bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of reduction temperature and sodium-based additives on nickel upgrading process of laterites ores
Authors: Shofi A , Rahmahwati A , Nurjaman F , Suharno B 
Published: July 2019

Abstract
In this present work, the selective reduction of nickel laterite was conducted by using 10 wt. % of sodium carbonate, sodium chloride and sodium sulphate as additives. The 5 wt. % of palm shell charcoal was used as the reductant. The selective reduction process for nickel laterite was carried out from 950ºC to 1150ºC for 60 minutes followed by wet magnetic separation using 500 Gausses permanent magnet. The characterization of reduced ore was performed by X-Ray Diffraction, optical microscope and Scanning Electron Microscope with Energy Dispersive X-Ray Spectroscopy, while the chemical composition of concentrate or ferronickel was identified by X-Ray Fluorescence. The results showed that the nickel grade was increased with the increasing of reduction temperature for nickel ore with sodium sulfate additive. Nevertheless, it was relatively constant for sodium carbonate and sodium chloride additive. Nickel recoveries found increased with the increasing of reduction temperatures of nickel ore with sodium-based additives. The ferronickel particle was agglomerated and growth with the increasing of reduction temperature, thus it provided favourable conditions for the separation of ferronickel from impurities in the magnetic separation process.
The effect of nitrogen dopant on hydrogenated graphene for hydrogen storage application
Authors: Ganta M , Susilo D N A , Sunnardianto G K , Handayani M 
Published: July 2019

Abstract
We investigated the effect of nitrogen dopant on the charge transfer rate (CTR) and reaction pathways of hydrogen molecule dissociation on graphene and nitrogen-doped graphene based upon first principle calculation. We found that the nitrogen atom form covalent bonds with the carbon atoms with bond length of C-N of 1.41 Å. The geometry optimization results in nitrogen doped pristine graphene revealed that nitrogen pulled downward the nearest neighbor of carbon atom, thus the structure is a bit downward. We found the charge transfer rates from hydrogen to carbon atom is decrease with respect to pristine graphene and nitrogen doping also can decrease the activation barrier of hydrogen molecule dissociation on graphene surfaces.
The effect of single and double vacancy on hydrogenated graphene for hydrogen storage application
Authors: Yahya M S , Sunnardianto G K , Handayani M 
Published: July 2019

Abstract
We investigated the effect of single and double vacancy on the charge transfer rate of dissociation of hydrogen molecule adsorb on graphene based upon density functional theory calculation for hydrogen storage application. Here, we would like to compare the effect of the single and double vacancy on the charge transfer rates of hydrogen molecule dissociation adsorbed on graphene. Before investigated the charge transfer rates, we optimized the structure of graphene, graphene with single and double vacancy and observed the interaction with hydrogen molecule. Preliminary result revealed that once hydrogen molecule is dissociated to be hydrogen atoms and adsorbed to the dangling bond, the charge transfer rates is decrease compared with the charge transfer from hydrogen to pristine graphene indicated that hydrogen atom absorbed on dangdling bond changing the orientation of hydrogen adsorbed. As for the C-H bond length is decrease around to be 1.11 Å compare to the pristine one 1.12 Å. We need to explore more on the reaction pathways to get the global picuture on the effect of single and double vacancy on the dissociation of hydrogen molecule on graphene surface.
Mechanical properties and curing characteristics of shape memory natural rubber
Authors: Setyadewi N M , Indrajati I N , Darmawan N 
Published: July 2019

Abstract
Natural rubber, which is a polydiene elastomer, is one of the attractive raw materials that could be developed as a shape memory polymer because of its high mechanical and elastic properties. This study aims to determine mechanical properties and curing characteristics of heat-induced shape memory polymer of natural rubber or herein after referred to shape memory natural rubber (SMNR). Natural rubber with different blend ratios of sulphur was prepared by a two-roll mill. The curing characteristics were determined using Moving Die Rheometer at 150°C. The effect of sulphur (0.75; 1.25; 1.5 phr) on mechanical properties such as tensile strength, tear strength and shape memory properties of the stearic acid swollen SMNR vulcanizates were investigated. This research showed that the higher sulphur amount gives the higher torque difference and higher mechanical properties. Shape memory compound swollen stearic acid exhibited shape recovery of 98-100% and shape fixity 59-88.5%.
Pitting corrosion resistance of CA6NM as geothermal turbine blade material in simulated artificial geothermal brine
Authors: Nikitasari A , Prasetyo M A , Riastuti R , Mabruri E 
Published: July 2019

Abstract
Fatigue failure of turbine blades originating from pitting corrosion is a critical issue for power plant. Herein, we study the pitting corrosion resistance of cast CA6NM as turbine blade material in simulated geothermal environment with and without CO2 gas by using cyclic polarization measurement. Three different molybdenum and nitrogen content of CA6NM were used for experiments: (i) CA6NM with a molybdenum content of 1 wt.% and without addition of nitrogen, (ii) CA6NM with a molybdenum content of 2 wt.% and without addition of nitrogen, (iii) CA6NM with a molybdenum content of 2 wt.% and nitrogen content 0.1 wt.%. The measurement reveals CA6NM with molybdenum 2 wt.% and nitrogen 0.1 wt.% is the most resistance to pitting corrosion in simulated artificial geothermal brine with and without CO2 gas.
Green simple microwave-assisted extraction (MAE) of cellulose from Theobroma cacao L. (TCL) husk
Authors: Ndruru S T C L , Wahyuningrum D , Bundjali B , Arcana I M 
Published: July 2019

Abstract
This work had successfully produced Theobroma cacao L. (TCL) husk-based cellulose used efficiently and friendly environmentally simple microwave-assisted extraction (MAE) method. The microwave-assisted heating time optimization of alkaline-treatment was carried out for 10, 20, 30 and 40 minutes. Microwave-assisted bleaching process was also conducted using green bleaching agent H2O2, and also utilizing microwave heating for 60 minutes. The followed treatment was filtered, neutralized, washed and overnight freeze-dried. Fourier transform infrared (FTIR) analysis confirmed common cellulose functional groups of TLC, are β-(1,4)-glycosidic bonds at ∼897 cm-1, O-H (hydrogen bond) at 3412 cm-1, C-H vibration at 2902 cm-1, C-O-C asymmetric at 1161 cm-1, and C-OH out-of-plane bending at 665 cm-1. FTIR analysis, in addition, also studied crystallinity ratio (CrR), hydrogen bond energy (E
H) and hydrogen bond distances (R
H), while particle size analyzer (PSA), X-ray diffraction (XRD) and thermogravimetry analysis (TGA) were carried out to confirm particles sizes, crystallinities and thermal stability properties of TCL husk, cellulose of TCL husk and commercial-microcrystalline cellulose (MCC), respectively.
Synthesis and characterization of mesoporous silica nanoparticles (MSNp) MCM 41 from natural waste rice husk
Authors: Purnawira B , Purwaningsih H , Ervianto Y , Pratiwi V M , Susanti D , Rochiem R , Purniawan A 
Published: July 2019

Abstract
Rice husk contains silica up to 86.9-97.3%, it potentially as precursor silica in the synthesis process of mesoporous silica MCM 41. First, use acid leaching as pre-treatment of rice husk extraction, followed by heat treatment at 600°C in the furnace, continued with sol-gel process to get amorphous silica. Mesoporous silica was synthesizing using CTAB as surfactant to assist porous of silica MCM 41 (CTAB-templated silica). CTAB concentration were 1, 1.25 and 1.5%. Mesoporous silica nanoparticle MCM 41 synthesized by sol-gel method, followed by hydrothermal and reflux methanol + HCl. X-ray diffraction pattern showed that silica has amorphous liked-structure, indicated by peak broadening at 2-theta around 22-24°. Fourier Transformed Infrared-FTIR shown functional group of Si-O, Si-O-H, Si-O-Si, -OH, Si-H, and Si-OH bond have been identified. Scanning electron microscope (SEM) shown particle agglomeration and particle sizes range between 311-482 nm. The desorption adsorption nitrogen analysis (BET analysis) showed that surface area and pore diameter at 1%, 1.25% and 1.5% CTAB have surface area 552.429 m2/g, 768.947 m2/g and 705.501 m2/g. In hence pore diameters are 3.4178 nm, 3.0517 nm and 3.4098 nm respectively.
Effect of austempering treatment time on strength, ductility, hardness, and abrasive wear resistance of JIS FCD 700 ductile iron
Authors: Rinaldo H , Januar M , Sinaga M M 
Published: July 2019

Abstract
The effects of austempering treatment time on the strength, ductility, hardness, and abrasive wear resistance of JIS FCD 700 were studied. The austempering was carried out at a temperature of 315 °C and treatment times of 19, 30, 50, and 77 mins. The results indicate that the variations of the austempering time alternate the mechanical properties of the material, depending on the retained phases in the microstructure. A higher retained austenite induces a higher abrasive wear resistance and strengths, while the presence of acicular ferrite produces a lower hardness. Moreover, the large number of losses in martensite and retained austenite phases deteriorate the overall mechanical performances, as exhibited in the austempering time longer than 50 min. It is found that the 50 min of austempering time yields the optimum performance in terms of strengths (tensile strength of 1058 MPa and yield strength of 859 MPa), ductility (4,08 %), hardness (37 HRC), and abrasive wear resistance (0,21 x 10-6 mm3/mm at 6,32 kg load). This optimum performance was achieved mainly due to the relatively larger amounts of retained austenite in the JIS FCD 700.
Preliminary Synthesis of Slow Release Fertilizer Material by Using Obsidian Rock
Authors: Solihin  , Handoko A D , Noviardi R R 
Published: July 2019

Abstract
Slow release fertilizer is a new kind of fertilizer in which the release rate of elements from fertilizer can be controlled. The controlling of nutrient component release rate lead to the increasing of fertilizer efficiency, decreasing agricultural cost, and decreasing ground water pollution. Obsidian from West Java, Indonesia is one the mineral that can be used to synthesize slow release fertilizer. By using this method, ordinary fertilizer is placed in the matrix of polymerized obsidian. The release test to the slow release fertilizer material shows that the material exhibits slow release property.
The Effect of deposition times on preparation of SnO2:F conductive glass by Indonesian local stannic chloride precursors
Authors: Arini Tri , Hanum Lalasari Latifa , Firdiyono F. , Andriyah Lia , Fahmi Gennady , Yustanti Erlina , Subhan Achmad , Herman Yuwono Akhmad 
Published: July 2019

Abstract
The performance of fluorine-doped tin oxide (FTO) as an alternative semiconductor besides indium tin oxide (ITO) has been investigated. Currently, the precursors often used in the manufacture of fluorine-doped tin oxide (FTO) are commercial precursors on the market. In the present work, a thin film FTO will be fabricated using a pyrolysis spray technique with an ultrasonic nebulizer using Indonesian local precursors of stannic chloride with the variation of deposition times (5, 10, 15, 20 and 25 minus). Thin films were characterized by using x-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet-visible (UV-Vis) spectroscopy, and four-point probes. The optimum result obtained by pyrolysis technique with a deposition time of 20 minutes and substrate temperature at 300 °C has a resistivity of 1.059 x 10−4 Ω.cm and transmittance 89.614%. Fluorine-doped tin oxide (FTO) fabricated by using these local Indonesian precursors promise for further development as a glass of dye-sensitized solar cells (DSSC).
The effect of first step holding time of low high austempering heat treatment to the mechanical properties of Austempered Ductile Iron (ADI)
Authors: Bandanadjaja B , Idamayanti D , Widarmansyah N , Lestarianto A 
Published: July 2019

Abstract
A low-high austempering process can be referred to as the application of undercooling condition in the austempering process of Austempered Ductile Iron (ADI). Undercooling condition promote more grain nucleation and producing finer grains with good mechanical properties. This study aims to investigate the influence of the first stage of lower temperature austempering holding time on its mechanical properties and find the best holding time which can produce the highest toughness of ADI materials. The experiment began with the heating of the nodular cast iron sample up to 927 °C and held for 120 minutes. Then it quenches to a liquid salt bath with a temperature of 260 °C as a lower temperature of the first austempering stage with a variation of holding time at 30, 60 and 90 minutes. Then it was transferred to a second salt bath medium of 400 °C as the second austempering stage with a holding time of 120 minutes then it was given the air cooling. The sample was tested by hardness, tensile, impact, and metallographic examination. The results show that the best toughness value in this research is obtained at 30 minutes holding time on first austempering stage with mechanical properties is tensile strength 1273 MPa, yield strength 1162 MPa, elongation 4,87% and impact value at 54.15 J. Value modulus of toughness is 5.93x107 J/m3.
Improvement of erosion resistance of alumina-phosphate ceramic coating on mild steel by SiC addition
Authors: Idamayanti D , Nurhakim I L , Bandanadjaja B , Purwadi W , Lilansa N 
Published: July 2019

Abstract
This research is focused on the application of the Al2O3-phosphate ceramic coating on mild steel surface to protect mild steel from erosion in coal dust environment. Erosion resistance of mild steel could be improved by overlay it with SiC in the Al2O3-phosphate ceramic coating. As a filler, Al2O3 was mixed with 20%, 40%, and 60% SiC by using aluminium phosphate as a binder and heated at 220 °C for 5 hours. X-ray diffraction testing was conducted to observe the phase of Al2O3-SiC phosphate ceramic coating. Meanwhile, surface morphology and adhesion characteristic of Al2O3-SiC phosphate ceramic coating were analyzed by scanning electron microscope. To analyze the erosion resistance quantitatively solid particle impingement test by applying gas jets at the right angle (90°) against a sample surface has been conducted. The results showed that Al2O3-SiC phosphate ceramic coating is strongly bound to the mild steel surface without the presence of any void. The higher the SiC content can increase the ceramic coating density and its erosion resistance. The SiC 60% produces four times higher erosion resistance than uncoated mild steel. The material characterization of Al2O3-SiC phosphate ceramic coating proves that SiC gives a significant impact on the enhancement of erosion resistance of the Al2O3-SiC phosphate ceramic coating.
Corrosion of carbon steel after exposure in the river of Sukabumi, West Java
Authors: Royani A , Prifiharni S , Nuraini L , Priyotomo G , Sundjono  , Purawiardi I , Gunawan H 
Published: July 2019

AbstractIn this study, the corrosion behavior of carbon steel had been investigated in the river of Sukabumi Region, West Java. The corrosion rates of those steels were measured by weight-loss method after exposure for certain periods of time in various depth of water (0 meters and 1 meter). The surface morphology and the composition of their corrosion product were characterized using scanning electron microscopy (SEM), XRD (X-ray diffractometer) and energy dispersive spectroscopy (EDS). After exposure, the entire surface of carbon steel was covered by corrosion product in all depth of water. On the basis of results, the corrosion rate of those steels was 19.86 mpy for 0 meters of depth and 7.01 mpy for 1 meter of depth after exposure for 76 days, respectively, which means the no protective oxides on the surface of carbon steel at 0 meters.
Synthesis of graphene oxide from used electrode graphite with controlled oxidation process
Authors: Handayani M , Ganta M , Susilo D N A , Yahya M S , Sunnardianto G. K. , Darsono N , Sulistiyono E , Setiawan I , Lestari F. P. , Erryani A. 
Published: July 2019

Abstract
Graphene oxide and reduced graphene oxide attract a lot of attention due to graphene provides some properties that suitable for wider application. Properties of graphene are unique since it can be tuned regarding to its controlled synthesis method and several treatments. This work, graphene oxide was synthesized from used graphite electrode by modified Hummer’s method in which oxidation process controlled. Zinc was used to produce reduced graphene oxide. Graphene oxide and reduced graphene oxide were characterized by SEM, EDS, FT-IR, UV-vis, and XRD. Effective strategy was studied to produce graphene oxide and reduced graphene oxide by controlling its oxidation process. These results prove that chemical and structural properties of graphene oxide and reduced graphene oxide depend on oxidation duration. Furthermore, carbon/oxygen ratio was studied to evaluate effective oxidation process.
Optical properties of ZnO nanorods derived from chemical bath deposition process with different seeds solution concentration
Authors: Suhaimi L , Yuwono A H 
Published: July 2019

Abstract
Owing to their high surface to volume ratio and fast electron transfer, zinc oxide (ZnO) nanorods have been well-known as potential nanostructured material for various applications including sensors, dye sensitized solar cells, optoelectronic, transparent heater and biomedical devices. Among other synthesizing techniques for obtaining ZnO nanorods, chemical bath deposition (CBD) has been thought as a simple and low-cost method. However, there are several processing parameters that need to be investigated for the above-mentioned applications where the highly optical transparency of thin film ZnO nanorods grown on glass substrates is one of important targets to be achieved. In this work, ZnO nanorods were synthesized through CBD process at low temperature (0°C) by using seed solution prepared by dissolving 1: 1 equimolar zinc nitrate tetrahydrate and hexamethylene tetraamine. For investigation purposes, three different concentration of seed solutions i.e. 0.005, 0.025 and 0.05 M were used. Thin films containing ZnO nanoseeds were formed by spin coating the precursors on the glass substrates, followed with annealing at 2000C for 5 minutes. Finally, the ZnO nanorods were further grown at 90ºC for 3 hours in the beaker glass using the same solution. Xray diffraction (XRD) analysis showed that all ZnO nanorods demonstrated a strong (002) peak belong to wurtzite phase. It was found that the estimated crystallite size and band gap energy (Eg
) for ZnO nanorods derived from the seed solutions of 0.005, 0.025 and 0.05 M were 21.42, 137.11, 171.39 nm, and 3.60, 3.20, 3.18 eV, respectively. However, the optical transparency was adversely lowered from about 75 to 40 % as a result of increased coverage of ZnO nanorods on the glass substrate. For transparent heater application where, a desired combination of high optical transparency and suitable electronic properties is needed, the current results were considered to be promising.
Titanium dissolution from decomposed Ilmenite using NaOH into the aqueous sulphuric acid solutions
Authors: Subagja R , Royani A 
Published: July 2019

Abstract
At present work, the experiment to dissolve titanium from the Indonesian Ilmenite into the aqueous sulphuric acid solutions has been done through the following process: Ilmenite decomposition using NaOH at temperature 800°C for 5 hours to produced decomposed Ilmenite, followed with titanium dissolution from the decomposed Ilmenite into the aqueous sulphuric acid solutions in the glass reactor. The variables used for dissolution process were covering: dissolution temperature from 30°C to 70°C, sulphuric acid concentrations from 5% to 15%, and dissolution time from 30 minutes up to 180 minutes. The influence of those all variables were observed on the titanium dissolution from the decomposed Ilmenite. Result of the dissolution experiment show that the dissolved titanium in the aqueous sulphuric acid solutions increased when the dissolution temperature was increased from 30°C to 60°C, sulphuric acid concentration were increased from 5% to 15% and dissolution time were extended from 30 minutes to 180 minutes.
Determination of compressive strength of 3D polymeric lattice structure as template in powder metallurgy
Authors: Utomo M S , Whulanza Y , Lestari F P , Erryani A , Kartika I , Alief N A 
Published: July 2019

Abstract
Powder metallurgy has been developed to fabricate metal foams from various materials including magnesium. One particular challenge on powder metallurgy is fabrication of highly-ordered and interconnected porous products. Pores interconnectivity is important in application of porous magnesium alloy for biodegradable orthopedic implants. Meanwhile, 3D polymeric printing technology offers capability to build precise and rapid lattice wireframe products in a simple and low-cost manner. Here, we design and validate the capability of 3D polymeric lattice as template in powder metallurgy for fabrication of magnesium-based biodegradable implants. Lattice structures were made of ABS, PLA, and PVA filaments. Lattice structures were cubical-shaped with uniform dimension and variations in pore size are included in the study. Both computational and experimental tests are performed to determine the compressive strength of the lattice structures. Uniaxial stress with uniform magnitude is applied to test the lattice structures. The resulting stress, strain, and deformation of the 3D polymeric lattice are observed. Variations in materials and pore size affect the stress, strain and deformation of the 3D polymeric lattice. Parameters can be further optimized to meet the requirement of the design and fabrication process in consideration of the tolerable stress, strain and deformation.