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Microstructural Stability and High-Temperature Oxidation Behavior of Al0.25CoCrCuFeNi High Entropy Alloy Muhammad, Fadhli; Lestari, Ernyta Mei; Achmad, Tria Laksana; Korda, Akhmad Ardian; Prawara, Budi; Prajitno, Djoko Hadi; Jihad, Bagus Hayatul; Setianto, Muhamad Hananuputra; Basuki, Eddy Agus
Metalurgi Vol 39, No 1 (2024): Metalurgi Vol. 39 No. 1 2024
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2024.745

Al0.25CoCrCuFeNi is a high-entropy alloy composed of transition metals, specifically designed for high-temperature applications owing to its favorable mechanical properties, high melting point, and excellent high-temperature resistance. This alloy has been identified as a promising material for space exploration, particularly in the fabrication of combustion chambers and rocket nozzles by the National Aeronautics and Space Agency. Ongoing alloy development involves modifying the elemental composition. This study reduced aluminum content in the equiatomic AlCoCrCuFeNi alloy to Al0.25CoCrCuFeNi, followed by isothermal oxidation treatments at 800, 900, and 1000℃. A series of experiments were conducted to investigate the microstructure stability and oxidation behavior of the Al0.25CoCrCuFeNi alloy. The alloying elements were melted using a single DC electric arc furnace, followed by homogenization at 1100°C for 10 hours in an inert atmosphere. Subsequently, samples were cut into coupons for isothermal oxidation testing at the desired temperatures for 2, 16, 40, and 168 hours. The oxidized samples were characterized using XRD (x-ray diffraction), SEM (scanning electron microscopy) equipped with EDS (energy-dispersive X-ray spectroscopy), optical microscopy, and Vickers hardness testing. The as-homogenized alloy consisted of two constituent phases: an FCC (face-centered cubic) phase in the dendritic region and a copper-rich FCC phase in the inter-dendritic region. The oxides formed during the oxidation process included Al2O3, Cr2O3, Fe3O4, CoO, CuO, NiO, and spinel oxides (Co,Ni,Cu)(Al,Cr,Fe)2O4), with distinct formation mechanisms at each temperature.

Rocket Velocity Estimation for RX-450 Launches Using Image Processing Junjunan, Soleh Fajar; Nugroho, Yuniarto Wimbo; Jihad, Bagus Hayatul
Jurnal Teknologi Dirgantara Vol 20, No 2 (2022): Jurnal Teknologi Dirgantara
Publisher : National Institute of Aeronautics and Space - LAPAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.jtd.2022.v20.a3935

The RX-450 rocket, developed by the Rocket Technology Center BRIN, serves various purposes, from sounding to military applications. This study focuses on estimating rocket velocity during the launch phase. Using MATLAB for image processing and OpenRocket for simulation, we explore the potential of image processing for velocity estimation, providing a cost-effective alternative. Results show velocity estimations trailing those of OpenRocket, attributed to friction force and setup differences. The study emphasizes the importance of camera positioning for accuracy. Despite differences, image processing shows promise, warranting further refinement

SIFAT TERMO-VISCOUS RESIN FENOLIK DENGAN RASIO MOLAR FORMALDEHID TERHADAP FENOL YANG BERBEDA Juwono, Ariadne Lakshmidevi; Asraf, Ahmedi; Jihad, Bagus Hayatul; Nugraha Thaha, Yudi
Al-Kimia Vol 12 No 2 (2024): DECEMBER
Publisher : Study Program of Chemistry - Alauddin State Islamic University of Makassar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24252/al-kimia.v12i2.50494

Phenolic resin is widely used as a matrix in the composite material. Understanding the thermo-viscous properties of the resin is essential because the viscosity is one of the main factors determining the success of the composite material fabrication. In this study, we synthesized the resin with formaldehyde to phenol molar ratio (F/P) of 1.1, 1.2, 1.3, and 1.4 and analyzed their viscosity as a function of temperature from 17℃ to 25℃. It was observed that the plot of the natural logarithm of the viscosity versus the reciprocal of the temperature of the synthesized phenolic resin is linear. Based on the slope of the Arrhenius plot, the Arrhenius energy of activation varies as a function of the F/P value. The resin’s Arrhenius energy of activation with an F/P value of 1.1, 1.2, 1.3, and 1.4 was 88.8 kJ⁄mol, 96.5 kJ⁄mol, 86.1 kJ⁄mol, and 81.4 kJ⁄mol, respectively. Furthermore, the differential scanning calorimetry (DSC) analysis was conducted on all resins. The endothermic reaction due to water evaporation was found to be dominated at a temperature of around 100℃, and the curing reaction peak of all resins took place at 150℃.

Classification of Skin Disease Images Using K-Nearest Neighbour (KNN) Ari Peryanto; Susanto, Dwi; Jihad, Bagus Hayatul
Journal of Advanced Health Informatics Research Vol. 2 No. 3 (2024)
Publisher : Peneliti Teknologi Teknik Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59247/jahir.v2i3.300

The skin is the outermost part of the human body that is often exposed to the environment, so it is easy to experience disease disorders. Some of the skin diseases that are often contracted in humans are ulcers, herpes, and warts. Untreated skin diseases will be very annoying because of the sensation of itching so it can cause irritation and inflammation. The ability to classify skin diseases using technology is one solution. This study uses the K-Nearest Neighbour (KNN) method to detect images of skin diseases. KNN is one of the machine learning methods with a calculation method based on the proximity of k. KNN was chosen because it is fast and has high-accuracy results. The results of the research that has been carried out have obtained results of accuracy of 63%, precision of 63%, recall of 63%, and F1 Score of 63%. From the results of the study, it can be concluded that disease detection using KNN has been successfully applied and can be used in classification.

Mass Optimization of Rocket Nozzles Using Ablative Materials: A Case Study on Indonesian Sounding Rockets Abrizal, Haryadi; Juwono, Ariadne Laksmidevi; Jihad, Bagus Hayatul
Indonesian Journal of Aerospace Vol. 23 No. 1 (2025): Indonesian Journal Of Aerospace
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/ijoa.2025.11394

This study presents a comprehensive redesign of the RX450 sounding rocket nozzleaimed at reducing mass while maintaining thermal and structural integrity. The baselinedesign, characterized by heavy steel casing and monolithic graphite liners, imposes significantlimitations on payload capacity and flight performance due to its weight and thermalmanagement challenges. The proposed design replaces the divergent section’s steel casingwith a combination of ablative silica-phenolic composite liners and aluminum 6061 structuralsupport, achieving a substantial mass reduction from approximately 59 kg to 14.5 kgin this critical region. Thermal simulations demonstrate that the addition of a glass-phenolicinsulation layer effectively limits heat transfer to the metallic casing, allowing for thinnerstructural components without compromising safety. Structural analyses confirm thatboth steel and aluminum sections maintain high safety factors under operational loads.Comparative evaluations of alternative configurations further highlight the benefits of advancedcomposite materials and innovative structural concepts, with the lightest modelreducing total nozzle mass by around 40% compared to the baseline. While these resultsare based on literature-derived properties and simplified assumptions, they underscore thepotential of integrating ablative composites and lightweight metals to enhance rocket nozzleperformance. Future work will focus on detailed thermochemical modeling, experimentalvalidation, and full-scale testing to confirm thermal-structural behavior and erosionrates. Overall, this study supports Indonesia’s strategic objective of advancing indigenousrocket technology through accessible, high-performance materials and design innovations.

Rocket Velocity Estimation for RX-450 Launches Using Image Processing Junjunan, Soleh Fajar; Nugroho, Yuniarto Wimbo; Jihad, Bagus Hayatul
Indonesian Journal of Aerospace Vol. 20 No. 2 (2022): Jurnal Teknologi Dirgantara
Publisher : BRIN Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.jtd.2022.v20.a3935

The RX-450 rocket, developed by the Rocket Technology Center BRIN, serves various purposes, from sounding to military applications. This study focuses on estimating rocket velocity during the launch phase. Using MATLAB for image processing and OpenRocket for simulation, we explore the potential of image processing for velocity estimation, providing a cost-effective alternative. Results show velocity estimations trailing those of OpenRocket, attributed to friction force and setup differences. The study emphasizes the importance of camera positioning for accuracy. Despite differences, image processing shows promise, warranting further refinement.

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