Papers by Akhmad Herman Yuwono
Metalurgi, Jun 6, 2023
Indonesia is one of the largest tin metal producers in the world, and one of its derivative produ... more 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 SnO 2 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.
Metalurgi, Oct 4, 2022
The flowability problem of a closed forging process in the heavy equipment industry is still wide... more The flowability problem of a closed forging process in the heavy equipment industry is still widely found. This problem may affect the quality of the product. To solve this problem, 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. In the experiment, the workpieces were hot forged at a heating temperatures of 1150 °C, 1200 °C, 1250 °C, and die to insert draft angles of 3°, 5°, and 7° to form undercarriage track roller products. The mechanical properties of the specimens taken from the workpieces were characterized through hardness and dimensional changes, 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 product with the specified diameter of 191.2 mm and height of 53.6 mm was obtained from the heating temperature of 1250 °C at the die insert draft angle of 7°. This characteristic agreed with the specified forging design for the undercarriage track roller.
The Effects of Annealing Temperature and Seed Layer on the Growth of ZnO Nanorods in a Chemical Bath Deposition Process
DOAJ (DOAJ: Directory of Open Access Journals), Oct 1, 2015
Zinc oxide (ZnO) nanorods have been considered as a potential semiconductor oxide material for th... more Zinc oxide (ZnO) nanorods have been considered as a potential semiconductor oxide material for the application of dye-sensitized solar cells (DSSC). Various experiments have been conducted to improve its nanostructural characteristics and functional properties in order to make it well suited for enhancing DSSC’ performance. Inspired by such studies, the ZnO nanorods array was grown on indium tin oxide (InSn2O3, ITO) substrate in the present work. For this purpose, a seed solution was prepared at low temperature (0 o C) using zinc nitrate tetrahydrate and hexamethylenetetramine. The ZnO seed layers were deposited onto ITO glass using a spin-coating technique and further annealed at two different temperatures, 200 and 400 o C. The seeding was also varied between one, three and five layers, prior to the growing process using the chemical bath deposition method (CBD). The results showed that the annealing temperatures significantly influenced the ZnO nanorods’ growth. The optimal condition was achieved by using three seed layers annealed at 200 o C, providing an average diameter of 157.58 nm, the biggest crystallite size (up to 59.63 nm), and a band-gap energy (Eg) of 3.27 eV. Based on the obtained properties, the growth of ZnO nanorods on ITO substrate in this work has the potential to be used for the application of dye-sensitized solar cells.
International Journal of Technology: IJ Tech, Dec 26, 2017
Interdisciplinary linkage in research is needed to develop better solutions that will meet the ne... more Interdisciplinary linkage in research is needed to develop better solutions that will meet the needs of industries for greater efficiency and environment-friendly standards. Research and innovation in the fields of thermofluid and materials science and engineering, as an interdisciplinary research field, need to be continuously encouraged so that the growing needs of industries, such as thermal storage, power generation, drag reduction, safety, manufacture, and industrial management, are met. More precise prediction methods and innovations in design and manufacturing processes continue to be undertaken by some researchers, as presented in this edition of the International Journal of Technology (IJTech). From these studies, we can see that the optimization of a product or system is determined by its mechanical parameters, material properties, and process management. At the close of this year, we are very pleased to present a special edition of IJTech. This special edition is a series containing some of the best papers we selected from the 15 th International Conference on Quality in Research (QiR) 2017, a two-year event organized by the Faculty of Engineering of Universitas Indonesia. We present 21 papers in the research areas of mechanical, material, and industrial engineering. This edition will cover studies in the fields of energy conversion and conservation, materials, and manufacture. The first paper, written by M.A. Budiyanto and T. Shinoda, investigates the stacking effect on power consumption in three stacks of refrigerated containers. The authors found that the stacking of refrigerated containers affected the temperature stratification in container surfaces and caused a different order of energy consumption in each tier of the containers. The authors stated that the results will help container port operators achieve energy saving in refrigerated containers through the proper arrangement of these containers. The second paper, written by F.A. Rayhan and A.S. Pamitran, develops and investigates the performance of a seawater ice slurry generator with a mechanical scraper. R-290 and R-22 were used as the working fluid for the refrigeration system. The study showed that the operation condition with a higher scraper RPM took more time to produce ice slurry, but it could prevent freezing. The higher was the pump RPM operation condition, the faster was the decrease in sea water temperature. The authors concluded that the performance of the refrigeration system with R-290 was better than that with R-22. The third paper, written by N.A. Abdullah, N. Putra, I.I. Hakim, and R.A. Koestoer, provides the latest information on the improvement of the liquid collection system (LCS) from an existing paper and concludes with some inputs and application strategies. The authors argued that research on liquid smoke based on thermofluid is necessary. The unavailability of data on thermal properties, including local materials from Indonesia, presents opportunities to researchers in Indonesia to study more about LCS especially that based on thermofluid.
The Effect of pH and Heat Treatment on the Porous TiO<sub>2</sub> Nanostructures Derived from Triblock Copolymer Templating-Precipitation Technique of TiOSO<sub>4</sub> Solution
Applied Mechanics and Materials, Feb 1, 2014
The synthesis and characterization of TiO2nanostructure has become intensive nowadays because of ... more The synthesis and characterization of TiO2nanostructure has become intensive nowadays because of its superior properties among other semiconductor materials. In this work, TiO2nanostructures have been derived from ilmenite mineral by using precipitation technique with various pH and calcination temperature. The resulting nanostructures were characterized to investigate the effects of those variables on the phase, crystallite size, and band gap energy. The characterization was performed by using XRD, FT-IR, UV-Vis DRS, SEM, EDS, and TEM. The results showed that TiO2sample prepared under low pH value of 0.3 demonstrated porous structures although they are not well-ordered yet, while the sample with a pH adjustment up to 7.0 provided nanotube structure. The biggest crystallite size of 3.43 nm and low band gap energy of 3.07 eV was obtained in the TiO2samples synthesized without pH adjustment and calcined at a a temperature of 300°C. This characteristics shows that TiO2nanostructure in this study is potential for the applications of dye sensitized solar cell (DSSC) and photocatalysist.
Investigating the effect of crystallite size on the optical properties of zinc oxide
Nucleation and Atmospheric Aerosols, 2023
Study of TiO2 nanotube crystal structure by rietveld analysis
Nucleation and Atmospheric Aerosols, 2023
Effect of ultrasonic pretreatment on electrochemical performance of LiFe0.5Mn0.5PO4/V/C composite in lithium-ion battery cathode
Nucleation and Atmospheric Aerosols, 2023
Synthesis and characterization of Ca-Less CCTO dielectric electroceramic materials
Nucleation and Atmospheric Aerosols, 2022
One-dimensional silver-titania nanocomposites as modification of photoanode for enhanced dye-sensitized solar cells – A review
Materials Today: Proceedings, 2022
Nucleation and Atmospheric Aerosols, 2018
Karya Rekaman Video "Implementasi Kesadaran Energi Terbarukan Bagi Siswa Sekolah Alam School Of Universe (Sou) Parung Bogor Melalui Program Nano - Education For Kids
pH effect upon sol–gel processing of titanium butoxide and lithium acetate precursors on the characteristics of Li4Ti5O12 as an anode for lithium-ion batteries
Bulletin of Materials Science, Jul 26, 2022
Peningkatan kristalinitas nanopartikel TiO 2 dalam nanokomposit keramik ─ polimer hasil proses sol − gel dengan metode kombinasi pra - anil dan pasca - hidrotermal
Sintesis dan karakterisasi struktur nano tio2 dari larutan tioso4 hasil ekstraksi bijih ilmenit bangka = Synthesis and characterization of tio2 nanostructure from tioso4 extracted from bangka ilmenite ore
Sintesis dan karakterisasi nanopartikel seng oksida (ZnO) dengan metode proses pengendapan kimia basah dan hidrotermal untuk aplikasi fotokatalis
Physical, microstructure enhancement of K0.5Na0.5NbO3- based lead-free ceramics prepared via two-step sintering
INTERNATIONAL CONFERENCE ON BIOENGINEERING AND TECHNOLOGY (IConBET2021)
Karakterisasi cacat fatik dengan gelombang lamb simetris mode nol menggunakan analisis signal time domain dan frekuensi domain = Characterisation of fatigue defects using zero order symmetrical mode lamb wave with time domain and frequency domain signals analysis
Fakultas Teknik Universitas Indonesia, 2016
EFFECT OF SINTERING TEMPERATURE ON THE ROLLED COPPER-SHEATHED MONOFILAMENT MgB2 SUPERCONDUCTING WIRE
Synthesis of titanium oxysulfate from ilmenite through hydrothermal, water leaching and sulfuric acid leaching routes
1ST INTERNATIONAL SEMINAR ON ADVANCES IN METALLURGY AND MATERIALS (i-SENAMM 2019), 2020
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Papers by Akhmad Herman Yuwono