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The thermophysical, rheological, and tribological properties in lubricant are essential for preserving the engines, power steering systems, and engine components from damage caused by friction and wear. The incorporation of nano-sized particles into lubricating oils has been reported to enhance these properties. Therefore, this study explores the impacts resulting from the incorporation of graphene, multiwalled carbon nanotubes (MWCNT), double-walled carbon nanotubes (DWCNT), and single-walled carbon nanotubes (SWCNT) at a quantity of 0.04 grams into the SAE 5W-30 base oil. These nanoparticles were synthesized using a two-step method, resulting in nanolubricants. The addition of carbon-based nanomaterials increases the density and decreases the viscosity of the base lubricant. The flow of nanolubricants exhibits non-Newtonian shear thinning behavior during the test at elevated temperatures. The results of the four-ball tribo-tester test reveal the increase of Coefficient of Friction (CoF) values and the extent of wear scar area. Further, the Scanning Electron Microscopy (SEM) analysis was employed to observe the wear morphology of the nanolubricants on the SKF RB-12.7/G20W ball bearing. Its results indicate a prevalence of groove-type wear as compared to conventional lubricants.

Friction Stir Welding (FSW) is commonly used in transportation industries but faces challenges when joining thick plates. To address this, double-side FSW (DFSW) has been introduced, involving two steps: FSW on one side, flipping the plate, and then FSW on the opposite side. However, this process is time-consuming. To overcome this, a one-step DFSW technique was developed, where two tools simultaneously operate on both sides. This study aimed to investigate the impact of tool rotation speed on the fatigue crack growth rate of AA6061-T6 in one-step DFSW. One-step DFSW was performed at different upper and lower tool rotational speeds: 1500/900 rpm, 1500/1200 rpm, and 1500/1500 rpm. Tensile and fatigue crack growth tests were conducted on the joined specimens. The microstructure of the welded joint and the surface fractures resulting from the tests were analyzed using a scanning electron microscope (SEM). Results showed that the specimen welded at 1500/1500 rpm exhibited the lowest fatigue crack growth rate. The Paris constants (C and n) were determined as 4.348E-08 and 4.16, respectively.

The production of UV-resistant films from biomaterials is currently an active field of research. ZnO nanoparticle polymer fillers have been found to improve UV-light opacity. However, using ZnO as a filler is relatively expensive and time-consuming for film preparation. Substituting some of the ZnO nanoparticles with Uncaria gambir extract has been suggested to reduce the cost of film production, as the phenolic hydroxyl group present in Uncaria gambir provides excellent UV resistance. This study characterized dry bacterial cellulose (BC) powder-based films immersed without and with polyvinyl alcohol/Uncaria gambir extract/ZnO (M) solution for 2 and 5 min. It was found that BC/M biocomposites blocked 100% of the UV light while remaining transparent to visible wavelengths. These bendable biocomposite films also presented high tensile and thermal resistance properties. Immersion for 5 min increased significantly tensile strength, elongation at break, and toughness of the biocomposite to 77.2 MPa, 12.3%, and 5.8 MJ/m3, an increase of 130%, 748%, and 2409%, respectively, compared to uncoated BC film. These results suggest the immersion method could provide more efficient, environmentally friendly biocomposite films with significant UV resistance.

The interest in metallic foam is increasing since their cellular structures have a unique combination of properties such as high stiffness, low density, lightweight, high specific strength, and thermal insulation. Commonly, the performance of metallic foam can be improved by the heat treatment process. However, the previous heat treatment methods still present the brittle crack path and the research on heat treatments of the metal foam properties is very limited. In this study, individual parameters in stress relieving treatment that contribute to Al-Foam properties were investigated. The stress-relieving process of the samples was performed using a vacuum furnace. The composition of aluminium foam was determined by X-Ray Fluorescence (XRF). The hardness test was conducted using a microhardness tester. Quasi-static compression test was conducted by a universal testing machine. From the SEM-EDX elemental images, it can be observed that traces of Ca, Fe, Ti, and Si have a homogeneous distribution in the Al-matrix. In the result obtained, the mechanical properties of aluminium alloy foam decrease when the heating temperature is enhanced. The mechanical properties of closed-cell aluminium alloy increase with the reduction of the holding temperature. This was due to the recovery and recrystallization process which depended on time and temperature during the heat treatment process. The mechanical properties of aluminium foam were raised after increasing the stabilization temperature. This finding was due to the vibrational atomic motion in the recovery process.

This study analyzes the tribological properties of 5W-30 synthetic oil with the addition of surfactants and oxide nanomaterials. This research used SAE 5W-30 lubricant base material with the addition of Aluminum Oxide (Al2O3), Titanium Dioxide (TiO2), and Hybrid Aluminum Oxide (Al2O3) - Titanium Dioxide (TiO2) nanomaterials. The nano lubricants were synthesized using a two-step method by adding nanomaterials by 0.05% volume fraction, followed by 50 ml of 5W-30 synthetic oil and polyvinylpyrrolidone (PVP) surfactant by 0.1%. Then, it was stirred using a magnetic stirrer for 20 minutes, followed by an ultrasonic homogenizer process for 30 minutes. Further, the nanolubricant was tested to identify its thermophysical properties, including density, dynamic viscosity, and sedimentation. It also underwent tribological testing, including wear, coefficient of friction, and surface roughness. Further, the nanomaterial was characterized using SEM, XRD, and FTIR. The morphological analysis using SEM suggested an irregular shape of the Al2O3 nanomaterial surface, while TiO2 has a spherical shape. Besides, phase identification with XRD testing showed corundum and anatase phases. Functional group analysis through the FTIR showedthe presence of Ti-O and Al-O. The highest density and viscosity results without surfactants were obtained in hybrid nanolubricant 779 kg/mm3 and 0.0579 Pa.s, while the use of surfactants resulted in 788.89 kg/mm3 of density and 0.0695 Pa.sviscosity. Tribological gray cast iron FC25 results in the best COF value observed in SAE 5W-30 + PVP-TiO2 lubrication (0.093). The lowest wear mass without surfactant was obtained in the Al2O3-TiO2 nanolubricant hybrid (0.02 grams), the lowest surface roughness in a mixture of PVP and TiO2 surfactants was 0.743 μm. Meanwhile, the surface morphology of gray cast iron FC25 with hybrid nanolubricant SAE 5W-30 (Al2O3-TiO2) and Nanolubricant SAE 5W-30+ (PVP-TiO2) produced the smoothest surface.

Nitrogen-dopped activated carbon was synthesized to see its effect on the characterization of the nitrogen surface functional groups, crystal size, and morphology of the resulting sample. Synthesis of nitrogen-doped activated carbon was carried out by varying the addition of Urea as a nitrogen doping source. Activated carbon compared its characteristics with variations in the concentration of added Urea to activated carbon, at 1:3 and 1:5. The FTIR results obtained were the presence of functional groups indicating the presence of nitrogen bonds in each sample. The crystallinity results showed that the samples were classified as crystalline and nitrogen doping influenced the size of the crystallinity of each sample. The morphology of nitrogen-doped activated carbon shows differences in the grain size of nitrogen-doped activated carbon. Crystallinity and morphology have been shown to affect battery anode performance. The more crystalline of anode material, the electrochemical properties are better. The smaller the grain size of the sample morphology, the stability of the battery cycle is to be great.

Microalgae Spirulina sp which has been cultivated by the Brackishwater Aquaculture Development Center, Situbondo Indonesia were tested for their potential energy performance using proximate analyzer, SEM-EDX, and thermogravimetry. The proximate analyzer showed volatile matter (VM), fixed carbon (FC), moisture, ash content (AC), total sulfur of microalgae Spirulina sp 68.15, 12.57, 11.22, 8.06, and 0.67 (wt%, ar), respectively, and the gross calorific value (GCV) is 4971 kcal/kg (dry basis). SEM-EDX test showed the morphology and chemical content of Spirulina sp. The content of microalgae Spirulina sp is dominated by carbon (C) and oxygen (O), then followed by chlorine (Cl), sodium (Na), potassium (K), sulfur (S), magnesium (Mg), and phosphorus (P). Thermogravimetry pyrolysis test of microalgae Spirulina sp resulted thermogravimetry (TG) analysis and derivative thermogravimetry (DTG) analysis curve, which is divided into three different steps. The moisture of microalga Spirulina sp was vaporized at the first step, started at 27°C, and finished at 173°C with a decomposed mass of about 13.81% of the total initial mass. The second step began at the end of vaporize moisture at about 173°C and ended at around 618 °C. The gasification process occurred in volatile matter content and resulted mass loss of about 57.9% of Spirulina sp total mass. The last step showed the process of gasification of residual substances, started at the end of the volatile matter step, 618°C, and stopped at 995°C with a decomposed mass of 24.6% from total mass.

Tujuan dari kegiatan ini adalah untuk meningkatkan kemampuan mengenal huruf hijaiyah awal pada siswa Taman Kanak-kanak (TK) ‘Aisyiyah Bustanul Athfal 16 Kota Malang dengan pemanfaatan media pembelajaran berupa alat permainan edukatif. Alat permainan edukatif ini bernama “Petak Pintar” yang mengambil konsep dari permainan tradisional engklek. Dengan sedikit modifikasi dan improvisasi, penggunaan alat permainan edukatif petak pintar ini dapat membuat pembelajaran menjadi lebih menyenangkan. Kegiatan pengabdian kepada masyarakat ini melibatkan lembaga sekolah TK ‘Aisyiyah Bustanul Athfal 16 Kota Malang sebagai mitra yaitu 6 orang guru dan 20 orang anak didik kelas B1, serta tim dari Universitas Negeri Malang. Hasil dari kegiatan pengabdian pada masyarakat ini adalah meningkatnya kemampuan mengenal huruf hijaiyah awal sesuai dengan yang ada dalam petak pintar tersebut. Kemampuan yang terdapat dalam pengembangan alat permainan edukatif petak pintar yaitu anak dapat mengenal warna (pada petak dan gaco), anak mampu mengenal macam-macam bentuk geometri (persegi panjang, persegi, dan setengah lingkaran), menyebutkan lambang huruf hijaiyah, menuliskan lambang huruf hijaiyah pada papan tulis yang telah disediakan, memasangkan 2 sampai 3 huruf hijaiyah sesuai perintah melalui gambar pada kartu.

A photoelectrochemical cell (PEC) is a device that converts solar energy into electrical energy stored in the form of hydrogen and oxygen. The n-type semiconductor that shows promising potential as a PEC cell device is known as ZnO. ZnO in the form of nanorods (NRs) is considered capable of increasing the conversion efficiency of PEC performance due to the large surface area. However, in the energy conversion process, the photoactive layer of the PEC cell corrode easily in the electrolyte solution, reducing the stability of the current produced and shortening the lifetime of the PEC cell. In this study, the stability improvement using solid electrolytes in photoelectrochemical technology was studied. Yttria Stabilized Zirconia is a type of solid electrolyte that has high mechanical properties and ionic conductivity. Activation of YSZ powder at various temperatures is considered very instrumental to the efficiency of the PEC cell device. XRD, SEM-EDX, and UV–Vis characterized the samples. For efficiency measurement through I–V testing, it is equipped with photodetectors such as photoresponse of current and voltage as well as photostability. The higher the YSZ activation temperature, several results were obtained, the larger ZnO NRs/YSZ particle size, the lower the thickness of the film, the higher the absorbance value, and the smaller the band gap. In addition, sample agglomeration occurs at the temperature with the lowest activation and sample response when irradiated enough. Finally, the efficiency of the cell increases, namely at the YSZ activation temperature of 1400 °C, where 1% is produced.

The demand for aluminum in various fields continuously grows, including in the automotive industry. In this industry, aluminum is used as the material for the spare part. Therefore, aluminum with high mechanical properties and low casting defects is required. One of the available alternatives for producing excellent aluminum is through aluminum casting, including die casting. Die casting offers low cost in mass manufacturing of complex shaped components with acceptable casting results. Further, the selection of die-casting parameters and the addition of reinforcing elements can also improve the mechanical properties of aluminum. In this study, we strengthened the Al-Si matrix using High Pressure Die Casting process with particles from snail shell powder (calcium carbonate). Further, this study also explores the mechanical properties and microstructure of the product produced through experiment and optimization. The optimization was adopted to identify the optimum parameter. For the optimization, we used the Taguchi method. Our analysis results suggested that the reinforcing agent from the snail shell powder has the CaO and Ca(OH) _2 phases, with a crystallite size of 106.59 nm. The morphology of the shell powder reinforcing agent showed the presence of agglomeration and interconnected structures, such as skeletons, with average particle size of 0.4 micro. The functional group of the shell powder reinforcing agent showed the OH band during the water absorption by CaO, along with asymmetric C–O with vibration from the carbonate group and Ca–O bound. The most excellent hardness level was identified from T8, with 86.33 HRB and die casting parameters of 0.15% reinforce agents, 750 °C temperature injection, and 50 MPa pressure. Meanwhile, the best tensile strength was found from the T9 sample, with 109,95 MPa and die casting parameters of 0.15% reinforce agents, 800 °C temperature injection, and 60 MPa pressure. Microstructure on the used piston die casting sample with snail shell powder reinforcing agent showed the presence of Al, Si, dendrite, and Al _4 Ca phases. The multiple response analysis on the three factors indicated that the reinforcing agent presented the most significant effects toward the tensile strength and hardness, followed by pressure and temperature injection. Meanwhile, the Taguchi method and ANOVA results showed the optimal parameter die casting was obtained from a combination of 0.15 wt% reinforce agent, 800 °C injection temperature, and 50 MPa pressure. A multiple linear regression mathematical model for tensile strength and hardness was developed from the observed data. In regression model, the value of R ^2 of tensile strength 74.02% and R ^2 of the hardness is 95,18% Thus, the developed model can be effectively used to predict the tensile strength and hardness

Friction Stir Welding (FSW) is a solid-state welding method that has diffusion and different metal structures can blend well. Friction stir welding (FSW) has a weakness, one of which is the lack of flexibility the welding process is only carried out on one side of the plate being welded, so it is not applied on thick materials. Double side friction stir welding is a double working process in which the plate to be welded is subjected to friction from two tools on opposite sides. In the DS-FSW welding process, the dimensions and geometry of the tool and pin greatly affect the quality of the joint. This study to determine the mechanical properties and corrosion rate of Double side friction stir welding aluminum 6061 with variation rotation speed and axis of top and bottom tools. The results of this radiographic test can be seen that specimen 4 welded with variations in speed and tool position has defects in the form of incomplete fusion (IF). The results of microstructural observations showed that the heat caused by the welding process resulted in recrystallization in the form of fine grains in the stirring area and there was no phase change. The highest hardness value in the welding area is specimen B. The largest bending value at the 1G welding positions is specimen D, which is 41.86 MPa with a strain value of 13.23%, while the smallest value at the 4G welding position is specimen A, which is 38.18 MPa with a strain value of 5.03%. The fracture and crack surfaces showed that crack initiation, propagation and material stirring failure occurred in all test specimens, even though the impact test specimen was cut in a small area of Incomplete Fusion, but the test results showed that there was still a surface of the parent metal that had not been stirred. The corrosion test method uses three electrode cells with corrosion media as a substitute for seawater with a salinity of 3.5% NaCl, result of corrosion test is specimen B at the 1G welding position has the highest corrosion rate value of 0.63856 mm/year and specimen An at the 1G welding position has the lowest corrosion rate of 0.058567 mm/year.

This study is motivated by the depletion of fossil fuels in nature, which is inversely proportional to the higher level of fuel oil consumption, so the need for alternative fuels, namely biodiesel. Biodiesel can be made using waste cooking oil because of its abundant quantity, low price, and not being reused. One of the efforts to achieve energy conservation and improve fuel quality is using bioadditives. A lemon essential oil can be used as a bio-additive because it is easily soluble in fuel and its oxygen-rich content can reduce the rate of fuel consumption. The process in this study is to produce biodiesel with waste cooking oil (WCO) using a transesterification process. Biodiesel samples containing the bioadditive lemon essential oil on B20 biodiesel with varying volume fraction (0%; 0.1%; 0.15%; 0.2%). In general, this research can be done in three steps. The first step is the characterization of the compound composition (GCMS) and functional group (FTIR) of diesel fuel, biodiesel, and lemon essential oil bioadditive. The second step is the characterization of the physicochemical properties (density, viscosity, flash point, calorific value) of B20 biodiesel with various concentrations of lemon essential oil bioadditive, then compared with SNI 7182:2015. The third step is determining the rate of fuel consumption in diesel engines. The results show that Biodiesel B20 with a volume fraction of 2% lemon essential oil bioadditive has a high ability to reduce the rate of fuel consumption. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Samarium cobalt is known as super high density magnetic material with large magnetic anisotropy energy. Samarium–cobalt exhibits manipulative magnetic properties as a rare-earth material which has different properties in a low sintering temperature. It is therefore of paramount importance to investigate samarium cobalt (Sm2Co17) magnetic properties in the low temperature sintering condition. Sm2Co17, which is utilized in this research, is synthesized via the sol–gel process at sintering temperatures of 400, 500, and 600 °C. Subsequently, the crystallites indicate the formation of a single-phase Sm2Co17 on all the samples in all temperature variations. Moreover, the peaks in the X-ray diffraction analysis of crystallite sizes calculated using the Scherrer equation are 17.730, 15.197, and 13.296 nm at 400, 500, and 600 °C. Through scanning electron microscopy, the particles are found to be relatively large and agglomerated, with average sizes of 143.65, 168.78, and 237.26 nm. The functional groups are also analyzed via Fourier-transform infrared spectroscopy, which results in the appearance of several bonds in the samples, for example, alkyl halides, alkanes, and esters with aromatic functional groups on the fingerprint area and alkynes, alkyl halides, and alcohol functional groups at a wavelength of above 1500 cm. The test results of the magnetic properties using vibrating-sample magnetometer (VSM) revealed high coercivity and retentivity in the samples sintered at 400 °C. However, the highest saturation occurs in the samples sintered at 600 ℃. At a low sintering temperature (below 1000 °C), samarium cobalt shows as the soft magnetic material. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Aluminum alloys emerged as one of the materials used in manufacturing automotive car bodies due to their advantageous properties such as high strength-to-weight ratio, relatively low cost, high ductility, and high corrosion resistance. However, joining aluminum alloys using fusion welding poses serious problems due to the high solubility of hydrogen gas, which causes porosity in welding metal. Subsequently, solid-state welding, such as friction stir welding (FSW), has been considered a porosity-free aluminum joining method. However, the method has limitations, such as low flexibility and the need for a complex clamping system. It is particularly problematic when welding plates. It causes the welding process to be carried out twice on opposite sides, resulting in longer production times. This study designed and assembled a one-step double-side FSW apparatus to address this challenge and conducted welding trials with various welding parameters. During the welding trial, the upper and lower tool rotation varied at 900/900 rpm and 1500/1500 rpm. As a result, one-step double-side FSW was successfully used for welding 6 mm aluminum without any porosity defects. Faster tool rotation results in a wider heat-affected area and higher tensile strength. In addition, the hard test showed that the one-step double-side FSW process had a lower hardness compared to the hardness of the base metal.

The shell and tube heat exchanger was a tool to exchange the heat energy between fluids with different temperatures that occurred through direct or indirect contact. The energy exchange in fluids could be occurred with the same phase (liquid to liquid or gas to gas) or two fluids with different phase. To date, the process of heat transfer in the industrial field was crucial in machine work. Therefore, there were studies directed to optimize and develop the function and thermal performance of a heat exchanger by adding Baffles to the side of the shell. Vortex flow that occurs with the addition of baffles will make the area of fluid contact in the shell with the tube wall larger, so the heat transfer between the two fluids will increase. This study aimed to obtain the efficiency of the heat exchanger and its effectiveness when put on parallel flow. The heat exchanger had the dimensions of 54.6 x 10-3 m in outer diameter and 22.4 x 10-3 m in inner diameter with a tube thickness of 3 mm. The variations on water flow from both fluids were 0.5, 1, 1.5, 2 l/min for hot water and 1, 2, 3, 4 l/min for cold water to obtain the effectiveness of heat exchanger on parallel flow. This research heated the hot fluid in electric heating and used water as the cold fluid. The results showed that heat exchanger with single segmental baffle was more efficient in reducing heat in hot water than heat exchanger without bafe. The flow of fluid affected the average temperature difference; the higher the flow of fluid created a more significant temperature difference. The use of single segmental baffle affected the average temperature difference that was higher than without the baffle. The use of single segmental baffle also influenced the heat transfer greater than without baffle because of the longer distance travelled by the fluid on single segmental baffle with the same flow. Thus, the heat transfer process that occurred was more significant by using a single segmental baffle.

Abstract This research aimed to investigate the structural and magnetic properties of Yttrium Iron Garnet by Ni-doped using self-combustion method. Ni-doped directly changed the structure into Y3Fe5-XNixO12 (x=0.00, 0.02, 0.04, 0.06, 0.08). Self-combustion method was obtained by stirring raw materials at room temperature (27°–28°C) and heated at 150°C until combustion occurred. The samples were sintered at 900°C with 120 minutes holding time. The phase identification revealed the cubic structure of garnet phase with the crystallite size from 62.73–62.87 nm. The molecular bonding from molecular bonding displayed Ni-O and Fe-O bonds, while the magnetic properties shown the highest saturation magnetization of 27.04 emu/g in the sample with additional Ni x=0.02, the highest magnetic remenance of 16.09 in the sample Ni x=0.02, and the highest coercivity of 0.029 in the sample with Ni x=0.08. This research, by adding nickel element, shows that the coercivity of Y3Fe5-XNixO12 decreased when the particle size is increased. The increase in Ni concentration as doping material cause the double exchange interaction and affected the lattice parameter, molecular bond, and magnetic properties.

Recent industrial developments have focused more and more on the applications of lightweight foamed concrete (LFC) in the construction industry, having advantages over normal-strength concrete. LFC, however, has several drawbacks including brittleness, high porosity, excessive drying shrinkage, rapid cracking, and low deformation resistance. Practical engineering typically chooses steel fiber or polymer fiber to increase the tensile and fracture resistance of LFC. The polypropylene twisted bundle fiber (PTBF) was added to the LFC with varying weight fractions of 0.0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5%. Three low densities of LFC were prepared, specifically 500 kg/m3, 700 kg/m3 and 900 kg/m3. The mechanical and durability properties of PTBF-reinforced LFC were determined through compression, flexural, splitting tensile, flow table, porosity, and water absorption tests. The results show that the addition of PTBF in LFC significantly improves the strength properties (compressive, flexural, and splitting tensile strengths) and reduces the water absorption capacity and porosity. The optimal weight fraction of PTBF was between 1.5 and 2.0% for mechanical properties enhancement. The inclusion of PTBF increased the ductility of LFC, and the specimens remain intact from loading to failure. The PTBF reduces the original cracks of the LFC and inhibits the development of further cracks in the LFC.

The impact of MgCO3 and Al2O3 additives on the thermal behavior of Spirulina platensis (SP) biomass during combustion in a thermal analyzer was evaluated to understand their catalytic effect in the decomposition process. The samples were pure SP and a mixture of SP and additives at mass fractions of 3, 6, and 9 (wt,%). Each sample of around 8.5 mg was mounted in a thermobalance and subjected to a furnace on a heating program of 10oC/min. The 100 ml/min air atmosphere was kept continuously flowing during the combustion process from 30–1200oC. The thermal behavior of the sample was then characterized from the thermogravimetric (TG) and derivative thermogravimetric (DTG) curves, those were recorded by a computer during the experiment. The Horowitz–Metzger method was used to evaluate the impact of additives on the kinetic parameters of the samples. The results indicated that the presence of additives shifted the main decomposition stage toward a lesser temperature. The rate of mass loss (ML) in the main decomposition zone decreased in the 1st peak and increased in the 2nd, in accordance with the increase in the fraction of additives. This indicates that additives play different roles during the decomposition process. The mass mean activation energy (Em) increased at the additive fraction of 3% for both MgCO3 and Al2O3, as well as at 6% MgCO3 compared to combustion with no additives. Conversely, the presence of greater additives promoted a shift in Em toward smaller values. These results confirm that both additives significantly influenced the thermal behavior and kinetics of the SP combustion.

During the solidification process, metal liquids turn into solid geometry units including the riser and gating system. The disruption in the liquid flow often causes shrinkage in the object. Critical Solid Fraction Point is a critical point where the continuous liquid supply turned solid and unable to pour to some sections. Simulation software can predict the critical solid fraction time of an object and the liquid supply behavior. The simulation helps the designer in the casting design. The application of low steel alloys in the cement industry, e.g., the Diaphragm, needs development to minimize the shrinkage. This research aimed to analyze the critical solid fraction point in the diaphragm steel casting products. The primary objective of this research was to predict the critical solid fraction point during solidification, started from the longest time in the riser/feeder using SOLIDCast 8.1.1 casting software and provided improvement recommendation to minimize the shrinkage.

This article reviewed the hematite α-Fe2O3, which focuses on its material properties, nanostructures, synthesis techniques, and its numerous applications. Researchers prepared the hematite nanostructure using the synthesis methods, such as hydrothermal, and, further, enhanced it by improving the techniques to accommodate the best performance for specific applications and to explore new applications of hematite in humidity sensing.

Nanoreinforce materials such as ZnO, eggshell, Al2O3, TiO2, and ZrO2 have been shown to improve the mechanical properties of Al-Si alloy. Nanomaterial Fe2O3 has many applications as catalysts reaction in electronic devices, for example, semiconductor materials, paint formulations, lithium rechargeable batteries, and is often applied in industrial fields. It is known that Fe2O3 can be synthesized through the stirring process on machine and method used will involve several steps that relatively take a long time. In this study, Al-Si alloy reinforced by using nanomaterial Fe2O3 which sintered at a temperature of 600°C for 3 hours aimed to improve mechanical and morphological properties of Al-Si alloy. The method used was stir casting, where this method was known as flexible, simple, and economic. The result of reinforcing Al-Si alloy by using nanomaterial Fe2O3 had affected on the hardness level of Al-Si alloys as evidenced by the fracture morphology that was brittle and had a light reflection

The effects of MnFe2O4 nanocatalyst addition toward HDPE plastic waste pyrolysis have been investigated by performing experiments on METTLER TOLEDE TGA DSC1 Simultaneous Thermal Analyzer at heating rates of 10oC/min by nitrogen and temperatures range from room temperature to 1000oC. The results of pyrolysis showed that the main polymer components of HDPE plastic waste, both, with and without MnFe2O4 nanocatalyst addition degraded in one stage. The MnFe2O4 nanocatalyst addition increases the maximum mass loss rate of HDPE plastic waste pyrolysis, however, it increase the degradation of the initial temperature.

Abstract Zinc ferrite (ZnFe2O4) nanoparticles have attracted the attention of researchers because of their unique chemical properties and particle-size-dependent magnetic properties. High-surface-area spinel ferrites have numerous technical applications in areas such as high-density information storage, ferrofluids, and catalysis. The coprecipitation technique is the preferred method for preparing nanoscale ZnFe2O4 because it results in a small crystals with a uniform size distribution. In this study, the synthesis was conducted in solution for 48 h, followed by sintering at 1000°C for 1.5–3.5 h. The smallest crystals (70.58 nm) were found in the sample sintered for 2.5 h. Fourier transform infrared spectroscopy (FTIR) functional-group analysis confirmed the presence of Fe–O and Zn–O bonds of cations in octahedral and tetrahedral sites. The ZnFe2O4 sintered for 3.5 h was superparamagnetic. The characterization results suggest that the obtained ZnFe2O4 could be used as a nanofluid in heat exchangers.

Metal casting process can be described as the process of making object by melting metal then poured into the desired mould. The mould that is commonly used is sand moulding. Binder which commonly used in sand casting process is bentonite. Bentonite is kind of mineral which can be run out if it is used continuously. The background of this study was to analyse the other binder that could reduce the use of bentonite by utilizing eggshell. This study aimed to analyse the hardness, microstructure, macrostructure, and fluidity of the cast which yielded by using variations of eggshell. The method that used was experimental method with a model of one-shot case study with descriptive analysis. The study result showed that the highest value of fluidity test was found at variation of 7% eggshell and 3% bentonite with hardness value of 180.86 HV. There were found several defects, casting result with variation of 4% eggshell and 3% bentonite found that there were ± 28 pinhole defects and ± 20 open grain defects. There were found ± 65 pinhole defects and ± 30 open grain structure defects in the casting result with variation 7% eggshell and 3% bentonite. The casting result with variation 10% eggshell and 3% bentonite had ± 50 pinhole defects and ± 30 open grain structure defects.

This study aimed to analyse the usage of Eggshell as mixture material of bentonite in metal casting process which used dried sand moulding. Eggshell variations in this study were 4%, 7%, 10% eggshell, and additional 3% of bentonite on each sample. This study used pre-experimental method and included to One-Shot Case Study model. The highest strength was found on the sample 3 ES 10%. Tensile strength of dried sand moulding reach up to 0.09 kg/cm2, the compressive strength of dried sand moulding reached up to 3.11 kg/cm2, and the shear strength of dried sand moulding reached up to 1.13 kg/cm2. Based on the test result indicated that permeability of sand moulding by heat treatment at 110ºC for 60 minutes at sample of 3 ES 10% was at 178.3 ml / min.

Electric arc welding with covered electrodes is ideally suited for flat plates. If this technique is employed for welding rigid bodies, the results would be of poor quality. One viable solution to weld rigid bodies is through friction welding. The study aimed to investigate the tensile strength of specimens subjected to friction welding with variations in rotational speed, friction time, and pressure and to examine the microstructure of friction welding joints. This research used the one-shot case study design and involved descriptive analysis. The descriptive analysis described the results of tensile testing and microstructure of welding joints. Results showed that the specimen subjected to a 2850 rpm rotational speed, 60-second friction duration, and 8 MPa pressure had the highest tensile strength of 15.19 Kgf, whereas that rotated at 2850 rpm under 8 MPa pressure for 80 seconds had the lowest tensile strength, i.e. 12.25 Kgf. The photomicrographs showed that the friction welding joints underwent no phase change, but the refinement of Mg2Si particles occurred in the Zpd and Zpl zones. Also, the Zud zone consisted of the same form of Mg2Si particles as the untreated specimen.

In metal forming, damage can be caused by several factors: load on the workpiece, initial heating temperature, and temperature due to the friction between the die and the material for pre-forming. The metal forming process can be executed in 2 ways, namely by hot working and cold working. During these two types of mechanical working process, the metal undergoes plastic deformation. In hot working, the required deformation force is relatively low, and changes in mechanical properties are also insignificant. In cold working, a higher force is required, but the strength of the metal will increase significantly. The use of simulation has become increasingly widespread to predict and describe process mechanisms and optimize the pre-forming process. The study was conducted using a three-dimensional (3D) simulation to predict the effect of variations in time, material and temperature on the damage of pre-forming blocks. The simulation results showed that the greatest damage occurred after 0.006 s and at 25 °C to the specimen 1 (Aluminium 1xxx) with the highest damage value of 0.011833 which occurred. Specimen 7 (Aluminium 3xxx) had the lowest damage with the value of 0.011542 which occurred after 0.010 s and at 25 °C.

The air pollution particle emitted from transportation in Indonesia Bay 2015 consist of 70.50% CO; 18.34% HC; 8.89% NOx; 0.88% SOx; 1.33%. These gases are very harmful to humans. To reduce the toxic gas effect, special treatment is needed, one of them is by applying catalyst on exhaust system. MnFe2O4 has the potential to bind the CO and HC elements contained in the exhaust gas. This study aims to investigate the effect of MnFe2O4 addition on catalityc converter towards CO gas and HC emissions of motor vehicles. Therefore, the percentage of exhaust reduction with and without applying MnFe2O4 on varied engine rotation using fuel with RON of 88, 90, 92 and 98 can be revealed. The results describe that the highest reduction precentage of CO content by applying MnFe2O4 nanoparticles as a catalyst for premium, pertalite and pertamax fuel are 34.1% (effective at low and high rotation); 31.1% (effective at all rotations); and 3.9% (effective at low rotation). On the other hand, the highest reduction percentage of HC content on premium, pertalite, pertamax and pertamax turbo fuel are 79.3% (effective in high rotation); 71.4% (effective at high rotation); 53,6% (effective in high rotation); and 2.1% (only effective at low rotation).

Severe effects of the mercury use on health as an amalgam material have required an alternative material in order to eliminate it from amalgam composition. This research was conducted to analyze the physical properties and compressibility of ZnO nanopowder as an alternative amalgam material. The physical properties including morphology, dimensions, and the atomic ratio were analyzed by SEM, XRD-XRF and EDX. Further, the compressibility was conducted by using hydraulic press machine. The results showed that ZnO has particle size of 14.34 nm with morphology classified as nanorods. In the compressibility test, both the variation of compression loadings and holding time have brought an effect on the significant increase of ZnO nanopowder density.

This study aimed to determine the toughness of casts produced by the sand casting process at various temperatures against brass, and to investigate the structure contained in the cast madeusing abrass metal mould. This study was experimental research that observed the results of a treatment applied to a specimen group. This pre-experimental study usedthe one-shot case study model in which a group of samples was given treatment. The results showed that the specimen poured at 900°C exhibiteda microstructure consisting ofgood Cu-Zn content, while that at 700°Chad the least Cu content. It indicates that the higher the temperature used for metal casting (brass), the more brittle the cast. The toughness of the materialwas influenced by the alloy composition and the pouring temperature of each specimen; the higher the pouring temperature, the better the treatment of alloy. The photomicrographs indicate that the higher the pouring temperature usedin the metal casting (brass), the lesser the carbon element contained in the material.

Direct detection of hydrocarbon by an active source using electromagnetic (EM) wave termed Sea Bed Logging (SBL) has shown very promising results. However, currently available electromagnetic wave technology has a number of challenges including sensitivity and lapsed time. Our initial response to this issue is to develop a ferrite-based EM wave detector for Sea Bed Logging (SBL). Ferrite bar and copper rings in various diameters were used as detector 1 (D1). For Detector 2 (D2), toroid added with copper wires in different lengths at the centre of it were used. The first experiment is to determine the inductance and resistance for both detectors by using LCR meter. We obtained the highest inductance value of 0.02530 mH at the ferrite bar when it was paired with a 15 cm diameter copper ring and 0.00526 mH for D2 using a 100 cm copper wire placed at the centre of the toroid. The highest resistivity for D1 was measured at ferrite bar paired with a 15 cm diameter copper ring and 1.099 Ω when using 20 cm length of copper wire. The second interest deals with voltage peak-to-peak (Vp-p) value for both detectors by using oscilloscope. The highest voltage value at the ferrite bar of D1 was 25.30 mV. While at D2, the highest voltage measured was 27.70 mV when using a 100 cm copper wire. The third premise is the comparison of sensitivity and lapsed time for both detectors. It was found that D1 was 61% more sensitive than D2 but had higher lapsed time than D2.

Cassava starch based bioplasticfor packaging application has great potency because of the various starch-producing plants in Indonesia.Bioplasticcan contribute to reduce the dependence on fossil fuels andpetroleumthat can solve the environmentalproblem.Thepurpose of this research is to find out the thermal decomposition and the activation energy of cassava starch based bioplastic. The methods weresynthesis bioplastic with cassava starch as main component and glycerol as plasticizer. The thermogravimetry analysis was conducted to obtain the decomposition process mechanism of bioplastic and the heating valueof bioplasticwas measured using theadiabatic bomb calorimetric. Data analysis was conducted using a fitting model approach with an acikalin method to determine the activation energy. The result of thethermogravimetricanalysis showed thatbioplasticisgraduallydecomposedto the moisture, volatilematter, fixed carbon, andash in four stages mechanism. Totally decomposition of bioplastic was 530°C, then all of bioplastic was become the ash. The activation energy in the early and primary thermal decomposition stages are 1.27 kJ/moland 22.62 kJ/mol, respectively and heating valueof bioplastic is 15.16 MJ/kg.

A binder is any material used to strengthen the bonding of moulding sand grains. The primary function of the binder is to hold the moulding sand and other materialstogether to produce high-quality casts. In this study, there were four binder compositions being tested, i.e. 5% bentonite + 5% Portland cement, 4% bentonite + 6% Portland cement, 6% bentonite + 4% Portland cement, and 7% bentonite + 3% Portland cement. Each specimen was measured for its compressive strength, shear strength, tensile strength and permeability. The highest compressive strength was obtained fromthe specimen composed of 6% bentonite+ 4% Portland cement. The highest shear strength was obtained from the moulding sand with 7% bentonite+ 3%Portland cement. The highest tensile strength was obtained fromthe specimen contained 5% bentonite+ 5% Portland cement. The specimen composed of 5% bentonite + 5% Portland cement had the lowest permeability of 131 ml/min, while that of 6% bentonite + 4% Portland cement had the highest permeability of 176 ml/min.

This paper investigates the effect of using metakaolin Artificial Lightweight Aggre­gates (ALWA) as a substitute for coarse aggregates to produce structural lightweight concrete. A combination of 10M NaOH solution and sodium silicate solution was used as alkali activator. The ratio between the metakaolin binder and the alkali activator used in producing metakaolin ALWA is 48%:52%, by mass. It is shown that metakaolin ALWA has higher abrasion and water absorption, and lower bulk density values compared to normal aggregates. To determine the effect of using metakaolin ALWA as coarse aggregates in concrete, three variations of ALWA dosages were used, i.e. 0%, 50%, and 100% of the total coarse aggregates, by volume. The results show that the compressive strength of concrete decreased along with the increase of ALWA content in the mixture. However, concrete using 100% ALWA as coarse aggregates meets the requirements of compressive strength and density of structural light weight concrete.

Direct detection of hydrocarbon by an active source using electromagnetic (EM) energy termed seabed logging (SBL) has shown very promising results. However, currently available electromagnetic wave technology has a number of challenges include sensitivity and frequency matching. This paper presents development of the carbon nanotubes (CNTs) as electromagnetic wave detector due to outstanding properties of carbon nanotubes. They are currently one of the desired materials for advanced technologies. Two types of detectors were developed in this work, carbon nanotube-based (D1) and without nanotube-based (D2) detectors. Various configuration and arrangement for each type of detector were investigated to determine the one with the highest detection measurement and stability of frequency stability of detection system. It was found that 20 turn-coils coil placed at its centre gives the maximum detection of induction voltage, 39.61 mV. However, the 20 turn- coils with CNTs which gives 36.50 mV is the preferred EM detectors due to the stability in frequency of the detection system.

Leaf spring, as one of the main components of the suspension system, serves the function of absorbing road shocks and any wheel vibrations, preventing them from being transmitted directly to the vehicle body. Moreover, it can increase the tire traction as well as support the weight of the vehicle and various kinds of external forces. Various studies on the use of composite materials for leaf springs have shown that the strength of composite leaf spring is similar to steel leaf spring with the same load carrying capacity. However, the composite leaf spring has the added advantage of being more lightweight. In fact, composite materials have been preferable for many purposes not only because of its properties but also its lightweight structure and cost effectiveness. The analysis process was carried out using the finite element method by means of ANSYS software to display the output of the analysis being performed. After the output is known, the amount of voltage in conventional, mounted, and progressive spring can be determined. Based on the data analysis, we concluded that conventional straight leaf springs produced a maximum voltage of 653.13 MPa and maximum deflection of 4367.1 mm. The results of the analysis using the finite element method showed that conventional leaf springs (both straight and not) are considered as the most effective model of leaf spring in terms of the power generated.

Today‟s major challenge for oil industry is to improve the oil recovery from the reservoir. Various enhanced oil recovery (EOR) methods have been applied in the field and the steam injection is one of the most favourable methods. The deep reservoir will result in failure of this method due to excessive heat dissipation. In this situation, generating and injecting steam may be uneconomical due to the tremendous reduction of the recovery. Some methods using nanotechnology have been introduced and elaborated. However, we propose the electromagnetic (EM) method as an alternative due to its long range transmission of the transverse waves. These EM waves, coupled with some nanoparticles (NP), can modify the surface energy. We propose an optimum conditions based on some parameters namely, frequency, flux density, space charge density and skin depth, employing Maxwell and Helmholtz equations which interact with some magnetic and dielectric nanoparticles. A newly-designed EM antenna with a very high flux density is the model for this specific purpose. The electrical energy from the antenna transfers the waves to the dielectric and resistive nanoparticles, which is then transferred to the fluid with high capillary force. This results in lower surface tension which reduces the oil viscosity. In order to investigate the transport phenomena of the nanoparticles in porous medium, we applied Darcy‟s law. Our preliminary study for scale model simulations showed that at a frequency of 0.125Hz, the electric field of the curve antenna with magnetic feeders was 4280% higher compared to the one without magnetic feeders,At a frequency of 0.125Hz, the magnetic field of the curve antenna with magnetic feeders was 3677% higher in comparison with the one without magnetic feeders. With the increasing frequency from 0.125Hz to 9Hz, the electric field and magnetic field of the antenna with feeders decreased by 99%. The permeability and porosity of glass beads packed column was 30.58mD and 25.87% respectively. It was observed that the cumulative recovery of oil reached 21.11% by using ZnO nanofluid with electromagnetic waves, 17.23% by using ZnO nanofluid without electromagnetic waves, 32.59% by using iron oxide nanofluid with electromagnetic waves, and 29.68% by using iron oxide nanofluid without electromagnetic waves. In summary, the use of ZnO and iron oxide nanoparticles as nanofluids with electromagnetic waves is considered the most effective to use in enhanced oil recovery.

The major factors determining the quality of sand casting products are the base sand and the composition of the sand mould and the binding material. In the foundry industry, the most commonly used binder for creating sand moulds is bentonite. However, the price of bentonite is likely to keep rising. This study aimed at discovering a new binder formula associated with the effect of binder composition i.e. bentonite, tapioca flour, and sago flour on the basis of its mechanical and physical properties. The new formula was expected to be a better binder in the production of sand moulds, resulting in high-quality casting products with minimal defects. Moreover, it is probable to be much more economical than bentonite. This research focused on testing the moulding sand composition with a number of different binders, i.e. bentonite, tapioca flour, and sago flour, each in a different proportion. The mixture of the moulding sand with each of the three binders will be tested in terms of its mechanical properties including compressive, shear, and tensile strength. Based on the test results, sago flour has the highest dry compressive strength of 28.6 N/cm2, whereas bentonite has the highest wet compressive strength, i.e. 11.83 N/cm2 and the highest wet shear strength i.e. 3.16 N/cm2. The binder with the highest dry shear strength is tapioca flour with 18.16 N/cm2. Regarding the tensile strength value, bentonite has the highest wet tensile strength of 0.85 N/cm2, while sago flour has the highest dry tensile strength of 1.73 N/cm2.

This research aimed to determine the effect of heat treatment temperature variations on the physical properties and the quail eggshell’s compressibility. The quail eggshells was obtained from the waste of restaurants and market traders and processed into powder form by ball milling method for 10 h and sintered at 900 °C, 1000 °C, and 1100 °C, a holding time of 1 h. The samples were characterized using x-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Pressure test for the compressibility result. The results showed that after the heat treatment process, the calcium carbonate phase (CaCO _3 ) was transformed into calcium oxide (CaO). The crystal size on raw material was 52.18 nm and no more than 50 nm in all heat treatment samples. Morphology of eggshells showed variations in the size and shape of grains such as round, rod, and square. Whereas the compressibility test results showed that the addition of charging to the test conducted increased the compressibility value (density). The results also showed physical properties such as pore size and grain size affected quail eggshells’ compressibility value.

In this study, a series of novel nickel catalysts supported on reduced graphene oxide nanosheets (Ni/rGO) with Ni loadings of 10, 15 and 20 wt% were successfully synthesized via the incipient wetness impregnation method. The physicochemical properties of the catalysts and rGO support were thoroughly characterized by thermogravimetric analyser, X-ray diffraction, fourier-transform infrared spectroscopy, Raman spectroscopy, N2 adsorption-desorption, temperature programmed reduction, temperature programmed CO2 desorption and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy. The properties of the catalysts are correlated to its catalytic activity for CO2 methanation which were investigated using three-phase slurry reactor at low temperature and pressure of 240 °C and 10 bar, respectively. Among the three catalysts of different Ni loading, Ni15/rGO shows the highest activity of 51% conversion of CO2 with total selectivity towards CH4. N2-physisorption and CO2-TPD analysis suggest that high catalytic performance of Ni15/rGO is attributed to the high surface area, strong basic sites and special support effect of rGO in anchoring the active metal.

Penyusunan buku teks harus menyesuaikan kurikulum yang ber­laku yaitu ku­rikulum 2013. Realita menunjukkan tidak semua bu­ku memiliki kualitas isi dan ke­se­suaian isi seperti KI dan KD dalam kurikulum. Ba­nyak buku teks yang disusun ti­dak menyesuaikan pendekatan scientific yang berlaku di kurikulum 2013. Kondisi ter­sebut bertentangan denganfungsi buku teks dibuat yaitu untuk menunjang proses bel­ajar sesuai materi KI dan KD yang tercantum dalam kurikulum 2013. Hal tersebut be­lumdipenuhi secara ideal ada beberapa buku teks perlu dikaji ulang.Peningkatan kua­­­litas buku teks, salah satunyabuku Mekanika dan Elemen Mesin SMK Kelas X, per­lu adanya kajian terkait kesesuaian isi buku yang dapat menunjang pem­bel­ajaran de­ngan pendekatan scientific sesuai dengan kurikulum 2013 serta bagaimana se­­­­­­­ha­rus­nya buku disusun dengan menggunakan pendekatan scientific.