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All Journal Jurnal Sains Materi Indonesia Metalurgi International Journal of Recent Technology and Applied Science (IJORTAS) Journal of Materials Exploration and Findings Makara Journal of Technology Metalurgi

Akhmad Herman Yuwono

Departemen Metalurgi Dan Material Fakultas Teknik Universitas Indonesia

Author-ID : 426772

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Electrical & Electronics Engineering Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering

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FABRIKASI NANOROD SENG OKSIDA (ZnO) MENGGUNAKAN METODE SOL-GEL DENGAN VARIASI KONSENTRASI POLYETHYLENE GLYCOL DAN WAKTU TUNDA EVAPORASI AMONIA Akhmad Herman Yuwono
Metalurgi Vol 26, No 2 (2011): Metalurgi Vol.26 No.2 Agustus 2011
Publisher : National Research and Innovation Agency (BRIN)

Seng oksida (ZnO) adalah salah satu material semikonduktor yang banyak digunakan dalam aplikasi katalitik, elektronik dan optoelektronik. Pada penelitian ini, ZnO nanorods telah berhasil disintesis menggunakan metode sol-gel dengan campuran (Zn(NO3 ) 2 .4H2 O), NH4 OH, dan polyethylene glycol (PEG). Variasi pada konsentrasi PEG dan penahanan laju evaporasi amoniak pada larutan telah dilakukan dan nanorod ZnO yang dihasilkan dikarakterisasi dengan XRD dan SEM untuk menginvestigasi perbedaan diameter, morfologi dan tingkat nanokristalinitas nanorod ZnO. Penambahan PEG dari 1 hingga 3 gram pada larutan meningkatkan ukuran diameter rata-rata nanorods dari 157 menjadi 464 nm. Namun demikian tidak didapatkan adanya peningkatan ukuran nanokristalit ZnO di dalam struktur solid nanorod tersebut. Pada variasi waktu tunda evaporasi amonia selama 1 dan 2 jam, terjadi penurunan diameter nanorod menjadi 410 dan 328 nm, sebagai perbandingan terhadap diameter nanorod ZnO tanpa proses penundaan evaporasi ammonia yang mencapai 464 nm. Sebaliknya, besar kristalit di dalam struktur nanorod ZnO bertambah dari 121,49 menjadi 166,59 nm sejalan dengan penambahan waktu tunda evaporasi ammonia dari 1 hingga 2 jam, sebagai perbandingan terhadap ukuran kristalit nanorod ZnO tanpa proses penundaan evaporasi ammonia yang hanya mencapai 94,77 nm. AbstractZinc oxide (ZnO) is one of semiconductor materials which has been widely used for catalytic, electronic and optoelectronic applications. In the present research, ZnO nanorod has been successfully synthesized through a sol-gel method using (Zn(NO3)2.4H2O), NH4Keywords: ZnO nanorods, PEG concentration, Evaporation delay time, Crystallinity OH, and polyethylene glycol (PEG) precusrors. Variation in PEG concentration and ammonia evaporation delay time were performed and the resulting ZnO nanorods were characterized by XRD and SEM to investigate the difference in diameter, morphology and nanocrystallinity. It was revellead that the addition of PEG concentration from 1 to 3 grams has increased the average diameter of ZnO nanorods from 157 to 464 nm. However, there was no an increase in the crystallite size on those nanorod solid structures. The ammonia evaporation delay time from 1 to 2 hours has resulted in a deacrease in the average diameter of ZnO nanorods from 410 to 328 nm, in comparison to those of without evaporation delay time which can reach up to 464 nm. By contrast, the average crystallite size of ZnO phase in the nanorod structures has increased from 121.49 to 166.59 nm when the evaporation delay time was prolonged from 1 to 2 hours, as compared to those of without evaporation delay time which can only reach 94.77 nm in size.

Combined Risk Based Inspection and Fault Tree Analysis for Repetitive 3-Phase Line Piping Leakage at West Java Offshore Topside Facility Yuliati, Dona; Yuwono, Akhmad Herman; Asral, D. Rizal; Dhaneswara, Donanta
Journal of Materials Exploration and Findings Vol. 2, No. 3
Publisher : UI Scholars Hub

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Hydrocarbon releases might result in serious consequences in various aspects. In addition to the contribution to environmental pollution, repetitive leakages need high repair costs. This study aim is to minimize potential repetitive leakage for other typical 3-phase piping systems. We conducted the risk assessment by adopting Risk Based Inspection (RBI) API 581 to identify risk level, calculating piping lifetime, recommended inspection plan and mitigations. The most relevant root causes can be obtained through quantitative Fault Tree Analysis (FTA). Observation and investigation was taken from eight 3-phase piping systems that experienced repetitive leakages. It has been found that the risk level of some piping systems in yellow and red areas with one pipe in an unfit condition. Next inspection and/or mitigation dates as results of RBI calculation shall be conducted to reduce risk levels and prevent leakage cases. FTA shows the most likely events are the sand problem in fluid, high CO2 content, material deficiency, and high fluid velocity. If the root causes are known earlier, preventive mitigation can be conducted to prevent hydrocarbon release in the other 3-phase piping systems, such as application of internal coating, injection corrosion inhibitor or inspection/monitoring program.

Residual Stress Measurement of Used Mining Dump Truck Frame for Remanufacturing Purposes Ferdiyanto, David; Sofyan, Nofrijon; Yuwono, Akhmad Herman; Dhaneswara, Donanta
Metalurgi Vol 38, No 3 (2023): Metalurgi Vol. 38 No. 3 2023
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2023.730

Remanufacturing the main frame of a mining dump truck can save cost, energy, and materials in heavy equipment industries. It also can reduce CO2 emissions for environmental preservation to achieve sustainability. However, since the mainframe received a dynamic load during operation, it presumably leaves accumulated residual stresses in the frame. The residual stress, particularly tensile residual stress, stands out as a primary contributing factor to the initiation of cracks, which may ultimately result in failures. In this paper, the residual stress of the used mining dump truck main frame was identified by modeling simulation using FEA (finite element analysis) and actual measurement using a portable x-ray residual stress analyzer with the cos α method. The results showed that the weld area subjected to dynamic loads exhibited the highest tensile residual stress, reaching approximately +772 MPa. This specific region emerges as a critical area demanding attention during the remanufacturing process. The application of PWHT (post-weld heat treatment) at 400 °C for 1 hour effectively reduced residual stress on the weld joint, predominantly tensile residual stress, by more than 80%.

MORPHOLOGY AND RESISTIVITY VALUE OF FLOURINE-DOPED TIN OXIDE (FTO) USING INDONESIAN LOCAL DIMETHYLTIN DICHLORIIDE (DTMC) PRECURSORS Rizki, Apti Mira; Yunita, Fariza Eka; Lalasari, Latifa Hanum; Irawan, Januar; Arini, Tri; Firdiyono, Florentinus; Andriyah, Lia; Natasha, Nadia Chrisayu; Yuwono, Akhmad Herman
Metalurgi Vol 37, No 3 (2022): Metalurgi Vol. 37 No. 3 Desember 2022
Publisher : National Research and Innovation Agency (BRIN)

Transparent Conductive Oxide (TCO) is the main component for solar cell fabrication. One of the promising types of TCO is fluorine-doped tin oxide (FTO). The method used in depositing the conductive layer of FTO is spray pyrolysis with an ultrasonic nebulizer. The precursor is a local Indonesian product, dimethyl tin dichloride (DMTC), with doping ammonium fluoride (NH4F). The variable that used in this study were variations in deposition time (5. 10. 15. 20, and 25 minutes) with a fixed substrate temperature at 300°C and doping variations (un-doped, 2 wt.% doped and 8 wt.% doped) to see the effect of adding F doping to the precursor solution. The resistivity value with deposition time of 5. 10. 15. 20 and 25 minute (2 wt.% doped) is 0.218x100; 0.449x10-1; 1,567x10-2; 0.676x10-2 0.377x10-2 Ω.cm. For doping variations (un-doped, 2 wt% doped and 8 wt% doped) the value is 0.883x10-2; 0.377x10-2; 0.506x10-3 Ω.cm. There is a decreasing trend in the resistivity values obtained along with the increase in deposition time and the addition of doping to obtain better conductive properties. The grain size will increase with increasing deposition time and the addition of doping. The optimum resistivity value obtained in this study was 0.377x10-2 Ω.cm, obtained at the deposition time of 25 minutes with 2 wt.% doping.

Effect of Heating Temperature and Die Insert Draft Angle on the Flowability of Hot Forged SCM435 Steel Sofyan, Nofrijon; Heruwiyono, Maulana; Yuwono, Akhmad Herman; Dhaneswara, Donanta
Metalurgi Vol 37, No 2 (2022): Metalurgi Vol. 37 No. 2 Agustus 2022
Publisher : National Research and Innovation Agency (BRIN)

The problem of flowability in a closed forging process for heavy equipment industry is still widely found and this may affect the quality of the resulting product. To obtain the solution for this problem, in this work, the effect of heating temperature and die insert draft angle on the characteristic of hot forged SCM435 steel used for undercarriage track roller has been examined. The workpieces were heated at temperature variations of 1150 °C, 1200 °C, 1250 °C and were hot forged at die insert draft angles of 3°, 5°, and 7° to form undercarriage track roller products. The mechanical properties of the products were characterized through hardness and dimension examination, whereas the microstructure was characterized using an optical microscope. The results showed that increasing the heating temperature and die insert draft angle resulted in good flowability. The best result was obtained from the heating temperature of 1250 °C at the die insert draft angle of 7°, with diameter and height of 191.2 mm and 53.6 mm, respectively. This characteristic of the obtained hot-forged product agreed with that of the specified forging design for the undercarriage track roller

Synthesis of Tin Oxide Nanocrystallites with Various Calcination Temperatures Using Co-Precipitation Method with Local Tin Chloride Precursor Panthoko, Norbert Egan Christo; Septiningrum, Fairuz; Yuwono, Akhmad Herman; Nurhidayah, Eka; Maulana, Fakhri Akbar; Sofyan, Nofrijon; Dhaneswara, Donanta; Lalasari, Latifa Hanum; Arini, Tri; Andriyah, Lia; Firdiyono, Florentinus; Ardianto, Yahya Winda; Pawan, Ria Wardhani
Metalurgi Vol 38, No 1 (2023): Metalurgi Vol. 38 No. 1 2023
Publisher : National Research and Innovation Agency (BRIN)

Indonesia is one of the largest tin metal producers in the world, and one of its derivative products is tin chloride (SnCl4). This material has been used as a raw ingredient for the production of organotin compounds such as methyltin mercaptide for PVC (polyvinyl chloride) plastic industry as a heat stabilizer. On the other hand, this precursor can be used to synthesize SnO2 nanomaterials, which have other strategic potentials, including photocatalysts and solar cell applications. In this study, the synthesis of SnO2 nanocrystallites was carried out using a local tin chloride precursor via the co-precipitation method, followed by a calcination process at temperatures of 300, 400, 500, and 600 °C, for further usage as an ETL (electron transport layer) in a PSC (perovskite solar cell) device. The basic properties characterization was carried out using XRD (X-ray diffraction), ultraviolet-visible (UV-Vis) spectroscopy, and SEM (scanning electron microscopy), while the photocurrent-voltage (I-V) curve photovoltaic performance of the device was performed using a semiconductor parameter analyzer. The characterization results showed that increasing the calcination temperature from 300 to 600 °C increased the average crystallite size from 1.19 to 13.75 nm and decreased the band gap energy from 3.57 to 3.10 eV. The highest PCE (power conversion efficiency) was obtained from the device fabricated with SnO2 nanocrystallites calcined at a temperature of 300 °C, which was 0.0024%. This result was obtained due to the highest transmittance of this sample as compared to others; the higher the transmittance, the better the performance of the ETL, which in turn increased the overall efficiency of the PSC

Study of Iron and Calcium Removal on Manganese Sulfate Precursors for Battery Cathode Raw Material Applications Hakim, Agsel Fauzia; Andriyah, Lia; Oediyani, Soesaptri; Lalasari, Latifa Hanum; Sulistiyono, Eko; Irawan, Januar; Arini, Tri; Yunita, Fariza Eka; Suharyanto, Ariyo; Setiawan, Iwan; Firdiyono, Florentinus; Yuwono, Akhmad Herman
Metalurgi Vol 39, No 2 (2024): Metalurgi Vol. 39 No. 2 2024
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2024.753

Global battery sales are expected to reach $310.8 billion in 2027, up 14.1% from 2020. 95% of the world's batteries are lead-acid, lithium-ion, or nickel-based. One of the most popular batteries on the global market is lithium-ion, which uses MnSO4 powder as its cathode raw material. Manganese sulfate-based lithium-ion batteries can be made using Indonesian resources, specifically manganese ore from Trenggalek. Trenggalek manganese ore is of poor quality and contains impurities, primarily Fe and Ca. To produce 98% powder manganese sulfate, the solution is prepared, reduced with briquette charcoal, leached, precipitated, carbonated, and crystallised. NH4OH reagent is used to remove Fe through precipitation, and the carbonatation process is employed to eliminate Ca, resulting in 97.237% purity of manganese sulfate powder product. This outcome is achieved under precipitation process conditions of [NH4OH 2M], T = 80 °C, pH = 4, t =180 minutes, while carbonatation process conditions are T=50 °C, t = 120 minutes.

Techno-Economic Analysis of On-Grid Rooftop PV Systems Integrated with BESS for Meeting the Energy Needs of Residential EV Home Charging Customers in Jakarta Eka Putri, Sonia; Yuwono, Akhmad Herman; Setiawan, Eko Adhi
International Journal of Recent Technology and Applied Science (IJORTAS) Vol 7 No 2: September 2025
Publisher : Lamintang Education and Training Centre, in collaboration with the International Association of Educators, Scientists, Technologists, and Engineers (IA-ESTE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36079/lamintang.ijortas-0702.851

The growing adoption of electric vehicles (EVs) in Indonesia, especially in urban areas like Jakarta, is expected to increase household electricity consumption. Rooftop solar photovoltaic (PV) systems integrated with battery energy storage systems (BESS) offer a promising solution to supply clean and self-sufficient energy. This study aims to assess the techno-economic feasibility of on-grid rooftop PV systems combined with BESS for residential EV home charging in Jakarta under various export compensation schemes and cost scenarios. Using the HOMER Grid software, three system configurations were simulated: grid-only, PV + BESS without export, and PV + BESS with 65% export compensation. The optimal setup consists of an 8.97 kW PV and 5 kWh BESS, yielding an internal rate of return (IRR) of 18%, a levelized cost of energy (LCOE) of $0.042/kWh, and a payback period of 5 years. Sensitivity analysis highlights that a minimum export compensation of 40% and projected cost reductions, especially in BESS are critical for long-term viability. A larger system with 15 kWh BESS becomes economically feasible after 2028, achieving a 16% IRR. Integrating rooftop PV and BESS could reduce CO₂ emissions by up to 9,932 kg/year compared to a grid-only system. Policy recommendations include export compensation of at least 40%, targeted investment incentives, and co-investment models involving PLN, PV providers, and EV dealers.

Maintenance Notes to Improve the Reliability of Wheel Flange Failure for Overhead Crane Burhanuddin, Fakhri; Yuwono, Akhmad Herman
Journal of Materials Exploration and Findings Vol. 3, No. 2
Publisher : UI Scholars Hub

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Overhead traveling cranes in the industry have utility workload classifications and require high standards of safety and reliability by mobilizing lifting and transporting capacity variants of steel products, equipment, and other supports. The crane wheels are the main support in moving the end carriage so that the crane can work according to its function. Failures in the operation and maintenance cycle have occurred. Therefore, proper repair and maintenance methods are highly needed to restore the original design function to its working integrity. Logic tree analysis was used to breakdown all causes of failure; thus, mitigation was performed by carrying out continuous improvements rather than investigations. In this work, failure of the wheel flange in asset integrity management was found to be correlated with other related components which refer to the data of international standard for carrying out the needed repairs.

Spin Coater Design with PID Algorithm Using Polynomial Regression Approach and Bias Tuning for TiO2 Deposition Process Andika, Geo Surya; Sofyan, Nofrijon; Dhaneswara, Donanta; Yuwono, Akhmad Herman
Journal of Materials Exploration and Findings Vol. 4, No. 1
Publisher : UI Scholars Hub

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The thin-film deposition technique using spin coating offers a cost-effective alternative to Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD). The spin-coating process requires precise control of the motor drive system to ensure that the rotational speed, measured in rotations per minute (RPM), aligns with the set point and remains stable. This study presents the design and development of a spin coater prototype to achieve uniform thin-film deposition. The control method employed utilizes a Proportional-Integral-Derivative (PID) algorithm, incorporating a polynomial approach with bias tuning. The PID control was chosen to achieve stable operation in a non-linear system. The performance of the non-linear PID control system is compared with an open-loop control system by evaluating the overshoot behavior. In the first experiment, a proximity sensor was tested to measure the spin coater motor's speed in an open-loop control configuration. The performance was evaluated using Mean Absolute Error (MAE) and Mean Absolute Percentage Error (MAPE) metrics, with results showing an MAE of 1358.6 RPM and a MAPE of 23.13% compared to a tachometer. In the second experiment, step-response testing was conducted using a closed-loop PID control system with a polynomial approach and bias tuning. Compared to the open-loop system, the closed-loop PID controller reduced overshoot to less than 3%. The RPM deviation between the spin coater and the tachometer was limited to range, approaching ideal conditions. The closed-loop control was tested within the 5000–9000 RPM range, where stable RPM regulation resulted in more uniform TiO2 thin-film distribution on glass substrates. This study highlights the effectiveness of closed-loop PID control in achieving precise rotational control, which is essential for enhancing the quality of thin-film deposition.

Co-Authors Achmad Subhan Achmad Subhan Alfian Ferdiansyah Alfian Ferdiansyah Alfian Ferdiansyah Amalia Sholehah, Amalia Andika, Geo Surya Andriyah, Lia Andriyah, Lia Anne Zulfia Ardianto, Yahya Winda Arif Rahman Arif Rahman Asral, D. Rizal Badrul Munir Badrul Munir, Badrul Bambang Priyono Bambang Suharno Burhanuddin, Fakhri Daniel Kurniawan Dhaneswara, Donanta Eka Putri, Sonia Eko Adhi Setiawan Eko Sulistiyono, Eko Elfi N Eny Kusrini Evvy Kartini F Firdiyono Ferdiyanto, David Firdiyono Firdiyono firdiyono, F Firdiyono, Firdiyono Florentinus Firdiyono Ghiska Ramahdita, Ghiska Hakim, Agsel Fauzia Heri Jodi, Heri Heruwiyono, Maulana Indriana Kartini Indriana Kartini Irawan, Januar Iwan Setiawan johansyah johansyah John Wang Lalasari, Latifa Hanum Lalasari, Latifa Hanum Latifa Hanum Lalasari Latifa Hanum Lalasari Lia Andriyah Lia Andriyah Mario Marfelly, Mario Maulana, Fakhri Akbar N, Elfi Natasha, Nadia Chrisayu Nofrijon Sofyan, Nofrijon Norifon Sofyan Nurhidayah, Eka Panthoko, Norbert Egan Christo Pawan, Ria Wardhani Pujianto, Togo Hadi Rizki, Apti Mira Septiningrum, Fairuz Soesaptri Oediyani Sofyan, Norifon Sri Harjanto Sri Harjanto Suharyanto, Ariyo Togo Hadi Pujianto Tri Arini Tri Arini, Tri Wahid Muhamad Furkon Rahmatulloh, Wahid Muhamad Furkon Wulandari Handini Wulandari Handini Yu Zhang Yuliati, Dona Yunita, Fariza Eka

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