographs revealed homogeneous distribution of powder mixture particles by mechanical alloying process at changing milling conditions.

In recent years, closed-cell porous Aluminum (Al) has drawn increasing attention, particularly in the applications requiring reduced weight and energy absorption capability such as in the automotive and aerospace industries. In the present work, porous Al with closed-cell structure was successfully fabricated by powder metallurgy technique using PMMA as a space holder. The effects of the amount of PMMA powder on the porosity, density, microstructure and compressive behaviors of the porous specimens were systematically evaluated. The results showed that closed-cell porous Al having different porosities (12%-32%) and densities (1.6478 g/cm³, 1.5125 g/cm³ and 1.305 g/cm³) could be produced by varying the amount of PMMA (20-30 wt %). Meanwhile, the compressive behavior results demonstrated that the plateau stress decreased and the energy absorption capacity increased with increasing amount of PMMA. However, the maximum energy absorption capacity was achieved in the closed-cell porous Al with the addition of 25 wt % PMMA. Therefore, fabrication of closed-cell porous Al using 25 wt % PMMA is considered as the optimal condition in the present study since the resultant closed-cell porous Al possessed good combinations of porosity, density and plateau stress, as well as energy absorption capacity.

Composites based on high density polyethylene (HDPE), ethylene propylene diene monomer (EPDM) and Organically Modified Montmorillonite (OMMT) clays were made by melt compounding followed by compression molding. Mechanical properties, X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to characterize the nanocomposites. The addition of clay, compatibilizer agent, Maleic Anhydride Polyethylene (MAPE) and irradiation technique, High Energy Electron Beam (EB) considerably improved the properties of nanocomposites. Tensile Strength and Modulus (MPa) were found to increase significantly with increasing clay content and decreasing as the clay content exceeds 4 vol%. The largest improvement in nanocomposite tensile properties occurred at clay loading of 4 vol% (2-8 vol%) with irradiation technique. The d spacings of the clay in nanocomposites were monitored using XRD and the extent of delamination was examined by TEM. TEM photomicrographs illustrated the intercalated and exfoliated structures of the nanocomposites with OMMT, MAPE and irradiation process.

Nanocomposites are the materials that are created by introducing nanoparticulates that always referred to as filler into the matrix. Blends of polypropylene (PP)/ethylene propylene diene monomer (EPDM)/Montmorillonite (MMT) were treated by compatibilizer MAPP and irradiation of electron beam. The effects on mechanical properties for both samples were compared with the untreated nanocomposites. Because each samples used different portion of clay loading, the effects of clay loading on mechanical properties is also observed. The sample is characterized by using Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), tensile test and impact test.

In this study, electron beam irradiated (EB) was applied as a crosslinker agent for both pristine high density polyethylene (HDPE) and HDPE/ ethylene propylene diene monomer (EPDM) nanocomposite systems. The doses rate for EB irradiated technique were varied between 50, 100, 150 and 200 kGy. The nanocomposites systems were first prepared via melt intercalation method with different organophilic montmorillonite (OMMT) loadings. It was found that, with 4 vol% organophilic montmorillonite (OMMT) loading, the barrier resistance of nanocomposite against oxygen transmission was significantly enhanced by EB irradiation dose rate of 100 kGy. The oxygen transmission for nanocomposite was reduced by 23.48%. The interplanar spacing, d-spacings of OMMT in nanocomposites were monitored using x-ray diffraction (XRD) and the extent of delamination was examined by transmission electron microscope (TEM). The wide angle of XRD patterns showed the increased interplanar spacing, d of clay layers, indicating enhanced compatibility between polymer matrix and OMMT with EB irradiation. TEM photomicrographs illustrated the mixed intercalated and partial exfoliated structures of the nanocomposites with the irradiation process.

Thermoplastic natural rubber hybrid composites reinforced with kenaf and short glass fibers were compounded by melt blending method using an internal mixer, Thermo Haake 600P. Thermoplastic natural rubbers (TPNR) were prepared from polypropylene (PP), natural rubber (NR) and liquid natural rubber (TPNR) with ratio 70:20:10, which were blended using internal mixer for 12 minutes at 180°C and rotor speed 40 r.p.m. Glass fiber was treated with silane coupling agent while TPNR reinforced kenaf fiber composite is using MAPP as a compatibilizer. TPNR hybrid composite with kenaf/glass fibers was prepared with fiber content (5, 10, 15, 20 volume % of fiber). Mechanical properties of the composites were investigated using tensile test[ 1 ], flexural, impact, and hardness test and scanning electron microscope (SEM)[ 1 ]. The incorporation of the treated or untreated fiber into TPNR has result in an increment of almost 100% of flexural modulus and impact strength as compared to TPNR matrix. However, the maximum stra...

In this study, the mechanical properties of gracilaria lichenoides with additional of plasticizer and filler were evaluated. For samples with the addition of 5.5% of plasticizer, produced low tensile strength and this results is vice versa with elongation at break results. The tensile strength of the bioplastic continuously decreases from 14.8 to 2.7MPa as the plasticizer increases up from 1.5% to 5.5%. This phenomenon was analyses under scanning electron microscope (SEM), it shows that, the formation of pores and crystal agglomeration at sample with 5.5% glycerin. To alter these flaws, squid bone is introduce as filler to the bioplastic. Based on the analysis, additional of 6% filler content did alter the tensile strength up to 8 MPa with 3% of the elongation at break.

This study aims to investigate the effect of tin (Sn) and magnesium (Mg) on the sintering response of sintered Al. Although this topic has been extensively reported, details on the combined effect of Sn and Mg that function as sintering additives are still limited. The current study discusses the effect of the combined use of Sn and Mg to assist aluminium (Al) in liquid phase sintering via the powder metallurgy technique. The results demonstrated that the densities of sintered Al increased from 2.5397 to 2.575 g/cm3 as the Sn content increased from 1.5 to 2.5 wt. % respectively. Accordingly, the physical characteristics of sintered Al were transformed from black to silver, which confirmed the reduction in the oxygen content (oxide layer reduction) from 0.58 to 0.44 wt. % respectively. Additionally, the microstructure of the resultant sintered Al demonstrated that effective wetting by Sn addition was obtained at its maximum content of 2.5 wt. % with a greater micro pores reduction and better metallurgical bonding between Al particles. Therefore, the introduction of different Sn content, along with Mg element, was found to further improve the sintering response of the resultant sintered Al that consequently improved its densities and physical characteristics.

Electron beam (EB) irradiation technique was introduced to modify the crystallization and oxygen (O2) barrier properties of high density-polyethylene (HDPE)/ethylene propylene diene monomer (EPDM) matrix and HDPE/EPDM filled withorganophilic montmorillonite (OMMT). The absorbed dose for EB-irradiation was fixed at 100 kGy. HDPE/EPDM matrix and HDPE/EPDM filled with OMMT at 4 vol% loading were prepared via melt intercalation method. It was found that the barrier resistance of HDPE/EPDM filled withOMMT against oxygen (O2) transmission was significantly enhanced by EB-irradiation absorbed dose of 100 kGy as compared to the control system. The crystallization temperature,Tc, and melting temperature,Tm, were also improved with the addition of OMMT along with the aids of EB-irradiation technique. Field emission scanning electron microscope (FESEM) revealed that the stacking condition of OMMT particles was greatly reduced by EB-irradiation treatment as evidenced by finer surface and less formation of voids.