Key Engineering Materials Vol. 971

Abstract: In the current research, titanium carbide (TiC) is used to reinforce the aluminium alloy (AA 6063) in stir-cast hybrid composites at concentrations of 5, 10, and 15 weight percent together with 3 weight percent of graphite. The application of this developed composite is mainly used for automobile suspension parts. The portrayal of characters was performed, and the mechanical properties of the fabricated samples were investigated. Composites with different TiC weight percentages have their mechanical properties, including hardness, tensile strength, compressive strength, and flexural strength, measured and assessed. The results are shows that AA 6063 alloy with 3 wt. percentage of graphite with an increasing weight percentage of TiC composites are better in the mechanical property. The hardness of the AA 6063 alloy composites is greater than that of the base matrix alloy. The tensile strength of Al 6063 alloy composites has been reported to grow with increasing TiC particle content and to be significantly higher than the strength of the matrix alloy. Also, the SEM microstructure images clearly shows that 15 weight percentage of TiC with 3 weight percentage of Graphite shows the maximum distribution in the matrix.

Abstract: Everyone now lives in a technologically highly hybridised environment; mobile technology is regarded as one of the most significant of all technologies. Inside the phone is the entire world. This article primarily focuses on recycling e-waste into composites (especially waste from mobile phones). The range of products used for this study included basic and smartphones. The primary product chosen was the display glass from smartphones. With the use of recent literature reviews, the problem was identified. Many studies focused on polyester resins with ceramic powders and their composites. The mobile display powder has been mixed with Polyester resin. The mobile phone display electronic waste (MPDEW), like polyester resin, was cost-effective. Mobile phone waste was used as filler in various proportions including 0, 5 and 10 %. To determine the effect of e-waste with polymer composites, the mechanical properties such as tensile, compression, flexural, and impact were undertaken. The scanning electron microscope was also used for the microstructural analysis.

Abstract: The end milling process plays a crucial role in shaping the material into surface structures that meet the stringent requirements of these demanding industries. The present paper aims to optimize the end milling process of Al6061 with nano tungsten carbide reinforcement at 6% by studying metal removal rate (MRR), and surface finish based on the parameters of depth of cut, feed, and cutting speed. The aluminium metal matrix composite is prepared with 6 weight percentage of nano tungsten carbide is reinforced with Al6061 alloy is casted by using stir casting method. RSM analysis is used to find the best operating condition by using L9 orthogonal array. The ANOVA result shows that cutting speed is the most domineering factor which influences the MRR and feed rate is the most influencing factor on surface roughness.

Abstract: Superalloys, referred to as nickel alloys, have several uses in engineering and are widely used in industries that are as diverse as chemical processing and food processing. The high thermal conductivity and high strength of these materials make them hard to remove material from with traditional processing techniques. The majority of modern techniques for machining harder materials are alternatives to older methods. The present study is focusing on Wire Electrical Discharge Machining (WEDM), a modern machining technique used for the processing of tougher materials. The aspiration of this work is to present a Taguchi-based Grey technique that can be used to optimize a number of different performance indicators. The connection between the input and output variables has been analyzed using a regression model. Taguchi's design approach has been applied to the design of trials, with the Pulse on/off time and the applied current serving as independent variables. For enhancing the multiple machining performance of nickel alloy during Wire Electrical Discharge Machining (WEDM), this experimental effort seeks to pinpoint the most effective variables. This is accomplished using the Taguchi-Grey method. The performance analysis offers producers with concrete proof of the efficiency of evolved systems, allowing them to make well-informed and effective choices.

Abstract: The investigation of biomass-based, cost-effective, efficient, and environmentally materials with high power density and fast ion/electron transfer is intensively carried out for the development of renewable energy storage devices. Pyrolysis and hydrothermal carbonization (HTC) are two common methods of thermochemical conversion to synthesize biomass-derived based carbon. Compared to the pyrolysis method, HTC is a more promising strategy because it can be carried out without a pre-drying process, has a high yield, low ash content, and requires a relatively low temperature (180-250 °C). The carbon produced from the HTC process is known as hydrochar. This study reports the acid-assisted hydrothermal carbonization temperature on the hydrochar properties and its application for supercapacitor electrodes. Hydrochar was synthesized from extracted avocado seed waste with potassium permanganate and sulfuric acid catalyst solution at 200 °C for 12 h. The effect of one- and two-stage HTC temperature on the hydrochar properties were compared. The hydrochar characterization includes yield, SEM, XRD, FTIR, and cyclic voltammetry analysis. According to the characterization and analysis results, hydrochar produced has the 3D porous network morphology and the highest specific capacitance of 73.54 F/g. In conclusion, hydrochar derived from avocado seed through the acid-assisted HTC can be a potential way for supercapacitor electrodes.

Abstract: Performance of seawater batteries is still limited by the sluggish nature of oxygen reduction reaction (ORR). One way to optimize the performance of the battery is by utilizing an electrocatalyst with the ability to increase the ORR rate of reaction. Nitrogen-doped carbon aerogel based on coir fiber is one of the alternatives because of its excellent electrocatalytic performance and was made from an abundant material. Carbon aerogel was obtained from pyrolyzing coir fiber-based aerogel cellulose. Nitrogen atom structure in carbon aerogel was affected by the temperature of cellulose aerogel pyrolysis. Pyridinic N content in the Nitrogen-doped carbon aerogel has effective for the activity of the ORR. The electrocatalytic performance of the carbon aerogel synthesized from coir fiber with nitrogen doping at the pyrolysis temperature of 600 °C was investigated in this study. The research process began with the synthesis of cellulose aerogel using urea-ammonia crosslinking precursor. Next, cellulose aerogel was pyrolyzed at 600 °C to create carbon aerogel. FTIR, XRD, CV, LSV, and LP were used to characterize the samples. The carbon aerogel was N-doped with pyridinic N, according to an analysis of the FTIR spectra. The carbon aerogel shows 4-electron ORR with kinetic current density (i_k) of 0.74 mA/cm² and current density (i_o) of 0.583 μA/cm², according to electrochemical performance analysis in 3.5% NaCl as electrolyte.

Abstract: Some areas in Indonesia have difficulty accessing electricity [1]. One of the alternative is sea water battery because of its good theoretical performance and great seawater potential in Indonesia [2]. However the performance is limited by the sluggish Oxygen Reduction Reaction, therefore electrocatalyst is needed to increase the rate of reaction [2]. Oil palm empty fruit bunch carbon aerogel is one of the alternative because of its excellent electrocatalytic performance and can be made from abundant material with high content of cellulose [3]. Carbon aerogel can be obtained from pyrolizing oil palm empty fruit bunch based aerogel cellulose. Activity of the Oxygen Reduction Reaction can be determined from pyridinic N concentration in the carbon aerogel [4]. This research focuses on synthesizing nitrogen-doped carbon aerogel from oil palm empty fruit bunch and characterized its electrocatalytic performance. Research started with synthesizing cellulose aerogel with urea-ammonia crosslinking precursor and followed by pyrolysis of cellulose aerogel to carbon aerogel at 600°C. Samples were characterized using FTIR, XRD, CV, LSV, and LP. The FTIR Spectra analysis shows that the carbon aerogel was N-doped with pyridinic N. Electrochemical performance analysis in 3.5% NaCl as electrolyte shows that carbon aerogel undergoes 2-electron ORR pathway with kinetic current density of i_k=0.107 mA/cm² and current density of i_o=0.295 μA/cm².

Abstract: Biogas has been effectively produced from solid as well as liquid biomass waste through anaerobic digestion (AD). It has been proved that AD is the most efficient technology and less environmental effect in converting biomass to biogas. However, it is challenging that the rate of biogas production might slow down by many factors. It requires continues research in order to overcome the problem, such as by adding an additive. The use of several additives for AD has received great attention due to the positive influence in improving the production performance of biogas in terms of process stability and efficiency, and production capacity. Among all types of additives, carbon material in the form of bio-char has been considered as the most profitable due to low cost and easy to produce from various carbon source materials. This study aimed to determine the characteristics of coffee pulp bio-char which will be used as an additive in biogas production from coffee mucilage by the AD method. Coffee pulp biomass and coffee mucilage were obtained from Aceh Tengah, Indonesia. Preparation of bio-char was carried out by washing and soaking of the coffee pulp with tap water for 24 hours, then drying under the sun for three days. Carbonization of dried coffee pulp was then performed using a pilot plant-scale pyrolysis reactor at temperature of 400 °C for 60 minutes. Resulting biochar was then ground and sieved to 60 mesh size. Based on to proximate analysis result, it was found that the moisture, ash, volatile matter, and fixed carbon contents were respectively 1.98%, 11.93%, 42.36%, and 43.72%. N₂-physisorption analysis of coffee-pulp bio-char suggested pore volume of 0.21 cm³/g. From BET calculation method it was found that the surface area was 224.1 m²/g. This high surface area is beneficial for providing sheltered spaces for microbes to attach and hindering them against metabolic inhibitors. The effect of adding biochar additives from coffee skin waste in the anaerobic digestion process of coffee mucilage waste provides significant results on the yield of biogas products. The yield of biogas products increased by 225% with the addition of 15 gr/L of biochar coffee pulp.

Abstract: In this study, the performance of dielectric barrier discharge (DBD) integrated with the aerobic process with the input voltage of 20 and 25 kV on the production of biogas; methane (CH₄), hydrogen (H₂), and carbon dioxide (CO₂) from palm oil mill effluent (POME) were investigated. The DBD and DBD integrated with the aerobic process (DBD + aerobic) treatment was also simulated using the theoretical stoichiometric of POME (in terms of carbohydrate) and the kinetic study using the first- and second-order kinetic model. The results showed only 0.58, 0.39, and 0.97 mol/L of CH₄, H_2, and CO₂, respectively, generated from the simulation model, which underperformed those experimental results. This may be due to the low concentration of carbohydrates given by the simulated stoichiometric reaction. However, both simulation and experimental results showed a rapid increase in biogas concentration in the initial reaction time in the DBD + aerobic reactor with an input voltage of 25 kV. The results showed that DBD + reactor produced CH₄, H_2, and CO₂ thirteen, twenty-three, and three times higher than DBD alone, respectively. This suggests that good performance was observed when the DBD was integrated with the aerobic process under the optimum input voltage. The study can give information on the optimum condition in a lab scale to produce CH₄, H_2, and CO₂ from POME.