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All Journal Rekayasa Mesin Makara Journal of Science Makara Journal of Technology
Wahyu Bambang Widayatno, Wahyu Bambang
Lembaga Ilmu Pengetahuan Indonesia (LIPI)
Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Electrical & Electronics Engineering Engineering Materials Science & Nanotechnology Mechanical Engineering

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Karakterisasi Serbuk Timah dari Sistem Atomisasi Gas Argon Panas - Sub Sistem Gas Alir Tabung Gas Basyir, Abdul; Aryanto, Didik; Jayadi, Jayadi; Widayatno, Wahyu Bambang; Wismogroho, Agus Sukarto
Jurnal Rekayasa Mesin Vol 12, No 1 (2021)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.jrm.2021.012.01.20

Abstract

The tin powder was used in some applications and technology such as for part manufacture through alloying, pressing, and sintering process, mixing material for the pyrotechnic application, the main material for solder pasta, mixing material on tin chemical, and others. Therefore, the demand for tin powder with a small size, spherical shape, and high purity is increasing severely. Indonesia (PT. Timah Tbk.) is one of the world’s largest producers of tin raw materials. This raw material can be processed be as powder by the atomization method. In this research, hot argon gas atomization system was used to generated tin powder. Raw tin was melted in a melting chamber with temperature variations of 600, 700, 800, and 900 °C. This experiment generates powder with a dominant size of 37 – 150 mm. Meanwhile, for size powder of 0 – 30 mm, dominated by size range of 0 – 10 mm. Furthermore, the size powder of 0 – 30 mm is composed of tin phase, without tin oxide. The tin powder of melting chamber temperature of 900 °C produces the largest tin powder with a size of 0 – 10 mm and spherical powder.
Effect of Mechanical Milling on the Total Phenolic Content and Antioxidant Activity of Garcinia mangostana Pericarp Nugroho, Dwi Wahyu; Daratika, Dyah Ayu; Kamila, Muthia; Togatorop, Lusiana; Rifada, Mohammad Aulia; Widayatno, Wahyu Bambang; Maulana, Syahrizal; Setyawati, Damai Ria; Mardliyati, Etik; Rochman, Nurul Taufiqu
Makara Journal of Science
Publisher : UI Scholars Hub

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Abstract

This study aimed to identify the effect of mechanical milling on the total phenolic content and antioxidant activity of mangosteen pericarp. Mangosteen pericarp was milled under different milling times (30, 90, 150, and 210 min). The particle morphology before and after milling was observed by scanning electron microscopy (SEM), and the average particle size was obtained from SEM images and analyzed statistically. The antioxidant activity was measured through the 2,2-diphenyl-1-picrylhydrazyl method. The total phenolic content for the non-milling sample was 14.52 × 104 µg GAE/g sample, and the highest total phenol content was 17.44 × 104 µg GAE/g sample for the sample milled for 210 min. The IC50 value decreased for samples with milling 150 and 210 min, which showed strong antioxidant activity, whereas the value of gallic acid equivalent increased. SEM observations showed the presence of agglomeration in the morphology of mangosteen pericarp samples. The average particle size of the mangosteen pericarp decreased as the milling time increased (up to 4499 nm for samples milled for 210 min). Therefore, mechanical milling had a significant effect on the phenolic content and antioxidant activity, which indicated an increase in the bioavailability of mangosteen pericarp.
Key Deposition Parameters for Short-type ZnO Nanosheets Electrodeposited Under Galvanostatic Mode Ensang Timuda, Gerald; Harjanto, Dhimas; Widayatno, Wahyu Bambang
Makara Journal of Science
Publisher : UI Scholars Hub

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Studies on the deposition of ZnO nanosheets grown vertically and perpendicular to conductive substrates have been conducted to obtain tall-type nanosheets (approximately 15 µm in height). However, some applications require short-type nanosheets with a height of about 1µm or less. In this study, short-type ZnO nanosheets were electrodeposited on indium-doped tin oxide substrates under galvanostatic (constant current) mode for a short deposition time. Then, the key parameters to form nanosheet layers with a height in the micrometer order and with good coverage were evaluated. Deposition was performed at 1 mA/cm2 for 60 s. Ar gas was initially bubbled into the electrolyte solution during electrodeposition to remove oxygen. Then, the solution was compared with solutions that did not undergo bubbling. Various electrolyte compositions (various concentrations of acetate and nitrate) were observed in solutions under the non-Ar bubbling condition. Moreover, the oxygen in the solution remarkably affected the morphology of the nanosheet, which became much denser and taller. Therefore, altering electrolyte composition affects morphology, although the effect is not as significant. Electrolyte composition must be optimized to produce the desired short and dense nanosheets because a low concentration of each anion leads to the production of a non-nanosheet layer, whereas a high concentration causes reduction in the density coverage of the nanosheet. A complete discussion of this phenomenon is presented in this study.
Mechanical Alloying-assisted Coating of Fe–Al Powders on Steel Substrate Noviyanto, Alfian; Harjanto, Sri; Widayatno, Wahyu Bambang; Wismogroho, Agus Sukarto; Amal, Muhamad Ikhlasul; Rochman, Nurul Taufiqu
Makara Journal of Technology Vol. 24, No. 3
Publisher : UI Scholars Hub

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Abstract

The coating layer of Fe–Al powders on the steel substrate was prepared by mechanical alloying at room temperature. Fe, Al, and the steel substrates were milled with high-energy ball milling for 32 h with a ball-to-powder ratio of 8 in an argon atmosphere to prevent oxidation during milling. Although mechanical alloying was performed for 32 h, no new phases were observed after mechanical alloying, as analyzed by X-ray diffraction. However, the crystallite size of the milled powders for 32 h decreased by factor two compared with the initial powders. Scanning electron micrographs showed that the coating layers formed >8 h after mechanical alloying. The intermetallic Fe3Al formed after the substrate was annealed at 500 ℃.
Co-Authors Abdul Basyir, Abdul Agus Sukarto Wismogroho, Agus Sukarto Amal, Muhamad Ikhlasul Daratika, Dyah Ayu Didik Aryanto Dwi Wahyu Nugroho Ensang Timuda, Gerald Etik Mardliyati, Etik Harjanto, Dhimas Jayadi Jayadi Kamila, Muthia Maulana, Syahrizal Noviyanto, Alfian Nurul Taufiqu Rochman Rifada, Mohammad Aulia SETYAWATI, DAMAI RIA Sri Harjanto Togatorop, Lusiana