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Effect of Applied Pressure During Sintering on the Densification and Mechanical Properties of SiCf/SiC Composites Prepared by Electrophoretic Infiltration Noviyanto, Alfian
Makara Journal of Science Vol. 24, No. 4
Publisher : UI Scholars Hub

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Abstract

SiC-fiber-reinforced SiC matrix ceramic (SiCf/SiC) composites were successfully fabricated by electrophoretic infiltration and sintering at various applied pressures. The effect of applied pressure (i.e., 5, 10, and 20 MPa) was thoroughly examined, and applied pressure appears to influence the densification and mechanical properties of SiCf/SiC composites. The densities of SiCf/SiC composites prepared at applied pressure of 5, 10, and 20 MPa were 2.99, 3.10, and 3.16 g/cm3, respectively. All samples showed dense microstructures in their matrix areas; however, many closed pores were found with increasing pressure. Pressure induced densification in the fiber area, and 20 MPa was determined to be the minimum pressure required for adequate densification. The liquid phase in the matrix area was effectively maintained at a high applied pressure, which resulted in densification. However, the liquid phase redistributed to the matrix or near the matrix area at applied pressures of MPa, leading to pores in the fiber areas of these samples. The highest flexural strength of 262 ± 18 MPa for the SiCf/SiC composite was achieved at an applied pressure of 20 MPa. Meanwhile, the flexural strengths of the composites prepared at 5 and 10 MPa were 198 ± 41 and 238 ± 32 MPa, respectively.
Effect of Milling on the Densification of SiC-BasedComposites from Polysilazane Noviyanto, Alfian; Nishimura, Toshiyuki
Makara Journal of Technology Vol. 20, No. 3
Publisher : UI Scholars Hub

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Abstract

High density SiC-based composites from polysilazane were fabricated by high energy milling and hot pressing. After cross-linking at 200 °C, the polysilazane was pyrolysed at 1000 °C in N2 for 2 h to form amorphous Si-C-N-O followed by high energy milling for 1 h. Milled amorphous Si-C-N-O was sintered in hot pressing at 1600 and 1700 °C for 1 h in vacuum under the applied pressure of 50 MPa. Although no sintering additives were used, dense SiC-based composites were obtained with this method. Sintered density was 3.04 g/cm3, while only 2.57 g/cm3 for amorphous Si-C-N-O without milling. It is suggested that the liquid phase generated during the formation of Si2N2O facilitated the densification of the composite.
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 ℃.
Stabilitasi Fasa Kalsium Pirofospat Pada Temperatur Tinggi Dengan Penambahan Zirkonia Huda, Ihsanul; Kusumaningrum, Retno; Sukmarani, Galuh; Noviyanto, Alfian
Syntax Literate Jurnal Ilmiah Indonesia
Publisher : CV. Ridwan Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1608.726 KB) | DOI: 10.36418/syntax-literate.v5i5.1134

Abstract

Kalsium Pirofospat adalah biomaterial yang sangat baik untuk digunakan sebagai pengganti tulang atau gigi yang rusak ataupun retak. Kalsium Pirofospat bersifat biokompatibel, bioaktif dan memiliki komposisi kimia yang mendekati komposisi pada tulang dan gigi manusia. Namun biomaterial ini memiliki kekurangan yaitu sifat mekanisnya yang rendah apabila digunakan untuk menerima beban yang berat. Peningkatan sifat mekanik kalsium pirofospat dapat dilakukan dengan menambahkan material zirkon. Oleh karena itu, pada penelitian ini dilakukan kajian perubahan fasa kalsium pirofospat dengan penambahan zirkon pada temperatur tinggi. Komposisi zirkonia yang ditambahkan sebesar 5% dan 10% (w/w). Pencampuran kalsium pirofosfat dilakukan menggunakan High Energy Milling (HEM) dengan Ball Powder Ratio (BPR) sebesar 5:1 selama 30 menit. Campuran selanjutnya dipanaskan pada temperatur 1000 selama 60 menit. Hasil karakterisasi menggunakan XRD menunjukan bahwa perlakuan pemanasan dapat mendekomposisi kalsium pirofosfat dan terbentuknya CaZrO3. Pemanasan juga menyebabkan ukuran partikel semakin besar. Hasil SEM menunjukkan ukuran mikrostruktur CPP TA yang semula 590±43nm menjadi CPP TAZ5 1,212±268µm dan CPP TAZ10 1,324±384µm. Sedangkan untuk CPP TB yang semula 455±32nm menjadi CPP TBZ5 1,112±546µm dan CPP TBZ10 1,123±392µm. Kata kunci: Kalsium Pirofospat, Zirkonia, High Energy Milling
Synthesis of Polystyrene Fiber Membranes Prepared by Electrospinning: Effect of AgNO3 on the Microstructure Budi, Hanifah Setyaning; Zulfi, Akmal; Setyaningsih, Lia Dwi; Fahroji, Muhammad; Amalia, Ratih; Angel, Julia; Arrosyid, Bagas Haqi; Handika, Gugus; Saputro, Kurniawan Eko; Noviyanto, Alfian; Rezeki, Yulianto Agung
JKPK (Jurnal Kimia dan Pendidikan Kimia) Vol 9, No 1 (2024): JKPK (Jurnal Kimia dan Pendidikan Kimia)
Publisher : Program Studi Pendidikan Kimia FKIP Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/jkpk.v9i1.84601

Abstract

Polystyrene (PS) is commonly employed in insulation, packaging, filters, and medical equipment, with recent studies exploring its potential in fiber membrane production. The electrospinning technique is discussed to synthesize PS fiber membranes with high porosity and controllable diameter. Additionally, incorporating silver nitrate into PS composite fibers is explored for enhanced functionalities such as catalytic activity, high electrical conductivity, and antibacterial activity. However, PS composite fiber membranes with silver nitrate (AgNO3) metal variations are rarely observed. This research aims to modify the microstructure of PS fiber membranes produced using electrospinning by adding silver nitrate (AgNO3) with varying concentrations. PS-Ag fiber membranes are produced using N,N-dimethylformamide (DMF) solvent, which serves as a solvent and a reducing agent for Ag. The results show that the effect of Ag affected the diameter of the PS-Ag fiber membrane, with an average diameter of around 3.67 - 6.93 micrometers. Degradation occurred in these samples at a strong broadening peak near ~1300 cm-1 until ~1600 cm-1 from the Raman results. The FTIR results show that the wavelength of ~3500 cm-1 indicated the presence of OH. The presence of OH indicates that the PS-Ag fiber membrane has the potential for water filtration application
Studi kelayakan ekonomi budidaya udang Litopenaeus vannamei: investasi nanobubble dalam meningkatkan produktivitas hasil panen Mauladani, Syifa; Rahmawati, Asri Ifani; Absirin, Muhammad Fahrurrozi; Saputra, Rizki Nugraha; Pratama, Aprian Fajar; Hidayatullah, Arief; Dwiarto, Agus; Syarif, Ahmad; Junaedi, Hardi; Cahyadi, Dedi; Saputra, Henry Kasman Hadi; Prabowo, Wendy Tri; Kartamiharja, Ujang Komarudin Asdani; Noviyanto, Alfian; Rochman, Nurul Taufiqu
Jurnal Akuakultur Indonesia Vol. 19 No. 1 (2020): Jurnal Akuakultur Indonesia
Publisher : Indonesian Society of Scientific Aquaculture (ISSA)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (172.468 KB) | DOI: 10.19027/jai.19.1.30-38

Abstract

Tujuan dari penelitian ini adalah untuk menentukan kelayakan ekonomi usaha budidaya udang Litopenaeus vannamei dengan padat tebar 400 ekor/m2 selama 56 hari. Penelitian ini dilakukan pada kolam HDPE berukuran 800 m2 dengan menggunakan nanobubble dan non-nanobubble. Tingkat sintasan udang dan total panen pada kolam nanobubble berturut-turut meningkat mencapai 92% dan 2.255 kg. Parameter ekonomi yang dihitung terdiri dari Net Present Value (NPV), Internal Rate of Return (IRR), Payback Period (PP), Break Even Point (BEP), Benefit Cost Ratio (B/C Ratio), dan Sensitivity Analysis (SA). Biaya investasi total yang dibutuhkan untuk budidaya ini yaitu Rp 182.887.700. Pendapatan per siklus diestimasi mencapai Rp 157.850.000 dengan harga jual Rp 70.000 per kg udang. PP diestimasi setelah 4 siklus dengan NPV Rp 172.329.247 diproyeksikan setelah 10 siklus. Nilai IRR diestimasi sebesar 18% dan BEP diraih setelah produksi udang mencapai 7.058 kg. Rasio B/C diestimasi sebesar 1,26 dan SA menunjukkan bahwa produktivitas merupakan parameter yang paling berpengaruh dalam analisis ini. Berdasarkan hasil studi, budidaya udang menggunakan nanobubble layak diberi investasi.
Pengaruh Variasi Densitas Resin PVC terhadap Koefisien Gesek dan Mikrostruktur Komposit Kampas Rem Berbasis Serat Sabut Kelapa dan Serbuk Arang Pandriana, Aap; Alva, Sagir; Noviyanto, Alfian; Kurniawan, Kurniawan
Jurnal Rekayasa Energi dan Mekanika Vol 5, No 1 (2025): JREM
Publisher : Institut Teknologi Nasional, Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26760/JREM.v5i1.50

Abstract

Penelitian ini bertujuan mengembangkan kampas rem ramah lingkungan berbahan komposit dengan menggunakan serat sabut kelapa sebagai penguat, serbuk arang batok kelapa sebagai pengisi, dan resin polivinil klorida (PVC) sebagai matriks. Proses pembuatan komposit dilakukan melalui metode hot press pada suhu 180 °C dan tekanan 7 MPa. Variasi resin PVC diperoleh dari perbedaan rasio pelarut cyclohexanone terhadap serbuk PVC, yaitu G01 (1,036 g/ml), G02 (1,069 g/ml), dan G03 (1,136 g/ml). Pengujian yang dilakukan meliputi pengukuran massa jenis, koefisien gesek, serta pengamatan struktur mikro menggunakan mikroskop optik. Hasil menunjukkan bahwa meningkatnya densitas resin sebanding dengan peningkatan massa jenis dan nilai koefisien gesek komposit. Spesimen G03 dengan densitas resin tertinggi menghasilkan nilai koefisien gesek tertinggi, yaitu 0,19. Hal ini menunjukkan bahwa kekuatan ikatan antar material semakin baik seiring peningkatan kandungan resin. Pengamatan struktur mikro memperlihatkan bahwa resin PVC lebih merata dan menyelimuti serat dengan lebih baik pada spesimen G03, yang mengindikasikan distribusi material yang lebih homogen dan ikatan antar fase yang lebih kuat. Hasil pengujian menunjukkan bahwa koefisien gesek meningkat seiring dengan peningkatan kandungan resin dan spesimen komposit G03 masuk dalam standar SAE J661-1997. (0,14–0,27), kondisi ini diduga disebabkan oleh pengujian yang dilakukan pada temperatur rendah. Secara keseluruhan, komposit ini memiliki potensi untuk digunakan sebagai kampas rem non-asbes yang aman, ringan, dan memiliki sifat mekanik serta mikrostruktur yang mendukung performa pengereman yang baik.
Unraveling the Density and Hardness of Sintered Hydroxyapatite: A Conclusive Comparison of Laboratory-Synthesized Versus Commercial Variants Ramdhani, Rizal Fauzuddin Noor; Arrosyid, Bagas Haqi; Noviyanto, Alfian
Jurnal Kimia Sains dan Aplikasi Vol 28, No 3 (2025): Volume 28 Issue 3 Year 2025
Publisher : Chemistry Department, Faculty of Sciences and Mathematics, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jksa.28.3.130-137

Abstract

Hydroxyapatite (HA) is a bioceramic widely utilized in the medical field as a substitute for bone and dental applications. The mechanical properties of HA are influenced by its microstructure, which varies based on the source of the material, whether it is commercially acquired or laboratory-synthesized. This study aims to investigate and compare the properties of commercially available HA with those of laboratory-synthesized HA, as well as their mixtures, focusing on density and hardness. To conduct this investigation, both laboratory-synthesized and commercial HA were sintered at temperatures of 800°C, 900°C, 1000°C, and 1100°C for a duration of two hours. Additionally, various mixtures of the two sources of HA were prepared in weight percent ratios of 0:100, 30:70, 50:50, 70:30, and 100:0 using a planetary ball mill, also for two hours. The density of sintered HA was determined using Archimedes’ principle, while its hardness was evaluated using a Vickers hardness tester. The findings revealed that laboratory-synthesized HA sintered at 1100°C exhibited the highest density and hardness, measuring 3.15 g/cm3 and 488.9 MPa, respectively. This superior performance can be attributed to the smaller particle size of the laboratory-synthesized HA, which enhances densification. The dense structure of the laboratory-synthesized HA results in reduced porosity and smaller grain sizes, as evidenced by scanning electron microscopy images. In contrast, the commercial HA achieved a density of only 3.00 g/cm3 at the same sintering temperature of 1100°C, attributable to poorer densification and a resultant porous microstructure. Notably, the mixture of commercial and laboratory-synthesized HA at a ratio of 30:70 demonstrated properties closely aligned with those of pure laboratory-synthesized HA, achieving a density of 3.14 g/cm3 and a hardness of 477.3 MPa. These results underscore the importance of source material and processing conditions in determining the mechanical properties of hydroxyapatite.