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Rokhmanto, Fendy
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Chemical Engineering, Chemistry & Bioengineering Computer Science & IT Earth & Planetary Sciences Electrical & Electronics Engineering Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Physics

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Pengaruh Waktu Tahan Homogenisasi Pada Struktur Mikro Dan Kekerasan Paduan Biomaterial Ti6Mo6Nb Sutowo, Cahya; Rokhmanto, Fendy
Jurnal Inovasi Ilmu Pengetahuan dan Teknologi (JIPTEK) Vol. 6 No. 1 (2024): Jurnal Inovasi Ilmu Pengetahuan dan Teknologi (JIPTEK)
Publisher : Universitas Pamulang

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Abstract

Meningkatnya kesejahteraan penduduk Indonesia berdampak pada peningkatan jumlah penduduk usia lanjut, dimana potensi terjadinya penyakit tulang degeneratif yang dideritapun semakin meningkat. Akibatnya kebutuhan akan biomaterial juga meningkat. Titanium paduan telah diaplikasikan sebagai biomaterial terbaik, salah satunya adalah Ti-6Al-4V namun unsur V pada paduan ini memiliki nilai toksisitas yang tinggi, sehingga perlu dilakukan penelitian untuk menggantikan material yang lebih cocok. Pada penelitian ini dikembangkan paduan beta Titanium Ti6Mo6Nb. Proses peleburan menggunakan tungku busur listrik vakum dalam lingkungan argon. Proses homogenizing pada temperatur 1100 °C, dengan waktu tahan selama 3, 6 dan 12 jam. Kemudian paduan didinginkan dengan cepat dan diukur nilai kekerasannya menggunakan metode mikro Vickers, sedangkan struktur mikro diamati menggunakan mikroskop optic. Waktu tahan proses homogenisasi mengakibatkan transformasi fasa beta menjadi lebih dominan dan meghaluskan butir ketika dilaksanakan dalam durasi yang lebih panjang. Nilai kekerasan tertinggi adalah 367 VHN, diperoleh pada waktu tahan 12 jam.
Pengaruh Perlakuan Termomekanik pada Paduan Titanium Ti-5Mo-9Nb Sutowo, Cahya; Rokhmanto, Fendy; Prasetyo, Agus Budi; Utama, Dedi Pria
Jurnal Inovasi Ilmu Pengetahuan dan Teknologi (JIPTEK) Vol. 7 No. 1 (2025): Jurnal Inovasi Ilmu Pengetahuan dan Teknologi (JIPTEK)
Publisher : Universitas Pamulang

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Abstract

Until now, more than 95% of the material needs for medical devices are still imported, independent mastery of technology can at least reduce dependence on imported implant materials. On the one hand, the increase in the welfare of the population in Indonesia today is directly proportional to the increase in life expectancy of the population. The above conditions will have an impact on the increase in the number of elderly people. The increase in the elderly population will potentially increase the occurrence of degenerative bone diseases suffered by the elderly. This study aims to analyze the effect of the thermomechanical process through hot rolling. The added Mo and Nb elements function as beta phase stabilizers which will certainly affect the microstructure and mechanical properties of titanium alloys. The thermomechanical heat treatment process is an advanced process where the homogenized ingot is then hot rolled at a temperature of 1100 °C in 3 rolling stages until it reaches a 50% reduction. Then characterized by observing the microstructure and mechanical properties. The thermomechanical process involves plastic deformation at high temperatures that affect changes in microstructure and mechanical properties. Plastic deformation combined with recrystallization results in smaller grain sizes, which improves mechanical properties with a relatively uniform increase of 429–450 VHN. Therefore, this thermomechanical processed Ti-5Mo-9Nb-based alloy has the potential for improved medical implant material applications. Abstrak: Sampai saat ini kebutuhan material untuk alat kesehatan lebih dari 95% masih impor, penguasaan teknologi secara mandiri setidaknya dapat mengurangi ketergantungan impor material implan. Di satu sisi, peningkatan kesejahteraan penduduk di Indonesia dewasa ini berbanding lurus dengan meningkatnya usia harapan hidup penduduk. Kondisi tersebut di atas akan berdampak terhadap peningkatan jumlah penduduk usia lanjut. Meningkatnya penduduk usia lanjut akan berpotensi pada terjadinya penyakit tulang degeneratif yang diderita oleh para lanjut usia akan semakin meningkat. Penelitian ini bertujuan untuk menganalisis pengaruh proses termomekanik melalui pengerolan panas. Unsur Mo dan Nb yang ditambahkan berfungsi sebagai penstabil fasa beta yang tentunya akan memengaruhi struktur mikro dan sifat mekanis paduan titanium. Proses perlakuan panas termomekanik merupakan proses lanjutan di mana ingot yang telah dihomogenisasi kemudian dilakukan pengerolan panas pada temperatur 1100 °C sebanyak 3 tahapan pengerolan sampai mencapai reduksi 50%. Kemudian dikarakterisasi melalui pengamatan struktur mikro dan sifat mekanik. Proses termomekanik melibatkan deformasi plastis pada suhu tinggi yang memengaruhi perubahan mikrostruktur dan sifat mekanis. Deformasi plastis yang dikombinasikan dengan rekristalisasi menyebabkan ukuran butir menjadi lebih kecil, yang meningkatkan sifat mekanis dengan peningkatan yang relatif seragam 429–450 VHN. Sehingga paduan berbasis Ti-5Mo-9Nb melalui proses termomekanik ini berpotensi untuk aplikasi material implan medis yang lebih baik.
Self-Healing Behavior of Hydrothermally Engineered HAp/PAA Coatings on Magnesium Alloy WE43 Erryani, Aprilia; Rokhmanto, Fendy; Setyawan, Albertus Deny Heri; Thaha, Yudi Nugraha; Zakiyuddin, Ahmad; Kartika, Ika; Harjanto, Sri
Metalurgi Vol 39, No 3 (2024): Metalurgi Vol. 39 No. 3 2024
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2024.780

Abstract

This work examines the self-healing properties and corrosion prevention mechanisms of hydrothermally synthesized HAp/PAA (hydroxyapatite/polyacrylic acid) composite coatings on magnesium alloy WE43. The coatings were produced with different PAA concentrations (0.15, 0.3, and 0.5 wt.%) by a hydrothermal method at 140 °C for 3 hours. The composite layers were analyzed using FTIR (fourier transform infrared spectroscopy), SEM (scanning electron microscopy), and EIS (electrochemical impedance spectroscopy) to assess their structural and electrochemical properties, as well as their self-healing capabilities via a scratch–immersion test in Hank’s solution at 37 °C for 48 hours. FTIR analysis confirmed the simultaneous presence of HAp and PAA phases without any chemical reaction, indicating physical contact through hydrogen bonding. The elevation of PAA concentration markedly affected coating morphology, resulting in denser and more uniform structures characterized by spherical HAp crystals at 0.5 wt.% PAA. SEM analysis following scratching and immersion demonstrated that the 0.5 wt.% PAA coating successfully preserved surface integrity and displayed partial restoration of the injured region via the reprecipitation of Ca–P compounds. The EIS findings indicated that the 0.5 wt.% PAA coating maintained the maximum impedance modulus (>10⁴ Ω·cm²) and a steady phase angle after 48 hours of immersion, therefore affirming its exceptional corrosion resistance and self-healing properties. The results demonstrate that an ideal PAA content fosters a dense, ion-responsive hybrid layer that effectively reinstates barrier characteristics following mechanical impairment. The hydrothermally produced 0.5 wt.% HAp/PAA coating offers an efficient self-healing and corrosion-resistant surface for WE43 magnesium alloy, indicating significant potential for use in next-generation biodegradable implant systems.
Corrosion Behavior of Equiatomic Bio-High Entropy Alloys CoCrMoMnNb Fabricated in Multiple Remelting Processes Rokhmanto, Fendy; Erryani, Aprilia; Setyawan, Albertus Deny Heri; Thaha, Yudi Nugraha; Zakiyuddin, Ahmad; Kartika, Ika; Harjanto, Sri
Metalurgi Vol 39, No 3 (2024): Metalurgi Vol. 39 No. 3 2024
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2024.782

Abstract

High-entropy alloys are described as equiatomic alloys of more than five elements or materials with five or more element constituents with a high mixing entropy (ΔSmix ≥ 1.5R), where the composition of the element is 5–35%, respectively. One application of HEA (high entropy alloys) materials is in the orthopedic field, where they are developed as biomaterials. Behavior, the correlation between the elemental distribution, and the microstructure of the material were investigated during multiple remelting processes known as Bio-HEAs. The development of Bio-HEAs is exciting in terms of design material, fabrication, and their properties. In this paper, the corrosion behavior and the correlation of the elemental distribution and the microstructure of the material were investigated during the multiple remelting process. The equiatomic CoCrMoMnNb was prepared in vacuum arc melting under an argon atmosphere and melted in a water-cooled copper mold. The total amount of ingot was approximately 25 grams, then flipped and remelted several times, 4, 8, and 12 cycles. The final composition of the alloys was confirmed by EDX (energy dispersive x-ray spectroscopy). The microstructure was investigated with an optical microscope and the SEM (scanning electron microscope). The corrosion parameter occurred in Hank’s solution at 37°C, at a scan rate of 1 mV/s. The CCM-MnNb fabricated with 8 cycles of the remelting process exhibits the lowest corrosion rate (0.0038 mmpy) and donor densities (2.67 × 10¹⁹ cm⁻³), while the charge transfer resistance number is the highest (18250.94 Ω cm⁻²). The outstanding corrosion resistance of the alloys is induced by the presence of the finer dendrites and the chromium oxide (Cr₂O₃) protective layer on the alloy's surface.
Co-Authors Ahmad Zakiyuddin Cahya Sutowo Erryani, Aprilia Ika Kartika Prasetyo, Agus Budi Setyawan, Albertus Deny Heri Sri Harjanto Thaha, Yudi Nugraha Utama, Dedi Pria